Gametogenesis is the process by which germ cells undergo meiosis to form gametes. Spermatogonia and oogonia are the germ cells that develop into sperm or eggs. Meiosis involves two divisions that reduce the number of chromosomes by half to form haploid gametes. In males, meiosis produces four sperm cells, while in females it produces one egg and three polar bodies. The timing of meiosis differs between males and females. In males, spermatogenesis occurs continuously from puberty, while in females the first meiotic division starts before birth but is completed just before ovulation. Eggs are protected by elaborate envelopes that develop after fertilization to safeguard the developing embryo.
Gametogenesis is the process of forming gametes (eggs and sperm) from gonads through meiosis. In males, spermatogenesis occurs in the testes through spermatocytogenesis, meiosis I and II, and spermiogenesis. In females, oogenesis occurs in the ovaries through follicular development, ovulation, and the luteal phase. Infertility can result from problems with gametogenesis like inflammation of the testes or failure of the ovaries to ovulate, as well as issues with the fallopian tubes, cervix, or uterus.
Spermatogenesis and oogenesis both use meiosis to produce gametes. Spermatogenesis occurs in the testes and results in 4 haploid sperm from one diploid germ cell. Oogenesis occurs in the ovaries and results in one haploid egg and 3 polar bodies from the original diploid oocyte. Both processes arrest at different stages of meiosis until fertilization.
This document discusses gametogenesis and fertilization in humans. It describes the processes of spermatogenesis in males, where spermatogonia undergo meiosis to form spermatids over 64 days, and oogenesis in females. Fertilization occurs when a sperm and egg unite in the uterine tubes, restoring the diploid chromosome number and determining the embryo's sex. The result can be a single embryo, or monozygotic or dizygotic twins in rare cases of splitting or separate eggs being fertilized.
The document summarizes the male and female reproductive systems in humans. It describes the key organs involved in sexual reproduction, including the ovaries and testes where gametes are produced, as well as the organs involved in transport and development of eggs and sperm. It also provides details on gametogenesis, the process of forming eggs and sperm, including spermatogenesis in the testes and oogenesis in the ovaries.
Gametogenesis is the process of developing mature gametes (eggs and sperm) through meiosis. Oogenesis involves the development of a primary oocyte into a secondary oocyte over many years in females. Spermatogenesis is the process where spermatogonia develop into spermatozoa in males. Fertilization occurs when a sperm penetrates an egg in the fallopian tube, and their genetic material combines to form a zygote, beginning the process of embryogenesis.
Oogenesis is the process by which oocytes are produced from primordial germ cells in females. It involves mitosis and meiosis. Primordial germ cells undergo mitosis to form primary oocytes, which then enter meiosis. During meiosis, primary oocytes become haploid secondary oocytes or polar bodies which later dissolve. Secondary oocytes may further divide into mature eggs or more polar bodies. Thus, oogenesis involves cell division and growth to form mature eggs for reproduction in females.
these slides are about the process of gametogenesis and fertilization as my previous slides its also reviewed by more than two books. hope you'll get what had u been looking for - thankyou
Spermatogenesis is the process by which sperm cells are produced in the testes in males. It involves the transformation of spermatogonia into mature sperm through two stages: spermatocytogenesis where primordial germ cells develop into spermatids, and spermiogenesis where spermatids are transformed into mature sperm. In humans, it takes approximately 74 days to complete and produces around 300 million sperm cells daily. Oogenesis is the similar process that occurs in females within the ovaries to produce eggs.
Gametogenesis is the process of forming gametes (eggs and sperm) from gonads through meiosis. In males, spermatogenesis occurs in the testes through spermatocytogenesis, meiosis I and II, and spermiogenesis. In females, oogenesis occurs in the ovaries through follicular development, ovulation, and the luteal phase. Infertility can result from problems with gametogenesis like inflammation of the testes or failure of the ovaries to ovulate, as well as issues with the fallopian tubes, cervix, or uterus.
Spermatogenesis and oogenesis both use meiosis to produce gametes. Spermatogenesis occurs in the testes and results in 4 haploid sperm from one diploid germ cell. Oogenesis occurs in the ovaries and results in one haploid egg and 3 polar bodies from the original diploid oocyte. Both processes arrest at different stages of meiosis until fertilization.
This document discusses gametogenesis and fertilization in humans. It describes the processes of spermatogenesis in males, where spermatogonia undergo meiosis to form spermatids over 64 days, and oogenesis in females. Fertilization occurs when a sperm and egg unite in the uterine tubes, restoring the diploid chromosome number and determining the embryo's sex. The result can be a single embryo, or monozygotic or dizygotic twins in rare cases of splitting or separate eggs being fertilized.
The document summarizes the male and female reproductive systems in humans. It describes the key organs involved in sexual reproduction, including the ovaries and testes where gametes are produced, as well as the organs involved in transport and development of eggs and sperm. It also provides details on gametogenesis, the process of forming eggs and sperm, including spermatogenesis in the testes and oogenesis in the ovaries.
Gametogenesis is the process of developing mature gametes (eggs and sperm) through meiosis. Oogenesis involves the development of a primary oocyte into a secondary oocyte over many years in females. Spermatogenesis is the process where spermatogonia develop into spermatozoa in males. Fertilization occurs when a sperm penetrates an egg in the fallopian tube, and their genetic material combines to form a zygote, beginning the process of embryogenesis.
Oogenesis is the process by which oocytes are produced from primordial germ cells in females. It involves mitosis and meiosis. Primordial germ cells undergo mitosis to form primary oocytes, which then enter meiosis. During meiosis, primary oocytes become haploid secondary oocytes or polar bodies which later dissolve. Secondary oocytes may further divide into mature eggs or more polar bodies. Thus, oogenesis involves cell division and growth to form mature eggs for reproduction in females.
these slides are about the process of gametogenesis and fertilization as my previous slides its also reviewed by more than two books. hope you'll get what had u been looking for - thankyou
Spermatogenesis is the process by which sperm cells are produced in the testes in males. It involves the transformation of spermatogonia into mature sperm through two stages: spermatocytogenesis where primordial germ cells develop into spermatids, and spermiogenesis where spermatids are transformed into mature sperm. In humans, it takes approximately 74 days to complete and produces around 300 million sperm cells daily. Oogenesis is the similar process that occurs in females within the ovaries to produce eggs.
The document describes several key processes in human development:
1. Gamete production and spermatogenesis/oogenesis which involve the formation of sperm and eggs through meiosis in the gonads.
2. Fertilization, which requires the sperm penetrating the egg's jelly coat and plasma membrane fusing with the egg's plasma membrane.
3. Cleavage, where the zygote rapidly divides through mitosis to form a morula then blastula.
4. Gastrulation creates the three germ layers and primitive streak that patterns the embryo.
5. Neurulation forms the neural tube which later becomes the brain and spinal cord through primary then secondary neurulation.
Spermatogenesis is the process by which sperm cells develop from stem cells in the seminiferous tubules of the testes. It begins with the mitotic division of spermatogonial stem cells into primary spermatocytes, which then undergo meiosis to form haploid spermatids. The spermatids develop tails and mature into spermatozoa through spermiogenesis. Sertoli cells support this process by maintaining the environment, secreting substances, and protecting the developing cells. Spermatogenesis is regulated by hormones like testosterone and FSH and sensitive to fluctuations in temperature.
Oogenesis is the process by which primary oocytes develop into mature eggs. It begins during fetal development with the creation of oogonia, which undergo mitosis to form millions of primary oocytes. After birth, the primary oocytes enter a growth phase where they increase in size within follicles in the ovaries. At puberty, some follicles undergo maturation where the oocytes resume and complete meiosis, resulting in the formation of secondary oocytes and polar bodies. Upon ovulation, a mature follicle ruptures and releases a secondary oocyte into the fallopian tube.
The document provides an overview of embryology, discussing key phases of human development from fertilization through birth. It describes gamete formation (spermatogenesis and oogenesis), the stages of pre-embryonic development (zygote, morula, blastocyst), and the prenatal and postnatal developmental periods. The structure and origin of male and female gametes are also summarized.
Oogenesis begins in the female embryo with primordial germ cells differentiating into oogonia that divide to form millions of germ cells. During gestation most oogonia die off while the remaining enter the first meiotic division to become primary oocytes that remain in the ovaries in a non-dividing state. At puberty, a drop in estrogen signals the release of hormones that stimulate around 20 primary oocytes to mature through meiosis I to become secondary oocytes with one being ovulated from its follicle while the others are reabsorbed. If the ovulated oocyte is fertilized, the empty follicle forms the corpus luteum which produces hormones to support pregnancy.
- A zygote is formed when a sperm fertilizes an ovum in the fallopian tube. It then undergoes cleavage, dividing rapidly through mitosis as it moves towards the uterus.
- By day 4 it has developed into a morula, a solid ball of 16 cells. It then forms a blastocyst with an inner cell mass and outer trophoblast layer.
- The blastocyst implants in the uterine wall around day 6, and the zona pellucida disintegrates allowing it to hatch out of its protective covering.
Fertilization is the process where a sperm unites with an ovum. It typically occurs in the ampullary part of the uterine tube. The sperm undergoes changes including capacitation, the acrosomal reaction, and fusion of the nuclei. This results in the formation of a zygote with a full diploid chromosome number. The zygote then undergoes cleavage as it is transported through the uterine tube, dividing into a 2-cell, 4-cell, 8-cell stage and so on over 3 days as it forms a morula.
Spermatogenesis is the process by which sperm are produced in the seminiferous tubules over 70-75 days. It is a continuous process throughout a man's lifetime where spermatogonia develop into mature sperm cells. The document then discusses maturation arrest, Sertoli cell-only syndrome, and Klinefelter syndrome as conditions that can affect spermatogenesis. Spermiogenesis is also mentioned, which is the differentiation of spermatids into functional spermatozoa through nuclear shaping, flagellum formation, acrosome formation, and shedding of the residual body.
In testis, the immature male germ cell (spermatogonia ) produce sperms by spermatogenesis
The spermatogonia ( sing. Spermatogonium ) present on the inside of seminiferous tubules multiply by mitotic division and increase in numbers
Each spermatogonium is diploid and contains 46 chromosomes
Some of the spermatogonia called primary spermatocytes periodically undergo meiosis.A primary spermatocyte completes the first meiotic division (reduction division) leading to formation of two equal, haploid cells called secondary spermatocyte, which have only 23 chromosomes
The secondary spermatocyte undergo the second meiotic division to produce four equal, haploid spermatids
1. Cleavage is the early mitotic divisions of the zygote that forms a hollow, multicellular blastocyst. The zygote undergoes a series of cleavages, reducing cell size and increasing metabolic rate.
2. Blastulation is the formation of the blastocyst from the morula. The outer cells of the morula form the trophoblast, which absorbs uterine fluid to form a blastocyst cavity. The inner cells remain as the embryoblast.
3. Implantation occurs when the blastocyst attaches to the uterine wall between 7-10 days after fertilization. The trophoblast cells invade the endometrium and secrete enzymes, forming
Oogenesis is the process by which ova or egg cells are formed in the ovaries. It involves three main phases: 1) the multiplication phase where primordial germ cells undergo mitosis to form oogonia, 2) the growth phase where the oocytes increase in size through protein and RNA synthesis, and 3) the maturation phase where the oocytes undergo the first meiotic division to form secondary oocytes, followed by ovulation and the second meiotic division after fertilization to form the ovum. Key events include cytoplasmic growth through organelle proliferation and yolk deposition, formation of the follicle surrounding the oocyte, and reduction of the chromosome number through meiosis.
The menstrual cycle involves changes in the ovaries and uterus driven by hormones. It begins at menarche and typically repeats every 21-35 days until menopause. Each cycle can be divided into the follicular phase, ovulation, and luteal phase. During the follicular phase, FSH stimulates follicle growth and estrogen production. Ovulation occurs when an LH surge causes an egg to be released. In the luteal phase, the corpus luteum produces progesterone to thicken the uterine lining if implantation occurs. If not, progesterone levels drop and menstruation begins, restarting the cycle.
There are three phases of spermatogenesis: spermatocytogenesis, meiosis, and spermiogenesis. Spermatocytogenesis involves the mitotic division of spermatogonia. Meiosis results in haploid cells called spermatids from diploid spermatogonia. During spermiogenesis, spermatids undergo morphological changes to form spermatozoa. Sertoli cells support this process through signaling molecules, forming a blood-testis barrier, and phagocytosing residual bodies. Testosterone and FSH regulate spermatogenesis through effects on Sertoli and germ cells.
1) Spermatogenesis and oogenesis both involve meiosis to produce haploid gametes from diploid germ cells.
2) In spermatogenesis, spermatogonia undergo mitosis and differentiate into spermatocytes, then spermatids through meiosis. Spermiogenesis transforms spermatids into mature sperm.
3) In oogenesis, oogonia become primary oocytes that arrest in prophase I until after puberty. A few complete meiosis I and II if fertilized, becoming ovulated ova.
The document discusses the process of fertilization and early embryonic development. It begins with an overview of the events of fertilization, including sperm penetration through the corona radiata and zona pellucida, the cortical reaction, and fusion of the male and female pronuclei. It then describes the early cleavage stages, where the zygote undergoes rapid cell divisions without growth to form a morula, followed by blastulation and implantation in the uterus. Key events include capacitation of sperm, the acrosomal reaction, prevention of polyspermy, and formation of the blastocyst from the inner cell mass and trophoblast.
This document summarizes the anatomy and fertilization process of human sperm and eggs. It describes that sperm are much smaller than eggs. Upon entering the fallopian tubes, sperm undergo capacitation over 5-7 hours to become able to fertilize eggs. Fertilization involves the sperm binding and fusing with the egg, preventing multiple sperm from entering through the zona reaction. This results in a zygote with a combined 46 chromosomes from the male and female pronuclei.
Implantation begins around 6 days after fertilization and is usually complete by 11-12 days. The blastocyst implants in the endometrium through enzymes produced by the trophoblast. Trophoblast cells penetrate the endometrium and develop into two layers. By 10 days the conceptus is fully embedded and a blood supply is established. The formation of the bilaminar embryonic disc and primary chorionic villi occurs around 13 days. Ectopic pregnancies can occur if implantation is outside the uterus, most commonly in the fallopian tubes.
The female reproductive cycle, also known as the menstrual cycle, occurs regularly in fertile women and involves changes in the hypothalamus, pituitary gland, ovaries, and endometrium. The average cycle is 28 days and includes the menstrual, proliferative, ovulatory, and secretory phases. During the cycle, levels of hormones like estrogen and progesterone rise and fall, regulating the thickening and shedding of the uterine lining. If pregnancy does not occur, menstruation begins and the cycle repeats.
The document summarizes key events that occur during the first two weeks of human development. During the first week, fertilization occurs along with cleavage and blastocyst formation. The blastocyst undergoes implantation in the uterus. In the second week, implantation is completed and the bilaminar embryonic disc forms. Extraembryonic structures like the amniotic cavity and yolk sac also develop in the second week.
1. Spermatogenesis (Spermatocytogenesis, Spermiogenesis, Spermiation, Shape and function of cells inside the Testis, Semen and sperm structure, Sperm journey after synthesis to outside)
1) El documento describe los procesos de espermatogénesis y espermiogénesis en el sexo masculino, y de ovogénesis en el sexo femenino, incluyendo la formación y maduración de los gametos.
2) También resume las etapas de la fertilización, incluyendo la penetración del espermatozoide a través de la zona pelúcida, la reacción del acrosoma, y la fusión de los pronúcleos masculino y femenino.
3) Finalmente, explica las primeras etapas del desarrol
El documento describe dos métodos de reproducción asexual en animales: la fragmentación y la gemación. La fragmentación ocurre cuando un individuo se divide en dos o más trozos, cada uno de los cuales puede reconstruir un organismo completo. En la gemación, un nuevo organismo emerge como una nueva yema o gema que puede desprenderse para convertirse en un nuevo individuo o permanecer unida a la célula madre para formar una colonia. La levadura y las hidras son ejemplos de organismos que se reproducen por gemación.
The document describes several key processes in human development:
1. Gamete production and spermatogenesis/oogenesis which involve the formation of sperm and eggs through meiosis in the gonads.
2. Fertilization, which requires the sperm penetrating the egg's jelly coat and plasma membrane fusing with the egg's plasma membrane.
3. Cleavage, where the zygote rapidly divides through mitosis to form a morula then blastula.
4. Gastrulation creates the three germ layers and primitive streak that patterns the embryo.
5. Neurulation forms the neural tube which later becomes the brain and spinal cord through primary then secondary neurulation.
Spermatogenesis is the process by which sperm cells develop from stem cells in the seminiferous tubules of the testes. It begins with the mitotic division of spermatogonial stem cells into primary spermatocytes, which then undergo meiosis to form haploid spermatids. The spermatids develop tails and mature into spermatozoa through spermiogenesis. Sertoli cells support this process by maintaining the environment, secreting substances, and protecting the developing cells. Spermatogenesis is regulated by hormones like testosterone and FSH and sensitive to fluctuations in temperature.
Oogenesis is the process by which primary oocytes develop into mature eggs. It begins during fetal development with the creation of oogonia, which undergo mitosis to form millions of primary oocytes. After birth, the primary oocytes enter a growth phase where they increase in size within follicles in the ovaries. At puberty, some follicles undergo maturation where the oocytes resume and complete meiosis, resulting in the formation of secondary oocytes and polar bodies. Upon ovulation, a mature follicle ruptures and releases a secondary oocyte into the fallopian tube.
The document provides an overview of embryology, discussing key phases of human development from fertilization through birth. It describes gamete formation (spermatogenesis and oogenesis), the stages of pre-embryonic development (zygote, morula, blastocyst), and the prenatal and postnatal developmental periods. The structure and origin of male and female gametes are also summarized.
Oogenesis begins in the female embryo with primordial germ cells differentiating into oogonia that divide to form millions of germ cells. During gestation most oogonia die off while the remaining enter the first meiotic division to become primary oocytes that remain in the ovaries in a non-dividing state. At puberty, a drop in estrogen signals the release of hormones that stimulate around 20 primary oocytes to mature through meiosis I to become secondary oocytes with one being ovulated from its follicle while the others are reabsorbed. If the ovulated oocyte is fertilized, the empty follicle forms the corpus luteum which produces hormones to support pregnancy.
- A zygote is formed when a sperm fertilizes an ovum in the fallopian tube. It then undergoes cleavage, dividing rapidly through mitosis as it moves towards the uterus.
- By day 4 it has developed into a morula, a solid ball of 16 cells. It then forms a blastocyst with an inner cell mass and outer trophoblast layer.
- The blastocyst implants in the uterine wall around day 6, and the zona pellucida disintegrates allowing it to hatch out of its protective covering.
Fertilization is the process where a sperm unites with an ovum. It typically occurs in the ampullary part of the uterine tube. The sperm undergoes changes including capacitation, the acrosomal reaction, and fusion of the nuclei. This results in the formation of a zygote with a full diploid chromosome number. The zygote then undergoes cleavage as it is transported through the uterine tube, dividing into a 2-cell, 4-cell, 8-cell stage and so on over 3 days as it forms a morula.
Spermatogenesis is the process by which sperm are produced in the seminiferous tubules over 70-75 days. It is a continuous process throughout a man's lifetime where spermatogonia develop into mature sperm cells. The document then discusses maturation arrest, Sertoli cell-only syndrome, and Klinefelter syndrome as conditions that can affect spermatogenesis. Spermiogenesis is also mentioned, which is the differentiation of spermatids into functional spermatozoa through nuclear shaping, flagellum formation, acrosome formation, and shedding of the residual body.
In testis, the immature male germ cell (spermatogonia ) produce sperms by spermatogenesis
The spermatogonia ( sing. Spermatogonium ) present on the inside of seminiferous tubules multiply by mitotic division and increase in numbers
Each spermatogonium is diploid and contains 46 chromosomes
Some of the spermatogonia called primary spermatocytes periodically undergo meiosis.A primary spermatocyte completes the first meiotic division (reduction division) leading to formation of two equal, haploid cells called secondary spermatocyte, which have only 23 chromosomes
The secondary spermatocyte undergo the second meiotic division to produce four equal, haploid spermatids
1. Cleavage is the early mitotic divisions of the zygote that forms a hollow, multicellular blastocyst. The zygote undergoes a series of cleavages, reducing cell size and increasing metabolic rate.
2. Blastulation is the formation of the blastocyst from the morula. The outer cells of the morula form the trophoblast, which absorbs uterine fluid to form a blastocyst cavity. The inner cells remain as the embryoblast.
3. Implantation occurs when the blastocyst attaches to the uterine wall between 7-10 days after fertilization. The trophoblast cells invade the endometrium and secrete enzymes, forming
Oogenesis is the process by which ova or egg cells are formed in the ovaries. It involves three main phases: 1) the multiplication phase where primordial germ cells undergo mitosis to form oogonia, 2) the growth phase where the oocytes increase in size through protein and RNA synthesis, and 3) the maturation phase where the oocytes undergo the first meiotic division to form secondary oocytes, followed by ovulation and the second meiotic division after fertilization to form the ovum. Key events include cytoplasmic growth through organelle proliferation and yolk deposition, formation of the follicle surrounding the oocyte, and reduction of the chromosome number through meiosis.
The menstrual cycle involves changes in the ovaries and uterus driven by hormones. It begins at menarche and typically repeats every 21-35 days until menopause. Each cycle can be divided into the follicular phase, ovulation, and luteal phase. During the follicular phase, FSH stimulates follicle growth and estrogen production. Ovulation occurs when an LH surge causes an egg to be released. In the luteal phase, the corpus luteum produces progesterone to thicken the uterine lining if implantation occurs. If not, progesterone levels drop and menstruation begins, restarting the cycle.
There are three phases of spermatogenesis: spermatocytogenesis, meiosis, and spermiogenesis. Spermatocytogenesis involves the mitotic division of spermatogonia. Meiosis results in haploid cells called spermatids from diploid spermatogonia. During spermiogenesis, spermatids undergo morphological changes to form spermatozoa. Sertoli cells support this process through signaling molecules, forming a blood-testis barrier, and phagocytosing residual bodies. Testosterone and FSH regulate spermatogenesis through effects on Sertoli and germ cells.
1) Spermatogenesis and oogenesis both involve meiosis to produce haploid gametes from diploid germ cells.
2) In spermatogenesis, spermatogonia undergo mitosis and differentiate into spermatocytes, then spermatids through meiosis. Spermiogenesis transforms spermatids into mature sperm.
3) In oogenesis, oogonia become primary oocytes that arrest in prophase I until after puberty. A few complete meiosis I and II if fertilized, becoming ovulated ova.
The document discusses the process of fertilization and early embryonic development. It begins with an overview of the events of fertilization, including sperm penetration through the corona radiata and zona pellucida, the cortical reaction, and fusion of the male and female pronuclei. It then describes the early cleavage stages, where the zygote undergoes rapid cell divisions without growth to form a morula, followed by blastulation and implantation in the uterus. Key events include capacitation of sperm, the acrosomal reaction, prevention of polyspermy, and formation of the blastocyst from the inner cell mass and trophoblast.
This document summarizes the anatomy and fertilization process of human sperm and eggs. It describes that sperm are much smaller than eggs. Upon entering the fallopian tubes, sperm undergo capacitation over 5-7 hours to become able to fertilize eggs. Fertilization involves the sperm binding and fusing with the egg, preventing multiple sperm from entering through the zona reaction. This results in a zygote with a combined 46 chromosomes from the male and female pronuclei.
Implantation begins around 6 days after fertilization and is usually complete by 11-12 days. The blastocyst implants in the endometrium through enzymes produced by the trophoblast. Trophoblast cells penetrate the endometrium and develop into two layers. By 10 days the conceptus is fully embedded and a blood supply is established. The formation of the bilaminar embryonic disc and primary chorionic villi occurs around 13 days. Ectopic pregnancies can occur if implantation is outside the uterus, most commonly in the fallopian tubes.
The female reproductive cycle, also known as the menstrual cycle, occurs regularly in fertile women and involves changes in the hypothalamus, pituitary gland, ovaries, and endometrium. The average cycle is 28 days and includes the menstrual, proliferative, ovulatory, and secretory phases. During the cycle, levels of hormones like estrogen and progesterone rise and fall, regulating the thickening and shedding of the uterine lining. If pregnancy does not occur, menstruation begins and the cycle repeats.
The document summarizes key events that occur during the first two weeks of human development. During the first week, fertilization occurs along with cleavage and blastocyst formation. The blastocyst undergoes implantation in the uterus. In the second week, implantation is completed and the bilaminar embryonic disc forms. Extraembryonic structures like the amniotic cavity and yolk sac also develop in the second week.
1. Spermatogenesis (Spermatocytogenesis, Spermiogenesis, Spermiation, Shape and function of cells inside the Testis, Semen and sperm structure, Sperm journey after synthesis to outside)
1) El documento describe los procesos de espermatogénesis y espermiogénesis en el sexo masculino, y de ovogénesis en el sexo femenino, incluyendo la formación y maduración de los gametos.
2) También resume las etapas de la fertilización, incluyendo la penetración del espermatozoide a través de la zona pelúcida, la reacción del acrosoma, y la fusión de los pronúcleos masculino y femenino.
3) Finalmente, explica las primeras etapas del desarrol
El documento describe dos métodos de reproducción asexual en animales: la fragmentación y la gemación. La fragmentación ocurre cuando un individuo se divide en dos o más trozos, cada uno de los cuales puede reconstruir un organismo completo. En la gemación, un nuevo organismo emerge como una nueva yema o gema que puede desprenderse para convertirse en un nuevo individuo o permanecer unida a la célula madre para formar una colonia. La levadura y las hidras son ejemplos de organismos que se reproducen por gemación.
Presentacion inicial sobre el desarrollo embrionario que contempla la gametogénesis humana.
Más información y materiales en www.profesorjano.org y en www.profesorjano.com
Reproducción sexual y asexual en las plantaselimaria82
El documento describe los diferentes tipos de reproducción en plantas, incluyendo la reproducción sexual y asexual. La reproducción sexual implica la fusión de gametos masculinos y femeninos, manteniendo la diversidad genética. La reproducción asexual no requiere de la fusión de gametos y ocurre a través de mecanismos como la bipartición, gemación, fragmentación y esporulación. Las plantas con flores atraen polinizadores mediante claves visuales, olfativas y néctar para lograr la polinización cruzada.
El documento describe 7 métodos de reproducción asexual en plantas, incluyendo bulbos, tubérculos, rizomas, estolones, hojas, injertos, estacas y acodos. Cada método involucra la formación de nuevas plantas a partir de partes vegetativas como tallos subterráneos, ramas o hojas sin necesidad de semillas o flores.
Este documento describe diferentes tipos de reproducción en plantas y animales. Explica que la reproducción asexual ocurre a través de métodos como la gemación, escición y poliembrionía en animales, y mediante rizomas, tubérculos, bulbos y estolones en plantas. También define la reproducción asexual y sexual, y cómo la reproducción permite a las especies perpetuarse a través del tiempo.
Reproducción asexual en animales y plantasfranmuperez
El documento describe dos tipos de reproducción asexual en animales y plantas. En animales son la escisión o fragmentación y la gemación. En plantas son la reproducción vegetativa a través de estolones, bulbos y tubérculos, y la reproducción por esporas donde células llamadas esporas se dividen para formar nuevos individuos.
Presentación donde se muestra las características de la reproducción sexual en los animales: Tipos de fecundación, tipos de desarrollo embrionario y postembrionario, etc.
La reproducción en plantas puede ser sexual o asexual. La reproducción sexual implica la fusión de gametos masculinos y femeninos, formando una semilla que luego germina en una nueva planta. La reproducción asexual ocurre cuando una parte de la planta, como un tallo o rama, se separa y desarrolla de forma independiente en una nueva planta, sin la necesidad de gametos. Algunas formas comunes de reproducción asexual en plantas incluyen la multiplicación vegetativa a través de esquejes, estacas e injertos.
El documento describe los tipos de reproducción en plantas, incluyendo la reproducción asexual y sexual. La reproducción asexual produce nuevos individuos idénticos al original a través de métodos como estolones, tubérculos y esquejes. La reproducción sexual requiere gametos y produce descendientes similares pero genéticamente diversos. También describe los ciclos de vida de briofitas, helechos y espermatofitas.
Gametogenesis espermatogenesis y ovogenesisAnna Adams
Este documento define la gametogénesis como la formación de gametos mediante la meiosis a partir de células germinales. Explica que la gametogénesis incluye la espermatogénesis, la producción de espermatozoides en los testículos, y la ovogénesis, la producción de ovocitos en los ovarios. Ambos procesos involucran la división celular meiótica para reducir el número de cromosomas de las células germinales diploides a las células haploides de los gametos.
Este es un trabajo para estudiantes como para cualquier tipo de persona que se interese sobre este tema.
Este trabajo trata de la gametogénesis, que consiste en los dos procesos de la creación de gametos (ovogénesis y espermiogénesis).
Meiosis produces haploid gametes from diploid germ cells in both males and females. In males, spermatogonia undergo meiosis to form sperm throughout life after puberty. In females, oogonia undergo meiosis with the first division starting before birth, but the process is arrested until ovulation near menstruation. This allows a single egg and several polar bodies to form, retaining more cytoplasm for early embryo development. Genetic recombination during meiosis generates diversity among gametes.
Cell division occurs through mitosis or meiosis. Mitosis produces two identical daughter cells from one parent cell during growth and repair. Meiosis produces four haploid gametes from one diploid cell during gametogenesis. During meiosis, homologous chromosomes pair up and may exchange genetic material through crossing over, resulting in genetic diversity among gametes. The two divisions of meiosis and the independent assortment of chromosomes ensure each gamete has a unique combination of the parental chromosomes.
Meiosis is a type of cell division that produces haploid gametes from a diploid cell for sexual reproduction. It involves two divisions and results in four haploid cells. During meiosis, homologous chromosomes pair and may exchange genetic material through crossing over, and then separate, reducing the chromosome number. This and the independent assortment of chromosomes during gamete formation introduces genetic variation that is important for evolution.
cell division & physiology of cell division, types, binary fission, meiosis, mitosis, regulation of cell cycle, cell cycle checkpoints, what is cyclin-dependent kinases and its importance
Meiosis is a type of cell division that reduces the number of chromosomes by half to produce gametes like eggs and sperm. It involves two nuclear divisions called Meiosis I and Meiosis II. In Meiosis I, homologous chromosomes pair up and may exchange genetic material through crossing over. This results in the separation of homologous chromosomes into daughter cells. Meiosis II then separates the sister chromatids, resulting in four haploid daughter cells each with half the number of chromosomes of the original cell. This allows for genetic variation in offspring through independent assortment and fertilization.
This document provides an overview of sexual and asexual reproduction in plants and animals. It discusses the process of cell division through mitosis, which results in two daughter cells that are identical to the parent cell. The four phases of mitosis - prophase, metaphase, anaphase and telophase - are described in detail. The stages of interphase and how the cell prepares for division are also outlined. The roles of chromosomes, genes, and other cellular structures in heredity and cell division are explained.
Mitosis is cell division that produces two daughter cells identical to the parent cell. It occurs in somatic cells and involves the four phases of prophase, metaphase, anaphase and telophase. Meiosis is a type of cell division that produces gametes with half the number of chromosomes, and occurs in germ cells. Meiosis has two rounds of division, Meiosis I and Meiosis II, which separates homologous chromosomes and sister chromatids respectively to generate four haploid daughter cells from one diploid parent cell. Mitosis and meiosis are important for growth, tissue repair, sexual reproduction, and genetic variation.
Gametogenesis is the process by which haploid gametes are formed from diploid precursor cells. In oogenesis, primary oocytes undergo cell division and differentiation through the phases of multiplication, growth, and maturation to form a single mature ovum. In spermatogenesis, spermatogonia undergo cell division and differentiation through the phases of multiplication, growth, and maturation to form mature sperm. Both processes involve meiotic cell division to halve the number of chromosomes and produce haploid gametes.
Meiosis is a type of cell division that produces gametes, or sex cells, with half the normal number of chromosomes. It was discovered by Oscar Hertwig in 1876 while studying sea urchin eggs. Meiosis involves two cell divisions: Meiosis I and Meiosis II. In Meiosis I, homologous chromosomes separate and move to opposite sides of the cell. This reduces the chromosome number by half. Meiosis II then separates the sister chromatids, resulting in four haploid daughter cells. Meiosis introduces genetic variation through independent assortment and crossing over during prophase I. This ensures offspring receive a unique set of chromosomes from each parent.
The document discusses different types of cell division: binary fission, mitosis, and meiosis. Binary fission is how prokaryotic cells divide, splitting their single DNA strand to form two identical daughter cells. Mitosis and meiosis are forms of cell division in eukaryotes. Mitosis produces two identical daughter cells through the phases of interphase, prophase, metaphase, anaphase and telophase. Meiosis involves two cell divisions and results in four haploid cells with half the normal genetic material.
Infer the significance of cell division.
Differentiate a DNA molecule, a chromosome, and a chromatid.
Characterize the phases of the cell cycle and their control points.
Describe the major events associated with stages of mitosis.
Explain the process of cytokinesis.
Learning Objectives
Describe the role of apoptosis in the life cycle of a cell.
Relate cancer as a result of the malfunction of the cell during the cell cycle.
The document discusses the cell cycle, which involves growth, functioning, and division of cells. It has two main types of cell division - mitosis and meiosis. Mitosis produces two identical cells and is involved in growth and repair. Meiosis produces gametes through two divisions and involves genetic mixing through crossing over. Precise control mechanisms regulate the cell cycle, and errors can lead to genetic conditions.
The document discusses the processes of cell division through mitosis and meiosis. It explains that mitosis produces two identical daughter cells and occurs in somatic cells, while meiosis produces four haploid daughter cells and occurs in germ cells to create gametes. Both processes go through similar stages of prophase, metaphase, anaphase and telophase, but meiosis involves two cell divisions to separate homologous chromosomes and then sister chromatids, resulting in four daughter cells each with half the number of chromosomes. The key difference is that mitosis maintains genetic variation, while meiosis increases it through independent assortment and crossing over.
Cell reproduction occurs through mitosis and meiosis. Mitosis produces identical daughter cells and occurs in somatic cells for growth and repair. Meiosis reduces the chromosome number by half and produces gametes involved in sexual reproduction, where the union of male and female gametes leads to fertilization and the formation of a new individual with a mix of genetic material.
- Gametogenesis is the production of gametes (sex cells) via meiosis from germ cells. This involves the formation of haploid egg and sperm cells from diploid precursor cells.
- Eggs undergo a process called oogenesis to form female gametes (ova/eggs). Sperm undergo spermatogenesis to form male gametes. Both involve mitosis, growth, and meiotic maturation.
- Mature eggs contain stored nutrients, proteins, mRNA and other materials necessary to support early embryonic development before the embryo can feed itself. Eggs accumulate these materials during oogenesis.
Cells undergo mitosis or meiosis to divide. Mitosis produces two identical daughter cells from one parent cell during normal cell growth and repair. Meiosis produces four haploid gametes from one diploid cell for sexual reproduction. During meiosis, homologous chromosomes pair up and may exchange DNA segments through crossing over, introducing genetic variation into the gametes. The first meiotic division separates homologous chromosomes, while the second division separates sister chromatids to produce four unique haploid cells.
Meiosis is the process by which germ cells are produced with half the normal number of chromosomes. It involves two cell divisions that result in four haploid cells from one original diploid cell. This ensures genetic variation between parents and offspring and maintains chromosome number from one generation to the next. Errors during meiosis can result in gametes with an extra or missing chromosome, leading to disorders like Down syndrome, Klinefelter syndrome, and Turner syndrome.
Mitosis is the process of normal cell division where the parent cell divides into two daughter cells that are genetically identical to the parent cell. It involves several stages - prophase, metaphase, anaphase and telophase. During prophase, chromosomes condense and the nuclear envelope breaks down. In metaphase, chromosomes line up along the center of the cell. In anaphase, chromosomes separate and move to opposite poles. In telophase, the nuclear envelope reforms and cytokinesis occurs to separate the cell contents. Mitosis ensures genetic inheritance and growth and replacement of cells.
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Discover how MongoDB Atlas and vector search technology can revolutionize your application's search capabilities. This comprehensive presentation covers:
* What is Vector Search?
* Importance and benefits of vector search
* Practical use cases across various industries
* Step-by-step implementation guide
* Live demos with code snippets
* Enhancing LLM capabilities with vector search
* Best practices and optimization strategies
Perfect for developers, AI enthusiasts, and tech leaders. Learn how to leverage MongoDB Atlas to deliver highly relevant, context-aware search results, transforming your data retrieval process. Stay ahead in tech innovation and maximize the potential of your applications.
#MongoDB #VectorSearch #AI #SemanticSearch #TechInnovation #DataScience #LLM #MachineLearning #SearchTechnology
HCL Notes und Domino Lizenzkostenreduzierung in der Welt von DLAUpanagenda
Webinar Recording: https://www.panagenda.com/webinars/hcl-notes-und-domino-lizenzkostenreduzierung-in-der-welt-von-dlau/
DLAU und die Lizenzen nach dem CCB- und CCX-Modell sind für viele in der HCL-Community seit letztem Jahr ein heißes Thema. Als Notes- oder Domino-Kunde haben Sie vielleicht mit unerwartet hohen Benutzerzahlen und Lizenzgebühren zu kämpfen. Sie fragen sich vielleicht, wie diese neue Art der Lizenzierung funktioniert und welchen Nutzen sie Ihnen bringt. Vor allem wollen Sie sicherlich Ihr Budget einhalten und Kosten sparen, wo immer möglich. Das verstehen wir und wir möchten Ihnen dabei helfen!
Wir erklären Ihnen, wie Sie häufige Konfigurationsprobleme lösen können, die dazu führen können, dass mehr Benutzer gezählt werden als nötig, und wie Sie überflüssige oder ungenutzte Konten identifizieren und entfernen können, um Geld zu sparen. Es gibt auch einige Ansätze, die zu unnötigen Ausgaben führen können, z. B. wenn ein Personendokument anstelle eines Mail-Ins für geteilte Mailboxen verwendet wird. Wir zeigen Ihnen solche Fälle und deren Lösungen. Und natürlich erklären wir Ihnen das neue Lizenzmodell.
Nehmen Sie an diesem Webinar teil, bei dem HCL-Ambassador Marc Thomas und Gastredner Franz Walder Ihnen diese neue Welt näherbringen. Es vermittelt Ihnen die Tools und das Know-how, um den Überblick zu bewahren. Sie werden in der Lage sein, Ihre Kosten durch eine optimierte Domino-Konfiguration zu reduzieren und auch in Zukunft gering zu halten.
Diese Themen werden behandelt
- Reduzierung der Lizenzkosten durch Auffinden und Beheben von Fehlkonfigurationen und überflüssigen Konten
- Wie funktionieren CCB- und CCX-Lizenzen wirklich?
- Verstehen des DLAU-Tools und wie man es am besten nutzt
- Tipps für häufige Problembereiche, wie z. B. Team-Postfächer, Funktions-/Testbenutzer usw.
- Praxisbeispiele und Best Practices zum sofortigen Umsetzen
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Guest Speaker Segment with Hannah Barrington: Dive into the world of dynamic real estate marketing with Hannah, the Marketing Manager at Workspace Group. Hear firsthand how their team generates engaging descriptions for thousands of office units by integrating diverse data sources—from PDF floorplans to web pages—using FME transformers, like OpenAIVisionConnector and AnthropicVisionConnector. This use case will show you how GenAI can streamline content creation for marketing across the board.
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Monitoring and Managing Anomaly Detection on OpenShift
Overview
Dive into the world of anomaly detection on edge devices with our comprehensive hands-on tutorial. This SlideShare presentation will guide you through the entire process, from data collection and model training to edge deployment and real-time monitoring. Perfect for those looking to implement robust anomaly detection systems on resource-constrained IoT/edge devices.
Key Topics Covered
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- Understand the fundamentals of anomaly detection and its importance in identifying unusual behavior or failures in systems.
2. Understanding Edge (IoT)
- Learn about edge computing and IoT, and how they enable real-time data processing and decision-making at the source.
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12. Jupyter Notebooks with Code Examples
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Webinar Recording: https://www.panagenda.com/webinars/hcl-notes-and-domino-license-cost-reduction-in-the-world-of-dlau/
The introduction of DLAU and the CCB & CCX licensing model caused quite a stir in the HCL community. As a Notes and Domino customer, you may have faced challenges with unexpected user counts and license costs. You probably have questions on how this new licensing approach works and how to benefit from it. Most importantly, you likely have budget constraints and want to save money where possible. Don’t worry, we can help with all of this!
We’ll show you how to fix common misconfigurations that cause higher-than-expected user counts, and how to identify accounts which you can deactivate to save money. There are also frequent patterns that can cause unnecessary cost, like using a person document instead of a mail-in for shared mailboxes. We’ll provide examples and solutions for those as well. And naturally we’ll explain the new licensing model.
Join HCL Ambassador Marc Thomas in this webinar with a special guest appearance from Franz Walder. It will give you the tools and know-how to stay on top of what is going on with Domino licensing. You will be able lower your cost through an optimized configuration and keep it low going forward.
These topics will be covered
- Reducing license cost by finding and fixing misconfigurations and superfluous accounts
- How do CCB and CCX licenses really work?
- Understanding the DLAU tool and how to best utilize it
- Tips for common problem areas, like team mailboxes, functional/test users, etc
- Practical examples and best practices to implement right away
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Choosing the right website developer is crucial for your business. This article covers essential factors to consider, including experience, portfolio, technical skills, communication, pricing, reputation & reviews, cost and budget considerations and post-launch support. Make an informed decision to ensure your website meets your business goals.
Things to Consider When Choosing a Website Developer for your Website | FODUU
Gametogenesis ppt
1. GAMETOGENESIS
BY:
MARTIN, Ezra D.
PLES, Janina Grace C.
AAPD2G
2. Meiosis is the first step in gametogenesis: separation of homologous
chromosomes into haploid daughter cells
Spermatogonia and oogonia are the germ cells that will eventually develop into the
mature sperm or egg
Primary spermatocyte or oocyte: the first step in this development is the duplication
of homologous chromosomes to get ready for meiosis
Secondary spermatocyte or oocyte: the
first meiotic division separates the
homologous chromosomes from each
parent
Spermatids or eggs: the second meiotic
division separates the 2 chromatids and
creates 4 haploid cells
In males, this eventually produces 4
sperm cells by the process of
spermiogenesis. In females, it produces
1 egg and 3 polar bodies. This allows
the egg to retain more cytoplasm to
support early stages of development
3. Meiosis generates tremendous genetic diversity. How many different types of
gametes can be generated by an individual (male or female) with 23 different
chromosomes?
5. The timing of meiosis differs in females and males
In males, the spermatogonia enter meiosis and produce sperm from puberty until
death.The process of sperm production takes only a few weeks. Each ejaculation
has 100 to 500 million sperm.
In females, this process is more complex.The first meiotic division starts before
birth but fails to proceed. It is eventually completed about one month before
ovulation in humans. In humans, the second meiotic division occurs just before the
actual process of fertilization occurs.
Thus, in females, the
completion of meiosis
can be delayed for
over 50 years. This is
not always good.
Only I egg produced
In addition, all meiosis
is ended in females at
menopause.
6. Homologous chromosomes form the synaptonemal complex
which facilitates crossing over and genetic diversity
During meiosis, homologous chromosomes
join together in pairs to form the
synaptonemal complex.
Each pair of chromatids is connected by
axial proteins. The 2 homologous
chromosomes are held together closely by
central element proteins.
A recombination nodule forms that contains
enzymes for cutting and splicing DNA.
Chromosomes are cut and joined crosswise
at points called chiasmata,seen when they
separate.
The exchange of genetic material is evident
when the chromosomes separate
This process is dangerous as it leads to
deletions and duplications of genetic
material. However, it is also valuable
because it increases genetic diversity and
facilitates evolution.
7. In older women, failure of the synaptonemal complex
to separate properly can cause genetic disease
Down syndrome is trisomy 21. It
results in short stature, round face
and mild to severe mental
retardation.
This is the failure of the 2
chromatids to separate during
meiosis 2. It results in one oocyte
receiving 2 instead of 1 chromatid.
In older women, long term
association of chromatids (i.e., over
50 years) results in the axial
proteins failure to separate.
Down syndrome occurs with a
frequency of 0.2% in women under
30 but at 3% in those over 45 years
of age.
8. Spermatogenesis occurs in the seminiferous tubules
The mammalian testes are divided into many lobules, and each lobule contains many
tiny seminiferous tubules.Sperm develop in an ordered fashion in these tubules. Cells
start to mature on the outside and move inward (towards the lumen) as the become
mature sperm.
Spermatogonia are the most primative cells. They differentiate as primary
spermatocyte
Sertoli cells are supporting cells that stretch from the lumen to the edge of the
tubule. They nourish the developing sperm. They form a blood-testis barrier to
control spermatogenesis (similar to the blood-brain barrier). These cells also inhibit
spermatogenesis before puberty and stimulate the process after puberty.
9. Spermiogenesis is the maturation process into sperm
The golgi vesicles combine to
form an acrosomal vesicle that
lies over the nucleus. Its full of
enzymes
Centosomes start to organize
microtubules into long flagella
Mitochondria start to localize next to the
flagella to provide ready energy
The nucleus condenses in size and is stabilized by special
proteins called protamines
The excess cytoplasm is pinched off as a residual body
(no need for organelles and cytoplasmic proteins)
Sperm are tiny, but highly specialized missiles for delivering the male genome:
Microfilaments shoot the acrosome into the egg to ‘harpoon it’ and pull it in.
The acrosome has enzymes for breaking into the egg.
The midpiece has large numbers of mitochondria for horsepower.
The tail has a powerful flagellum for driving the sperm into the proximity of the egg (in
humans, through the uterus and up into the oviduct.
10. Spermatogonia and oogonia are stem cells
What is a stem cell?
Stem cells have 3 properties: 1. They are undifferentiated cells
2. They have potential for self renewal
3. They are able to undergo differentiation to form committed
progenitor cells (a fancy word for all types of differentiated
adult cells such as muscle, bone, skin, etc)
11. The goal of oogenesis is to produce one egg
with massive amounts of cytoplasm
In many organisms, such as frogs and birds, the egg must contain all the nutrients
to support the entire process of embryonic development
In humans, the egg does not need to grow so large because the fertilized egg only
needs to support growth until it implants in the uterus. The placenta then nourishes
development.
In some organisms, such as frogs,
oocytes grow to extremely large
size and they have very active
chromosomes that synthesize large
amounts of RNA. In contrast to
sperm which are tiny cells, oocytes
are among the largest cells in the
body.
Oocytes contain Lampbrush
chromosomes: look like brushes
that were used years ago to clean
lamps. Frog oocytes can contain
200,000 times as many ribosomes
as a normal cell.
12. Oocytes have a very small nucleus / cytoplasm ratio
Most normal cells have several times as much cytoplasm as nucleus. This allows the
nucleus to make enough mRNA and rRNA to keep up with the cytoplasm and cell
needs.
In some species, oocytes have a tremendously tiny nucleus to cytoplasm ratio. They
must have a large amount of cytoplasm and ribosomes to make all of the proteins
needed for embryonic development.
The nucleus is just not large enough to keep up and maintain enough transcription to
generate all of the needed components. However, oocytes have developed
specializations to deal with this problem.
1. Ribosomal RNA genes are often amplified in oocytes. This allows more templates
to transcribe more rRNA.
13. Specializations allow the egg to accumulate cytoplasm:
nurse cells allow oocytes of insects
to produce massive amounts of RNA
In Drosophila melanogaster, the oogonia are called
ctyoblasts, and they undergo an unusual specialization
They undergo multiple mitotic divisions, but fail to
undergo cytokinesis (cell division). Thus, they all remain
connected to the original cell as cytocytes
One of the lucky cytocysts becomes the oocyte
The other 15 become nurse cells. They make large
amounts of RNA and nutrients but they send it all to the
oocyte. This allows the oocyte to accumulate massive
amounts of cytoplasm to support development (15 nuclei
instead of 1).
15. Vitellogenesis is the process of producing the major yolk proteins
Yolk: animal eggs contain large amounts of protein, lipid, and glycogen to nourish
the embryo. These materials are collectively called yolk.
Yolk is minimal in animal eggs that sustain only the first portion of embryogenesis
(humans and many mammals that have a placenta need only support cleavage for
several days before implantation into the uterus).
However, yolk is stored in large amounts in the eggs of birds and reptiles because
their eggs have to support the entire process of development.
Yolk proteins are synthesized in the liver in vertebrates, or in the fat body of insects
(an analogous organ)
Animal – vegetal polarity: In eggs
that have a lot of yolk, the yolk is
concentrated in the vegetal pole.
The animal pole contains the
nucleus and relatively little yolk.
The yolk in the vegetal pole
interferes with cytokinesis during
the process of cleavage leading to
incomplete cleavage.
16. Maturation processes prepare the oocyte
for ovulation and fertilization
Most oocytes of different species are arrested in the first meiotic division.
Oocyte maturation begins officially when this block is removed and meiosis starts
once again.
1. The nuclear membrane breaks down and DNA starts to condense into
chromosomes
2. The permeability of the oocyte plasma membrane changes so it can function
outside of the ovary.
3. The plasma membrane develops receptors to interact with the sperm
Fertilization occurs at different stages of oocyte maturation:
How is oocyte maturation
initiated?
17. Control of oocyte maturation has been studied extensively in frogs
Oocyte maturation is controlled by hormone interactions between the pituitary and
follicle cells. Pituitary o gonadotropin hormone c
progesterone s triggers oocyte maturation by activating c-mos expression
C-mos activates maturation promoting factor, the same activity as M-phase promoting
factor, that is composed of cyclin B and cyclin dependent kinase 1The exact
mechanism isn’t understood.
If c-mos is inactivated by antisense
oligonucleotides, no oocyte maturation
occurs. On the other hand, if extra c-mos
is injected it triggers oocyte maturation
before it is ready.
MPF does many things, although the
exact pathways have yet to be found. It
causesbreakdown of the nuclear
envelopeby phosphorylating nuclear
lamins (proteins stabilizing the envelope),
it triggerschanges in the oocyte plasma
membrane, it stimulatesovulation, and it
causescondensation of chromosomes.
18. Development of mammalian oocytes occurs within the ovary
In the mammalian ovary, the oocytes are closely associated with somatic cells
called granulosa cells which aid oocyte maturation and ovulation.
The timing of oocyte maturation and ovulation varies in different mammals.
Ovulation can be stimulated by seasonal cues, the process of mating, or in
primates, by the monthly cycle regulated by hormones such as estradiol,
produced by the granulosa cells.
19. Eggs are protected by elaborate envelopes
Vitelline envelope: a glycoprotein layer covers the plasma membrane of all eggs.
This acts to protect the egg.
Eggs that are deposited in water have a jelly-like coating that surrounds the egg
(frogs eggs)
Eggs that are deposited on land have particularly elaborate envelopes. The eggs of
birds have a vitelline envelope, a fibrous layer, an outer layer of albumin (egg
white), and a shell composed of calcium carbonate. The outer envelopes are
synthesized in the oviduct after the egg has been fertilized.