Organogenesis
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Organogenesis is the process by which the three germ layers (ectoderm, endoderm, and mesoderm) develop into internal organs through proliferation, migration, reaggregation and differentiation of cells. This process occurs between weeks 3 to 8 of development in utero. During this critical period, environmental factors can greatly impact development by disturbing key processes like cell division, apoptosis, gene expression and metabolism. Exposure to teratogens during organogenesis raises the risk of birth defects and structural abnormalities, while exposure later in pregnancy is less likely to cause such defects.
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Gametogenesis
Gametogenesis is the process by which haploid gametes are formed from diploid germ cells through meiosis. It occurs in the gonads (ovaries in females and testes in males) and results in the production of eggs in females through oogenesis and sperm in males through spermatogenesis. Both processes involve germ cells undergoing cell division and differentiation through meiosis to form mature haploid gametes - eggs in females and sperm in males - that can fuse during fertilization to form a new diploid organism.
Oogenesis
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.
Introduction of development biology
Developmental biology is the study of the processes by which organisms grow and develop. It expanded on classical embryology by using modern molecular techniques and genetic approaches. Some key areas of study include differentiation, morphogenesis, growth, reproduction, evolution, and environmental influences. Early debates centered around whether embryonic structures were preformed in the egg (preformationism) or arose de novo through epigenesis. Landmark studies in the 1800s by scientists like Pander, von Baer, and Rathke established germ layer formation and embryonic development principles. Lineage tracing techniques using dyes were later developed to track cell lineages in living embryos of organisms like tunicates, amphibians, zebrafish, and frogs.
morphogenetic movements-developmental biology
Morphogenetic movements involve the rearrangement of cells during embryonic development through processes like gastrulation, tubulation, and organogenesis. These movements are caused by large-scale cell movements and changes in cell behavior, and result in changes to embryonic shape and structure. Key morphogenetic processes include cell division, size, shape, adhesion, death, and interactions with the extracellular matrix. Critical examples are the invagination of epithelial sheets during gastrulation and selective outgrowth of limb buds through differential proliferation.
Cleavage: Definition, types, and mechanism
Early embryonic development involves a series of key stages:
1. Cleavage - The fertilized egg undergoes rapid, synchronized cell divisions without growth to form a solid ball of cells called a morula.
2. Blastulation - Cell divisions continue and a fluid-filled cavity called a blastocoel forms, establishing polarity and transforming the morula into a hollow ball of cells called a blastula.
3. Gastrulation - Cells migrate and rearrange through morphogenetic movements to form the three primary germ layers - ectoderm, endoderm, and mesoderm - establishing the body plan of the embryo.
Cleavage
1. Cleavage is the first phase of embryonic development after fertilization where the fertilized egg undergoes rapid, indirect cell divisions (mitosis) without an increase in overall size to form a multicellular embryo.
2. The pattern of cleavage depends on how much yolk is present in the egg. Eggs with little yolk (isolecithal) undergo total cleavage (holoblastic), while eggs with more yolk have partial cleavage (meroblastic).
3. In amphibians, which have mesoleithal eggs, cleavage is initially equal but becomes unequal with larger vegetal and smaller animal cells. This leads to the formation of a blastula with a fluid-filled cavity (
FATE Map
A chart showing the fate of each part of an early embryo, in a particular blastula stage is called fate maps. It is done because the correct interpretation of gastrulation is impossible without the knowledge of the position which are the presumptive germinal layers (Ectoderm, Mesoderm and Endoderm) occupy in blastula.
Fate mapping is a method used in developmental biology to study the embryonic origin of various adult tissues and structures. The "fate" of each cell or group of cells is mapped onto the embryo, showing which parts of the embryo will develop into which tissue. When carried out at single-cell resolution, this process is called cell lineage tracing. It is also used to trace the development of tumors.
Fertilization in sea urchin
Fertilization in sea urchins involves several key steps:
1) Sperm are attracted to eggs via chemotaxis using peptides like resact.
2) The acrosomal reaction allows sperm to penetrate the egg jelly and bindin aids binding to the egg.
3) Prevention of polyspermy involves a fast block changing membrane potential and slow block from cortical granule exocytosis.
4) Metabolic activation and pronuclear fusion within the egg forms a zygote, completing fertilization.
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Oogenesis
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.
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Developmental biology is the study of the processes by which organisms grow and develop. It expanded on classical embryology by using modern molecular techniques and genetic approaches. Some key areas of study include differentiation, morphogenesis, growth, reproduction, evolution, and environmental influences. Early debates centered around whether embryonic structures were preformed in the egg (preformationism) or arose de novo through epigenesis. Landmark studies in the 1800s by scientists like Pander, von Baer, and Rathke established germ layer formation and embryonic development principles. Lineage tracing techniques using dyes were later developed to track cell lineages in living embryos of organisms like tunicates, amphibians, zebrafish, and frogs.
morphogenetic movements-developmental biology
Morphogenetic movements involve the rearrangement of cells during embryonic development through processes like gastrulation, tubulation, and organogenesis. These movements are caused by large-scale cell movements and changes in cell behavior, and result in changes to embryonic shape and structure. Key morphogenetic processes include cell division, size, shape, adhesion, death, and interactions with the extracellular matrix. Critical examples are the invagination of epithelial sheets during gastrulation and selective outgrowth of limb buds through differential proliferation.
Cleavage: Definition, types, and mechanism
Early embryonic development involves a series of key stages:
1. Cleavage - The fertilized egg undergoes rapid, synchronized cell divisions without growth to form a solid ball of cells called a morula.
2. Blastulation - Cell divisions continue and a fluid-filled cavity called a blastocoel forms, establishing polarity and transforming the morula into a hollow ball of cells called a blastula.
3. Gastrulation - Cells migrate and rearrange through morphogenetic movements to form the three primary germ layers - ectoderm, endoderm, and mesoderm - establishing the body plan of the embryo.
Cleavage
1. Cleavage is the first phase of embryonic development after fertilization where the fertilized egg undergoes rapid, indirect cell divisions (mitosis) without an increase in overall size to form a multicellular embryo.
2. The pattern of cleavage depends on how much yolk is present in the egg. Eggs with little yolk (isolecithal) undergo total cleavage (holoblastic), while eggs with more yolk have partial cleavage (meroblastic).
3. In amphibians, which have mesoleithal eggs, cleavage is initially equal but becomes unequal with larger vegetal and smaller animal cells. This leads to the formation of a blastula with a fluid-filled cavity (
FATE Map
A chart showing the fate of each part of an early embryo, in a particular blastula stage is called fate maps. It is done because the correct interpretation of gastrulation is impossible without the knowledge of the position which are the presumptive germinal layers (Ectoderm, Mesoderm and Endoderm) occupy in blastula.
Fate mapping is a method used in developmental biology to study the embryonic origin of various adult tissues and structures. The "fate" of each cell or group of cells is mapped onto the embryo, showing which parts of the embryo will develop into which tissue. When carried out at single-cell resolution, this process is called cell lineage tracing. It is also used to trace the development of tumors.
Fertilization in sea urchin
Fertilization in sea urchins involves several key steps:
1) Sperm are attracted to eggs via chemotaxis using peptides like resact.
2) The acrosomal reaction allows sperm to penetrate the egg jelly and bindin aids binding to the egg.
3) Prevention of polyspermy involves a fast block changing membrane potential and slow block from cortical granule exocytosis.
4) Metabolic activation and pronuclear fusion within the egg forms a zygote, completing fertilization.
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Blastulation
The document summarizes the process of blastulation in embryonic development. It describes how the zygote undergoes cleavage, forming blastomeres that arrange into a structure called a morula. The morula then develops into the blastula stage, where the cells form a blastoderm layer surrounding an interior cavity called the blastocoel. There are different types of blastulae depending on features like whether the blastocoel is present, the number of cell layers in the blastoderm, and how yolk is distributed. Key blastula types include coeloblastula, stereoblastula, periblastula, discoblastula, and blastocyst.
Gastrulation
Gastrulation is the process by which the three germ layers (ectoderm, mesoderm, endoderm) are formed in the embryo through cell movements. In amphibians, cells from the blastula's outer layer invaginate and involute to form the inner layers. The blastocoel is replaced by the archenteron. In birds, the epiblast and hypoblast layers are initially formed; the epiblast gives rise solely to the three germ layers. Gastrulation rearranges cells into layers that will develop into tissues and organs.
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The document discusses the process of fertilization and the acrosome reaction. It describes how:
1) Upon contact with the egg's jelly coat, the acrosome reaction is initiated, causing enzymes to be released from the acrosome to digest the coat.
2) This reaction fuses the acrosomal membrane with the sperm cell membrane, releasing enzymes that allow the sperm to penetrate the vitelline envelope and reach the egg.
3) The influx of calcium triggers the extension of the acrosomal process through actin polymerization, allowing the sperm to penetrate the zona pellucida and fuse with the egg membrane.
Axis and pattern formation in amphibia
Amphibian development begins with fertilization and cortical rotation that establishes dorsal-ventral polarity. Cleavage is holoblastic but unequal, forming a blastula with large yolky cells in the vegetal pole. Gastrulation involves bottle cell invagination, dorsal mesoderm involution, and ectoderm epiboly. The organizer tissue directs body axis formation through beta-catenin signaling in the dorsal region. Left-right asymmetry results from nodal gene expression induced by cilia rotation in the organizer. Amphibians like Xenopus laevis are widely used models for studying these developmental processes.
Cleavage
This document discusses various aspects of cleavage in fertilized eggs. It begins by defining cleavage as the process of segmentation of the zygote into multiple cells or blastomeres following fertilization. The blastomeres initially remain closely associated but later form a hollow sphere called a blastula. Three key points are made: 1) Cleavage prepares the groundwork for embryonic design by producing cells, 2) It establishes conditions for gastrulation, the next developmental stage. 3) Distinct planes of cell division exist during early cleavage. The document then describes different types of cleavage patterns and their relationships to embryonic cell fate determination.
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2) Epigenesis theory, advocated by Wolff, stated that differentiation occurs after fertilization from an undifferentiated egg or sperm, and is the universally accepted view.
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Gametogenesis is the process by which haploid gametes are formed from diploid germ cells in the gonads. There are two types: spermatogenesis and oogenesis. Spermatogenesis occurs in the testes and involves the formation of sperm from spermatogonia over 74 days, involving multiplication, growth, and maturation phases. Oogenesis occurs in the ovaries and also involves three phases to form ova from oogonia. The resulting gametes, sperm and ovum, differ in structure according to their roles in fertilization. Sperm are small, motile cells specialized for movement, while ovum are larger stationary cells specialized to receive sperm and support development.
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Gastrulation is the process by which the three primary germ layers (endoderm, mesoderm, ectoderm) are formed in frog embryos through coordinated cell movements. In Xenopus embryos, gastrulation begins with bottle-shaped cells invaginating at the equatorial marginal zone to form the blastopore slit. These cells become the dorsal blastopore lip. Additional mesodermal and endodermal precursor cells involute through the expanding blastopore, eventually forming a ring around the yolky endoderm and completing germ layer formation. Fate mapping studies track the origins and locations of precursor cells during gastrulation.
acrosome reaction
The document discusses the process of fertilization and the acrosome reaction. It describes how:
1) Upon contact with the egg's jelly coat, the acrosome reaction is initiated, causing enzymes to be released from the acrosome to digest the coat.
2) This reaction fuses the acrosomal membrane with the sperm cell membrane, releasing enzymes that allow the sperm to penetrate the vitelline envelope and reach the egg.
3) The influx of calcium triggers the extension of the acrosomal process through actin polymerization, allowing the sperm to penetrate the zona pellucida and fuse with the egg membrane.
Axis and pattern formation in amphibia
Amphibian development begins with fertilization and cortical rotation that establishes dorsal-ventral polarity. Cleavage is holoblastic but unequal, forming a blastula with large yolky cells in the vegetal pole. Gastrulation involves bottle cell invagination, dorsal mesoderm involution, and ectoderm epiboly. The organizer tissue directs body axis formation through beta-catenin signaling in the dorsal region. Left-right asymmetry results from nodal gene expression induced by cilia rotation in the organizer. Amphibians like Xenopus laevis are widely used models for studying these developmental processes.
Cleavage
This document discusses various aspects of cleavage in fertilized eggs. It begins by defining cleavage as the process of segmentation of the zygote into multiple cells or blastomeres following fertilization. The blastomeres initially remain closely associated but later form a hollow sphere called a blastula. Three key points are made: 1) Cleavage prepares the groundwork for embryonic design by producing cells, 2) It establishes conditions for gastrulation, the next developmental stage. 3) Distinct planes of cell division exist during early cleavage. The document then describes different types of cleavage patterns and their relationships to embryonic cell fate determination.
Oogenesis
presentation on oogenesis of fertilisation process full details about it u will never find it anywhere else have full details about the ovum formation polar bodies and everything . so explore here
Oogenesis
This document is an assignment on oogenesis submitted by a student. It contains a definition of oogenesis and describes the three main phases of oogenesis - the multiplication phase, growth phase, and maturation phase. During the growth phase, the oocyte undergoes two periods of growth: the previtellogenesis growth period and vitellogenesis growth period. In the previtellogenesis growth period, there is growth of nuclear and cytoplasmic substances as the oocyte increases in size, while vitellogenesis involves the synthesis and accumulation of yolk proteins and other nutrients. The assignment provides details on the key cellular and molecular events that occur during these different phases and periods of oogenesis.
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This document summarizes limb development in vertebrates using the chicken wing and mouse forelimb as models. It describes how the limb develops axes and patterns of differentiated tissues over time. The early limb bud consists of undifferentiated mesenchymal cells covered by ectoderm. As the bud elongates, the thickened apical ectodermal ridge and differences in expansion across the limb axes influence patterning and contribute to formation of proximal versus distal structures. While chicken wings and mouse forelimbs follow similar developmental processes, there are some differences in morphology and growth.
Theories of preformation, pangenesis, epigenesis,
The document summarizes several historical theories of embryological development:
1) Preformation theory proposed that embryos existed preformed and fully formed within the egg or sperm, simply needing to grow larger. This was later disproven.
2) Epigenesis theory, advocated by Wolff, stated that differentiation occurs after fertilization from an undifferentiated egg or sperm, and is the universally accepted view.
3) Pangenesis theory proposed by Darwin involved "gemmules" transmitting traits, but lacked scientific basis.
4) Axial gradient theory proposed physiological gradients along the axis determine development and regeneration, with Child expanding on this view quantitatively.
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El documento describe las etapas del desarrollo embrionario humano desde la cuarta hasta la octava semana de gestación. Durante este periodo se forman los principales órganos a través de los procesos de organogénesis, crecimiento y diferenciación celular. Los tejidos se derivan de las tres capas germinales primarias - ectodermo, mesodermo y endodermo - y se organizan a través de la aparición y fusión de estructuras como los somitos, pliegues neurales y membranas embrionarias.
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Critical period hypothesis
The document discusses the critical period hypothesis (CPH) which proposes that there is an ideal window of time for acquiring language skills, especially grammar. The CPH originated in the 1950s and was explored further by Lenneberg in 1967. Studies on brain lateralization and language development in feral children like Victor and Genie provide support. The effects on phonology, syntax and grammar are discussed. Different theorists propose varying ages for the end of the critical period from 5 to 15 years old. Alternative views also exist that link language learning more to mental abilities than age.
My critical period hypothesis (cph)
The document discusses the critical period hypothesis in second language acquisition. The critical period hypothesis proposes that there is an ideal time period in a person's life for acquiring language skills, and that after a certain age it becomes much more difficult to acquire a new language. The document outlines the historical background of the hypothesis, provides examples of studies that both support and contradict it, and discusses ongoing debates around its claims. It ultimately concludes that while early language acquisition may confer some advantages, there is not enough evidence currently to say whether there truly is a critical period for second language learning.
Periodo embrionario y fetal
Este documento presenta las diferentes etapas del desarrollo embrionario y fetal desde la fecundación hasta el nacimiento, describiendo los cambios físicos y funcionales que ocurren semana a semana. Se explica cómo el embrión se convierte en un feto completamente formado a las 12 semanas y cómo sus órganos y sistemas continúan madurando hasta el nacimiento.
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definition ,cause ,signs ,smptoms ,diagnosis ,differential diagnosis ,complications ,prevention ,vaccine
Unit 5 animal reproduction and development
This document provides an overview of animal reproduction and development. It discusses both asexual and sexual reproduction in animals. Asexual reproduction occurs through fission, budding, fragmentation, and parthenogenesis. Sexual reproduction involves the fusion of male and female gametes during internal or external fertilization. After fertilization, embryonic development proceeds through cleavage, gastrulation, and organogenesis stages. The embryo develops three germ layers that give rise to different tissues and organs. Parental care helps many animals ensure the survival of offspring to reproductive age.
Angiosperm (seed formation and development)
Daisy Capon is a PhD student studying crop science. Her research focuses on angiosperm seed formation and development. She outlines the key stages of male and female gametophyte development, including microsporogenesis, microgametogenesis, megasporogenesis, and megagametogenesis. She then discusses seed formation, including the roles of the integuments, nucellus, and embryo sac. The structures and development of plant embryos are also examined, from fertilization through the cotyledon, hypocotyl, and radicle stages. Finally, she analyzes the chemical composition of seeds and factors that affect it.
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The document discusses the formation of germ layers from the fertilized ovum through the blastocyst stage. Key points include:
1) Cleavage of the ovum leads to the formation of the morula with an inner cell mass and outer trophoblast layer. Further development creates the blastocyst containing an inner cell mass surrounded by fluid.
2) The inner cell mass of the blastocyst gives rise to the three germ layers - endoderm, ectoderm, and mesoderm. The trophoblast gives rise to extraembryonic structures.
3) Structures that form include the amniotic cavity, yolk sac, and extraembryonic mesoderm which
Organogenesis & somatic hybridrization
Organogenesis is the process by which plant organs like roots, shoots, flowers develop from explants. It is influenced by physical factors like light and temperature, and chemical factors like cytokinins and auxins. Organogenesis has advantages like being cheap, fast, and allowing for easy scaling up. Somatic hybridization involves fusing protoplasts from two plant species using techniques like PEG-mediated fusion. It allows for transferring genes between sexually incompatible plants but has challenges like low regeneration rates and hybrid viability. It differs from organogenesis in producing bipolar embryos without connections to parent tissue.
How seed is formed
A seed is formed through fertilization. A pollen grain sticks to the stigma of a flower and grows a pollen tube containing sperm cells. One sperm cell fertilizes the egg cell to form a zygote, while the other fertilizes another cell to form endosperm stored food tissue. The fertilized ovule develops into a seed containing the new plant and stored food within a fruit that grows from the ovary.
Flowers
The document discusses the parts of flowers including the sepals, petals, stamens, carpels, and receptacle. It describes the essential floral parts and their structures. The document also covers floral variations such as completeness, sexuality, number of parts, symmetry, position of the ovary, and placentation. Finally, it discusses different types of inflorescences including racemes, panicles, spikes, catkins, spadices, cymes, corymbs, umbels, heads, and fascicles.
Desarrollo Embrionario
El documento describe las distintas etapas del desarrollo embrionario: la segmentación del zigoto en mórula y blástula, la gastrulación donde se forman las tres capas germinales y la organogénesis donde se desarrollan los órganos. También explica el proceso de la implantación, la formación de la placenta y sus funciones para el intercambio de nutrientes entre la madre y el feto.
SEX DETERMINATION (GENETICS)
Sex determination in humans and many other organisms is controlled genetically by sex chromosomes. In humans, females have two X chromosomes (XX) while males have one X and one Y chromosome (XY). The SRY gene on the Y chromosome determines male development. Other common sex determination systems include the XX-XO system in insects where females are XX and males XO, and the ZW-ZZ system in birds where females are ZW and males ZZ. Single genes have also been found to determine sex in some species like Drosophila and maize.
Symmetry Presentation By Sharanya
The document discusses different types of symmetry, including line symmetry and rotational symmetry. Line symmetry occurs when one half of an object is a mirror image of the other half. Rotational symmetry is when an object looks the same after being rotated around a center point by a certain number of degrees. Examples are given of different shapes and objects that demonstrate line symmetry, such as butterflies and smiley faces, as well as rotational symmetry, including triangles, pizzas, and flowers.
Radial symmetry
Radial symmetry is a type of balance where parts of an object are arranged around a central point. There are three types of balance: radial symmetry, mirror/bilateral symmetry, and asymmetry. Radial symmetry is seen in both natural objects like snowflakes and human-made objects like mandalas, kaleidoscopes, and rose windows in cathedrals. To create radial symmetry, a circle is divided into equal sections and the same pattern is repeated in each section.
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acne vulgaris -Mpharm (2nd semester) Cosmetics and cosmeceuticals
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Gene Expression System-viral gene delivery Mpharm(Pharamaceutics)
Gene Expression System-viral gene delivery Mpharm(Pharamaceutics)
Organogenesis
- 1. Organogenesis Critical period of Organogenesis By: Gajaan S Tossif G 512
- 2. Organogenesis Organogenesis is the process by which the ectoderm, endoderm, and mesoderm develop into the internal organs of the organism. Cells of each germ layer proliferate, migrate, reaggregate and differentiate into various tissues that form the organs (organogenesis)
- 4. How does it occur? The germ layers in organogenesis differ by three processes: • folds, • splits, and • Condensation Cells of each germ layer proliferate, migrate, reaggregate and differentiate into various tissues that form the organs (organogenesis)
- 5. When does it occur? Internal organs initiate development in humans within the 3rd to 8th weeks in utero.
- 10. Embryonic stage • Week 3: Beginning development of the brain, heart, blood cells, circulatory system, spinal cord, and digestive system. • Week 4: Beginning development of bones, facial structures, and limbs (presence of arm and leg buds); continuing development of the heart (which begins to beat), brain, and nervous tissue. • Week 5: Beginning development of eyes, nose, kidneys, lungs; continuing development of the heart (formation of valves), brain, nervous tissue, and digestive tract. • Week 6: Beginning development of hands, feet, and digits; continuing development of brain, heart, and circulation system. • Week 7: Beginning development of hair follicles, nipples, eyelids, and sex organs (testes or ovaries); first formation of urine in the kidneys and first evidence of brain waves. • Week 8: Facial features more distinct, internal organs well developed, the brain can signal for muscles to move, heart development ends, external sex organs begin to form. By the end of the embryonic stage, all essential external and internal structures have been formed. The embryo is now referred to as a fetus.
- 12. video please!!!
- 13. CRITICAL PERIODS OF DEVELOPMENT It is a specific time during which the environment has its greatest impact on an individual's development.
- 14. if you drink, I will also drink
- 15. Why it is critical period? Because it will disturb the processes of developments: • Control of cell division, • Apoptosis, • Gene expression, and • Cellular metabolism
- 16. During pre-embronic stage • The effects of maternal drug use on the development of the fetus are dependent upon the stage of embryonic and fetal development, as well as the dosage of the substance. After fertilization occurs, the embryo is highly resistant to birth defects, but the results of a high dose teratogen could result in death. Intake of teratogens during this preembryonic stage could also result in normal development if the teratogenic substance is stopped before the embryonic stage of development.
- 17. During embryonic stage • During the embryonic stage of development (weeks 3-8), the effects of teratogens are increasingly detrimental. Organs begin forming during the embryonic stage, and harmful teratogens can result in miscarriage, and structural abnormalities. • Once the embryonic stage is complete, the fetal period begins at week 9 and continues until full term at week 38. Teratogens taken during this period can result in improper organ functioning, delayed growth, but seldom result in birth defects .