FIRST WEEK OF DEVELOPMENT.pptx
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1. Fertilization involves the fusion of an egg and sperm, forming a zygote with a full set of chromosomes. The zygote then undergoes cleavage, forming a morula by day 3 and a blastocyst by day 5 as it travels down the fallopian tube. 2. The blastocyst implants in the uterine wall around 1 week after fertilization. The trophoblast cells of the blastocyst initiate implantation and will later form the placenta, while the inner cell mass gives rise to the embryo. 3. During the first week, the zygote develops from a single cell through cleavage, compaction, blastulation and begins implantation in the uterus.
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GENERAL EMBRYOLOGY
During the first two weeks of development, the fertilized egg undergoes cell division through cleavage to form a blastocyst. The blastocyst implants in the uterine wall and begins to develop two cell layers - the outer trophoblast and inner cell mass. The trophoblast layer further separates into cytotrophoblast and syncytiotrophoblast. The syncytiotrophoblast starts to invade the maternal tissues and establish placenta. Meanwhile, the cell mass develops into the amniotic cavity and the yolk sac to support the growing embryo. Primary villi also begin to form on the trophoblast as the basis for later placenta development.
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The document summarizes key events during the first and second weeks of human embryonic development:
- In the first week, the fertilized egg undergoes cleavage and compaction to form a morula, which then develops into a blastocyst as it travels through the fallopian tube. The blastocyst implants in the uterine wall around day 6.
- In the second week, the blastocyst becomes fully embedded. The outer cell mass differentiates into trophoblast layers, while the inner cell mass forms the hypoblast and epiblast. Primary villi and the chorionic cavity develop as the embryo becomes established.
- By the end of the second week, the main cavities and cell layers
I week of development
1) The document discusses the key stages in the first week of human development including fertilization, cleavage, formation of the morula and blastocyst, and implantation.
2) Fertilization involves the fusion of an ovum and spermatozoa to form a zygote, which occurs in the fallopian tube. The zygote then undergoes cleavage divisions as it moves through the uterine tube.
3) By day 5-6, the blastocyst has formed with an inner cell mass and outer trophoblast layer. The blastocyst implants in the endometrium around day 7, initiating formation of the placenta and decidua. Abnormal implantation can result in
I week of development
1) The document discusses the key stages in the first week of human development including fertilization, cleavage, formation of the morula and blastocyst, and implantation.
2) Fertilization involves the fusion of an ovum and spermatozoa to form a zygote, which occurs in the fallopian tube. The zygote then undergoes cleavage divisions as it moves through the uterine tube.
3) By day 5-6, the blastocyst has formed with an inner cell mass and outer trophoblast layer. Around day 7, the blastocyst implants in the uterine lining, initiating formation of the placenta and decidua. Abnormal implantation can result in ect
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Cleavage, implantation of the embryo and bilaminar
1. Cleavage is the initial phase of rapid cell division of the zygote following fertilization which generates a large number of cells without growth. This leads to the formation of a solid ball of cells called a morula.
2. Implantation of the blastocyst in the uterine lining begins around day 7. The trophoblast cells erode into the endometrium and the blastocyst is fully embedded by day 10.
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During the first two weeks of development, the fertilized egg undergoes cell division through cleavage to form a blastocyst. The blastocyst implants in the uterine wall and begins to develop two cell layers - the outer trophoblast and inner cell mass. The trophoblast layer further separates into cytotrophoblast and syncytiotrophoblast. The syncytiotrophoblast starts to invade the maternal tissues and establish placenta. Meanwhile, the cell mass develops into the amniotic cavity and the yolk sac to support the growing embryo. Primary villi also begin to form on the trophoblast as the basis for later placenta development.
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The document summarizes key events during the first and second weeks of human embryonic development:
- In the first week, the fertilized egg undergoes cleavage and compaction to form a morula, which then develops into a blastocyst as it travels through the fallopian tube. The blastocyst implants in the uterine wall around day 6.
- In the second week, the blastocyst becomes fully embedded. The outer cell mass differentiates into trophoblast layers, while the inner cell mass forms the hypoblast and epiblast. Primary villi and the chorionic cavity develop as the embryo becomes established.
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2) Fertilization involves the fusion of an ovum and spermatozoa to form a zygote, which occurs in the fallopian tube. The zygote then undergoes cleavage divisions as it moves through the uterine tube.
3) By day 5-6, the blastocyst has formed with an inner cell mass and outer trophoblast layer. The blastocyst implants in the endometrium around day 7, initiating formation of the placenta and decidua. Abnormal implantation can result in
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1) The document discusses the key stages in the first week of human development including fertilization, cleavage, formation of the morula and blastocyst, and implantation.
2) Fertilization involves the fusion of an ovum and spermatozoa to form a zygote, which occurs in the fallopian tube. The zygote then undergoes cleavage divisions as it moves through the uterine tube.
3) By day 5-6, the blastocyst has formed with an inner cell mass and outer trophoblast layer. Around day 7, the blastocyst implants in the uterine lining, initiating formation of the placenta and decidua. Abnormal implantation can result in ect
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The document discusses the processes of ovulation, fertilization, and implantation. It explains that ovulation is triggered by hormones like LH and FSH, leading to the release of an egg. If fertilization by sperm occurs, the fertilized egg undergoes cell division and develops into a blastocyst over a week. The blastocyst then implants in the uterus by attaching to the endometrial lining with the help of hormonal changes brought on by the corpus luteum.
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1. Cleavage is the initial phase of rapid cell division of the zygote following fertilization which generates a large number of cells without growth. This leads to the formation of a solid ball of cells called a morula.
2. Implantation of the blastocyst in the uterine lining begins around day 7. The trophoblast cells erode into the endometrium and the blastocyst is fully embedded by day 10.
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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.
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2) By day 5, the embryo has developed into a blastocyst stage and begins to implant in the uterine wall. Implantation is completed by day 12.
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Fertilization normally occurs in the ampulla of the uterine tube within 24 hours of ovulation. It is a complex interaction between male and female gametes that forms a zygote. The zygote then undergoes cleavage as it travels through the fallopian tube to the uterus. Around 6-7 days after fertilization, the embryo implants itself into the uterine wall, forming the placenta and embryo from the trophoblast and inner cell mass respectively.
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fertilization.pptx
Fertilization is the process by which an egg is fertilized by a sperm to produce a new organism. It begins with the collision of sperm and egg and ends with the formation of a single-celled zygote. Fertilization usually occurs in the fallopian tubes. The zygote then undergoes cell division called cleavage over the next few days as it is transported down the fallopian tube through the uterus and into the womb. By the fourth day, it develops into a hollow ball of cells called a blastocyst which implants in the uterine wall, where it continues to develop into an embryo.
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First week of development after fertilization.pptx
1.CLEAVAGE
Cleavage consists of repeated mitotic divisions of the zygote, resulting in a rapid increase in the number of cells
[Moore et al, 2016]
At this stage, each cell is called a blastomere
Occurs as the zygote passes along the uterine tube towards the uterus
Zygote is still within the zona pellucida
Approximately 3 days after fertilization, cells of the compacted embryo divide again to form a 16-cell morula (mulberry).
2.The zygote undergoes repeated division, passing through these stages:
2-cell stage
4-cell stage
8-cell stage
16-cell stage
When there are 16 or more blastomeres, the zygote is considered a morula (a hollow ball of cells)
3.MORULA
After the zygote formation, typical mitotic division of the nucleus occurs by producing two blastomeres.
The two cell stage is reached approximately 30 hours after fertilization. Each contains equal cytoplasmic volume and chromosome numbers.
The blastomeres continue to divide by binary division through 4, 8, 16 cell stage until a cluster of cells is formed and is called morula, resembling a mulberry.
As the total volume of the cell mass is not increased and the zona pellucida remains intact, the morula
after spending about 3 days in the uterine tube enters the uterine cavity through the narrow uterine ostium (1 mm) on the 4th day in the 16-64 cell stage.
4.The transport is a slow process and is controlled by muscular contraction and movement of the cilia. The central cell of the morula is known as inner cell mass which forms the embryo proper and the peripheral cells are called outer cell mass which will form protective and nutritive membranes of the embryo.
5.BLASTULATION
● Compaction
o The blastomeres change shape and tightly align themselves against each other to form a compact ball of cells
Blastulation
The process wherein the morula is transformed into a blastula/blastocyst
A group of cells compact around the edge/periphery à will form the outer cell mass
Another group of cells group together on one side à will form the inner cell mass
A blastula/blastocyst is a ball of cells with an outer cell mass, inner cell mass, and a hollow, fluid-filled cavity
6.Blastocyst formation
4 days post-fertilization, a fluid-filled space appears-called blastocystic cavity.
fluid passes from uterus through zona pellucida to the cavity.
as fluid in cavity increases, blastomeres separate into 2 parts
thin, outer cell layer = trophoblast
inner cell mass = embryoblast
the conceptus is now called a blastocyst.
blastocysts floats in uterine cavity for about 2 days
zona pellucida degenerates,
8.As the cells become more functional, they differentiate
Outer cell mass à Trophoblast
Inner cell mass à Embryoblast
The trophoblast differentiates into two specialized layers that are important for the placenta:
Cytotrophoblast
Syncytiotrophoblast
9.The embryoblast will differentiate into a bilaminar disk, which is made up of:
Epiblast
Hypoblast
10.QUICK OVERVIEW
After Fertilization:
The anterior pituitary releas
3 GEN EMBRYOLOGY third Week 3 germ layer .pptx
third wk there is formation of three germ layers. primitive streek and prochordal plate forms the intra embyyonic mesoderm. the epiblast cells replace all the 3 germ layers. iem is converted to paraxial, intermediate and lateral plate mesoderms
Reproductive physiology of pregnancy
Reproductive physiology of pregnancyShri Alpesh N. Patel Postgraduate Institute of Science and Research
The document provides information about the process of pregnancy from fertilization through birth in 3 sentences:
Fertilization occurs when the genetic material from a sperm and egg merge in the fallopian tube, forming a zygote which undergoes cell division and implants in the uterus, developing into an embryo and fetus over 38 weeks until birth. The placenta forms and secretes hormones like progesterone, estrogen, hCG, and others to support the pregnancy and development of the fetus, while the fetus develops all its major organ systems, tripling in size by the third trimester before birth. Maternal changes include support of the corpus luteum in early pregnancy and taking over hormone production by the placenta, enlargINTRODUCTION TO EMBRYOLOGY ANATOMY-2.pptx
- Fertilization occurs when a sperm fuses with an ovum to form a single cell called a zygote. This begins the process of embryonic development.
- Cleavage involves rapid cell divisions of the zygote over the first few days, forming a solid ball of cells called a morula.
- By day 4, the morula has further developed into a blastocyst containing an inner cell mass that will form the embryo and outer trophoblast cells that will develop into the placenta. Around day 6, the blastocyst implants in the uterine wall.
Embryonic development SlideShare.
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
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1.CLEAVAGE
Cleavage consists of repeated mitotic divisions of the zygote, resulting in a rapid increase in the number of cells
[Moore et al, 2016]
At this stage, each cell is called a blastomere
Occurs as the zygote passes along the uterine tube towards the uterus
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After the zygote formation, typical mitotic division of the nucleus occurs by producing two blastomeres.
The two cell stage is reached approximately 30 hours after fertilization. Each contains equal cytoplasmic volume and chromosome numbers.
The blastomeres continue to divide by binary division through 4, 8, 16 cell stage until a cluster of cells is formed and is called morula, resembling a mulberry.
As the total volume of the cell mass is not increased and the zona pellucida remains intact, the morula
after spending about 3 days in the uterine tube enters the uterine cavity through the narrow uterine ostium (1 mm) on the 4th day in the 16-64 cell stage.
4.The transport is a slow process and is controlled by muscular contraction and movement of the cilia. The central cell of the morula is known as inner cell mass which forms the embryo proper and the peripheral cells are called outer cell mass which will form protective and nutritive membranes of the embryo.
5.BLASTULATION
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o The blastomeres change shape and tightly align themselves against each other to form a compact ball of cells
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The process wherein the morula is transformed into a blastula/blastocyst
A group of cells compact around the edge/periphery à will form the outer cell mass
Another group of cells group together on one side à will form the inner cell mass
A blastula/blastocyst is a ball of cells with an outer cell mass, inner cell mass, and a hollow, fluid-filled cavity
6.Blastocyst formation
4 days post-fertilization, a fluid-filled space appears-called blastocystic cavity.
fluid passes from uterus through zona pellucida to the cavity.
as fluid in cavity increases, blastomeres separate into 2 parts
thin, outer cell layer = trophoblast
inner cell mass = embryoblast
the conceptus is now called a blastocyst.
blastocysts floats in uterine cavity for about 2 days
zona pellucida degenerates,
8.As the cells become more functional, they differentiate
Outer cell mass à Trophoblast
Inner cell mass à Embryoblast
The trophoblast differentiates into two specialized layers that are important for the placenta:
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9.The embryoblast will differentiate into a bilaminar disk, which is made up of:
Epiblast
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Reproductive physiology of pregnancy
Reproductive physiology of pregnancyShri Alpesh N. Patel Postgraduate Institute of Science and Research
The document provides information about the process of pregnancy from fertilization through birth in 3 sentences:
Fertilization occurs when the genetic material from a sperm and egg merge in the fallopian tube, forming a zygote which undergoes cell division and implants in the uterus, developing into an embryo and fetus over 38 weeks until birth. The placenta forms and secretes hormones like progesterone, estrogen, hCG, and others to support the pregnancy and development of the fetus, while the fetus develops all its major organ systems, tripling in size by the third trimester before birth. Maternal changes include support of the corpus luteum in early pregnancy and taking over hormone production by the placenta, enlargINTRODUCTION TO EMBRYOLOGY ANATOMY-2.pptx
- Fertilization occurs when a sperm fuses with an ovum to form a single cell called a zygote. This begins the process of embryonic development.
- Cleavage involves rapid cell divisions of the zygote over the first few days, forming a solid ball of cells called a morula.
- By day 4, the morula has further developed into a blastocyst containing an inner cell mass that will form the embryo and outer trophoblast cells that will develop into the placenta. Around day 6, the blastocyst implants in the uterine wall.
Embryonic development SlideShare.
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
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FIRST WEEK OF DEVELOPMENT.pptx
- 1. PROF. DR. AISHA QAMAR
- 2. • Describe the phases of fertilization • Describe the events of first week of development
- 3. At the end of this session, students should be able to: Describe the first week of human development with reference to: 1. Fertilization process 2. Cleavage of the zygote 3. Blastogenesis 4. Initiation of implantation
- 4. • Q-1. A newborn baby girl showed upward slanting eyes, depressed nasal bridge and simian crease in hand, but her muscle tone was normal. Karyotyping revealed that some cells had an extra copy of chromosome 21, while other cells were normal
- 5. • Q-2. A 35-year-old primigravida presented to the emergency room with profuse bleeding per vagina after 2 months of secondary amenorrhea. The karyotyping of the aborted conceptus was done which showed triploidy
- 6. • Fertilization • Cleavage • Blastocyst formation • Initiation of implantation
- 7. • Process by which male and female germ cells fuse • Site: ampullary region of fallopian/ uterine tube
- 8. Capacitation: period of conditioning (7 hours) Acrosome reaction: occurs after binding to zona pellucida Induced by zona proteins Release of enzymes like trypsin and acrosin-like substances
- 9. • Phases 1. Penetration of corona radiata 2. Penetration of zona pellucida 3. Fusion of oocyte and sperm cell membranes Takes approximately 24 hours
- 10. Capacitated sperm passes freely through corona radiata Results mainly from action of enzyme hyaluronidase released from acrosome of sperm Tubal mucosal enzymes Movement of sperm tail
- 11. • Facilitated by release of acrosomal enzymes like acrosin, esterase, and neuriamidase • Zona reaction: prevents polyspermy
- 12. • Results in: • completion of 2nd meiotic division of oocyte and • formation of female pronucleus • Replicates its DNA
- 13. • Nucleus of sperm enlarges to form male pronucleus • Tail degenerates • Both pronuclei identical • Replicate their DNA • Oocyte containing two haploid pronuclei is known as ootid
- 14. • Pronuclei fuse into a single diploid aggregation of chromosomes, ootid becomes zygote • Chromosomes become arranged on a cleavage spindle
- 15. • Completes second meiotic division • Restores diploid number of chromosomes • Results in variation of human species • Determines chromosomal sex of embryo • Causes metabolic activation of zygote
- 16. Repeated mitotic divisions of zygote (blastomeres) Cells become smaller with each division Zygote lies within zona pellucida Division of zygote into blastomeres begins 30 hrs after fertilization
- 17. • Compaction: After nine-cell stage, blastomeres tightly align themselves to form a compact ball of cells • 12 to 32- blastomere stage is called morula, formed on 3rd day after fertilization
- 18. Fluid filled cavity (blastocoele) appears as it enters uterus Divides blastomeres into 2 parts; 1. Outer cell mass/ Trophoblast: placenta 2. Inner cell mass/ Embryoblast: embryo
- 20. Early pregnancy factor (immunosupressant protein) secreted by trophoblast 24-48 hours after fertilization Forms basis of pregnancy test zona pellucida degenerates
- 21. • As blastocyst attaches to uterine endometrium, trophoblast differentiates into • Cytotrophoblast and • Syncytiotrophoblast
- 22. • Starts on appox day 6 (day 20 of a 28 day cycle) • Trophoblast proliferates rapidly • By end first week, blastocyst superficially implanted in compact layer of endometrium
- 23. • A layer of cells, hypoblast, appears at day 7 on surface of embryoblast facing blastocele • Arises by delamination of blastomeres from embryoblast
- 24. • Triploid conception • Sex ratio • IVF and embryo transfer • Mosaicism • Early spontaneous abortions
- 26. Q-1. A newborn baby girl showed upward slanting eyes, depressed nasal bridge and simian crease in hand, but her muscle tone was normal. Karyotyping revealed that some cells of her body had an extra copy of chromosome 21, while other cells were normal • a. Which condition was most likely present in this neonate? • b. Exlain the reasons for having two types of chromosome constitution on karyotyping
- 27. Q-2. A 35-year-old primigravida presented to ER with profuse bleeding per vagina after 2 months of secondary amenorrhea. The karyotyping of the aborted conceptus was done which showed triploidy. • a. What is the reason for above condition? • b. Which step in fertilization prevents above mentioned condition?
- 28. • Langman’s Medical Embryology: Saddler TW; 12th Edition, 2012 • The developing human. Moore et al., 11th Edition; 2019