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Questions and Answers
What is the importance of sperm capacitation?
What is the importance of sperm capacitation?
- It allows the sperm to undergo changes that enable it to fertilize an egg (correct)
- It triggers the release of the egg from the ovary
- It initiates the process of implantation
- It prevents the sperm from reaching the egg
What are the mechanisms behind the blocks to polyspermy?
What are the mechanisms behind the blocks to polyspermy?
- Fusion of multiple eggs with a single sperm
- Release of multiple eggs simultaneously
- Acrosome reaction preventing entry of multiple sperms (correct)
- Inhibition of sperm production
What is fertilization?
What is fertilization?
- The process of implantation
- The formation of the placenta
- The release of the egg from the ovary
- The fusion of a sperm's chromosomes with those of an egg to form a zygote (correct)
What is the composition of the chorion?
What is the composition of the chorion?
What structure does the Neural Tube eventually develop into?
What structure does the Neural Tube eventually develop into?
Which cells give rise to cranial, spinal, and sympathetic ganglia?
Which cells give rise to cranial, spinal, and sympathetic ganglia?
What marks the beginning of mesodermal differentiation in the embryonic disc?
What marks the beginning of mesodermal differentiation in the embryonic disc?
Which mesodermal structure contributes to the formation of vertebrae, skin, and muscles?
Which mesodermal structure contributes to the formation of vertebrae, skin, and muscles?
What do the intermediate mesoderm and lateral plate mesoderm form, respectively?
What do the intermediate mesoderm and lateral plate mesoderm form, respectively?
What leads to pressure on abdominal and pelvic organs during pregnancy?
What leads to pressure on abdominal and pelvic organs during pregnancy?
Which hormone causes pelvic ligaments and pubic symphysis to relax during pregnancy?
Which hormone causes pelvic ligaments and pubic symphysis to relax during pregnancy?
What is the approximate weight gain during pregnancy?
What is the approximate weight gain during pregnancy?
Which structures are influenced by placental growth hormone, human placental lactogen, and corticotropin-releasing hormone?
Which structures are influenced by placental growth hormone, human placental lactogen, and corticotropin-releasing hormone?
What is the conceptus called from fertilization through week 8?
What is the conceptus called from fertilization through week 8?
When is fertilization most likely to occur for successful fertilization?
When is fertilization most likely to occur for successful fertilization?
What is the process enhancing sperm motility and membrane fragility before fertilization?
What is the process enhancing sperm motility and membrane fragility before fertilization?
What encapsulates the ovulated oocyte?
What encapsulates the ovulated oocyte?
How is monospermy ensured in humans?
How is monospermy ensured in humans?
What occurs as maternal and paternal chromosomes combine?
What occurs as maternal and paternal chromosomes combine?
What is the period of rapid mitotic divisions of the zygote without intervening growth called?
What is the period of rapid mitotic divisions of the zygote without intervening growth called?
What is the blastocyst composed of?
What is the blastocyst composed of?
What is the role of the trophoblast?
What is the role of the trophoblast?
When does implantation begin after ovulation?
When does implantation begin after ovulation?
What is the conceptus called from week 9 through birth?
What is the conceptus called from week 9 through birth?
What is the first cell of a new individual?
What is the first cell of a new individual?
Which hormone can lead to spontaneous abortion if its levels diminish?
Which hormone can lead to spontaneous abortion if its levels diminish?
What is the role of estrogens and progesterone during pregnancy?
What is the role of estrogens and progesterone during pregnancy?
Which structure becomes the structural base for the umbilical cord in humans?
Which structure becomes the structural base for the umbilical cord in humans?
What provides a protective, temperature-regulated environment for the embryo?
What provides a protective, temperature-regulated environment for the embryo?
Which membrane forms part of the gut, is a source of early blood cells, and facilitates germ cell migration?
Which membrane forms part of the gut, is a source of early blood cells, and facilitates germ cell migration?
What transforms the two-layered embryonic disc into a three-layered embryo with primary germ layers?
What transforms the two-layered embryonic disc into a three-layered embryo with primary germ layers?
Which germ layer forms the nervous system and skin structures?
Which germ layer forms the nervous system and skin structures?
What does endoderm form?
What does endoderm form?
What does mesoderm form?
What does mesoderm form?
What does organogenesis involve?
What does organogenesis involve?
What leads to the formation of the brain and spinal cord from the ectoderm?
What leads to the formation of the brain and spinal cord from the ectoderm?
What is the role of hCG in pregnancy?
What is the role of hCG in pregnancy?
What is the function of the trophoblast during implantation?
What is the function of the trophoblast during implantation?
When does the placenta assume the role of progesterone and estrogen production?
When does the placenta assume the role of progesterone and estrogen production?
What is the origin of the placenta?
What is the origin of the placenta?
What is the function of the syncytiotrophoblast?
What is the function of the syncytiotrophoblast?
What happens if the endometrium is not optimally mature?
What happens if the endometrium is not optimally mature?
What is the approximate duration of successful implantation?
What is the approximate duration of successful implantation?
What is the function of the decidua capsularis?
What is the function of the decidua capsularis?
What is the primary function of the chorionic villi during placental formation?
What is the primary function of the chorionic villi during placental formation?
What hormone rescues the corpus luteum and prevents its degeneration?
What hormone rescues the corpus luteum and prevents its degeneration?
When does the placenta begin to produce estrogens and progesterone?
When does the placenta begin to produce estrogens and progesterone?
What is the timeline for the completion of successful implantation?
What is the timeline for the completion of successful implantation?
Study Notes
Embryonic Development and Organogenesis
- Inadequate placental hormones can lead to spontaneous abortion if hCG levels diminish
- Throughout pregnancy, blood levels of estrogens and progesterone increase, encouraging mammary gland growth
- The placenta also produces human placental lactogen and relaxin
- The blastocyst is converted to a Gastrula, with three primary germ layers forming
- Extraembryonic membranes include the amnion, yolk sac, allantois, and chorion
- The amnion provides a protective, temperature-regulated environment for the embryo
- The yolk sac forms part of the gut, is a source of early blood cells, and facilitates germ cell migration
- The allantois becomes the structural base for the umbilical cord in humans
- Gastrulation transforms the two-layered embryonic disc into a three-layered embryo with primary germ layers
- Ectoderm forms nervous system and skin structures, endoderm forms linings of digestive and respiratory systems, and mesoderm forms other body structures
- Organogenesis involves the differentiation of the germ layers to form body organs and systems
- Neurulation, induced by chemical signals from the notochord, leads to the formation of the brain and spinal cord from the ectoderm
Implantation and Formation of the Placenta
- The endometrium becomes receptive to implantation due to surging levels of ovarian hormones.
- If the endometrium is not optimally mature, the blastocyst fails to attach and implants when it finds a suitable site.
- Trophoblast cells adhere to the endometrium and secrete digestive enzymes and growth factors.
- The trophoblast proliferates and forms two distinct layers: Cytotrophoblast and Syncytiotrophoblast.
- Successful implantation takes about five days and is usually completed by day 12 of the menstrual cycle.
- The embryo rescues the corpus luteum by secreting human chorionic gonadotropin (hCG).
- hCG prevents the mother's immune system from rejecting the implanted embryo.
- The placenta assumes the role of progesterone and estrogen production between the second and third month.
- The placenta is a temporary organ originating from both embryonic and maternal tissues.
- The formation of the placenta involves the development of chorionic villi and the invasion of maternal blood vessels.
- The placenta detaches and sloughs off after birth, and the decidua capsularis expands to accommodate the fetus.
- The placenta secretes hCG from the beginning, but its ability to produce estrogens and progesterone matures more slowly.
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Description
Test your knowledge of embryonic development and placental formation with this quiz. Explore the stages of organogenesis, germ layer differentiation, implantation, and the role of hormones in pregnancy.
