10 Questions
What is the process of cell division that leads to the formation of a blastocyst?
Cleavage
Which layer of the blastocyst becomes the pre-embryo, amnion, yolk sac, and allantois?
Inner cell mass
What are the three germ layers formed during gastrulation?
Ectoderm, mesoderm, and endoderm
From which layer is the epidermis derived?
Ectoderm
What is the name of the area of rapidly proliferating mesenchymal cells in limb development?
Progress zone
When does eye development occur during embryonic development?
Third to tenth week
What is the cause of spina bifida?
Incomplete neural tube closure
What is the name of the process whereby the neural plate is transformed into the neural tube?
Neurulation
What is the name of the stem cells that give rise to all the blood cells?
Hemangioblasts
What is the name of the stage that covers the time from fertilization until implantation in the uterus is completed?
Germinal stage
Study Notes
- Human embryonic development is the formation of the human embryo through cell division and differentiation.
- Fertilization occurs when a sperm cell fuses with an egg cell to form a zygote.
- The germinal stage covers the time from fertilization until implantation in the uterus is completed, lasting around 10 days.
- Cleavage is the process of cell division that leads to the formation of a blastocyst.
- The blastocyst has an outer layer of cells called the trophoblast and an inner cell mass that will become the embryo.
- The trophoblast develops into the fetal part of the placenta while the inner cell mass becomes the pre-embryo, amnion, yolk sac, and allantois.
- Implantation occurs when the blastocyst attaches to the endometrium of the uterus.
- The hypoblast and epiblast layers form the bilaminar germ disc, which will become the embryo.
- The syncytiotrophoblast grows and forms primary villi, which penetrate the endometrium.
- The endometrial lining becomes a secretory lining in preparation for accepting the embryo.
- The syncytiotrophoblast implants the blastocyst in the decidual epithelium to form the placenta.
- The placenta connects the embryo to the uterine wall and sustains the developing embryo.
- The embryonic disc is a bilaminar disc of two layers, an upper layer called the epiblast and a lower layer called the hypoblast.
- Gastrulation reorganizes the two-layer embryo into a three-layer embryo and gives the embryo its specific orientation.
- The three germ layers are the ectoderm, mesoderm, and endoderm, and are formed as three overlapping flat discs.
- Neurulation refers to the folding process whereby the neural plate is transformed into the neural tube.
- Organogenesis is the development of the organs that begins during the third to eighth week and continues until birth.
- Haematopoietic stem cells that give rise to all the blood cells develop from the mesoderm.
- Blood islands develop outside the embryo, on the umbilical vesicle, allantois, connecting stalk, and chorion, from mesodermal hemangioblasts.
- The development of the nervous system begins with the formation of the neural plate, which serves as the basis for the nervous system.
- The heart starts to beat and pump blood at around 22 days.
- The respiratory system develops from the lung bud, which appears in the ventral wall of the foregut about four weeks into development.
- Three different kidney systems form in the developing embryo: the pronephros, the mesonephros and the metanephros.
- The superficial layer of the skin, the epidermis, is derived from the ectoderm.
- Late in the fourth week, the superior part of the neural tube bends ventrally as the cephalic flexure at the level of the future midbrain.
- The face and neck develop from the third to the eighth week.
- The inner ear, middle ear, and outer ear have distinct embryological origins.
- The digestive system starts to develop from the third week and by the twelfth week, the organs have correctly positioned themselves.
- The urinary system develops through the formation of the pronephros, mesonephros, and metanephros.
- Cranial neural crest cells migrate to the pharyngeal arches as neural stem cells, where they develop into neurons.
- Eye development occurs from the third to tenth week of embryonic development.
- Limb development begins at the end of the fourth week.
- Limb buds consist of ectoderm and mesenchyme.
- The progress zone is an area of rapidly proliferating mesenchymal cells.
- Toxic exposures during embryonic period can cause major congenital malformations.
- Preimplantation genetic diagnosis allows selection of embryos without defined genetic diseases.
- Sacrococcygeal teratomas are related to primitive streak remnants.
- First arch syndromes are caused by the failure of neural crest cells to migrate.
- Spina bifida is a result of incomplete neural tube closure.
- Vertically transmitted infections can be passed from mother to unborn child at any stage of development.
Test your knowledge on human embryonic development with this informative quiz. From fertilization to organogenesis, this quiz covers the key stages and processes involved in the formation of a human embryo. Challenge yourself with questions on the germinal stage, gastrulation, neurulation, and much more. Discover how the different organ systems develop and the potential risks and complications that can arise during embryonic development. Whether you're a student of biology, medicine, or simply curious about the miracle of life, this quiz is
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