Back to AI Flashcard MakerAnatomy and Physiology /Histology Pre-Embryonic - Reverse Part 2
Histology Pre-Embryonic - Reverse Part 2
This deck covers key concepts and events in early embryonic development, focusing on the formation of various embryonic structures and processes.
a short lived combination of hypoblast cells and extracellular matrix. At day 9-10 of embryonic development, cells from the hypoblast begin to migrate to the embryonic
exocoelomic membrane
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Key Terms
Term
Definition
a short lived combination of hypoblast cells and extracellular matrix. At day 9-10 of embryonic development, cells from the hypoblast begin to migrate to the embryonic
exocoelomic membrane
forms adjacent to the hypoblast, and spaces appear in it which unit to form the large chorionic cavity (CC).
Extraembryonic mesoderm (EM)
"pinched off" from the pYS (primary yolk sac)
secondary (definitive) yolk sac (sYS)
hypoblast cells which have migrated to line the blastocyst cavity. It later becomes secondary yolk sac after part of it is pinched off. Thereafter its remnants degenerates.
Primary yolk sac
Zygote formed after fertilization in ampulla of uterine tube
Day 1
Morula enters uterus
Day 4
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| Term | Definition |
|---|---|
a short lived combination of hypoblast cells and extracellular matrix. At day 9-10 of embryonic development, cells from the hypoblast begin to migrate to the embryonic | exocoelomic membrane |
forms adjacent to the hypoblast, and spaces appear in it which unit to form the large chorionic cavity (CC). | Extraembryonic mesoderm (EM) |
"pinched off" from the pYS (primary yolk sac) | secondary (definitive) yolk sac (sYS) |
hypoblast cells which have migrated to line the blastocyst cavity. It later becomes secondary yolk sac after part of it is pinched off. Thereafter its remnants degenerates. | Primary yolk sac |
Zygote formed after fertilization in ampulla of uterine tube | Day 1 |
Morula enters uterus | Day 4 |
Implantation of blastocyst begins | Day 6 |
Positive pregnancy test, detectable hCG levels. | Day 8 |
1. Implantation completed (uteroplacental circulation established) 2. Bilaminar disc formed (hypoblast & epiblast appear). | End of Week 2 |
Extraembryonic mesoderm + cytotrophoblast + syncytiotrophoblast | chorion = |
blastocyst cavity, embryoblast, trophoblast, embryonic/abembryonic poles | Blastocyst |
gastrulation, neuralation, body folding | Week 3 Events |
Loosely arranged, migratory. formed via epithelial-mesenchymal transformation at the primitive streak & node | mesenchymal cells |
sites of epiblast invagination. regress & degenerate at the end of week 4 when gastrulation completes. | Primitive streak and node |
head-tail axis | Cephalocaudal |
front-back axis | Ventral-dorsal |
Cephalocaudal, Ventral-dorsal, left-right | body axes |
future mouth | oropharyngeal membrane |
future anus | cloacal membrane |
structure which includes the transformation of the neural plate into the neural tube. induces formation of neural tube (future brain, spinal cord) | Neurulation |
failure of rostral neuropore to close | Anencephaly |
failure of caudal neuropore to close | Spina bifida |
Forms gut tube from endoderm and mesoderm around the secondary yolk sac. Also forms intraembryonic cavity. | Lateral body folding |
becomes thoracic and abdominopelvic cavities, froms during lateral body folding | intraembryonic cavity |
Relocates primitive mouth and heart to adult position, is driven by longitudinal growth of the neural tube | Cephalocaudal body folding |
helps the embryo exchange gases and handle liquid waste. | Allantois |
Tail regresses, limbs elongate & rotate, digits appear; face develops. Organogenesis. Greatest risk of birth defects in week 5. | Week 4 to 8 |
gametes and epithelial cells lining digestive organs, respiratory airways, and some urogenital passages. | Endoderm |
epidermis & its derivatives (hair, nails, glands) | Surface Ectoderm |
neural tube gives rise to the brain and spinal cord. | Neuroectoderm |
differentiates into somites (somitomeres in head region), becomes dermis, skeletal muscle, vertebrae & ribs. lateral to (at the side of) the neural tube. | Paraxial Mesoderm |
urogenital system (majority) | Intermediate mesoderm |
CT of body wall & limbs | Lateral plate mesoderm (parietal layer) |
GI/respiratory organs (excelpt epithelial lining) | Lateral plate mesoderm (visceral layer) |
fluid rich ECM with multipotent mesenchymal cells | Mesenchyme |
bilaterally paired blocks of paraxial mesoderm that form along the anterior-posterior axis of the developing embryo. They give rise to sclerotome, myotome, dermatome for each body segment. | Somites |
cleveage, compaction, morula formed, cavitation, blastocyst formed, zona pellucida hatching, implantation initiated | Week 1 Cellular Events |
axial skeleton | sclerotome |
dermis | dermatome |
skeletal muscle | myotome |