Formation of Intraembryonic Mesoderm; Notochord Flashcards Preview

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Flashcards in Formation of Intraembryonic Mesoderm; Notochord Deck (11):
1

What is the name of the process by which the intreembryonic mesoderm forms?

What larger process is it the 1st step of?

What triggers it?

Gastrulation - bilaminar > trilaminar disc

- 1st step of morphogenesis the development of bodily form

- triggered by Bone Morphogenetic Proteins (BMPs)

2

What are the 3 main steps of gastrulation?

  1. Primitive Streak Formation
  2. Germ Layer Formation
  3. Notochord Formation

3

How/when does the primitive streak form?

Include all the parts of it.

Beginning of 3rd week:

  1. epiblast cells proliferate and migrate to median plane caudocranially
  2. cranial end proliferates more to form primitive node
  3. primitive groove + pit form in streak + node (respectively) via epiblast invagination

4

When does the primitive streak eventually disappear?

end of 4th week

5

How do the germ layers of the trilaminar disc form?

(Special kinds of cells, signal molecules, movements, etc.)

  1. epithelial-to-mesenchymal transition (EMT) occurs to epiblast cells via FGF8
  2. mesenchymal cells migrate downard and become mesoblast
  3. TGF-B induces mesoderm formation from mesoblast
  4. mesenchymal cells displace hypoblast to form endoderm and epiblasts become ectoderm

6

What happens to the shape of the embryo during gastrulation?

as primitive streak + notochord form it moves through 3 general shapes

  1. egg
  2. pear
  3. slipper

 

7

What is the acronym for notochord formation?

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  1. Process - prim. pit invaginates > notochordal process 
  2. Canal - pit extend to form notochordal canal
  3. Fusion - noto. process floor fuses with endoderm
  4. Degeneration - holes form in fused layers btwn canal + yolk sac
  5. Plate - holes fuse, floor disappears, roof  = notochordal plate
  6. Infolding - noto. plate infolds cranio-caudally to form notochord
  7. Neurenteric Canal - neur. canal briefly remains at site of prim. pit
  8. Detachment - notochord fully detaches from endoderm and remains in mesoderm

8

What appears around day 16 in the caudal wall of the yolk sac?

What are its functions?

What does it become?

allantois - diverticulum of yolk sac > connecting stalk

- remains small in humans b/c its respiratory/urinary functions done by placenta + amniotic sac

- involved in early blood formation + development of bladder

- becomes urachus + median umbilical ligament

- its vessels become umbilical arteries + veins

 

9

What are some of the derivatives of the ectoderm?

  • epidermis
  • CNS
  • PNS
  • sensory epithelia
  • otic + lens placodes

10

What are the derivatives of the endoderm?

  • GI epithelium
  • Glands of GI (liver, pancreas)
  • Resp. epithelium
  • Tonsils
  • Tympanic Epithelium
  • Thyroid Gland

 

GGRTTTh - Growth

11

What are some derivatives of the mesoderm?