Embryology: Principles Flashcards Preview

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Flashcards in Embryology: Principles Deck (34)
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1
Q

how long does pregnancy last

A

9 months, 38-40 weeks, 3 trimesters

2
Q

what period are weeks 0-3

A

conceptus/embryo

3
Q

what period are weeks 3-8

A

embryonic period

4
Q

what period are weeks 9-40

A

foetal period

5
Q

what are the 6 phases of embryogenesis (in order)

A
  • gametogenesis
  • fertilisation
  • cleavage
  • gastrulation
  • formation of a body plan
  • organogenesis
6
Q

gamete

A

cell with a chromosome complement of 23 (haploid)

7
Q

spermatogenesis

A

formation of male gametes

8
Q

when does spermatogenesis occur

A

at puberty and continues throughout life

9
Q

how long is once cycle of spermatogenesis

A

~64 days

10
Q

production of sperm (increases/decreases) with age

A

decreases

11
Q

sperm contain how many chromosomes and what sex chromosome(s)

A

22 X/Y

12
Q

oogenesis

A

formation of female gametes

13
Q

when does oogenesis occur

A

starts in development (arrests in prophase of meiosis) and begins again in puberty, stopping in menopause

14
Q

when is female reproductive life span determined

A

in foetal life

15
Q

fertilisation

A

fusion of female and male gametes to form zygote

16
Q

zygote

A

diploid cell with full chromosome complement

17
Q

cleavage

A

rapid mitotic cell division with NO increase in size (stays in same area as original zygote)

18
Q

the zygote forms a _ then _

A

morula, blastocyst

19
Q

morula

A

16+ cells

20
Q

blastocyst

A

days 1-4

21
Q

gastrulation

A

formation of germ layers and boxy axes established

22
Q

germ layers

A

ectoderm (external), mesoderm (middle) and endoderm (internal)

23
Q

formation of body plan

A

embryonic folding

24
Q

organogenesis

A

formation of organs and organ systems

25
Q

when are the basis of all organs and systems in place

A

end of embryonic period (develops throughout foetal period)

26
Q

what happens in the foetal period (5)

A
  • weight gain (3rd trimester) and growth (2nd trimester)
  • tissues mature and become functional
  • sexual differentiation
  • bone laid down
  • connections made in CNS
27
Q

what are the 6 primary processes

A
  • cell division
  • differentiation
  • apoptosis
  • cell migration
  • induction
  • cell attachment
28
Q

cell attachments

A

physical/functional linkages, formation of tissues

29
Q

induction

A

ability of one cell to cause another to differentiate

30
Q

name the 2 secondary processes

A
  • axis formation/polarity

- folding/rotation

31
Q

axis formation/polarity

A

which way is which - cells know where they are in relation to others and the embryo

32
Q

folding/rotation

A

entire embryo and strictures fold allowing formation of complex organ structures and giving the embryo its 3D structure

33
Q

what 3 factors control development of the embryo

A
  • genetic
  • epigenetic
  • environmental
34
Q

epigenetic

A

preferential expression of either maternal or paternal genes

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