Embryology: Principles Flashcards

1
Q

how long does pregnancy last

A

9 months, 38-40 weeks, 3 trimesters

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2
Q

what period are weeks 0-3

A

conceptus/embryo

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3
Q

what period are weeks 3-8

A

embryonic period

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4
Q

what period are weeks 9-40

A

foetal period

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5
Q

what are the 6 phases of embryogenesis (in order)

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

gamete

A

cell with a chromosome complement of 23 (haploid)

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7
Q

spermatogenesis

A

formation of male gametes

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8
Q

when does spermatogenesis occur

A

at puberty and continues throughout life

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9
Q

how long is once cycle of spermatogenesis

A

~64 days

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10
Q

production of sperm (increases/decreases) with age

A

decreases

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11
Q

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

A

22 X/Y

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12
Q

oogenesis

A

formation of female gametes

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13
Q

when does oogenesis occur

A

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

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14
Q

when is female reproductive life span determined

A

in foetal life

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15
Q

fertilisation

A

fusion of female and male gametes to form zygote

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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

20
Q

blastocyst

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
when are the basis of all organs and systems in place
end of embryonic period (develops throughout foetal period)
26
what happens in the foetal period (5)
- weight gain (3rd trimester) and growth (2nd trimester) - tissues mature and become functional - sexual differentiation - bone laid down - connections made in CNS
27
what are the 6 primary processes
- cell division - differentiation - apoptosis - cell migration - induction - cell attachment
28
cell attachments
physical/functional linkages, formation of tissues
29
induction
ability of one cell to cause another to differentiate
30
name the 2 secondary processes
- axis formation/polarity | - folding/rotation
31
axis formation/polarity
which way is which - cells know where they are in relation to others and the embryo
32
folding/rotation
entire embryo and strictures fold allowing formation of complex organ structures and giving the embryo its 3D structure
33
what 3 factors control development of the embryo
- genetic - epigenetic - environmental
34
epigenetic
preferential expression of either maternal or paternal genes