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Year 1 Week 12 - Embryology > Embryology 1 - Gametogenesis > Flashcards

Embryology 1 - Gametogenesis Flashcards

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1
Q

a working definition of ‘sex’

A

blending genetic characteristics of two individuals of the n^th generation to create the (n+1)^th generation

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2
Q

disadvantages of sex

A

need to find a partner
dilution of a ‘perfect’ set of genes

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3
Q

advantages of sex

A

each individual has a new mix of genes that give it immunity to pathogens - the red queen syndrome
each individual has a new mix of genes that determine its environmental interactions

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4
Q

female gametes

A

not many, large gametes - ova
provide nurture - yolk, placenta, milk

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5
Q

male gametes

A

many small gametes - spermatozoa
provides nurture behaviourally or not at all

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6
Q

general strategy of sexual reproduction

A

single gametes fuse to form a single cell which then divides many times

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7
Q

germ line

A

produce gametes

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8
Q

somatic cells

A

produce everything other than gametes

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9
Q

what does myoid mean

A

muscle like

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10
Q

spermatogonia

A

stem cells
some differentiate into spermatocytes which differentiate into sperm cells

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11
Q

sertoli cells

A

provide metabolic support

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12
Q

spermatogenesis

A

proliferation of germ line stem cells by mitosis
reduction to haploid state by meiosis
differentiation into mature spermatozoa

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13
Q

mitotic proliferation

A

begins at puberty
produces about 10,000 sperm per second
typically about 10^8 sperm/ml of semen

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14
Q

where does mitotic proliferation take place

A

in the basal side of the tubule - the side furthest from the lumen

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15
Q

what does the hypothalamus secrete for mitotic proliferation

A

gonadotrophin releasing hormone - GnRH

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16
Q

what does the anterior pituitary gland secrete for mitotic proliferation

A

follicle stimulating hormone (FSH) and luteinising hormone (LH)

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17
Q

what does FSH act on

A

sertoli cells

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18
Q

what does LH act on

A

leydig’s cells

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19
Q

what does testosterone act on

A

sertoli cells

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20
Q

what would an immune response against sperm result in

A

subfertility

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21
Q

when does sperm production begin

A

at puberty

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22
Q

what prevents sperm cells reaching immune system

A

immune cells on luminal side
continuous tight junctions

23
Q

orch-

A

prefix for testis
e.g. orchidectomy, cryporchidism
named after orchid

24
Q

maturation of sperm

A

sperm are shed and flow to epididymis (by moving passively along tubules) which alters seminal fluid
epididymal secretions (glycoproteins etc) activate sperm and make them capable of swimming

25
Q

features of the female reproductive system

A

uterus
vagina
oviduct = fallopian tube
ovary
cervix uteri

26
Q

when do females have germ line stem cells

A

as foetuses but not as children or adults

27
Q

rate of female gamete production

A

13 per year

28
Q

rate of male gamete production

A

150 billion per year

29
Q

what are primordial follicles

A

oocytes surrounded by less differentiated squamous granulosa cells and are derived from oocyte nests

30
Q

what are primary follicles

A

oocytes surrounded by a single layer of cuboidal granulosa cells that have initiated follicle development

31
Q

what type of cells are granulosa cells

A

somatic cells

32
Q

when does the pituitary gland start producing FSH

A

puberty

33
Q

what is stimulated by FSH

A

some follicles resume development
a surge each month promotes development in around 50 or more follicles

34
Q

what happens during the primary follicle phase

A

oocyte grows and synthesises rRNA and mRNA. does not progress further through meiosis

35
Q

what is a ripening follicle

A

results in an increase in oestrogen levels, as oestrogen is secreted by follicular cells

36
Q

what happens during the ripening follicle phase

A

oocyte synthesises a glycoprotein zona pellucida, and granulosa cells multiply

37
Q

what are granulosa cells linked by

A

cytoplasmic bridges

38
Q

what do granulosa cells secrete

A

follicular fluid - forms fluid-filled ‘antrum’

39
Q

what does the developing follicle depend on

A

receiving a surge of LH from pituitary gland
thecal cells bind LH. cells dies without LH surge

40
Q

what does the LH surge stimulate

A

further maturation of the follicle to become a Graafian follicle at the surface of the ovary

41
Q

what kind of process is follicle death

A

an active process - will destroy itself

42
Q

what does atretic mean

A

dying follicle
from ‘atresia’ - withering

43
Q

process of preovulatory growth following LH surge

A

primary oocyte > completion of meiosis 1 > secondary oocyte > arrest in meiosis 2 > connection with granulosa lost
takes about 12 hours

44
Q

what happens once oocyte is mature

A

digests way out of edge of ovary and enters fallopian tube

45
Q

when is meiosis 2 complete

A

never unless fertilisation occurs

46
Q

what do the remains of the ruptured follicle become

A

the corpus luteum - looks yellow

47
Q

what does the corpus luteum do

A

produces hormones - progesterone, oestrogen - that prepare the lining of the uterus to receive an embryo
unless woman is pregnant, the CL dies after around a week

48
Q

what is the early antral stage

A

a ‘make or break’ time for each follicle
survival depends on adequate stimulation by FSH

49
Q

what happens if the antral follicle does not receive enough FSH

A

the follicle matures further to become a Graafian follicle at the surface of the ovary
becomes more sensitive to FSH, makes a signal back to pituitary gland with oestrogen to reduce FSH levels

50
Q

what do falling FSH levels prevent

A

recruitment of further follicles in that cycle - dominant follicle has increased sensitivity so still has enough FSH stimulation even with lower serum levels

51
Q

how many follicles usually mature

A

one

52
Q

what do oestrogen detection blocking drugs do

A

drive higher and longer duration production of endogenous FSH, and more follicles mature

53
Q

what does FSH ultimately do

A

prevents atresia at critical stage

54
Q

what does LH ultimately do

A

drives ovulation and maintains corpus luteum

Year 1 Week 12 - Embryology (5 decks)

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