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Y3 repro > repro embryology > Flashcards

repro embryology Flashcards

1
Q

what forms the urogenital system

A

intermediate plate mesoderm

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2
Q

how is the timeline for reproductive organogenesis different to the other systems

A

extends beyond 8 weeks

extends beyond post-natal period

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3
Q

which system forms the template for parts of the reproductive system

A

urinary system

the 2 systems have close embryological links

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4
Q

how many sets of kidneys develop

A

3

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5
Q

what are the 3 sets of kidneys that develop embryologically

A

pronephros - cervical region, vestigial
mesonephros - thoracolumbar region, briefly functional
metanephros - pelvic region, functional

each acts as a template for subsequent stage

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6
Q

which set of kidneys does the reproductive system develop from

A

mesonephros

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7
Q

when does genital (gonadal) ridge formation occur

A

week 5-6

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8
Q

what occurs during genital ridge formation

A

6wks - mesonephros forms along ovoid structure in association with thoracic and upper lumbar vertebrae
medial part of mesonephrc ridge becomes thickened to form a gential ridge

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9
Q

germ cells and the genital ridge

A

germ cells migrate into the genital ridge to form the indifferent gonad
stem cells embed into primitive sex cords (formed from mesenchyme of genital ridges)

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10
Q

where do the migrating stem cells come from

A

yolk sac via dorsal mesentery

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11
Q

what happens if the germ cells don’t migrate

A

no gonads are formed

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12
Q

why is it known as an indifferent gonad at this stage

A

there is no differentiation yet between male and female

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13
Q

formation of the paramesonephric duct

A

epithelium of the mesonephros invaginates to form a tube

this tube becomes the paramesonephric duct

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14
Q

where does the paramesonephric duct develop

A

lateral to developing gonads and existing mesonephric duct

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15
Q

describe the shape of the paramesonephric duct

A

funnel shaped cranial end
opens into peritoneal cavity

caudally, crosses ventral to mesonephric ducts
this projects into the dorsal wall of urogenital sinus

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16
Q

3 primitive structures of reproductive system

A

indifferent gonad
mesonephric duct
paramesonephric duct

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17
Q

alternative name for mesonephric duct

A

Wolffian duct

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18
Q

alternative name for paramesonephric duct

A

Mullerian duct

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19
Q

what do the primitive reproductive structures develop into in males

A

indifferent gonad - testes
mesonephric duct - vas deferens, seminal vesicles grow as outpouchings from mesonephric duct
paramesonephric duct - disappears
urogenital sinus forms bladder, urethra and prostate

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20
Q

what do the primitive reproductive structures develop into in females

A

indifferent gonad - ovaries
mesonephric duct - disappear
paramesonephric duct - fallopian tube, uterus and cervix
urogenital sinus forms bladder and lower part of vagina

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21
Q

what determines whether the indifferent gonads become male testes or female ovaries

A

chromosomes - XX or XY

Y chromosome has an SRY region - sex determining region

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22
Q

what protein does SRY encode for

A

encodes for a protein called TDF - testis determining factor

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23
Q

which cells express the SRY

A

primordial supporting cells (within the sex cords of the indifferent gonad) express the SRY

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24
Q

what are the actions of TDF

A

makes indifferent gonad develop into a testis

transforms primordial cells into sertoli cells

25
Q

what do sertoli cells secreting

A

MIS - mullerian inhibiting substance

26
Q

what are the actions of MIS

A

causes paramesonephric duct to degenerate

causes cells in interstitium to transform into Leydig cells

27
Q

what do Leydig cells secrete and what is the result of this

A

testosterone

helps in further development of male external genitalia

28
Q

timeline for testis development - wk5-6

A

wk5 - 1y sex cords, medulla and cortex

wk6 - primordial germ cells incorporated into 1y sex cords

29
Q

timeline for testis development -wk7

A

TDF stimulates 1y sex cords -> extend into medulla -> seminiferous cords -> tubules
seminiferous cords branch, ends anastamose -> rete testis of medulla
mesothelium lost when thick capsule forms (tunica albuginea)
mesenchyme between cords gives rise to interstitial cells of Leydig

30
Q

timeline for testis development -wk8

A

Leydig cells produce testosteroneand other hormones -> stimulates masculine differentiation of mesonephric ducts and external genitalia

paramesonephric duct degenerates in males

31
Q

where do the seminal vesicles grow from

A

outgrowth from caudal end of mesonephric duct

32
Q

where does the prostate grow from

A

outgrowth from urethra (from urogenital sinus)

33
Q

why does the indifferent gonad become the ovary in females

A

no SRY region, absence of TDF

gonad develops into an ovary by default

34
Q

development of the ovary, up to wk10

A

1y sex cords degenerate, leaving primordial germ cells

wk 10 - 2y sex cords develop from surface epithelium, primordial germ cells are incorporated

35
Q

development of the ovary - wk16

A

primordial germ cells bud off with single surrounding layer of cortical cord cells to form primordial follicles
active mitosis of these early primordial follicles to form additional follicles

36
Q

development of the ovary - 7mths-birth

A

7mths - all follicles have formed
oocytes enter meiosis and arrested in prophase 1st meiotic division
some follicular atresia by birth

37
Q

post-natal ovarian development

A

many follicles become atretic before puberty
after puberty - hormonal influences stimulate 12-15 follicles for each cycle to develop
only 1 follicle reaches maturity and ovulation
continues until menopause

38
Q

how many primordial follicles present in the ovary at birth

A

~2mln

39
Q

where do the tubular components of the female reproductive system come from

A

absence of testosterone - degeneration of mesonephros and mesonephric duct
paramesonephric ducts develop to give rise to female genital tract

40
Q

origin of female genital tract

A

cranial end of paramesonephric duct becomes associated with ovary
caudal end of paramesonephric ducts (uterovaginal primordium) becomes uterus and superior part of vagina
inferior part of vagina from urogenital sinus
mesonephric duct degenerates

41
Q

where do the gonads initially form

A

lumbar region

positional changes occur as development takes place

42
Q

descent of gonads - testis

A

wk7 - T10 level, diaphragm undescended
wk12 - level of deep inguinal ring, remains until 7mths
39wks - enters scrotum

43
Q

descent of gonads - ovaries

A

wk7 - T10
wk12 - broad ligament
round ligament drawn through inguinal canal to attach to labrum majorum

44
Q

what causes the descent of the testis

A

gubernaculum - fibrous cord

shortens and contracts and pulls the testis down through the abdominal wall via inguinal canal into the scrotum

45
Q

how can intestinal contents pass through the inguinal canal

A

processus vaginalis not completely closed off
weak point
intestinal contents pass through deep ring and inguinal canal and out through superficial ring
indirect inguinal hernia

46
Q

what is linked to the descent of the gonads

A

male - formation of larger inguinal canal, more likely to develop hernias
female - presence of round ligament and its passage through the inguinal canal

47
Q

gubernaculum in females

A

pulls the ovary down from original thoracolumbar region to pelvis
once in the pelvic cavity it stops contracting
then degenerates and forms fibrous cord - ovarian ligament and round ligament

48
Q

why are females less prone to developing inguinal hernias

A

ovary doesn’t pass through inguinal canal

inguinal canal in females is narrower

49
Q

3 examples of congenital abnormalities

A

undescended testis
remnants of mesonephric duct in females e.g. gartner’s cysts
anomalies of paramesonephric duct in female

50
Q

what is cryptorchidism

A

abscence of testes in scrotum

51
Q

4 types of crytptorchidism

A

undescended
ectopic
retractile testis
absent testes

52
Q

3 complications of undescended testis

A

infertility
malignant transformation - germ cell tumours
testicular torsion

53
Q

locations of undescended testis

A

abdominal
inguinal
prescrotal (prepubic)

54
Q

management of undescended testis

A

orchiopexy

55
Q

where can remnants of the mesonephric ducts in females occur

A

epoophoron - near the ovary
paraoophoron - within the broad ligament
Gartner’s cyst - close to vagina

56
Q

impacts of remnants of the mesonephric ducts

A

can impact female fertility

57
Q

anomalies of paramesonephric duct

A

complete duplication - 2 vagina, 2 uteri with one tube each
bicornuate uterus
septate uterus
arcuate uterus

58
Q

impacts of anomalies of paramesonephric duct

A

can all affect implantation of fertilised embryo

Y3 repro (47 decks)

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