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Repro > Embryogenesis of Pituitary Gland and Reproductive Tract > Flashcards

Embryogenesis of Pituitary Gland and Reproductive Tract Flashcards

1
Q

what 3 features does the primitive embyro brain have?

A
  1. infundibulum
  2. Rathke’s pouch
  3. stomodeum
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2
Q

is the infundibulum in the primitive brain the same as the one in the oviduct?

A

no

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3
Q

what is the stomodeum?

A

embryonic mouth

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4
Q

in the first stage of development of the pituitary gland, what is happening?

A
  1. infundibulum starts to grow down to Rathke’s puch

2. Rathke’s pouch grows up towards infundibulum

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5
Q

what happens in the second stage pf pituitary gland development?

A
  1. infundibulum keeps growing down

2. Rathke’s stalk regresses to separate it from embyronic mouth

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6
Q

what happens in the 3rd stage of pituitary gland development?

A

sphenoid bone develops around Rathke-infundibulum structure

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7
Q

what happens in the final stage of embryonic pituitary gland development?

A

the sella turcica is formed, which is a pocket that contains what is now called the pituitary gland

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8
Q

where does the posterior pituitary come from?

A

infundibulum of brain

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9
Q

where does the anterior pituitary come from?

A

Rathke’s pouch

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10
Q

what happens to the primordial germ cells of the yolk sac during embyonic development?

A

they migrate to the genintal/gonadal ridge (in the midgut)

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11
Q

what do the primordial germ cells become once they settle at the genital/gonadal ridge?

A

primitive sex chords

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12
Q

list the order of kidneys in embryonic development and their fates

A
  1. pronephros: regresses
  2. mesonephros: becomes portions of the repro tract
  3. metenephros: will become adult kidney and urinary ducts
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13
Q

what was done in the Jost experiments?

A

embyros were castrated prior to fetal development

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14
Q

what was found about the paramesonephric/mullerian ducts in the Jost experiments?

A

they became structures of female tract

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15
Q

what was found about the mesonephric/wolffian ducts in the Jost experiments?

A

they became structures of the male tract

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16
Q

when both ducts were castrated in the Jost experiments, what was the default setting of an embryo?

A

female

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17
Q

list the order of sex determination (5)

A
  1. chromosomal sex
  2. gonadal sex
  3. hormonal sex
  4. phenotypic sex
  5. brain and/or behavioral sex
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18
Q

what animals have a single pair of sex chromosomes?

A

mammals and avians

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19
Q

for what animals is sex environmentally determined? (temp affects sex)

A

sea worms, fish, reptiles

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20
Q

what animals have multiple sex chromosomes?

A

invertebrates, insects, reptiles

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21
Q

what does haplodiploidy mean?

A

only females have sex chromosomes

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22
Q

what animals are haplodiploidy?

A

bees, spiders

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23
Q

what chromosome determines sex in mammals?

A

Y, only need one Y to be a male

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24
Q

what is the important gene on the Y chromosome that codes for testis determining factor?

A

SRY gene

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25
Q

what does testis determining factor cause? (3)

A
  1. primary sex chord (seminiferous tubule) development
  2. sertoli cell development
  3. anti-mullerian hormone production by sertoli cells
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26
Q

what does testis determining factor do? (2)

A
  1. codes for a DNA binding protein

2. acts as a transcription factor

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27
Q

what happens in the absence of SRY?

A

secondary sex chords (egg nests) develop

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28
Q

name 3 things that other genes on the Y chromosome are responsible for

A
  1. spermatogenesis
  2. androgen production
  3. long bone growth
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29
Q

why are males taller on average than females?

A

because the SRY gene codes for long bone growth

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30
Q

what is different about the sex chromosomes of birds?

A

the female is the heterozygote (ZW) and the male is the homozygote (ZZ)

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31
Q

where is the SRY gene found in birds (on which chromosome)?

A

on the Z chromosome

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32
Q

is SRY the only sex determining gene in birds? why or why not?

A

it is not, because it is found on the Z chromosome, which both males and females have

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33
Q

in testicular development, what is found in/develops from the primary, epithelial, or medullary sex chords? (2)

A
  1. primordial germ cells (gonocytes)

2. pre-sertoli cells

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34
Q

what do gonocytes (primordial germ cells) become?

A

spermatogonia

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35
Q

what is AMH?

A

anti-mullerian hormone

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36
Q

what are the 2 functions of AMH?

A
  1. leydig cell differentiation

2. degeneration of Mullerian duct

37
Q

from which germ layer does the prostate derive?

A

the ectoderm

38
Q

list the flow of development of an XY male (6)

A
  1. testis determining factor (SRY gene product)
  2. testes develop
  3. sertoli cells secrete anti-mullerian hormone (AMH)
  4. AMH causes leydig cell differentiation and mullerian duct degeneration
  5. leydig cells produce testosterone
  6. testosterone causes development of the male duct system
  7. testosterone is combine with 5a reductase to form dihydrotestosterone, which causes development of penis, scrotum, and accessory sex glands (prostate, cowper’s)
39
Q

what are the 3 components of the male duct system?

A
  1. epididymis
  2. vas deferens
  3. seminal vesicles
40
Q

list the flow of development of an XX female (4)

A
  1. no TDF, bc no SRY gene
  2. ovaries develop in absence of TDF
  3. lack of testosterone causes wolffian duct to regress
  4. no AMH leads to Mullerian ducts becoming female repro organs
41
Q

what female organs develop from the mullerian ducts? (4)

A
  1. oviducts
  2. uterus
  3. cervix
  4. anterior region of vagina
42
Q

what happens to the Mullerian ducts as they develop in females?

A

originally two ducts, one on each side of repro tract, will either form uterine horns or fuse depending on species

43
Q

where does the female repro tract develop?

A

outside the peritoneum

44
Q

how does the broad ligament form?

A

the peritoneal cavity, with the membrane, pulls together, and fuses into broad ligament

45
Q

when does external genitalia become distinctly male or female?

A

around week 7-8 of gestation

46
Q

what allows for the female phenotype?

A

absence of dihydrotestosterone

47
Q

what big thing needs to form in the brain to distinguish male from female?

A

female hypothalamus needs surge center

48
Q

what happened to female rats when they were given testosterone shortly after birth?

A

they failed to copulate or cycle normally like females as adults

49
Q

what type of nucleus was found in female rats given testosterone shortly after birth? what does this mean?

A

sexually dimorphic nucleus, some male and some female traits in hypothalamus

50
Q

list three differences in behavior between males and females

A
  1. aggression
  2. childhood play
  3. 3D visual rotation- males usually better
51
Q

what gender is the hypothalamus inherently?

A

inherently female

52
Q

what must males do to their surge centers?

A

must “defeminize” surge center to make it inoperative

53
Q

how do males defeminize their surge centers?

A
  1. testosterone crosses the blood-brain barrier, is converted to estradiol and defeminizes the surge center
  2. androgens (produced postnatally) polish off the process
54
Q

what is Alpha-fetoprotein (AFP)?

A

a protein that binds estradiol and prevents it from crossing the blood-brain barrier

55
Q

where is AFP produced? (2)

A

in the embryonic yolk sac and fetal liver

56
Q

what type of protein is AFP?

A

a glycoprotein

57
Q

do males produce AFP? how does that affect them?

A

they do, it just doesn’t do much in males

58
Q

why does AFP not do much in males?

A

AFP is not interested in testosterone, so testosterone can cross the blood brain barrier and defeminize surge center once converted to estradiol

59
Q

sum up brain differentiation is males (6)

A
  1. testis produces testosterone (T)
  2. T crosses blood brain barrier
  3. T is converted to estradiol by aromatase
  4. estradiol defeminizes hypothalamus
  5. androgen exposure is necessary postnatally
  6. hypothalamus now has tonic center only
60
Q

sum up brain differentiation in females (5)

A
  1. ovary produces estradiol
  2. AFP binds estradiol
  3. binding prevents estradiol from crossing blood-brain barrier
  4. surge center forms bc hypothalamus not defeminized
  5. hypothalamus now has tonic and surge center
61
Q

how does testicular descent begin?

A

with fusion of peritoneum and gubernaculum

62
Q

what happens to the gubernaculum once fused with peritoneum?

A

rapid, visceral growth of testis in the scrotal cavity

63
Q

what does regression of the gubernaculum cause?

A

causes testis to pull down from bottom, testis pulled onto scrotum

64
Q

when the gubernaculum is fully regressed, describe the space between the visceral and parietal tunica vaginalis?

A

continuous with peritoneum

65
Q

give 2 problems that can occur with testicular descent

A
  1. cryptorchid

2. inguinal hernia

66
Q

describe heritability of cryptorchidism

A

highly heritable

67
Q

give the 2 type of cryptorchidism

A
  1. unilateral

2. bilateral

68
Q

what is the fertility of a unilateral cryptorchid?

A

one testis fails to descend, but one is still fertile

69
Q

what is the fertility of a bilateral cryptorchid?

A

when both testes fail to descend, never fertile if not corrected before puberty

70
Q

what risk comes with cryptorchidism?

A

higher percentage develop testicular cancer

71
Q

what does surgical correction of cryptorchidism do? what does it not do?

A

can fix fertility, but does not decrease cancer risk

72
Q

describe an inguinal hernia

A

part of intestine gets pulled into scrotum with testes during testicular descent

73
Q

what causes cryptorchidism?

A

germ cells fail to multiply and then die, leaving sertoli cells only in seminiferous tubules

74
Q

what can happen as a result of an inguinal hernia?

A

blood supply to intestine is cut off, resulting in necrosis and an incomplete digestive system

75
Q

when does a freemartin happen?

A

female born twin to a bull

76
Q

what happens placentally with a freemartin?

A

placenta membranes fuse and share a common blood supply

77
Q

what does the shared blood supply of a freemartin and her bull twin cause and why?

A

since testes develop first, female will be exposed to testosterone and anti-mullerian hormone before her own ovarian formation

78
Q

what happens to the twins when a freemartin is rpesent?

A

animals are chimeric (WBC from other twin), and TDF (SRY) is expressed in both individuals

79
Q

describe the ovaries of a freemartin

A

ovaries do not grow but are chimeric, are ovotestis!

80
Q

what is the result of ovotestes, hormonally and genetically?

A

SRY and therefore AMH and testosterone are produced, causing further changes and adult male behavior

81
Q

what does the AMH from the bull twin do to a freemartin?

A

blocks mullerian ducts, resulting in formation of a posterior vagina only, but on anterior vagina, no cervix, no uterus, etc.

82
Q

what does the testosterone from the bull twin do to a freemartin?

A
  1. clitoral enlargement

2. brain changes like that of a male

83
Q

what can freemartins be used for due to their adult male behavior?

A

estrus detectors!

84
Q

are all freemartin abnormalities the same?

A

no, they exist on a continuum

85
Q

what causes complete androgen sensitivity in an XY individual?

A

no androgen receptor

86
Q

will testes still produce testosterone in an XY individual with no androgen receptor? what is the result?

A

yes, but no testosterone response so no Wolffian duct development

87
Q

is AMH still present in an XY individual with an no androgen receptor? what is the result?

A

yes, will cause Mullerian ducts to regress, meaning external genitalia will be female due to lack of androgen

88
Q

what is a 5a reductase deficiency in an XY individual called?

A

guevodoces

89
Q

describe what happens in guevodoces

A
  1. testis produce T
  2. AMH is present so Mullerian ducts regresses
  3. Wolffian ducts develop normally
  4. pseudovagina and female external genitalia
  5. at puberty may differentiate into more of a phenotypic male

Repro (18 decks)

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