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SF4 Exam 2 > Sexual Differentiation > Flashcards

Sexual Differentiation Flashcards

1
Q

male and female embryos contain duplicate sets of what?

A

genital ducts

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2
Q

the two sets of genital ducts in the embryo have the potential to become what

A

male or female internal genitalia

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3
Q

what determines whether an indifferent gonad develops into an ovary or testis

A

chromosomal content

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4
Q

development of embryonic structure into male and female reproductive organs and external genitalia depends on?

A

fetal hormone production

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5
Q

sex determination begins with what

A

commitment of the indifferent gonads to become testis or ovaries

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6
Q

sex chromosome complement of a person can be assessed how

A

maximum number of Barr bodies and fluorescent staining to detect Y-chromosomes

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7
Q

what gene is essential for promoting the differentiation of a biopotential gonad into testis

A

SRY (sex determining region on the y chromosome)

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8
Q

what are the pseudoautosomal regions of the Y chromosome

A

regions at the distal ends of the Y chromosome that are homologous to regions at the distal ends of the X chromosomes

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9
Q

where is the SRY gene located on the Y chromosome

A

close to the autosomal region on the short arm (p) of the Y chromosome

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10
Q

what sex chromosome is largest

A

X is much larger than Y

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11
Q

due to the size of the X chromosome what happens in each somatic cell of female embryos

A

one X is inactivated

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12
Q

what is an inactivated X called

A

Barr body

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13
Q

maximum number of barr bodies in a somatic diploid cell is equal to?

A

number of X chromosomes minus 1

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14
Q

the X chromosome from what parent is inactivated in female somatic cells

A

randomly occurs so 1/2 will have maternally-derived X chromosomes and 1/2 will have paternally-derived X chromosomes

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15
Q

what, if anything, escapes X inactivation

A

genes in pseudoautosomal regions of the X chromosomes

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16
Q

genital (gonadal) ridge

what is it

A

formed from epithelial and underlying mesenchymal cells proliferate making a thickened area along ventromedial surface of the mesonephros

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17
Q

primitive sex chords (what are they)

A

finger-like projections that proliferate from the epithelium into the underlying mesenchyme
(remains attached to epithelium during its early development)

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18
Q

genital (gonadal) ridge

when is it formed

A

5th week

form epithelium and underlying mesenchyme

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19
Q

before the 7th week gonads of both sexes are?

A

identical in appearance and referred to as indifferent gonads

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20
Q

indifferent gonad (parts)

A

external cortex

internal medulla

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21
Q

the precursor supporting cells of the indifferent embryo can differentiate into what

A 
Sertoli Cells (XY embryo)
Granolas Cells (XX embryo)
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22
Q

Primordial Germ Cells (PGCs)

where do they originate

A

outside the gonad

seen in yolk sac endoderm 3-4weeks post conception

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23
Q

Primordial Germ Cells (PGCs)

when and where do they migrate

A

5th week post conception

migrate from yolk sac ectoderm along dorsal mesentery of hindgut to the genital (gonadal) ridge

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24
Q

what happens to PGCs as they migrate

A

undergo cell division and extensive genetic reprogramming which involves the activation of genes and various epigenetic changes

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25
Q

what happens to PGCs as they enter developing genital (gonadal) ridge

A

rapidly surrounded by chords of somatic cells

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26
Q

Once surrounded by somatic cells PGCs commit to what

A

developmental pathway which leads them to become:
gonocytes (prespermatogonia)
oogonia

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27
Q

what determines the type of gonad the genial ridge will become

A

sex chromosomes present in somatic cells

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28
Q

what is the gene product of the SRY gene

A

a transcription factor

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29
Q

what is the major action of the transcription factor produced by SRY

A

SOX9 gene

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30
Q

SOX9 gene (what does it do where is it)

A 
master regulator of Sertoli cell differentiation
chromosome 17q (long arm)
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31
Q

in the formation of testis what differentiates and what regresses from the indifferent gonad

A

medulla differentiates

cortex regresses

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32
Q

in the formation of ovaries what differentiates and what regresses from the indifferent gonad

A

cortex differentiates

medulla regresses

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33
Q

what is the first discernible event of testis differentiation

A

appearance of Sertolic cells in medulla of indifferent gonad b/w 6-7 weeks of gestation

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34
Q

Stroll cells aggregate around what to form what

A

aggregate around gonocytes (PGCs of testis)

form testis cords

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35
Q

testis cords (what are they)

A

formed from Sertoli cells and gonocytes

precursors to seminiferous tubules

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36
Q

what happens to gonocytes within testis cords

A

enter mitotic arrest at 10-12 weeks

(most are differentiated in prespermatogonia

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37
Q

Leydig Cells (when and where do they appear)

A

functional leydig cells appear between developing seminiferous tubules b/w week 8 and 9

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38
Q

Sertoli Cells (what do they release)

A

paracrine factors that play a role in recruiting mesenchymal cells to developing testis

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39
Q

mesenchymal cells recruited to developing testis differentiate into what?

A

peritubular myoid cells
endothelial cells that form male-specific vasculature
Leydig cells

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40
Q

Lydia cells (what do they produce)

A

testosterone

Insulin-like 3(INSL-3)

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41
Q

seminiferous tubules can form in the absence of what

A

germ cells

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42
Q

meiosis of germ cells begins when in males

A

puberty

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43
Q

presence of more than one X with a Y does what

A

alters process of testicular development

44
Q

Klinefelter Syndrome (cause)

A

47, XXY male

caused my meiotic nondisjunction

45
Q

primitive sex cords later in development become what

A

tunica albuginea

46
Q

primitive sex cords give rise to what

A

testis cords which become seminiferous tubules and rete testis of the mature testis

47
Q

seminiferous tubules are what until puberty

A

solid

48
Q

differentiation of ovary from indifferent gonad requires what

A

invasion of cortex by primordial germ cells
reactivation of the inactivated X chromosome in the germ cells
absence of SRY gene

49
Q

When SRY absent but no germ cells or only one X what happen

A

ovary begins to differentiate but the developing ovary will regress

50
Q

ovarian dysgenesis is associated with what

A

45, X karyotype

Turner Syndrome

51
Q

PGCs that migrate to presumptive ovary do what

A

proliferate rapidly and differentiate into oogonia

52
Q

what happens to some oogonia in about 11 weeks gestation

A

leave pool of proliferating cells and enter into meiosis

53
Q

oogonia that leave pool and enter meiosis are known as what

A

primary oocytes

54
Q

meiosis of primary oocytes is arrested when

A

prophase of first meiotic division

55
Q

what happens to other oogonia with the onset of oogonial meiosis

A

atresia (form of programed cell death)

56
Q

primordial follicles (when do they arise)

A

week 13

57
Q

primordial follicles (how are they formed)

A

arise a pregranulosa cells aggregate to form a single layer of cells around the primitive oocyte

58
Q

number of germ cells in ovary peaks when and then what happens

A

20 weeks and then declines

59
Q

what leads to the decline in number go female germ cells after week 20

A

decrease in rate of oogonial mitosis
the atresia of oogonia that are not incorporated into follicles
the atresia of follicles that start to mature

60
Q

what happens to follicles that mature in utero

A

interrupted by follicular atresia

61
Q

all of primordial follicles that a woman will have are formed when?

A

by the time an infant is 6 months old

62
Q

seminiferous tubules develop when in gestation

A

6-7 weeks in

63
Q

leydig cells develop and secrete testosterone when in gestation

A

8-9 weeks

64
Q

oogenesis begins when in gestation

A

11-12 weeks

65
Q

formation of primordial follicles happens when in gestation

A

13 weeks

66
Q

preantral follicles are present when in gestation

A

26 weeks

67
Q

in developing ovary what happens to primitive sex cords

A

grow into medulla and degenerate

68
Q

cortical cords (what are they)

A

represent a second wave or cord formation that occurs during week 7
extend from surface epithelium into the underlying mesenchyme

69
Q

as the cortical cords increase in size what happens to them

A

PGCs are incorporated into them

70
Q

after week 13 (about week 16) the cortical cords begin to break up into what

A

distinct cell clusters (primordial follicles)

71
Q

primordial follicles consist of what kinds of cells

A

primary oocyte surrounded by a single layer of pregranulosa cells
each follicle is surrounded by a basal lamina

72
Q

what are the two sets of genital ducts

A

mesonephric or wolffian ducts

paramesonephric or mullerian ducts

73
Q

both genital ducts empty into where

A

urogenital sinus

74
Q

wolffian ducts differentiate into what

A

epididymis
vas deferens
seminal vesicles
ejaculatory ducts

75
Q

mullerian ducts differentiate into

A

fallopian tubes
uterus
cervix
upper third of vagina

76
Q

mullerian ducts (describe shape)

A

cranial end is funnel-shaped and opens into peritoneal cavity
caudal end fuse to form uterovaginal primordium

77
Q

uterovaginal primordium (how is it formed)

A

fusion of caudal end of mullein ducts

78
Q

differentiation of male internal genital tract involves what

A

mullerian duct regression and wolffian duct development

79
Q

differentiation of male internal genital tract requires what

A

hormones produced by the fetal testes

80
Q

anti-mullerian hormone (AMH)

where is it released, what does it do

A

released by sertoli cells

induces apoptosis of mullerian ducts

81
Q

AMH induced mullerian duct regression occurs when

A

weeks 7-10

82
Q

AMH induced mullerian duct regression (what is special about it after week 8)

A

time sensitive

ducts are non responsive after week 8

83
Q

what stimulates testosterone production by the fetal testes

A

chorionic gonadotropin (hCG)

84
Q

wolffian duct differentiation begins when and in response to what

A

week 9

testosterone produced by fetal leydig cells

85
Q

differentiation of genital ducts along female lines occurs how (in relation to hormones)

A

absence of hormone stimulation

86
Q

what happens to wolffian ducts w/o testosterone

A

destabilize and undergo regression

87
Q

syndrome of persistent mullein ducts (what is it/cause)

A

rare condition that can occur when a normal genotypic and phenotypic male cannot synthesize AMH or has defective AMH receptor

88
Q

syndrome of persistent mullein ducts (symptoms)

A

testes dont descend

mullerian duct derivatives (fallopian tubes, uterus, cervix, upper 1/3 of vagina) persist but underdeveloped

89
Q

what are the undifferentiated external genitalia

A

genital tubercle
genital fold
labioscrotal swelling

90
Q

differentiation of indifferent external genital structures of the embryo along male lines requires what

A

dihydrotestosterone (DHT)

91
Q

dihydrotestosterone (DHT) is formed how

A

derived from testosterone using 5-alpha reductase

92
Q

absence of androgen stimulation what happens to external genitalia

A

develop along female lines

93
Q

the genital tubercle gives rise to what structures

A

glans penis or clitoris

94
Q

genital swelling gives rise to what

A

labia majora or scrotum

95
Q

genital folds form what

A

vental folds of the penis

labia minora

96
Q

urogenital sinus becomes what in males and when

A

prostatic buds develop by week 10

97
Q

urogenital sinus becomes what in females

A

lower part of vagina from walls of sinus

98
Q

what effect do female sex hormones have on differentiation of urogenital sinus and external genitalia

A

none

99
Q

what effect do female sex hormones have on differentiation of internal genitalia

A

none

100
Q

Syndrome of complete androgen resistance (what is it)

A

testes capable of secreting androgens will be present in the abdominal cavity

101
Q

Syndrome of complete androgen resistance (symptoms)

A

both male and female internal genitalia are absent
external genitalia and secondary sexual characteristics are female
pubic hair will be scant or absent

102
Q

5-alpha-reductase deficiency

A

internal genitalia will develop along male lines and the external genitalia will be ambiguous due to incomplete masculinization
child may be mistaken for female at birth
further masculinization of external genitalia will occur at puberty

103
Q

excessive amounts of androgens in utero to a 46, XX embryo does what

A

virilization of the external genital

if exposure after 12 weeks- clitoral hypertrophy

104
Q

Insulins-Like peptide 3 (INSL 3)

what is it where is it produced

A

leydig cells

linked to transabdominal phase of testicular descent

105
Q

cryptorchidism (what is it)

A

failure of descent of one or more testis

106
Q

scrotal descent happens when

A

b/w weeks 25-32

107
Q

what two hormones play a role in testicular descent

A

INSL 3
Testosterone
(both from leydig cells)

SF4 Exam 2 (13 decks)

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