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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
what happens to PGCs as they enter developing genital (gonadal) ridge
rapidly surrounded by chords of somatic cells
26
Once surrounded by somatic cells PGCs commit to what
developmental pathway which leads them to become: gonocytes (prespermatogonia) oogonia
27
what determines the type of gonad the genial ridge will become
sex chromosomes present in somatic cells
28
what is the gene product of the SRY gene
a transcription factor
29
what is the major action of the transcription factor produced by SRY
SOX9 gene
30
SOX9 gene (what does it do where is it)
``` master regulator of Sertoli cell differentiation chromosome 17q (long arm) ```
31
in the formation of testis what differentiates and what regresses from the indifferent gonad
medulla differentiates | cortex regresses
32
in the formation of ovaries what differentiates and what regresses from the indifferent gonad
cortex differentiates | medulla regresses
33
what is the first discernible event of testis differentiation
appearance of Sertolic cells in medulla of indifferent gonad b/w 6-7 weeks of gestation
34
Stroll cells aggregate around what to form what
aggregate around gonocytes (PGCs of testis) | form testis cords
35
testis cords (what are they)
formed from Sertoli cells and gonocytes | precursors to seminiferous tubules
36
what happens to gonocytes within testis cords
enter mitotic arrest at 10-12 weeks | (most are differentiated in prespermatogonia
37
Leydig Cells (when and where do they appear)
functional leydig cells appear between developing seminiferous tubules b/w week 8 and 9
38
Sertoli Cells (what do they release)
paracrine factors that play a role in recruiting mesenchymal cells to developing testis
39
mesenchymal cells recruited to developing testis differentiate into what?
peritubular myoid cells endothelial cells that form male-specific vasculature Leydig cells
40
Lydia cells (what do they produce)
testosterone | Insulin-like 3(INSL-3)
41
seminiferous tubules can form in the absence of what
germ cells
42
meiosis of germ cells begins when in males
puberty
43
presence of more than one X with a Y does what
alters process of testicular development
44
Klinefelter Syndrome (cause)
47, XXY male | caused my meiotic nondisjunction
45
primitive sex cords later in development become what
tunica albuginea
46
primitive sex cords give rise to what
testis cords which become seminiferous tubules and rete testis of the mature testis
47
seminiferous tubules are what until puberty
solid
48
differentiation of ovary from indifferent gonad requires what
invasion of cortex by primordial germ cells reactivation of the inactivated X chromosome in the germ cells absence of SRY gene
49
When SRY absent but no germ cells or only one X what happen
ovary begins to differentiate but the developing ovary will regress
50
ovarian dysgenesis is associated with what
45, X karyotype | Turner Syndrome
51
PGCs that migrate to presumptive ovary do what
proliferate rapidly and differentiate into oogonia
52
what happens to some oogonia in about 11 weeks gestation
leave pool of proliferating cells and enter into meiosis
53
oogonia that leave pool and enter meiosis are known as what
primary oocytes
54
meiosis of primary oocytes is arrested when
prophase of first meiotic division
55
what happens to other oogonia with the onset of oogonial meiosis
atresia (form of programed cell death)
56
primordial follicles (when do they arise)
week 13
57
primordial follicles (how are they formed)
arise a pregranulosa cells aggregate to form a single layer of cells around the primitive oocyte
58
number of germ cells in ovary peaks when and then what happens
20 weeks and then declines
59
what leads to the decline in number go female germ cells after week 20
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
what happens to follicles that mature in utero
interrupted by follicular atresia
61
all of primordial follicles that a woman will have are formed when?
by the time an infant is 6 months old
62
seminiferous tubules develop when in gestation
6-7 weeks in
63
leydig cells develop and secrete testosterone when in gestation
8-9 weeks
64
oogenesis begins when in gestation
11-12 weeks
65
formation of primordial follicles happens when in gestation
13 weeks
66
preantral follicles are present when in gestation
26 weeks
67
in developing ovary what happens to primitive sex cords
grow into medulla and degenerate
68
cortical cords (what are they)
represent a second wave or cord formation that occurs during week 7 extend from surface epithelium into the underlying mesenchyme
69
as the cortical cords increase in size what happens to them
PGCs are incorporated into them
70
after week 13 (about week 16) the cortical cords begin to break up into what
distinct cell clusters (primordial follicles)
71
primordial follicles consist of what kinds of cells
primary oocyte surrounded by a single layer of pregranulosa cells each follicle is surrounded by a basal lamina
72
what are the two sets of genital ducts
mesonephric or wolffian ducts | paramesonephric or mullerian ducts
73
both genital ducts empty into where
urogenital sinus
74
wolffian ducts differentiate into what
epididymis vas deferens seminal vesicles ejaculatory ducts
75
mullerian ducts differentiate into
fallopian tubes uterus cervix upper third of vagina
76
mullerian ducts (describe shape)
cranial end is funnel-shaped and opens into peritoneal cavity caudal end fuse to form uterovaginal primordium
77
uterovaginal primordium (how is it formed)
fusion of caudal end of mullein ducts
78
differentiation of male internal genital tract involves what
mullerian duct regression and wolffian duct development
79
differentiation of male internal genital tract requires what
hormones produced by the fetal testes
80
anti-mullerian hormone (AMH) | where is it released, what does it do
released by sertoli cells | induces apoptosis of mullerian ducts
81
AMH induced mullerian duct regression occurs when
weeks 7-10
82
AMH induced mullerian duct regression (what is special about it after week 8)
time sensitive | ducts are non responsive after week 8
83
what stimulates testosterone production by the fetal testes
chorionic gonadotropin (hCG)
84
wolffian duct differentiation begins when and in response to what
week 9 | testosterone produced by fetal leydig cells
85
differentiation of genital ducts along female lines occurs how (in relation to hormones)
absence of hormone stimulation
86
what happens to wolffian ducts w/o testosterone
destabilize and undergo regression
87
syndrome of persistent mullein ducts (what is it/cause)
rare condition that can occur when a normal genotypic and phenotypic male cannot synthesize AMH or has defective AMH receptor
88
syndrome of persistent mullein ducts (symptoms)
testes dont descend | mullerian duct derivatives (fallopian tubes, uterus, cervix, upper 1/3 of vagina) persist but underdeveloped
89
what are the undifferentiated external genitalia
genital tubercle genital fold labioscrotal swelling
90
differentiation of indifferent external genital structures of the embryo along male lines requires what
dihydrotestosterone (DHT)
91
dihydrotestosterone (DHT) is formed how
derived from testosterone using 5-alpha reductase
92
absence of androgen stimulation what happens to external genitalia
develop along female lines
93
the genital tubercle gives rise to what structures
glans penis or clitoris
94
genital swelling gives rise to what
labia majora or scrotum
95
genital folds form what
vental folds of the penis | labia minora
96
urogenital sinus becomes what in males and when
prostatic buds develop by week 10
97
urogenital sinus becomes what in females
lower part of vagina from walls of sinus
98
what effect do female sex hormones have on differentiation of urogenital sinus and external genitalia
none
99
what effect do female sex hormones have on differentiation of internal genitalia
none
100
Syndrome of complete androgen resistance (what is it)
testes capable of secreting androgens will be present in the abdominal cavity
101
Syndrome of complete androgen resistance (symptoms)
both male and female internal genitalia are absent external genitalia and secondary sexual characteristics are female pubic hair will be scant or absent
102
5-alpha-reductase deficiency
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
excessive amounts of androgens in utero to a 46, XX embryo does what
virilization of the external genital | if exposure after 12 weeks- clitoral hypertrophy
104
Insulins-Like peptide 3 (INSL 3) | what is it where is it produced
leydig cells | linked to transabdominal phase of testicular descent
105
cryptorchidism (what is it)
failure of descent of one or more testis
106
scrotal descent happens when
b/w weeks 25-32
107
what two hormones play a role in testicular descent
INSL 3 Testosterone (both from leydig cells)

SF4 Exam 2 (13 decks)

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