Sexual Differentiation

Question 1

describe sexual differentiation?

Answer 1

● Undifferentiated stage = 0-7 weeks gestation
○ Male and female external genitals the same (= bipotential)
■ Urogenital + urethral folds
■ Genital + urethral grooves + tubercle
■ Genital tubercle
■ Labioscrotal swelling
○ Male and female internal genitalia the same - undifferentiated sex glands
● Paternal CHR decides sex - gives Y (default = female)
● Y chromosome: SRY gene, acts to promote male reproductive differentiation
○ SRY gene (produces) → Testis-determining-factor TDF (produces) → proteins → Leydig (testosterone → wolffian duct + external genitalia) + Sertoli cells (Mullerian-inhibiting-substance → regression of mullerian duct)
● X chromosome: DSS gene (region that may contain several genes, still being researched), acts to promote female reproductive differentiation.)
● Sexual differentiation: Gonadal development
○ 8 weeks gestation
● Y chromosome synthesis of H-Y antigen
○ Male: H-Y antigen causes undifferentiated sex glands to develop into testes
○ Female: lack of H-Y antigen causes undifferentiated sex glands to develop into ovaries

Question 2

when do we see the undifferentiated stage?

Answer 2

0-7 weeks gestation
we see:

■ Urogenital + urethral folds
■ Genital + urethral grooves + tubercle
■ Genital tubercle
■ Labioscrotal swelling

also, Male and female internal genitalia the same - undifferentiated sex glands

Question 3

which CHR decides sex?

Answer 3

paternal CHR decides the sex, which gives the Y, though default is female

Question 4

this chromosome or gene acts to promote male reproductive differentiation?

Answer 4

Y chromosome, SRY gene

Question 5

how does the male reproductive differentiation pathway occur?

Answer 5

SRY gene (produces) → Testis-determining-factor TDF (produces) → proteins → Leydig (testosterone → wolffian duct + external genitalia) + Sertoli cells (Mullerian-inhibiting-substance → regression of mullerian duct)

Question 6

this chromosome or gene acts to promote female reproductive differentiation?

Answer 6

X chromosome: DSS gene (region that may contain several genes, still being researched), acts to promote female reproductive differentiation.)

Question 7

when does sexual differentiation occur?

Answer 7

8 weeks gestation and we begin to see gonadal development

Question 8

Y chromosome synthesis involves this gene?

Answer 8

H-Y antigen

Question 9

what is the function of the male : H-Y antigen, the effect when the Y chromosome produces this?

Answer 9

causes undifferentiated sex glands to develop into testes

Question 10

what is the effect in the lack of the H-Y antigen for the female?

Answer 10

causes undifferentiated sex glands to develop into ovaries

Question 11

this duct will develop into fallopian tubes, uterus, inner vagina?

Answer 11

Mullerian ducts

Question 12

this duct will develop into epididymis, vas deferens, and seminal vesicles?

Answer 12

Wolffian ducts

Question 13

duct development is also known as?

Answer 13

Sexual differentiation, note that in the beginning both sexes start out with two systems

Question 14

what hormone is the male (XY) chromosome responsible for secreting?

Answer 14

testosterone and Mullerian-inhibiting hormone

Question 15

what does testosterone have on duct development? what about the Mullerian-inhibiting hormone?

Answer 15

Wolffian ducts develop; Mullerian-inhibiting hormone inhibits further development of Mullerian ducts and so they shrink and degenerate

Question 16

how is sexual differentiation affected in terms of testosterone and mullerian inhibiting hormone?

Answer 16

Absence of Mullerian-inhibiting hormone - Mullerian ducts develop

Absence of testosterone - Wolffian ducts degenerate

Question 17

where does testes development begin? effect in the failure of them descending?

Answer 17

Starts in abdomen and descends down

failure to descend + damages seminiferous tubules/diminished testicular function= cryptorchidism

Question 18

what are disorders affecting hormonal processes?

Answer 18

Androgen Insensitivity Syndrome (AIS) + Fetally androgenized female + DHT-deficient male

Question 19

this syndrome is due to Internal female anatomy not developed; no functional ovaries, therefore no breast development, menstruation, or fertility.

Answer 19

(XO) or Turners Syndrome, though there is normal external female genitalia

1 in 2000 births

Often have other health problems, including heart, kidney, thyroid problems, and diabetes

Question 20

what are the characteristics and symptoms associated with Turner’s Syndrome?

Answer 20

short stature, low hairline, shield-shaped thorax, wide-spaced nipples, short MC IV, small fingernails, brown spots (nevi), neck fold, constricted aorta, poor breast development, deformed elbows, rudimentary ovaries = gonadal streak (underdeveloped gonad structure), no menstruation

Question 21

this medical condition is a endocrine disorder in which the male has an undersized penis with testes, Typically sterile, Low interest in sex, Somewhat feminized physical characteristics

Answer 21

XXY Klinefelter Syndrome, generally 1 in 500 male births

If desired, the XXY boy can increase male secondary sex characteristics (body hair, reduced breast development, increased muscle development) w/testosterone treatment

Question 22

what are the symptoms of Klinefelter Syndrome?

Answer 22

frontal baldness absent, less chest hair growth, breast development, feminine public hair pattern, small testicular size, poor beard growth, narrow shoulders, wide hips, long arms + legs