Reproduction 4 - sexual determination and diffrentiation Flashcards
GENETIC SEX
Type of sex chromosome
GONADAL SEX
Type of gonads: ovaries or testes?
GENITAL OR PHENOTYPIC SEX
Type of internal and external genitalia
Chromosomal or genetic sex is determine when?
At the exact moment of fertilization
Gonadal sex determine by
Chromosomal sex
The presence of what on the Y chromosome dictates male differentiation of bipotential gonads?
SRY gene = testes
Klinefelter’s syndrome
Male XXY
- X impairs spermatogensis
- osteoporosis
What determines female differentiation of bipotential gonads?
A sense of Y chromosome = ovaries
Turner’ syndrome
Lack of X chromosome
Female XO = streaked ovaries
- no uterus
- no functional follicle = no menstration
Genetically or phenotypic sex determined by
Factors produced by gonads
In MALES, Genetically or phenotypic sex determined by
The testes secreting MIH from Sertoli cells.
Mullerian inhibiting hormone (MIH)
- causes regression of Müllerian duct = regression of female tract.
testosterone from leydig cells cause
Development of male INTERAL genitalia
Testosterone converts to
dihydrotestosterone (DHT)
dihydrotestosterone (DHT) causes
Masculinization of male EXTERNAL genitalia
What are male external and interal gentalia determined by?
Internal = testosterone
External = dihydrotestosterone (DHT)
Müllerian duct gives rise to everything of
FEMALE structures
Wolffish duct gives rise to everything of
MALE structures.
In FEMALES, Genetically or phenotypic sex determined by
Absence Testosterone prevents MIH = allows for Müllerian duct to grow = internal genitalia
absence of DHT prevents masculinization of
external genitalia
Female differentiation happens by
default
Presence of MIH =
Absence of MIH=
Presence of MIH = wolffian duct = MALE
Absence of MIH= Müllerian duct = FEMALE
Bipotential gonads can develop to
Either testes or ovaries
Bipotential INTERAL genitalia that would give a potential female results in
Mullarian ducts = uterus, oviduct…
Bipotential INTERAL genitalia that would give a potential male results in
Wolffian ducts = epidiymas, vas defarans, seminal vesicles
Bipotential EXTERNAL gentalia for male and female need:
MIS+testosterone +Insl3 = penis (MALE)
No MIH, T, Insl3 = vagina (FEMALE)