What is the definition of someones sex?
- the biological distinction between male and female
- terms male and female describe sexual features, phenotypes
- how a person identifies (psychologically) and/or expresses themselves
- set of social beliefs about what it means to be a woman or man vary from one society (culture) to another and over time
In which weeks are genital ridges formed from mesenchymal tissue?
What are genital ridges formed from?
Where do primordial germ cells migrate from and to during fetal development of gonads?
Migrate from yolk sac to the connective tisue of the gonadal ridges.
What des each gonadal ridge differentiate into?
Sex cords and coelomic epithelium
What determines a male sex?
Y chromosome containing Sex determining region of Y chromosome (SRY).
The initiation of the formation of the testes depends on the presence of the...
SRY gene (turns on expression of TDF)
What does the expression of the SRY gene in sertoli cells cause?
Massive proliferaion of the sex cords.
What forms the testis cords?
The sex cords joining with the ingrowing mesonephric ducts (tubules).
Seminiferous cords are formed from:
Testis cords joining with PGCs
What 3 structures lead to the seminiferous tubules?
PCGs + Prospermatogonia + Sertoli cells
What causes the development of the female phenotype?
Failure to form teste and absence of androgen
What happens to the coelomic and mesonephric epithelium in the gonad cortex of female?
It condenses, surrounding the PGCs (primordial follicles containing oogonia)
Wht do mesenchymal cells secrete and give rise to in the female gonadal development?
Secrete basement membrane and give rise to granulosa cells. Some mesenchymal cells differentiate into theca cells
Is the development of the male internal genitalia an active or passive process?
Active, requires endocrine action
Why is the SRY gene no longer expressed during the formation of the male internal genitalia?
Testes have resumed the role of sexual differentiation
What causes development of the Wolffian duct and external genitalia?
Leydig cells producing androgen
What occurs to the Wolffian duct as the testes descend?
Develops into epididymis, vas deferens, and seminal vesicles.
What causes the degeneration of the Mullerian ducts in males?
Sertoli cells secreting Anti-Mullerian Hormone (AMH)
What causes the development of the Mullerian duct?
Absence of Androgen and anti-mullerian hormone
What does the mullerian duct develop into?
Oviducts, Uterus, Cervix, Upper vagina
What is Turner syndrome?
An embryo w/ 45 chromosomes, only one X, no Y. Normal autosomal complement.
What occurs to development of reproductive characteristics during Turners syndrome? Why?
Formation of Ovaries + External Female genitalia
Absence of SRY-> No testes -> no AMH -> Mullerian grow, Wollfian regress.
Presence of only one X = Death of oocytes and ovarian dysgenesis. = Infertile.
What is Klienfelter syndrome?
An embryo w/ 47 chromosomes, Two XX oneY
Normal autosomal complement
What occurs to development of reproductive characteristics of someone with Kleinfelters syndrome? Why?
Y chromosome = Testes formation
Testosterone = Wolffian duct formation
AMH =Mullerian duct degeneration
Male exernal genitalia.
Two XX chromosomes = Death of germ cells (hyperactivity). Exocrine testes dysgenesis = Infertile
What occurs to development of reproductive characteristics for someone with removed gonads of normal male and female fetuses.
- No gonads (removed)
- Both develope female internal and external genitalia.
Castrated female genotype (Like Turners) for both = Infertile
What is Testicular Feminisation?
Androgen Insensitivity Syndrom (AIS)
Normale MALE XY genotype
Both Wolffian and bipotential tissues of external gentialia are insensitive to androgen (Lack effective receptors)
What would happen to the development of sexual genitalia in individuals with Testicular feminisation
- Normal Testes, Androgen, AMH (Sertoli)
- Regression of both Wolffin and Mullerian ducts- no internal organs
-Normal Female external genitalia
- Genetically Male but phenotypically Female
- Genetically fertile but in practice, infertile
What is androgenital syndrome?
Congenital Andrenal Hyperplasia(CAH)
Normal XX female genotype
Hyperactive adrenal gland = high androgen levels