Pathways to Men & Women: Sex Differentiation Flashcards
The SRY gene instructs the expression for..?
The testis
When is the sex of the embryo determined?
At fertilisation
In humans, which of males or females are heterogametic sex?
Males
What does SRY stand for?
Sex determining Region of the Y Chromosome
How do we know SRY gene is specifically involved in sex determination of a male? Give two points of evidence
XXsxr = Sex Reversal Syndrome, whereby the patient is male. Caused by translocation of the SRY gene onto the X chromosome
XY Females = Swyer Syndrome, whereby the female is XY but has a missing / mutated SRY gene
Which embryonic structure does the embryonic gonad originate from?
Genital ridge primordia
Which embryonic structure does the gametes originate from?
Primordial germ cells (PGC) in the embryonic yolk sac
In males and females, the Primordial germ cells colonise which aspects of the Genital Ridge Primordia..?
Males: the medulla
Females: the cortex
What are the embryonic derivatives of the Sex cords (Seminephorous tubules / Primordial Follicles)?
Coelomic epithelia
In males, what happens to the cortex and medulla?
Medulla develops into testis
Cortex degenerates
In females, what happens to the cortex and medulla?
Medulla degenerates
Cortex develops into an ovary
What is a Sertoli cell?
Somatic cells of the testis essential for testis formation and spermatogenesis
What is a Granulosa cell?
A somatic cell of the sex cord that is closely associated with the developing female oocytes in the ovaries
How does SRY act?
SRY acts on SOX2, which induces expression of PGD2 which induces expression of FGF9
SRY is only required for testis development in the first few stages. After that, testis development is self-sustaining. How?
PDG2 and FGF9 mantains a feedback loop to keep SOX9 active without SRY
