Questions and Correct Answers With
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What is different about birds genetic sex?
XX is male
XY is female
What is different about the genetic sex of fish?
Can be either (XX or XY) depending on species
Sometimes determined by temperature
Some have the ability to switch
What gene does the Y chromosome carry which is important in sex differentiation?
SRY gene
Testosterone---->DHT by
enzyme 5 alpha reductase
Testosterone---->estradiol by
aromatase enzyme
PDG
are stem cells in the gonads
What is the SRY gene?
Sex Reversal Y gene
AKA as TDF (testis determining factor)
How does the SRY gene differentiate gonads?
Turns on Sox 9, a box set of genes which influences sertoli and leydig cells to differentiate the gonads
into testis
What do the Sertoli cells produce under the influence of the SRY gene?
MIF - mullarian-inhibiting factor
Causes the mullerian duct regression
What do the Leydig cells produce under the influence of the SRY gene?
, Testosterone
- development of Wolffian ducts
(Vas deferens, seminal vesicles, epidymis)
- DHT >> penis and scrotum development
What duct is preprogrammed to develop?
Mullerian
What hormone masculinizes the brain?
estradiol
What protein in females prevents estradiol from crossing the BBB and masculinizing the brain?
alpha fetoprotein produced by the liver binds and degrades estradiol
Why can male brains be masculinized?
Testosterone isn't bound by alpha fetoprotein so it crosses the BBB, attaches to receptors and is
converted into estradiol
Once masculinized, the male brain converts into what three parts?
Pulse generator
Aggression center
Libido center
Describe the pulse generator
- releases GnRH in pulses 90 min
- negative feedback from:
progesterone
estradiol
testosterone
DHT
Describe the aggression center
estradiol causes the production of testosterone receptors
testosterone can trigger aggression
Libido center
Maintained with estradiol receptors
T--->Estradiol induces male libido effects
De la Chapelle disorder
XX
SRY translocation onto X chromsome
Tract: male