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...
BMS 430 Exam 3 study guide with
solutions
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
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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
, 3|Page
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
Phenotype: male
Brain: male
under developed--->doesn't act like man
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