Exam 2 Flashcards
Sry
activates cells within the gonads to produce testes determining factor
What develops first female or male tract
male tract
Anti-Mullerian Duct Hormone
regresses the female tract
What allows the wolfian duct in females to regress
absence of testorone
Male external genetalia growth
urethral groove grows and becomes the body of the penis, scrotal swelling and the phallus grows
Female external genetalia growth
the phallus shrinks and there is labial swelling
What causes homosexual behavior in cattle
high estrogen
Why don’t males need a surge center
once at a certain age they are constantly producing sperm cells as opposed to females who have a limited number of oocytes and need the surge to ovulate.
How does the surge center regress in males
It starts as indifferent
Then the testorone circulates and due to it being a small steroid it passes through the blood brain barrier
Then in the brain aromatase converts the testorone to estrogen
The high concentration of estrogen in the brain does not allow for growth of the surge center
Why doesn’t estrogen knock out the surge center in females
The females have alphafetal protein which binds to the estrogen in the body and because of the large protein size it can not go through the blood brain barrier
Sexual Dimorphism in the brain
The pre optic area is bigger in males than females as it helps them find mates
True hermaphrodites
both male and female internal and external genetalia
EX: some fish release both ova and sperm released from separate orifices and the fertilization is external
XY Genetic Pseudo-Hermaphrodite
Mixed internal tract, external female, the cells are not responsive testerone
XX Genetic Pseudo-Hermaphrodite
Ovary,, Mixed tract, external male, adrenal produces excess androgen
Freemartinism
both male and female tracts are present. Most commonly occurs in cattle
When does freemartinism most often occur
It occurs when cow has twins and one is a heifer calf and one is a bull calf. The bull calf develops normally and the female is the free Martin
How/Why does freemartinism occur in cattle
-The bull calf becomes a bull first, and the cows share placental blood until day 84. The reduced concentrations of AMH and androgens in the heifer calf from the blood of the bull calf causes the change in developing tract and start of sexual differentiation
Female sexual development in hyenas
-have an enlarged clitoris that resembles a penis
-nonfunctional vagina
-does not have an obvious phenotypic sex
How do female hyenas mate and give birth if they have a nonfunctional vagina
-mating occurs through the clitoris
-painful due to the small size that the fetus has to pass through
Why do female hyenas have these charecteristics
A lot of androgen production by the dam when pregnant and because of that there is natural virilization of the females in utero and changes how external genetalia forms
Puberty Definition
the time at which an animal becomes functionally capable of reproducing
Why can’t the age when behavioral traits are expressed not be an indicator of puberty in males
-can be influenced by other factors and can happen at a very young age
Why can’t the age at 1st ejaculation be an indicator of puberty in males
The first ejaculations often are
-not fertile
-only seminal plasma
-can not cause pregnancy
Why can’t when spermatozoa 1st appear in ejacualte not be an indicator of puberty in males
usually does not reach the critical threshold that would deem them functionally capable of producing