Quiz 2 Lecture Notes Flashcards
genetic/chromosomal sex
XX and XY
gonadal sex
ovary vs testis
must first have ____ sex to form phenotypic sex
gonad
phenotypic sex
- tubular repro tract
- external genitalia
- secondary sex characteristics
- brain sexual behavior
homogametic sex
XX female
heterogametic sex
XY male
if there is no external stimuli the default is to go…
female
sex determining region Y
SRY gene
X chromosome inactivation
in females one of the X chromosomes is inactivated and appears as the Barr body in the somatic cells of females
birds chromosomes for male and female
homogametic: ZZ male
heterogametic: ZW female
abnormal chromosomes can occur: if there is a Y in the sequence it will be a _______, if there is NO Y in the sequence it will be a ________
male, female
sequence of development of reproductive system
- indifferent stage (biopotential gonad)
- development of gonads (testes and ovaries)
- development of tubular reproductive tract
- development of external genitalia
- sexual development of brain
WT1 and SF1
- WT1 = Wilms Tumor Gene
- SF1 = Steroidogenic Factor 1
how the biopotential gonads are formed
the formation of the genital ridge begins on the ventral surface of the _____________ as paired thickenings of the coelomic epithelial layer
mesonephros
genital ridge is changed to the biopotential gonad by…
WT1 and SF1
PGCs
primordial germ cells
what does PGCs form?
sperm or oocyte
how are gonads developed?
migration of PGCs from the yolk sac to the genital ridge (biopotential gonads)
SRY Protein = transcription factor
meaning that when the protein attached to the DNA it will tell the genes to express SOX9
testis determining gene
SOX9
Sertoli cells
cells that keep sperm alive
what is a key event in testis formation?
sertoli cell formation
female duct
mullerin duct
what structures are in the mullerian duct?
oviduct, uterus, cervix, anterior vagina
male duct
wolffian duct
what structures are in the wolffian duct?
rete testis, epididymis, vesticular/accessory glands
in the early embryonic stage, the embryo has both male and female tracts, what happens to the other?
it degenerates
2 important things to form the wolffian duct
- testosterone (stimulates growth)
- antimullerian hormone
antimullerian hormone
- form sertoli cells
- degenerates/inhibits the female reproductive tract
decent of testis into the scrotum
gonads are formed inside the body but need to move to the outside to have cooler temperatures to form sperm
chriptorchid
testis stay inside the body (testicular degeneration)
2 things that assist in decent of the testis
- increasing abdominal pressure
- shortening/shrinkage of gubernaculum ligament
what can we do if decent of testis is not occurring?
- give testosterone
- surgery
3 origins of male and female genitalia
- genital tubercle
- genital fold
- genital swelling
genital tubercle
penis or clitoris
genital fold
prepuce or vulva (inner)
genital swelling
scrotum or vulva (outer)
need a ______ testosterone hormone to go male
strong
testosterone is converted by ________ to make the more powerful form of _____________________
5a-reductase, 5a-dihydrotestosterone
normal testosterone can make the male tract but will _______ make external genitalia
NOT
freemartinism
in cows the placenta is fused together, so when male and female twins share a placenta they will also share hormones, so the female will get testosterone and AMH causing her mullerian tract to not fully develop making her sterile (but external genitalia will be normal because it is a different mechanism)
sexual development of brain: male
high amount of estrogen in the brain
sexual development of brain: male (explanation)
testis produces testosterone, testosterone is a small molecule that can pass through the blood brain barrier, once inside the brain testosterone is converted to estrogen by the aromatase enzyme, the high amount of estrogen in the brain tells the brain neurons (pre optic nucleus) to go male
pre optic area sensitive period
a short amount of time that determines if the brain will go male or female
sexual development of brain: female
estrogen binds to alpha fetoprotein which cannot pass through the brain barrier
sexual development of brain: female (explanation)
the ovary produced estrogen and the fetus liver produces alpha fetoprotein and secretes it into the blood where it can bind to an estrogen hormone, this makes the molecule larger and it cannot pass into the blood brain barrier resulting in a low amount of estrogen int eh brain
testicular feminization
- XY = testes
- problem: no testosterone receptors
- there is testosterone and AMH still being made.. so no testosterone to form the wolffian tract and AMH will degenerate the muellirian tract (no male or female tract),
- external genetalia will be female (no strong testosterone)
- brain will be male (testosterone still goes to brain)
androgenital syndrome
- XX = ovaries
- Andro = Male
- problem: testosterone is made by the fetal adrenal, a lot of testosterone is being made but NO AMH
- tubular tract is male and female
- male genitalia
- brain is male
persistent mullerian duct
- XY = testis
- persistent mullerian = mullerian no degenerated
- problem: testosterone made but NO AMH
- male and female tract
- male genitalia and brain
“penis at twelve”
- XY = testes
- problem: NO alpha reductase enzyme activity
- external genitalia is a female at birth and male at puberty because the fetus cannot make enough testosterone for make male genitalia but at puberty there is enough
- male tubular tract and brain
functions of the testes
- exocrine = sperm formation
- endocrine = testosterone
seminiferous tubules
where sperm is formed
rete testis
collecting tubules of sperm
(from seminiferous tubules to the rete testis)
efferent ducts
where the sperm moves after the rate testis and moves them into the head of the epididymis
epididymis
- head, body, and tail
- sperm matures as it moves through
- mature sperm is stored in the tail
vas deferens (ductus deference)
moves mature sperm from the epididymis to the body
leydig cells
produce testosterone
type A spermatogonium divides into 2 cells:
- a replacement cell called type B spermatogonium
- becomes sperm
why is it important that the type A spermatogonium divides into 2 different cells?
because it allows male to have an unlimited amount of sperm
stages of sperm development
- type A spermatogonium divides
- pachytene primary spermatocyte
- early spermatid
- late spermaid
- sperm
what occurs to the sperm cells if the testicle gets too hot?
sperm will not form, if the spermatogonium layer is affected / degenerates the male will become sterile
4 mechanisms of testicular thermoregulation
- scrotum
- tunica dartos muscle
- cremaster muscle
- pampiniform plexus
testicular thermoregulation: scrotum
nerve cells in the scrotum to regulate the temperature in the animal
(if it is warm, it will increase respiration)
testicular thermoregulation: tunica dartos muscle
- thin layer of muscle lining the scrotum
- cold = contract/shrink to decrease surface area
- warm = relax to increase the surface area of the scrotum
testicular thermoregulation: cremaster muscle
- connects the testicle to the iguanal canal
- cold = pull close to the body
- warm = relax and push away from the body
testicular thermoregulation: pampiniform plexus
- highly convolutes vein network that surrounds the arteries
- the veins carry cold blood while the arteries carry warm blood, so the veins are able to cool the arteries
