Week 3 Flashcards
________ the theory that all sex information is determined by chromosomal information then the gonads are responsible for further differentiation in life
central dogma
_________ occurs in alligators and turtles. Temperature of egg determines gonadal sex
environmental sex determination
In alligators
high temperature is more females. Reverse in turtles
______________
Mammals: XX and XY
Birds: ZZ male and ZW female
Fruit flies: XX female and XY male
genetic sex differentiations
________ is mamalian determining number of X chromosomes is irrelevant
mammalian Y chromosome
The local on the Y chromosome ___________ is the testis determining factor of the Y chromosome
TDY
The gene in the TDY locus involved in testes development is the ________
SRY genes
deletion of the SRY gene. results in
XY gonadal females
Sryexpressed in undifferentiated gonadal ridge
•Sryinduces differentiation of _________, the first testicular cells!!
Sertoli cells
•Sryincreases expression of ________an ancient testis differentiation gene, causes cascade of events to commit gonad to testicular fate
Sox9,
__________ develops in absence of Sry, no matter what the sex chromosome complement (XX or XY)
•Ovary
- Males have all of the genes to make an _________
* Females have all the genes to make a ________ except ____________
ovary.
testis, except Sry (and a few Y genes needed for spermatogenesis).
SEX in BIRDS
Birds ZZ male (testes) ZW female (ovary) Female has a small W chromosome lacking in male (like male mammal’s Y)
SEX in FLYS
•Presence of Y chromosome is irrelevant to maleness
•X:A ratio is sex determining, if 1 then female (2X or more), if <1 (1X)
then male.
what is the 20th century dogma
- genetics determines the sex of the gonads
- sex differences are determined by hormones
_________ becomes oviduct, uterus, upper vagina
mullein duct
__________ becomes a efferent duct, ducts deferens, epididymus, and associated glands
wolfian duct
Genetics and the appropriate hormones cause the appropriate duct system to develop and the _______________
opposite to degenerate
___________ secrete Müllerian Inhibiting Hormone, causes involution of female ducts (oviducts, uterus, upper vagina)
Sertoli cells
__________ secrete testosterone which causes masculine differentiation (penis, scrotum, sperm ducts, brain, liver, physique)
•Leydig cell
•Hormone effects are __________
permanent and irreversible
a burst of _________ caused wolfing duct to develop
testosterone
Each sex’s phenotype emerges from a previously undifferentiated state
•Undifferentiated state is _________could go either way –some sex-specific force causes the sex difference, pushes the system in one direction
bi-potential,
- Both sexes have same undifferentiated form
* Male (scrotum, penis) and female (vaginal labia, clitoris) derive from ________
same precursor
___________ internal genitalia are present in both sexes
•Male (Wolffian) and female (Müllerian)
Permenate: Gonadal hormone-induced
irreversible commitment of a tissue to a masculine phenotype.
Gonadal hormone-induced____________of a tissue to a masculine phenotype
irreversible commitment
What are the primary sex hormones
estradiol, testosterone, progesterone
______________ pathway is the conversion of cholesterol into testosterone and progesterone
stereogenic pathway
The male hormone (testosterone is the precursor to
estrogen
____________ estrogen synthase is an enzyme responsible for a key step in the biosynthesis of estrogens
aromatase
_________ converts testosterone to dihydrotestosterone which is vital for masculinization
5 alpha reductase
After gonadectomy and E2+P treatment of adult rats
Females display ___________
Males____________
female reproductive behavior and have an LH surge\
do not display female behavior nor have an LH surge
When females are treated with testosterone after birth. They perform less lordosis this is because
testosterone defemivnized behavior
When castrated males are injected with E and P what happens
They exhibited lordosis because testicular secretions are not present to defense behavior
Males deprived of testosterone (T) from the testes develop_______
•Females given testosterone around the time of birth exhibit __________
•Testosterone_________ sex behavior!
•
female patterns of behavior;
less female behavior;
DEFEMINIZES
What about male sex behavior (i.e. mounting?)
Males deprived of T neonatally do not _________
males, and females given T neonatally do __________
Testosterone _________ sex behavior!
mount like normal
mount more than normal females.
MASCULINIZES
rhesus monkey and psedohemaphrodites
Pseudohermaphroditesdaughters
of pregnant mothers treated with T
rhesus monkey and psedohemaphrodites
Pseudohermaphroditesdaughters
of pregnant mothers treated with T
These hemaphrodiets showed more male like behavior in terms of play and pursuit play
_______________
Sex Difference in CNS male and female
Spinal Nucleus of the Bulbocavernosus (SNB)
_____________ control cupping or rat penis
medial bulbocavernosus and lateral bulbocavernosus
Males and females behave differently because of sex differences in their brains caused _______________ in a manner similar to external genitals and reproductive ducts.
by testicular secretions
1) Established by exposure to T during a critical perinatal period.
3) Blocked by perinatal exposure to an aromatase inhibitor.
4) Blocked by embryonic/postnatal exposure to ER blockers.
2) Masculine brain development is blocked by perinatal castration.
Conclusion: C
reation of neural substrates that motivate
masculineand NOT femininereproductive behaviors
established in males by testicular T converted to E2 in brain and E2 binding to ER. (estrogen receptor) in POA (preoperative area)!
testicular T converted to E2 in brain and E2 binding to _________ in ________
ER. (estrogen receptor) in POA (preoperative area)!
