Reproductive system Flashcards
Sequential process of sexual differentiation
- Establishment of genetic sex 2. Translation of genetic sex into gonadal sex 3. Translation of gonadal sex into phenotypic sex
What will happen in an organism if there are ovaries or testis
By default we are going to be
Women
i.e The TESTES are essential for male sexual differentiation, but the
ovaries are NOT necessary for female differentiation
Pre-requisites for normal sex differentiation
v Normal intact chromosome complement
v Fully functioning sex determination genes
v Intact steroidogenic pathway and receptors
Can you change sex in canada?
v As of 2014, several provinces allow birth certificate
changes without sex reassignment surgery being required
When in chromosomes male and female phenotype
Do sex xhromosomes recombine?
In women all along the chromosome
In male: only in PAR1 and PAR2 regions
SRY gene is very close to recombinant region of PAR, what it can result in
SRY protein has what capacity
To bond to DNA and induce transcription of other genes
What is the main target of SRY gene
SOX9 and then other genes-> testicular developemnt -> male
No SRY->other TFs are induced->ovarian development
What centers control secretion of LH/FSH post-puberty in males
Tonic centers that will control GnRH release
How the brain becomes male
testosterone can cross brain blood barrier, where it is converted to estradiol, which causes “defeninization” by inhibiting the development of surge centers
Why surge centers are important for females?
Female retains surge center and together with tonic centers they control LH/FSH after puberty.
During puberty->surge release of GnRH-> resposnsible for ovulation and reproductive cycle
How surge centers are developed in females?
estradiol which is produced in ovaries during embryonic developement is boind to alpha fetoprotein in fetus and thus cannot cross BBB-> surge center develops-> female hypothalamus
2 functions of gonads
gametogenesis
hormonogenesis
4 main roles of hromogenesis
gametogenesis
electrolyte homeostasis
fuel and protein metabolism
adiposity and muscle mass
when increases in testosterone happen in people
fetal, neonatal and then puberty
what is happening for the first time during puberty in boys
ejaculation-semenarche
what is going on on the level of hypothalamus in puberty
- Before puberty in the females and male, tonic and surge centers release low amplitude and frequency of GnRH
- after puberty the female, tonic center produces higher levels of GnRH because of increased frequency (basal for both male and female). female only-> The surge center controls the preovulatory surge of GnRH
Can gonads produce steroids befre puberty?
Yes just at a lower level
where axons of GnRH neurons might end
in hypophyseal portal capillaries->anterior pituitary
other brain areas and may affect sexual behavior
where GnRH is synthesized apart from the brain
GnRH is also synthesized in the placenta, gonads,
breast, lymphocytes and the pituitary, but function
unknown
what is the nature of LH and FSH
glycoproteins
how FSH and LH are similar and different
alpha subunit is common and beta is different
what can happen to FSH and LH in circulation
Some changes in glycosylation
may occur in circulation →
different isoforms with slightly
different biological properties
receptor through which LH and FSH work
G-linked: Activation of
adenylate cyclase and also
phospholipase C
in what manner FSH and LH are released
Pulsatile release (in repsonse to GnRH)
What happens upon binding of LH and FSH
v Increase of intracellular
cholesterol.
v Transport of cholesterol to the
inner mitochondrial membrane by
StAR
v Conversion to pregnenolone-> steroid production
What are target cells for LH and FSH in male and female
v Testis: Only LH is steroidogenic
(acts on Leydig cells).
v Ovaries: Both LH and FSH are
steroidogenic act on two cell
types (theca and granulosa cells)
what are 2 types of the cell in oocyte
theca cells
and granula cells that immediately surround the ovum
How estrogen can be inhibitory and stimulatory at the same time?
at low concentrations->inhibitory, at high-> positive feedback
how follicle grow ? in what pattern
Wave cycle
This is cow, but the same idea
one dominant follicle in the end
LH surge is responsible for what in female
Ovulation
Hormonal profile during estrous cycle (LH, progesterone, LH, FSH)
Progesterone- from corpus luteum
Estrogen and FSH are high in opposite times
How luteal phase is determined
When progesterone concentration is high
when low->follicular
