Topic 7.7 Flashcards
Which factors causes the testes to begin devlping?
TDF = testis determining factor
When does TDF appear?
7th gestational week
When do the ovaries start developing?
At 9th week of gestational dvlpmt
How does TDF influence differenciation?
by associating with SF1 and upregulating genes like SOX9
What is the role of SOX9? (2)
- Induces development of primary sex cords
- Inhibits beta-catenin which mediates female development
What are the 2 hormones required for the development of male phenotype?
- Antimullerian hormone (AMH)
- Testosterone
Which cells secrete AMH?
sertoli cells
Which cells secrete testosterone?
leydig cells
What is the role of testosterone?
It promotes growth and differentiation of wolffian duct
What does the wolffian duct give rise to? (4)
- Epididymis
- vas deferens
- seminal vesicles
- ejaculatory ducts
What converts testosterone to DHT? (3)
- prostate
- seminal vesicles
- epididymis
What happens if there is no SRY?
R-spondin 1 and Wnt4 act together to stabilize B-catenin
What does B-catenin do?
It inhibits SOX-9 and induces the development of female phenotype
What do the indifferent gonads consist of?
outer cortex and inner medulla
Where are the indifferent gonads located?
near the hindgut in the gonadal ridge
Which part of the indifferent gonads to testis develop from?
from the medulla
Which part of the indifferent gonads to ovary develop from?
form the cortex
How do semineferous tubes form?
From excavation of the primitive sex chords
How do spermatogonia form?
From primordial germ cells
How do sertoli cells form?
from sex cords
How do rete testis form?
from dorsal part of the gonas
how do efferent ductules form?
from mesonephric tubules
when do male fetal testes begin to secrete testosterone?
at the 7th gestational week
Which stucture first starts secreting testosterone in fetal life?
the genital ridges
When do plasma [testosterone] peak in fetal life?
at the 2nd trimester
what drives the first testosterone peak? (2)
maternal HcG and fetal LH
When do the testis decend into the scrotum
last 2-3 months of gestation
what is chryptorchidism?
non descent of testis at birth
When is the second peak of testosterone?
within the 1st year of life
When does development of internal genitalia occur?
at the 9th gestational week
What influences development of internal genitalia in men?
testosterone produced by leydig cells
Where does the prostate develop from?
from endoderm of prostatic urethra
Which 2 factors produced by sertoli cells aid in development of male internal genitalia
- AMH
2. Androgen-binding protein : ABP, binds and maintains a high testosterone concentration locally
Which enzyme catalyzes testosterone to DHT
5 alpha-reductase
What degenerates in female internal genitalia? (2)
- mesonephros
- wolffian duct
What does each of the 3 functional region of the mullerian duct develop into?
- Upper end : fimbria
- Middle ends : fuse :fundus an body of uterus
- Distal end : uterovaginal primordium
When does development of external genitalia happen?
13th gestational week
What will the cloaca be divided into?
into the urogenital sinus and the rectum
Where do the mullerian and wolffian ducts empty?
into the urogenital sinus
What are the 3 parts of the uroG sinus?
- vesicle part
- pelvic part
- phallic part
What is each part of the uroG sinus for males?
- vesicle part - bladder
- pelvic part - prostatic urethra
- phallic part - penile urethra
What is each part of the uroG sinus for females?
- vesicle part - bladder
- pelvic part - entire urethra
- phallic part - vaginal vestibule
What creates the vaginal lumen?
resorption of the center of the vaginal plate
What is the remnant of the vagina in males?
prostatic utricle
What does the genital tubercle develop into for males and females?
m : glans penis
f : clitoris
What does the urogenital fold develop into for males and females?
m : penile shaft
f : labia minora
What does the labioscrotal swellings develop into for males and females?
m : scrotum
f : labia majora
What forms the mons pubis in females?
the ventral fusion of the labioscrotal swellings
What is adrenarche ?
increased androgen production from zona reticularis of adrenal medulla
When does adrenarche happen?
around age 7
What is pubarche ?
appearance of peripheral hair
What is gonadarche?
the earliest gonadal changes of puberty
What starts gonadarche?
the (now) pulsatile secretion of GnRH
Which hormones increase GnRH production during puberty? (3)
- Leptin
- IGF-1
- Insulin (by increasing fat deposition)
Which hormone decreases GnRH secretion during puberty?
Ghrelin
What is spermarchy and when does it happen?
First appearence of sperm, at age 13
What does puberty in girls involve? (3)
- menarche
- thelarche (breast dvlpmt)
- adrenarche
Which hormone impacts the development of the alveoli of the breasts?
- progesterone
Which hormone impacts the development of the ducts of the breasts?
- estrogen
Which hormones impacts the development of the mass of the breasts?
- insulin
- GH
- glucocorticoid
- thyroxine
