Sexual Development Flashcards
What is genetic sex?
determined by chromosomal compliment contributed by egg and sperm
What is gonadal sex?
differentiation of the bipotential embryonic gonad into an ovary or testis
What is phenotypic sex?
depending on the hormones secreted by gonads
What is locus?
position on a chromosome where groups of genes are located
What is phenotype?
gene via the protein they produce can contribute to a certain trait
What is inheritance?
trait/gene passed to offspring as autosomal or sex linked (depending on chromosome)
dominant and recessive
What causes chromosome abnormalities?
faulty cell division in zygote fertilization, faulty division of germ cells during oo/spermatogenesis
What is the importance of x inactivation?
ensures that there isn’t a dosage effect, healthier one stays “on”
What is the turners syndrome genotype?
x
What does estrogen do in development? Where is it secreted from?
secreted from the ovary
supports development of Mullerian duct into uterus, oviduct, vagina
What important hormone needs to be in the developing male? what does it do?
Anti-Mullerian (AMH): causes degradation of mullerian duct
What is the bipotential stage? When does it differentiate?
undifferentiated gonads (early development), week 7
What is the genial ridge?
derived from intermediate mesoderm (1-3 layers of embryo (blood, heart, kidney, gonads)
What happens at 4-6 weeks of development?
proliferation of the epithelium to form primitive sex chords
What are primordial germ cells (PGC)?
primary undifferentiated stem cells that will differentiate towards gametes
When do PGCs migrate to proliferated epithelium?
4-6 weeks
When do PGCs turn from diploid to haploid cells?
they divide by mitosis until critical number is reached
How long does it take for an xy fetus to fully differentiate?
14-16 weeks
What is the importance of the wolffian duct?
forms into the epididymis, vas deferens, seminal vesicle
What cells secrete AMH?
Sertoli
What are the steps for forming the rete testis and the testis cords (2)
lose connection with surface wall epithelium, cords hollow out to become tubules
What is the urogenital region?
near cloacal opening, converts testosterone to DHT
What is the importance of DHT?
promotes formation of penis and prostate gland (internal male genitalia)
How long does it take for an xx fetus to differentiate?
20 weeks
What makes up a follicule? 3
germ cell (ova), cortical cells (granulosa), theca cells
What forms mullerian duct?
estrogen from mother and fetal follicules
What causes the degeneration of the wolffian duct?
lack of testosterone
What is the Sry gene? What does it encode?
sex determining region on y chromosome (not only gene needed for male development tho)
encodes transcription factors
What happened to xx mice injected with Sry?
developed testis and penis but no sperm
What is the Sry equivalent in birds?
DMRTI
What is the Sox9 gene?
autosomal gene that regulates expression of AMH
When is the Sox9 gene expressed?
after sry expression in the genital ridge
What is sterioidogeneic factor 1 (SF1?)
autosomal gene that is important in initial early development of gonad
binds to AMH promotor to activate expression of AMH in sertoli
What is the Dax1 gene?
x chromosome but males need it
expressed in genital ridge just after sry expression and may be important for spermatogenesis
klinefelters syndrome people have dosage problem
What is the klinefelters genotype?
xxy
What is the Wnt4 gene?
autosomal gene that encode protein hormone that repressed male differentiation (antagonizes sox9)
What is the indifferent stage genitalia?
genital fold, genital swelling, genital tubercle
What is the critical stage of masculinization?
8-12 weeks
What is the genial tubercule (male and female)
m: penis
f: clitoris
What is the urethra fold m and f?
m corpus spngiosum
f labia minora
what is the labioscrotal swelling m and f?
m scrotum
f labia majora
what is the urogeniatal sinus m and f?
m prostate
f vagina
What type of secretion do males and females have?
m tonic
f cyclic
What happens in freemartinism?
male and female twin calves, 95% sterile female
caused by connected placenta that allows for hormone transfer
