Reproduction Flashcards
What will occur with gonadal development if someone is XO?
Ovarian (gonadal) streaks.
Ducting and external genitalia will be normal female.
What portion of the Y chromosome determines sex?
SRY
Makes TDF (testis0determining factor)
What stage are primary oocytes in?
Diplotene stage
Part of prophase.
How many daughter cells are produced per germ cell in spermatogenesis?
Oogenesis?
Spermatogenesis = 4 Oogenesis = 1 and polar bodies
What does the Coelomic Epithelium develop into?
Sertoli cells in XY male
Granulosa cells in XX female
Sertoli cells release antimullerian hormone
What do mesenchymal cells develop into?
XY: Leydig cells
XX: Theca cells
Leydig cells –> androgens
Theca cells –> E2
What determines gonadal development?
It is genetically determined & hormone-independent.
This makes sense since the gonads are the source of sex hormones.
What does the gonadal medulla develop into?
The cortex?
Medulla = seminiferous tubules, spermatogonia, sertoli, leydig
Cortex: Secondary sex cords, oogonia, theca, granulosa
Medulla results from XY, Cortex results from XX.
What do Sertoli cells secrete?
Antimullerian hormone
What do Leydig cells secrete?
Testosterone
What do Theca cells secrete?
E2
What is testosterone’s effect on duct development?
Testosterone keeps Wolffian ducts around
What is Antimullerian hormone’s (AMH’s) effects on ductal development?
It regresses Müllerian ducts.
What enzyme catalyzes Testosterone –> DHT?
5-alpha-reductase
What drug blocks 5-alpha-reductase?
Propecia
Turner’s Syndrome:
Genetics?
Gonads?
External genitalia?
XO
Streak gonads
Female external genitalia
What determines female/male pseudohermaphroditism?
If testes are present –> male pseudo…
If both types of gonads present –> hermaphroditism
Androgen Resistance:
Genetics?
Gonads?
Exterior appearance?
Genetics: XY; X-linked androgen receptor is messed up.
Internal testis present
Looks like female; no axillary/pubic hair present.
Klinefelter’s Syndrome:
Genetics?
Symptoms?
XXY
Infertile; uppter:lower segment is off; short arms; gynecomastia; triangle pubic hair.
This is the most common form of primary testicular failure.
Kallmann’s Syndrome:
Symptoms?
Cause?
Symptoms: anosmia, microphallus
Cause: GnRH neurons can’t get into CNS (congenital)
Female Pseudohermaphroditism:
Cause?
Symptoms?
Cause = prenatal exposure to androgens
Symptoms: clitoromegaly, possible urogenital sinus, advanced skeletal age.
Where do spermatagonia travel as they develop into spermatids?
Inward toward the lumen of a seminiferous tubule.
What catalyzes Testosterone —> E2?
Aromatase
What is spermiogenesis?
Spermatogenesis?
Spermeation?
Spermiogenesis = maturation & remodeling of sperm
Spermatogenesis = Spermiogenesis + Spermeation
Spermeation = Extrusion of flagellated spermatozoa into lumen of seminiferous tubule and removal of remaining cytoplasm as residual body.
When do sperm become haploid?
During the second meiotic division.
Secondary spermatocyte —-> Spermatid
What is the acrosome?
Membranous cap filled with digestive enzymes.
What forms the blood/testis barrier?
Tight junctions between Sertoli cells keep Ig’s away from developing sperm.
What function does the epididymis serve?
It is a reservoir for sperm and allows their maturation.
Sperm gain motility and lose their cytoplasm while being stored.
What purpose does the prostate gland serve?
It secretes alkaline additives to the semen. This helps to neutralize the acidic vagina.
What does PSA measure?
Prostate-Specific Antigen.
It is used as a clinical indicator of prostate hyperplasia and prostate cancer.
What purpose do the seminal vesicles serve?
They secrete prostaglandins, which cause uterine and Fallopian tube contraction. This facilitates sperm movement.
How is LH regulated?
GnRH stimulates it.
Testosterone is converted to estrogen in the hypothalamus and feedback inhibits GnRH release.
What is the major regulator of FSH?
Inhibin
What occurs in Leydig cells, in response to LH?
LH –> GPCR –> PKA –> transcription.
Testosterone is produced, as well as sterol-carrier protein & sterol-activating protein.
What occurs in Sertoli cells in response to FSH?
FSH –> GPCR –> PK –> transcription.
^Androgen Receptors
^Aromatase
^Growth factors for spermatogenesis
^Inhibin synthesis
What cells release inhibin/activin?
What is their endocrine action?
What is their paracrine action?
Sertoli cells release them.
They work like their namesake when influencing the pituitary (endocrine), but they work OPPOSITE of their namesake when influencing Leydig cells (paracrine).
What is the effect of Testosterone on Sertoli cells?
It stimulates them indirectly, this is mediated by stimulating Peritubular Myoid cells, which stimulate Sertoli cells.
What are the paracrine inhibitors of Leydig cells?
Activin & E2
How do germ cells regulate their own levels?
They release signals that cause inhibin release from Sertoli cells.
If there are many dividing germ cells –> inhibin release –> decreased FSH –> levels return to normal