ARTS repro Flashcards
the gonads are indifferent in the
first 5 weeks of gestational life
phenotypic sex (external genitalia) in M vs F
Male
1. penis
2. scrotum
3. penile urethra
Female
1. clitoris
2. labia majora/ minora
3. lower 1/3 of vagina
2 important facts about the Y chromosome (SRY gene)
- Contains the SRY (sex region Y) gene
- SRY gene encodes the TDF (testes determining factor), which is a nuclear transcription factor
what is the relationship between testosterone and testes determining factor
SRY gene encodes for TDF
= TDF causes development of testes in embryogenesis
= testes produce testosterone
what is the role of TDF in males (in relation to the 2 types of cells)
TDF produces
1. SERTOLI cells
= produce MULLERIAN inhibiting substance
= no mullerian duct development
- LEYDIG cells
= produce testosterone
= development of WOLFFIAN duct
= give rise to INTERNAL genitalia
LEYDIG CELLS
= produce testosterone
= converted to DHT via 5 alpha reductase enzyme
= give rise to EXTERNAL genitalia
what is the significance of the lack of TDF in females? (3 roles)
No TDF means…
1. no MIS
= production of mullerian duct
= give rise to internal genitalia
- estradiol production
= give rise to external genitalia - no testosterone
= no wolffian duct
what is the internal vs external genitalia of F
Internal
1. uterus
2. oviduct
3. upper vagina
External
1. clitoris
2. labia majora and minora
3. lower vagina
what is the internal vs external genitalia of M
Internal
1. Vas deference
2. Epididymis
3. Seminal Vesicles
External
1. Penis
2. Penile Urethra
3. SCROTUM
function of the SERTOLI cells
- provide nutrients to differentiating sperm
- blood testes barrier
- secrete aqueous fluid to aid transport into epididymis
- secrete ABP (androgen binding protein) into semiferous tubule = keep testosterone levels high
what are the 2 functions of the testes
- spermatogenesis
- testosterone secretion
how does the testes maintain its temperature?
lower temperature:
countercurrent arrangement of pampiniform plexus
= facilitate heat exchange
what is the functional unit of the testes?
seminiferous tubules
what are the 4 functions of the sertoli cells?
- provide nutrients to differentiating sperm
- tight junctions between sertoli cells of seminiferous tubules = blood-testes-barrier
- secretes aqueous testicular fluid
= easier transportation of sperm into epidiymis - secrete ABP (androgen binding protein) into semiferous tubule
= allows for transport of testosterone and maintained concentration of testosterone
what is the importance of the blood-testes-barrier?
- prevent toxins from entering seminiferous tubules
- maintain the unique chemical composition of seminiferous tubule fluid
funfact: blood testes barrier only forms at early stages of puberty in humans
**ANY DISRUPTION TO THIS BARRIER CAN RESULT IN INFERTILITY
what is the blood-testes-barrier made out of?
tight junctions of sertoli cells
where are ABPs found and what is their function
ABPs circulate around the testes
function:
1. transport testosterone from seminiferous tubules and epididymis
2. bind to testosterone
= prevent premature breakdown/ metabolism of testosterone
how is testosterone linked to the development of the internal & external male genitalia?
testosterone –> internal
testosterone – 5 alpha reductase –> DHT –> external
what are the 3 stages of spermatogenesis
PGD
- proliferation (spermatogonia –mitosis–> spermatocyte)
- growth (spermatocyte –meiosis–> spermatids)
- differentiation (spermatid –> mature sperm)
what happens during the differentiation stage of SPERMATOgenesis
SPERMIOgenesis:
- loss of cytoplasm
- development of flagella
spermatids (haploid) –> spermatozoa/ mature sperm
what is the route of the sperm during sexual arousal?
epididymis –> vas deferens –> urethra
what nutrients does the vas deferens provide, and what is the purpose of it?
CITRATE AND FRUCTOSE
= nourish ejaculated sperm
- increase sperm motility (give it energy)
- increase sperm viability
what is the seminal vesicle fluid rich in?
- fructose
- give sperm energy to move - prostaglandins
- make cervical mucus more penetrable to sperm
- induce peristaltic contraction in uterus and fallopian tube (allow egg to move) - fibrinogen
- liquifies the semen
= coagulating agent when semen is deposited in female reproductive tract
what does the prostate gland add to the ejaculate?
adds a milky aqueous solution
- citrate
- enzymes
- calcium
semen vs vaginal fluid alkaline or acidic?
semen: alkaline
vaginal fluid: acidic
= neutralises each other
= increase sperm motility
what is capacitation?
penultimate step in maturation of mammilian spermatozoa - allows the sperm to penetrate the egg
cholesterol an other inhibitory substances on the head of sperm are removed by secretion from female repro tract
= sperm can release acrosomal enzymes
what are acrosomal enzymes known as, and what is their function?
acrosome located in the sperm head contains proteolytic enzymes
= break down proteins at zona pellucida
= allows for sperm to penetrate the egg
what are some of the key acrosomal enzymes?
- hyaluronidase –> breaks down hyaluronic acid, which holds the zona pellucida together
- acrosin –> serine protease enzyme that digests proteins in the zone pellucida
where is GnRH released from?
hypothalamus
