4314 After Quiz 1 to Exam

Mullerian Ducts

-develop into female reproductive organs

-oviduct, uterus, cervix, anterior vagina

Wolffian Ducts

-develop into male repro tract

-epididymis, vas deferens, vesicular glands

Hormones involved in development of tubular repro tracts

-testosterone: from testes, stim wolffian duct to develop

-antimullerian hormone: from sertoli cells, prevents development of mullerian ducts

Are mullerian and wolffian ducts present in both male and female embryos?

-yes

-mullerian will naturally develop and wolffian will regress without hormone intervention

What is the source of external genitalia?

urogenital sinus

Three Tissues for development of external genitalia

-gential tubercle: penis or clitoris

-genital fold: prepuce or inner vulva

-genital swelling: scrotum or outer vulva

What is required to develop male external genitals

-testosterone has to be converted to 5a-dihydrotestosterone (DHT)

-thorugh 5a-reductase enzyme

Alpha Fetoprotein

-secreted from liver

-binding affinity for estrogen

Sexual development of male brain

-testosterone from testis crosses blood brain barrier

-aromatase converts to estrogen

-estrogen in brain causes male differentiation

Sexual development of female brain

-estrogen produced by ovaries

-alpha fetoprotein binds to estrogen

-estrogen cannot cross blood brain barrier because it is too large when binded to the protein

-causes low levels of estrogen in brain, so its female differentiation

When does sexual differentiation of the brain occur?

-depends on species

-if happens at birth, castration can cause female brain

Testicular Feminization

-XY

-testes

-testosterone and antimullerian hormone, but no testosterone receptor activity

-no male or female tract

-female external genitalia

-male brain

Androgenital Syndrome

-XX

-ovaries

-testosterone (fetal adrenal gland)

-male and female tract

-male external genitalia

-male brain

Persistent Mullerian Duct

-XY

-testes

-testosterone, no AMH or AMH activity

-male and female tract

-male external genitalia

-male brain

Penis at 12

-XY

-testes

-testosterone and AMH

-no alpha reductase enzyme: no DHT

-male tract

-female external genitalia at birth, male at puberty

-male brain

Function of Testes

-exocrine: produce spermatozoa in seminiferous tubules

-endocrine: produce testosterone in leydig cells

Path of sperm cells out of testes

-seminiferous tubules: sperm prod

-rete testis: sperm collection

-efferent ducts: fluid absorption

-epididymis: head, body, tail, transports, concentrates, matures, and stores sperm

-vas deferens: sperm into body through inguinal canal

-urethra

Where are leydig cells in relation to seminiferous tubules?

-outside/between them

Where are sertoli cells in relation to seminiferous tubules

-inside

Sertoli Cells

-provide nourishment for sperm cells

-produce AMH

Leydig Cells

-produce testosterone

4 things for thermoregulation of testicular temperature

-scrotum

-dartos muscle

-cremaster muscle

-pampiniform plexus

Scrotum

-has sweat glands

-thermosensitive neurons connected to respiratory center in brain to increase respiration

Tunica Dartos Muscle

-lines the scrotum

-contracts in cold weather to shrink scrotum

-relaxes in heat to increase SA for heat dissipation

Cremaster Muscle

-move testes closer to or further from body in response to heat

-contract in cold

-relax in heat

Pampiniform Plexus

-network of veins from scrotum that form network around arteries

-allow for heat exchange between cooled blood from testes and warm blood from body

Functions of spermatic cord

-provide nerves, blood vessels, and lymphatic vessels of testes

-contains pampiniform plexus

-contains cremaster muscle

-contains vas deferens

3 Main Accessory Glands

-seminal vesicles: volume of fluid (bulls and boars) and gel portion (stallion)

-prostate gland: secrete fluid to activate and protect sperm

-cowper's or bulbourethral gland: flush and clean out urethra

Bulbospongiosus Muscle

-surrounds cowper's gland

-stims contraction to clear out urethra for sperm

-sends pulse down corpus sponginosum penis to move sperm out

Function of Accessory Glands

-fluid volume

-nutrients

-buffer: vagina is acidic

-decapacitation: keep sperm from being activated too soon

Urethralis Muscle

pushes semen up to where it can be ejaculated

Ischiocaverosus Muscle

-important for erection

-pressure on cura to block venous return from penis

Erection in Ruminants

-vasodilation of helicine arteries: increase blood flow into cavernous space of the corpus cavernosum

-ischiocovernosus muscle contracts to block venous return by applying pressure on crura: compression forces blood into erection canals to fill corpus cavernosum

-decrease venous return and increase blood flow with subsequent increasing bp

-retractor penis muscles relax and sigmoid flexure straghtens

Emission

-contractions of tail of epididymis and vas deferens stimulated by oxytocin

-moves sperm into pelvic urethra in front of colliculus seminalis

-mix fluid of accessory glands

Ejaculation

-contraction of urethralis muscle moves semen out of root of penis

-contraction of bulbospongious muscle sends pulse down corpus spongiosum penis to move sperm out

After ejaculation

-ischiocavernosus muscle stops contracting

-venous return resumes

-bp in corpus cavernosum decreases

-retractor penis muscles contract to form sigmoid flexure

Acrosome

-on head of sperm

-has digestive enzymes to get into egg

Mitochondrial Sheath

-in midpiece of sperm

-drives swimming

Dense Fibers in Sperm Tail

-not for contracting

-provide rigidity

-9

9 + 2 Axoneme

-how sperm tails move

-dynein fibers move

What do we look at to determine the viability of sperm?

-motility: progressive

-morphology