male reproductive system

male repro system

• produce male gametes (sperm)

• pathway of sperm from the testis to outside

• produces male sex hormones (testosterone)

• produce various components of the ejaculate

• delivers sperm to the female

male sex organs

primary sex organs

• testes

accessory sex organs

• ducts, tubules, penis, prostate gland, bulbourethral gland, seminal vesicles

scrotum

• located outside body between the thighs

  • external location helps to keep testes cooler

  • cremaster muscle maintains testes temperature

    • relaxes during elevated temp

    • contracts during cold temps

  • perineum: between scrotum and anus

spermatic cord

bundle that carriers blood vessels and nerves to testes

• travels from abdomen to scrotum

• originates in ingunial canal: passageway through the inferior abdominal wall

Structures within spermatic cord

• testicular artery (gonadal artery)

• pampiniform plexus

  • plexus of testicular veins surrounding testicular artery

  • cools arterial blood

• testicular nerve

• vas deferens

• cremaster muscle

testes

• housed within the scrotum

function:

• produce sperm

• release testosterone

testes capsule

• the capsule surrounding the testes is made up of two layers

1) tunica vaginalis:

• serous membrane with parietal and visceral layers

• cavity in between layers

2) tunica albuginea

• lies deep to visceral layer of tunica vaginalis

• invaginations from septa: divides testes into lobules, approx 250 lobules/testis

testes; lobules and interstitial spaces

lobules

• lobes of the testes created by invagination of the capsule

• contains areas (seminiferous tubules) where sperm is produced

Interstitial space

• spaces surrounding seminiferous tubules

• contain interstitial cells that secrete testosterone

testicular ducts

seminiferous tubules

• contain germ cells that produce sperm beginning at puberty

• spermiogenesis

straight tubules

• duct where sperm travels from individual seminiferous tubules

rete testis

• receive sperm from multiple straight tubules

efferent ductules

• lead away from rete testes

epididymis

• 12ft long series of tightly coiled ducts

• area where sperm is stored until ejaculation

• allows sperm to fully mature

epididymis

• extends from the head on the superior surface of testis to the tail on the posterior surface

• takes 20 days for sperm to get through

  • store sperm until fully mature and motile

  • sperm cells that leave too early are not capable of fertilization

  • sperm that is stored for too long is reabsorbed

  • sperm may be stored for several months

ductus deferens

• pathway

  • receives sperm from epididymis

  • travels within spermatic cord

  • leaves spermatic cord and travels on posteriolateral surface of bladder

  • terminates where bladder and prostate gland meet

• ampulla of ductus deferns: enlargement of vas deferens

  • enlargement of vas deferens at its terminal portion

ejaculatory duct

small duct within the prostate gland that receives sperm from testes and fluid from seminal vesicle during ejaculation

• 1-2 cm long

urethra

• transport semen from ejaculatory duct to outside of the body

three regions

• prostatic urethra: within the prostate gland

• membranous urethra: within urogenital diaphragm

• penile (spongy) urethra: length of the penis

sperm

• male gamete produced in the testes

• about 1500 are made every heartbeat

• about 20 million sperm cells per mL of ejaculate

• typically 5% of ejaculatory volume

• much smaller in comparison to oocytes

• 3 main components to a sperm cell: head, midpiece, flagellum

sperm: head, midpiece and flagellum

head of sperm: front portion containing the nucleus and the acrosome

• acrosome: special lysosome containing hydrolytic enzymes that helps the sperm get into the oocyte

midpiece of sperm: middle portion containing multiple mitochondria (produces ATP for tail movement)

flagellum: long protrusion of the cell containing microtubules that allows locomotion

pathway of sperm

sperm and fluid travel from the seminiferous tubules → straight tubules → rete testis → efferent ductules → ductus deferens→ ejaculatory duct → prostate gland → urethra

special fluid is picked up along the way at the seminal vesicle, bulbourethral gland, and prostate gland to create semen

accessory glands

1) seminal vesicles

• located on posterior side of bladder, lateral to ampulla of vas deferens

• secretes alkaline (basic) fluid containing

  • fructose: nourishment

  • prostaglandins: promotes uterine contraction

  • coagulating proteins

• semen: seminal fluid and sperm

  • 60% of volume comes from seminal vesicles

2) prostate gland

• located inferior to bladder

• secretes directly into prostatic urethra

• secretes prostate fluid

  • neutralizing solution (to neutralize acidic conditions in vagina)

  • prostate-specific antigen (PSA): enzyme to liquify semen following ejaculation so sperm can swim freely

  • other components

3) bulbourethral glands

• small paired glands located on either side of membranous urethra

• secrete into spongy urethra

• bulbourethral fluid:

  • mucus to protect and clean urethra

  • also acts as lubricant during sexual intercourse

  • 5% of semen is bulbourethral fluid

ejaculate

ejaculate: when semen is released from the body

• 3-5mls/ejaculation

• 5% of volume is sperm containing 200-500 million sperm

sperm takes 2 weeks from release into lumen of seminiferous tubule to appearance in ejaculate

• very sexually active males may have low sperm count because of fewer sperm cells from epididymis

• semen volume remain the same since seminal fluid is primary component

penis

urethra: tube leading from the urinary bladder to the outside

penis: organ that allows transfer of sperm to female

corpora cavernosa and corpus spongiosum: tissue that can engorge by rapidly filling with blood

• as arteries fill the tissue with blood, veins are constricted and blood cannot leave

male reproductive tract

glans penis: spongy bulbous structure at the distal end of the penis

• high sensitive

• stimulation of the plans is involved in ejaculation

prepuce (foreskin): skin covering the end of the penis

• covers and protects glans penis

• produces smegma: lubricating and moistening substance

• circumcision: removal of prepuce

penis: internal anatomy

• inside the penis are three erectile bodies

corpora cavernosa:

• singular: corpus cavernosum

• 2 paired bodies

• located dorsolaterally

• ends at the glands of the penis

corpus spongiosum

• single body that lies ventral to corpora cavernosa

• surrounds spongy urethra

• continues within glands: makes glands larger during arousal

structure of erectile bodies:

• composed of venous spaces surrounding a central artery

during sexual arousal, blood enters central artery and flows into venous space

ejaculation

emission: release of sperm into the vas deferens and urethra

ejaculaton: expulsion of semen from penis with help of urethral contractions

homologs

homologs: strucutres that come from common developmental origins and serve a common purpose

• ovaries and testes: makes gametes and sex hormones

• clitoris and glans of penis: arousal and sexual pleasure

• labia majora and scrotum: protect and cover repro structures

• vestibular glands and bulbourethral glands: secrete mucin for lubrication