CH 25 - Reproductive System - Male

reproductive system contribute to

homeostasis to other body system

primary sex organs

gonad “seeds” - testes and ovaries

primary sex organs

• produce sex cells (gametes); sperm and ovum

• produce sex hormones (development, maintenance, and function)

accessory sex organs

glands and external gentialia

glands -

nourish gametes and transport them towards the outside of the body

route of sperm from the testis

epididymis → vas deferens → ejaculatory duct → urethra

asscessory sex glands

seminal vesicles, prostate (“walnut shaped”), bulbourethral gland (Cowper’s gland)

testes are located externally within

the scrotum “pouch”

external positioning puts the

male’s “entire genetic heritage in a vulnerable position”

viable sperm cannot be produced at the

core body temperature of 37 C

superficial positional provides an

environment 3 C cooler than body temperature

testes are elevated closer to the body under

cold conditions

cremaster muscle “a suspender” -

bands of skeletal muscle that elevates the testis

dartos -

layer of smooth muscle that wrinkles scrotal skin (increases thickness % reduces heat loss)

warm conditions

• move further away under warm conditions

• increases the skin surface available for cooling (sweating)

arterial supply of the testes

testicular arteries branch from aorta in the superior abdomen

testicular veins arise from the

pampiniform plexus and run parallel and run parallel to testicular partiers

veins of the panpiniform plexus surrounds arteries like

veins and absorb heat from the arterial blood cooling it before it enters the testes

testes inverted by

parasympathetic and sympathetic divisions of ANS

the abundant visceral sensory nerve transmit impulses that result in

agonizing pain and nausea when the testes are hit forcefully

each testis is enclosed in a

serous sac - the tunica vaginalis

deep to tunica vaginalis is

the tunica albuginea (fibrous capsule of the testes)

septal extensions of this later divide each testis into

250-300 lobules

lobules contain 1-4 coiled

seminiferous tubules

seminiferous tubules are

site of sperm production

seminiferous tubules

• separated by areolar CT

• consists of a thick stratified epithelium surrounding a hollow central lumen

seminiferous tubules - epithelium consists of spherical

spermatogenic cells embedded in sustentocytes (supporting cells); aka “Sertoli cells”

seminiferous tubules convey nutrients to

the spermatogenic cells

• actively move these cells toward the tubule lumen

seminiferous tubules - they phagocytize the cytoplasm that is shed during

sperm formation

seminiferous tubules - secrete testicular fluid into

the tubule lumen

• helps to push perm through the tubule and out of the testes

other cell types involved in the production of sperm

• interstitial (leydig) cells

• mysid cell

• sustentocyte (Sertoli cells)

• spermatogenic cells

interstitial (leydig) cells

secrete sex hormones (testosterone)

• located within CT between tubules

myoid cells

help move sperm and testicular fluids through tubules and out of testis

• smooth muscle-like cells that surround seminiferous tubules

sustenotcyte (Sertoli cells)

surround, support, and nourish developing sperm

spermatogenic cells

embedded within Sertoli cells

• cells that are in the process of forming sperm

• differentiate sequentially as they move towards the lumen s

sperm leave the seminiferous tubules and enter into

the epididymis

head of the epididymis contains

different ductules, which empty into the duct of the epididymis

• duct of the epididymis completes the head and forms all of the body and tail of this organ

immature sperm (immotile) leave the testis and

moves slowly through the duct of the epididymis

20 day period, sperm gain the ability to

swim and the ability to fertilize the egg via the acrosome reaction

sperm can be stored in the epididymis for

several months; eventually phagocytized by the epithelial cells of the duct of the epididymis

ductus deferens

transports sperm during ejaculation

walls of the vas deferens is made of

smooth muscle that creates strong peristaltic waves to propel sperm during ejaculation

histology of vas deferens

• inner mucosa - psuedostratified epithelium

• thick muscularis

• adventitia (CT)

vasectomy

minor surgery to block perm from reach the semen that is ejaculated from the penis

• semen still exists, but has no sperm (soaked up by the body)

• vas deferens is cut

spermatic cord

cord-like structure formed by the vas deferens and surrounding tissue

• runs from the deep inguinal rings down to each testicle

• deep inguinal ring and surrounding tissues are weak areas of the the abdominal wall

• supports the testes in the scrotum

the urethra carries

sperm from the ejaculatory ducts to outside the male body

urethra product most

of the semen (sperm + secretions of accessory glands)

seminal gland

secretes 60% of semen volume

• fluid contains fructose, sperm motility enhancers, and prostaglandins

prostaglandins have

“hormone-like effects”, promote uterine contractions

• substances that suppress female immune response against semen

• enzymes that clot semen in the vagina and then liquify it so that sperm can swim out p

prostate -

secretes 25-30% of semen volume

• consists of 25-30 compound tubuloalveolar glands

• contains sperm motility enhancers

prostate specific antigen (PSA)

one of the enzymes that liquify semen; levels can be measures as a screening method for prostate cancer

bulbourethral gland

produces a mucus

• mucus enters the spongy urethra prior to ejaculation → neutralizes traces of acidic urine and lubricates urethra

external anatomy of penis

• root

• glans penis

• prepuce

• erectile bodies

glans penis

distal expanded end

prepuce

foreskin; removed during circumcision

erectile bodies

sponge like network, filled with vascular spaces

erectile bodies consist of

one corpus spongiosum and two corpora cavernosa

corpus spongiosum

surrounds spongy urethra

coropora cavernosa

contain sinuses; make up most of the penis

erection

engorgement of erectile bodies with blood; parasympathetic control

ejaculation

contraction of smooth muscle throughout reproductive ducts and glands

• bulbospongiosus muscle squeezes semen through urethra; sympathetic control

male perineum

contains scrotum, root of penis, anus

• diamond-shaped area between

  • pubic symphysis anteriorly, coccyx posteriorly, ischial tuberosities laterally

spermatogenesis

formation of sperm, occurs within seminiferous tubules throughout a man’s life

spermatogenesis divided into

three stages as spermatocytes move from the peripheral region of the seminiferous tubules to the lumen

spermatogenesis stages

1. formation of spermatocytes

2. meiosis

3. spermatogenesis

spermatogenesis is controlled by

follicle stimulation hormone and testosterone

spermatogenesis - stage 1

spermatogonia divide by mitosis

• type A - maintain the germ cells

• type B - differentiate into primary spermatocytes

spermatogenesis - stage 2

meiosis I and II

• meiosis I - forms two secondary spermatocytes

• meiosis II - each spermatocyte forms two spermatids

spermatogenesis stage 3

transformation of spermatid into a sperm

• spermatids differentiate into sperm

• spermatozoa shed superfluous cytoplasm

• composed of head, mid piece, and tail

acrosome

contains enzymes that allow the sperm to penetrate the egg

acrosomal reaction

reaction that occurs in the acrosome of the sperm as it approaches the egg

in acrosomal reaction, releases surface antigens necessary for binding to

the egg’s cell membrane, enzymes responsible for breaking through the egg’s tough coating and allowing fertilization

circumcision

removal of foreskin

• proponents contend that it reduces risk of penal cancer and infections of the glans, urethra, and urinary tract; and reduces risk of STDs

• opponents charge that it is a medically unnecessary procedure

testicular cancer

-Affects 1 of 50,000 males

–Commonly from early-stage spermatogenic cells

–Increase of 50% from 1974 to 1990

–Cured in 95% of cases

prostate cancer

–Slow-growing—arises from

peripheral glands

–Risk factors

• fatty diet, genetic predisposition

erectile dysfunction

-Risk factors

● diabetes, vascular disturbances, drugs/alcohol,

depression/anxiety