male reproductive system -...

Male reproductive system

consists of the testes and a series of ducts

and glands

Sperm are produced in the testes and are

transported through the reproductive

ducts: epididymis , ductus deferens,

ejaculatory duct, and urethra

The reproductive glands produce

secretions that become part of the semen,

the fluid that is ejaculated from the urethra

testes

are located in the scrotum, a sac of skin

between the upper thighs.

The temperature.

in the male fetus, the testes develop near

the kidneys, then descend into the

scrotum just before birth.

Cryptorchidism is the condition in which

the testes fail to descend ( sterility)

Normal sperm production requires a temperature

about 2–3C below core body temperature

Each testis is about 1.5 inches long by 1

inch wide (4cm X2.5cm)

divided internally into lobes.

Each lobe contains several seminiferous

tubules, in which spermatogenesis takes

place.

Layers of testes:

1- tunica vaginalis: serous membrane which is derived from the peritoneum

and forms during the descent of the testes

2- tunica albuginea : white fibrous capsule composed of dense irregular connective

tissue; it extends inward, forming septa that divide the testis into lobules. Each of

the 200–300 lobules contains one to three tightly coiled tubules, the seminiferous

tubules , where sperm are produced.

tunica vaginalis

tunica albuginea

Blood supply

Lymphatic drainage

In the spaces between adjacent seminiferous

tubules are clusters of cells called Leydig

(interstitial) cells . These cells secrete

testosterone

Spermatogenesis

the process of meiosis as it takes place in the testes, the site of sperm production. Within each testes are the seminiferous tubules that contain spermatogonia, or sperm-generating cells. These cells divide first by mitosis to produce primary spermatocytes.

For each primary spermatocyte that undergoes meiosis, four functional sperm cells are produced.

spermatogenesis takes 65–75 days.

spermatogonium

spermatid

sperm

1ry spermatocyte

2ndry spermatocyte

Spermiogenesis

- The final stage of spermatogenesis

- is the development of haploid spermatids into sperm

- No cell division occurs in spermiogenesis; each spermatid becomes a

single sperm cell

- During this process, spherical spermatids transform into elongated,

slender sperm.

Sperm

The head contains the 23 chromosomes.

the acrosome, On the tip of the head is

which contains enzymes to digest the

membrane of an egg cell.

Within the middle piece are mitochondria

that produce ATP.

The flagellum provides motility,requires

ATP.

Sperm from the seminiferous tubules enter

a tubular network called the rete testis,

then enter the epididymis, the first of the

reproductive ducts.

epididymis

a tube about 20 feet (6 m) long

coiled on the posterior surface of each

testis.

the sperm complete their maturation

Smooth muscle in the wall of the

epididymis propels the sperm into the

ductus deferens.

It is lined with pseudostratified columnar epithelium and encircled by layers of

smooth muscle. The free surfaces of the columnar cells contain stereocilia (long,

branching microvilli that increase the surface area for the reabsorption of

degenerated sperm.

the epididymis is the site of sperm maturation

Ductus deferens

vas deferens – cordlike

extends from the epididymis into the abdominal cavity through the inguinal canal. 45 cm

This canal is an opening in the abdominal wall for the spermatic cord, a connective tissue sheath that contains the ductus deferens, testicular blood vessels and nerves

extends upward over the urinary bladder, then down the posterior side to join the ejaculatory duct on its own side.

The smooth muscle layer of ductus deferens contracts in waves of peristalsis as part of ejaculation.

The dilated terminal portion of the ductus deferens is the

ampulla

Inguinal canal

Oblique passageway through the lower

anterior abdominal wall

In male; allow structures to pass to and

from the testes

In female; permits the passage of round

ligament of uterus

Transmit ilioinguinal nerves in both sexes

About 1.5 inch

From deep inguinal ring to medially the

superficial inguinal ring

deep (abdominal) inguinal ring, a slitlike opening in the aponeurosis of the transversus

abdominis muscle; the canal ends at the superficial (subcutaneous) inguinal ring, a

triangular opening in the aponeurosis of the external oblique muscle.

Spermatic cord

The collection of structures passing

through inguinal canal

Covered by three concentric layers of

fascia

contents

Vas deferens

Testicular A

Testicular V ( pampiniform plexus)

Testicular lymph

Autonomic nerves

Remains of processus vaginalis

Cremastric A

A of vas deferens

Genital branch of genitofemoral n

Coverings

External spermatic fascia (derived from external

abdominal muscle)

Cremasteric fascia (derived from internal abdominal

muscle)

Internal spermatic fascia (derived from transversalis

fascia)

Sperm production begins at puberty (10-

14 years), and millions of sperm are

formed each day in the testes.

Ejaculatory ducts

Each of the two ejaculatory ducts receives

sperm from the ductus deferens and the

secretion of the seminal vesicle on its own

side.

is formed by the union of the duct from the

seminal vesicle and the ampulla of the

ductus (vas) deferens

Both ejaculatory ducts empty into the

single urethra.

Seminal vesicles

lobulated organs about 2 inches long

The paired seminal vesicles are posterior

to the urinary bladder.

fructose → energy

alkaline → sperm motility.

Their upper ends are widely separated

and their lower ends are close together

Prostate gland

A muscular gland /conical

surrounds the first inch of the urethra

lies between the neck of the bladder

above and the urogenital diaphragm

Milky fluid containing citric acid and acid

phosphatase

The smooth muscle of the prostate gland

contracts during ejaculation to contribute

to the expulsion of semen from the

urethra.

Structure of prostate

divided into five lobes.

The anterior lobe

The median or middle lobe

The posterior lobe

The right and left lateral lobes

Ant ----symphysis pubis

Post--- ampulla of rectum

Sup----neck of bladder

Inf----urogenital diaphragm

Bulbourethral glands

Also called Cowper's glands

are located below the prostate gland

empty into the urethra.

Their alkaline secretions coats the interior

of the urethra just before ejaculation,

which will neutralize any acidic urine that

might be present.

Semen

consists of sperm and the secretions of

the seminal vesicles, prostate gland, and

bulbourethral glands

its average pH is about 7.4.

approximately 2-4 ml of semen is expelled.

Each milliliter of semen contains about

100 million sperm cells.