The Male Reproductive System

Michael Hall PhD

University of California

Los Angeles

Components of the Male Reproductive System

Embryology of Gonad Development

Medulla Cortex

Mesenchyme

Genital ridge

Male Female

6 weeks (male = female)

7-8 weeks

Functions of Testes

1. Spermatogenesis-production of sperma. spermatocytogenesis-mitotic division of

spermatogoniab. meiosis-production of haploid spermatidsc. spermiogenesis-maturation of spermatids to

spermatozoa

2. Steroidogenesis-production of steroid hormones

Testis

Vas deferens

Body of epididymis

Rete testis

Mediastinum testis

Tail of epididymisTubuli recti

Head of epididymis

Efferent ducts

Seminiferous tubule

Septum

Tunica albuginea

Tunica vaginalis

Seminiferous tubules

T. albuginea

Components of the seminiferous epithelium

Lumen

Spermatid

Primaryspermatocytes

Secondaryspermatocyte

Spermatogonium

Basal lamina

Sertoli cellnucleus

Sertoli cellcytoplasm

Spermatozoa

(2N)

(4N)

(2N)

(N)(N)

CT

(DNA)

Spermatogenesis-production of sperm

a. spermatocytogenesis-mitotic division of spermatogonia (2N) to primary spermatocytes (4N)

b. meiosis-two successive divisions producing haploid spermatids (N)

c. spermiogenesis-maturation of spermatids to spermatozoa (non-motile)

Cross section of a seminiferous tubule

Leydig

Spermiogenesis

Sertoli Cells

Lumen

Spermatid

Primaryspermatocytes

Secondaryspermatocyte

Spermatogonium

Basal lamina

Sertoli cellnucleus

Sertoli cellcytoplasm

Spermatozoa

(2N)

(4N)

(2N)

(N)(N)

CT

(DNA)

Junctional complex

JC

Sertoli cells form tight junctions

Functions of Sertoli Cells

1. Support, protection, and nutritional regulation of the developing spermatozoa

2. Phagocytosis of residual bodies3. Secretion of testicular fluid into lumen4. Production of Androgen Binding Protein (ABP)5. Secretion of Inhibin (suppresses FSH secretion)

Components of the seminiferous epithelium

Lumen

Spermatid

Primaryspermatocyte

Secondaryspermatocyte

Spermatogonium

Basal lamina

Sertoli cellnucleus

Sertoli cellcytoplasm

Spermatozoa

(2N)

(4N)

(2N)

(N)(N)

Sertoli cells in seminiferous tubule

Sertoli cell

Sertoli cells

Leydig cells lie in the CT between the seminiferous tubules

Leydig cells

Early spermatids

Leydig cells

Leydig cells

Seminiferous tubule

Seminiferous tubuleSeminiferous tubule

Seminiferous tubule

Leydig cells

The prime function of the Leydig cells is the production of testosterone. Testosteronehas many separate but interrelated functions:

a). differentiation and maturation of sperm in the seminiferous tubule (200x testosterone) b). Development and secretory activity of accessory sex glands ( seminal vesicle, prostate and bulbourethral glandsc). development of male secondary sex characteristics(facial and pubic hair, muscularity, libido, obnoxious behavior, voice etc.)

Function of Leydig cells and Testosterone

Hormonal control of spermatogenesisHypothalamus

GnRH

1.LH stimulates synthesis of male sex hormones by Leydig cells

1

2

2.FSH stimulates Sertoli cells tosynthesize ABP

3.Leydig cellsproduce testosteronea) into bloodb) into tubule

3

LH

FSH

Inhibin fromSertoli cells

Seminiferous tubule

Components of the Genital Duct System

prostategland

urethra

seminal vesicle

epididymis

efferent ducts

rete testis

b-u gland

vas deferens

Rete testis

Components of the Genital Duct System

prostategland

urethra

seminal vesicle

ampulla

epididymis

efferent ducts

rete testis

b-u gland

vas deferens

Efferent duct Epididymis

smooth muscle

smooth muscle

sc

cilia

Components of the Genital Duct System

prostategland

urethra

seminal vesicle

ampulla

epididymis

efferent ducts

rete testis

b-u gland

vas deferens

Efferent duct Epididymis

smooth muscle

smooth muscle

sc

cilia

Components of the Genital Duct System

prostategland

urethra

seminal vesicle

ampulla

epididymis

efferent ducts

rete testis

b-u gland

vas deferens

Vas deferensVas deferens

Smooth musclelayers

IL

C

OL

Vas deferens

stereocilia

smooth muscle

Components of the Genital Duct System

prostategland

urethra

seminal vesicle

ampulla

epididymis

efferent ducts

rete testis

b-u gland

vas deferens

spermaticcord

Spermatic cord

vas deferens

pampiniformplexus

cremastermuscle

Pampiniform plexus of spermatic cord

Nerve

Arteries and veins

Vasectomy

The Accessory Sex Glands

prostategland

urethra

seminal vesicle

b-u gland

SM

Epithelium

Seminal vesicle

1

2

1. Cross section of a single, highly coiled seminal vesicle surrounded by smooth muscle

2. High magnification of the mucosa of a seminal vesicle

Mucosal glands

Submucosal glands

Main glands

Capsule

Smooth muscle

Urethra

Bladder

Prostate Gland

Prostate Gland

Prostatic concretions

Glands and ducts

SM

Smooth muscle and elastic fibers

Epithelium

Glands and ducts

Prostate Gland

PC

Bulbourethral gland

prostategland

urethra

seminal vesicle

ampulla

epididymis

efferent ducts

rete testis

b-u gland

vas deferens

The Penis-has two functions:1. Urination2. Reproduction

Corpora cavernosa

Corpus spongiosumUrethra

Tunicaalbuginea

The Penis

Skin

erectile tissue

Penis: Erectile Tissue

endothelial cells line cavernous spaces

elastic fibers and smooth muscle

trabeculae

The Penis

Blood flow to corpus cavernosaand mechanism of erection

Helicine artery

Mechanism of action of Viagra

Viagra

Penile vascular smooth muscle cell relaxation

(Loss of erection)

GTP

See, the problem is that God gives men a brain and a penis and only enough blood to run one of them at a time.

Robin Williams

SemenSemen consists of spermatozoa and secretions ofthe accessory sex glands, which follow one another in adefinite sequence:

During arousal: Bulbourethral gland secretes mucous-like secretionwhich lubricates the urethraAt ejaculation:1. Prostate gland secretion—proteolytic enzyme

rich 2. Spermatazoa are ejected 3. Seminal vesicle secretion follows—nutrient rich

NB: Spermatozoa comprise only 5% of semen

Thank youIt’s been great—but it’s time to be going home(my wife’s wondering where I’ve gone!)

bon voyage et bonne chance!