MALE REPRODUCTIVE SYSTEM I

MALE REPRODUCTIVE

PHYSIOLOGY

I

Dr. Nilesh Kate(MBBS. MD)

DR NILESH N KATEASSOCIATE PROFESSORESIC MEDICAL COLLEGE

GULBARGA.

An Overview of the Male reproductive system

Gonads :- Testis Accessory sex

glands :- Seminal Vesicles, Prostate Gland, Bulbourethral Glands

Ducts :- Epididymis, Vas deferens,Ejaculatory ductsUrethra

Supporting structures :-Spermatic CordScrotumPenis

TESTES

Primary reproductive organs or gonads. Correspond with ovaries Functions --

Production of sperm. Secrete Testosterone.

Suspended outside the body cavity by scrotum

FUNCTIONAL ANATOMY OF TESTES Location – suspended by spermatic cord into the scrotum. Weight – 25 gms. Coverings (inner to outer)

1) Tunica vasculosa – innermost --- made up of loose connective tissue.2) Tunica albuginea – Fibrous capsule of testes.

Consists of collagen fibers & elastic fibres. Mediastinal testis – posterior part expand into

thick mass.Numerous septa from it divide testes into Lobules.

STRUCTURE OF TESTES

Fibrous capsule – tunica albuginea – surrounds testes

Scrotal cavity – lined by tunica vaginalis – parietal and visceral layers (between 2 layers small amount of fluid is present)

Figs 27-4/5

TESTES Blood supply.

Arterial – testicular artery branch of abdominal aorta.

Venous – joins Pampiniform plexus anterior to Ductus deferens.

Lymphatic drainage – lumbar & preaortic lymph nodes.

Saturday, April 25, 2015

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GROSS STRUCTURE

Rete Testes

Each lobule contains

•Seminiferous tubule (1) Compartment…80 cm long2 parts –

Convoluted partStraight part. (20-30) joins to form Rete testes.It gives 20 efferent ductules to form head of Epididymis.

•Interstitial compartment


Seminiferous Tubules Capsule– Fibroelastic

connective tissue. Basement

membrane ( basal lamina)

Epithelial layer. (complex stratified) 2 compartments basal

& adluminal


Seminiferous Tubule

Primary spermatocytes

Spermatids

sertoli cell

SpermMICROSCOPIC STRUCTURE

Seminiferous Tubules


CELLS Spermatogenic cells

4-8 layers. Extend from basal

lamina to lumen. Basal compartment

early stages of spermatogenesis.

Adluminal – later stages like sec Spermatocytes, early late Spermatids & spermatozoa.

CELLS SERTOLI CELLS Pyramidal shape. Occupies both compartments Forms tight junctions. Form blood-testes barrier:

Prevents autoimmune destruction of sperm..

Prevents immune attack. Maintain luminal fluid

composition. ( low in glucose & proteins

High in androgen & potassium.


SERTOLI CELLS FUNCTION

Physical Support and nutrition

Phagocytize residual bodies

Secrete MIS, Inhibin, Transport Proteins (Fe & Cu), Plasminogen activator, Oestrogen (aromatase), Seminiferous tubular fluids.

Secrete androgen-binding protein (ABP): Binds to testosterone and concentrates

testosterone in the tubules.

Spermatogenesis Definition:-

Formation of spermatozoa from spermatogonia Characteristic features:-

` PubertyMitosis and Meiosis1 spermatogonium form 512 spermatidsDuration 74 daysNon-motile in semineferous tubules

Spermatogenesis

Spermatogonium (46)

Mitosis Daughter Cells (46)

Spermatogenesis

Spermatogonium (46)

MitosisDaughter Cells (46)

GrowthPrimary Spermatocyte (46)

Meiosis ISecondary Spermatocytes (23)

Spermatogonium

Meiosis IIEarly Spermatids (23)

Spermatogenesis

Spermatogonium (46)




Spermatogonium


SpermiogenesisLate Spermatids (23)

Spermatogenesis

Spermatogonium (46)




Spermatogonium


SpermiogenesisLate Spermatids (23)

Spermatozoa (23)

(Lumen)

SPERMIOGENESIS Nucleus – Head Centriole – proximal forms

basal body & distal forms axial filaments

Golgi app – cap (Proteolytic enzymes)

Mitochondria – surrounds tail (movements)

Cell membrane -- coverings

EM of a Mature sperm cell

55-65 micrometre in length

STRUCTURE OF SPERMATOZOON (55-65 μm)

Head Acrosome

NeckBasal body

TailMiddle piecePrincipal pieceEnd piece

Axoneme – central skeleton. Fibrous sheath Mitochondria – ATP for

motility.

SPERMATOZOA 120 millions per day Maturation and capacitation

Role of Epididymis – secretions makes more motile

Role of seminal vesicle and prostate gland – stimulate sperm motility

Role of female genital tract – Uterus & tubular musculature – sucking effect.

Capacitation – Get ability to fertilize in female genital tract.

FACTORS AFFECTING SPERMATOGENESIS

Temperature. Need lower than body temp

(320c) Mechanisms – location

outside, evaporative cooling in scrotum, countercurrent heat exchanger in artery & vein.

Defective --Hot bath, Cryptorchidism & varicocoele

Seasonal variation Sperm count more in

winter than in summer. Infectious diseases.

Mumps – degeneration of semineferous tubules

Hormonal control

SEMEN Fluid ejaculated during orgasm. Volume --2-5 ml/ ejaculate Vas deferens contribute 10%- Seminal vesicle- 60% Prostate gland- 30% pH -7.5 Fibrinogen-help for coagulum- It dissolves after 15 to 30 min

because of fibrinolysin.(from Prostate) Life span of the sperm in the vagina 1-2 days. Low temp.-several week . -100’C(frozen for years)

COMPOSITION OF HUMAN SEMEN

Color : White, opalescent Specific gravity : 1.028 pH : 7.35 – 7. 50 Sperm count : 35-200 million

average about 100 million/ml.

Fructose (1.5 – 6.5mg/ ml) Phosphorylcholine Ergothioneine Ascorbic acid Flavins Prostaglandins

From seminal vesicles

(contributes 60% of total volume )

COMPOSITION OF HUMAN SEMEN

Spermine Citric acid Cholesterol, Phospholipids Fibrinolysin, fibrinogenase Zinc Acid phosphatase calcium Phosphate Bicarbonate

Hyaluronidase

From prostate

(contributes 30% of total volume )

buffers

Epididymis

~ 7 m longHead - superior,

receives spermatozoa

Body – distal and inferior

Tail - leads to Ductus deferens

Rete testis and Efferent ductules

EPIDIDYMIS

Route of exit of Sperm Nutrition Provide Motility

Function: Sperm storage and maturation

Epididymis

VAS DEFERENS

Continuation of tail of epididymis Route of exit of sperm Ductus deferens stores sperm Vasectomy – ligated and sectioned

Function: Transport sperm to urethra

Vas Deferens

SEMINAL VESSICLES.

Do not store sperm Provide the bulk of the semen, a mixture

of secretions, sperm and mucous Fructose and prostaglandins from

seminal vesicles

Function: Produce 60% of alkaline semen including fructose to provide energy for

sperm.

Ejaculatory DuctSEMINAL VESSICLES

Bulbourethral glands (Cowper’s glands)

Pea size, paired, at base of penis

Produce about 10% of semen

Alkaline mucus - function??

Protection from acidic Ph in vagina

Function: Secretes mucous & alkaline buffers to neutralize acidic conditions of urethra.

Cowper’s Gland

PROSTATE GLAND.

Largest accessory glands

Alkalinity and clotting enzymes from prostate.

Function: Produces up to 1/3 of the semen & includes nutrients & enzymes to

activate sperm.

Prostate

Pathway of Sperm

Seminiferous tubules Rete testis Epididymis Vas (Ductus) deferens Ampulla of vas deferens Ejaculatory duct Prostatic urethra Membranous urethra Penile (spongy) urethra

Fig 27.8

URETHRA: EJACULATION

During emission phase of ejaculation sperm are emptied into urethra by sympathetically induced contractions

Motor neuron induced contractions of skeletal muscles at base of penis expell the semen during expulsion phase of ejaculation

Functions: Transport urine & semen

Urethra

Bladder

SPERMATIC CORD Suspends the testes Contains –

Ductus deferensVessels and nerves

Coverings –Internal spermatic fasciaCremastric fasciaExternal spermatic fascia

Spermatic CordCan be palpated as it passes over the pubic brim.

Constituents :

1. Pampiniform plexus of spermatic vein

2. Spermatic artery

3. Ductus (vas) deferens

4. Lymphatics

5. Nerves-ilioinguinal and genitofemoral

Fig 27.3

SCROTUM

Function: supports and protects testes

Structure: Skin & underlying superficial fascia Dartos muscle in dermis Cremaster muscle - continuous

with abdominal wall muscles (?)

Involuntary contraction (cremasteric reflex) in response to ________

Scrotal sac forms 2 separate chambers

Cremaster muscle

Function: Maintain temperature of testes approx. 30 C below normal body

temp.

Scrotum

PenisRoot - fixed to ischial ramus

Body with erectile tissue.

Glans – enlargement of corpus spongiosum

Prepuce - foreskin – partially covers glans and surrounds external urethral meatus (may be removed in circumcision.)

Preputial glands - produce smegma (supports bacterial growth, such as E. coli)

Fig 27.9

Functions: Urination and Copulation

Penis

MALE SEXUAL ACT

Stages of the male sexual act1.Erection2.Emission 3.Ejaculation NERVE SUPPLYi) Parasympathetic nerve (nervi erigentis) (S2, S3 and S4 ): Supply to the erectile tissue of the penis. Takes part in erection of penis.-impotance.

ii) Sympathetic nerves (hypogastric nerve) (T12, L1, L2):Supply to epididymis, vasdeferens,seminal vesicles, ejaculatory ducts. Takes part in emission. iii)Somatic (pudendal nerve) (S2,S3 and S4): Supply to bulbus cavernosus.It takes part in ejaculation.

Sexual sensations Sexual end organs. Sexual signals pass trough pudendal nerve. Penis.

Pudental nerve Sacral plexes Undefined of the brain

STAGES PENILE ERECTION Role of parasympathetic nerves Erection ---- by sacral portion of spinal cord- pelvic

nerves- penis Nitric oxide – vasoactive peptide ach relax the

artery of the penis & relax the trabecular network of smooth muscles fibres in the erected tissue of corpora cavarnosa and corpora spongiosa

Arterial blood – venous blood occluded by compressing central vein of penis.

Ballooning effect erectile tissue –penis become hard & elongated

LUBRICATION Parasympathetic stimulation- promotes erection &

urethral gland & bulbourethral gland to secrete mucus

Mucus help for lubrication at coitus.

Most of the lubrication of coitus is produced by female sex organ.

Painful sensation- inhibit sexual sensation

EMISSION & EJACULATION Sympathetic nerve T12 L1 L2 hypogastric and pelvic sympathetic

nerve plexus to intiate emission and ejaculation

Contraction of vasdeferns

Expulsion of semen in to urethra Contract prostate & seminal vesicle Expel prostatic and seminal fluid in to

urethra All the fluid mix in the internal

urethra with mucus –emission. it is called fore runner of the ejaculation

Filling of the urethra

Pundenal nerve

Sacral

Feeling a sudden fullness & excite rhythmical contraction

Contraction of ischiocavernous & bulbocavernous muscle

Compress the base of the penile erection

Rhythmical , wavelike impulse in pressure

Ejaculation of semen from the urethra to the exterior ejaculation

Emission and ejaculation is called male orgasm .

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Health & Medicine

MALE REPRODUCTIVE SYSTEM I