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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
1
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
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Seminiferous Tubules Capsule– Fibroelastic
connective tissue. Basement
membrane ( basal lamina)
Epithelial layer. (complex stratified) 2 compartments basal
& adluminal
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Seminiferous Tubule
Primary spermatocytes
Spermatids
sertoli cell
SpermMICROSCOPIC STRUCTURE
Seminiferous Tubules
Saturday, April 25, 2015
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.
Saturday, April 25, 2015
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)
MitosisDaughter Cells (46)
GrowthPrimary Spermatocyte (46)
Meiosis ISecondary Spermatocytes (23)
Spermatogonium
Meiosis IIEarly Spermatids (23)
SpermiogenesisLate Spermatids (23)
Spermatogenesis
Spermatogonium (46)
MitosisDaughter Cells (46)
GrowthPrimary Spermatocyte (46)
Meiosis ISecondary Spermatocytes (23)
Spermatogonium
Meiosis IIEarly Spermatids (23)
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 .
THANK YOU