- The male reproductive system is located in the pelvis region
- It includes a pair of testes along with accessory ducts, glands and the external genitalia.
- The testes are situated outside the abdominal cavity within a pouch called scrotum.
- The scrotum helps in maintaining the low temperature of the testes (2–2.5o C lower than the normal internal body temperature) necessary for spermatogenesis.
- Normal testicles form early in a baby boy’s growth.
- They form in the lower belly (abdomen), but descend, or “drop,” into the scrotum toward the end of pregnancy
- Normal testicles attach themselves with stretchable tissue in the bottom of the scrotum.
- This is controlled by the baby’s normal hormones.
- An undescended testicle (or “testis”) is when it fails to drop into the normal place in the scrotum.
- Undescended testicles are also linked to a higher risk of:
• Testicular cancer in adulthood
• Testicular torsion (twisting of the chord that brings blood to the scrotum)
• Developing a hernia near the groin - In adults, each testis is
• Oval in shape,
• Length of about 4 to 5 cm and
• Width of about 2 to 3 cm.
• The testis is covered by a dense covering.
• Each testis has about 250 compartments called TESTICULAR LOBULES.
• Each lobule contains in which sperms are produced.
• Each seminiferous tubule is lined on its inside by two types of cells called male germ cells (spermatogonia) and Sertoli cells.
• The MALE GERM CELLS undergo meiotic divisions finally leading to sperm formation, while SERTOLI CELLS provide nutrition to the germ cells
TESTIS
- Male gonads; Homologous to ovary
- Suspended in scrotum by spermatid cord ; lies obliquely
- Compressed side to side; Oval in shape
- The regions outside the seminiferous tubules called INTERSTITIAL SPACES, contain small blood vessels and INTERSTITIAL CELLS or LEYDIG CELLS
- Leydig cells synthesise and secrete testicular hormones called ANDROGENS
- Other immunologically competent cells are also present
- Inhibin is a protein secreted by the Sertoli cells in men and by the granulosa cells in women It inhibits the synthesis and release of the follicle-stimulating hormone in the pituitary gland and reduces the hypothalamic LH – releasing hormone content.
- Testes covered by three layers
• Tunica vaginalis (Outer cover)
• Tunica albuginea (Middle dense cover; Fibrous capsule)
• Tunica vasculosa (Inner cover - A fibrous cord called “Gubernaculum” connects testis with scrotal wall
- Descent of the testis through the inguinal canal is by the guidance of the fibrous strand called the gubernaculum.
- ORCHIDECTOMY à Orchiectomy is a surgical procedure in which one or both testicles are removed. The removal of both testicles is the surgical form of castration.
SEMINIFEROUS TUBULE
- 60 cm in length
- 0.2 mm diameter
- Total length in both testis = 275 yards (1 yard:0.91 meter)
- Have germinal epithelium which is consist of Cuboidal epithelium
SPERMATOGOMIA OR MALE GERM CELLS :-
- Endodermal origin
- It is present as 4 to 8 layers
- Induced by FSH for sperm production
SERTOLI CELLS OR SUSTENCULAR CELLS :-
- Columnar large cells
- Provide nourishment to germ cells
LEYDIG CELLS
- Mesodermal origin
- Influenced by ICSH (In males, where LH had also been called interstitial cell–stimulating hormone, it stimulates Leydig cell production of testosterone)
FUNCTIONS OF TESTIS
- Production of Sperm
- Secretion of male sex hormone
THE MALE SEX ACCESSORY DUCTS
- The male sex accessory ducts include RETE TESTIS, VASA EFFERENTIA,EPIDIDYMIS and VAS DEFERENS
- The SEMINIFEROUS TUBULES of the testis open into the VASA EFFERENTIA through RETE TESTIS The VASA EFFERENTIA leave the testis and open into EPIDIDYMIS located along the posterior surface of each testis.
- The EPIDIDYMIS leads to VAS DEFERENS that ascends to the abdomen and loops over the urinary bladder
EPIDIDYMIS
- Located along the posterior surface of the testis
- Tightly coiled structure; 5 to 6 meter long if stretched out
- Several tubes called Vasa efferentia conduct sperm into epididymis
- A pair of epididymis originated from Wolffian duct of embryo
- There are three parts of Epididymis
1. Caput Epididymis (Anterior part)
2. Corpus Epididymis (Middle part)
3. Cauda Epididymis (Posterior part) - Epididymis store & nourish sperms
THE MALE ACCESSORY GLANDS
- The male accessory glands include
• Paired SEMINAL VESICLES,
• A PROSTATE and
• Paired BULBOURETHRAL GLANDS.
• Secretions of these glands constitute the SEMINAL PLASMA which is rich in fructose, calcium and certain enzymes.
• The secretions of BULBOURETHRAL GLANDS also helps in the lubrication of the penis
SEMINAL VESICLES
- Situated behind the urinary bladder: at the junction of vas deferens & prostate gland
- It’s like narrow long pouch; having a muscular wall
- Two in number
- Produces an alkaline secretion (pH – 7.4)
- Contribute 60% volume to semen
- Secretion contains fructose which serves as energy source for the spermatozoa
- Secretion also contains prostaglandins (hormone like fatty acids; helps in contraction)
- Fructose produces by seminal vesicles provide a forensic test for rape
PROSTATE GLAND
- One in number ; situated at first part of urethra
- Contains prostatic utricle and acini ; covered by a capsule
- Contribute 15 -30% of volume of semen
- Secretion à slightly acidic to alkaline (6.5 to 7.31) ; acidic is due to CITRIC ACID
- Prostate secretion contains :
• Citric acid
• Acid phosphatase
• Peosinogen
• Fibrinolysin & Fibrinogenase
• Albumin
• Prostaglandins - Prostate secretion contains substances important for sperm mobility
- Inflammation of prostate à Prostatitis ; Prostate enlarged so urination becomes difficult
- The pH of expressed prostatic secretion was acid with a mean of 6.7 in men without inflammatory prostatic disease, it reached a mean of 8.1 in those with chronic bacterial prostatitis.
- BPH à BENIGN PROSTATE HYPERTROPHY ; Common condition in elderly male
BULBOURETHRAL GLANDS
- Also called COWPER’S GLAND
- One pair ; situated beneath bladder & behind urethra
- Present only in male mammals
- Slightly alkaline secretion ; acts as lubricant for penis ; it neutralises any urine in urethra
SEMINAL PLASMA :- Secretion of seminal gland + Secretion of prostate + Secretion of bulbourethral
gland
URETHRA
- Thick walled muscular duct ; longer in male than in female
- Also called “urinogenital duct” because it’s a common passage for both urine and semen
- Opens at the tip of penis through Urethral meatus
PENIS
- External genitelia
- Male organ of copulation
- Vascular, spongy and erectile structure; pendulous organ which is suspended from pubic region to in front of scrotum
- Ordinarily is remains flaccid (small and limp) but on sexual arousal it becomes long, hard and erect ; size of erect penis is around 14 – 15 cm
- Penis mostly formed of three cylindrical chord of spongy erectile tissue
- Two of these are thick and situated in parallel position on right and left side -> forming thick part of penis : these chord known as CORPOUS CAVERNOSUM
- Third smaller chord known as CORPUS SPONGIOSUM
- Corpus spongiosum form a bulged and conical structure at the tip of penis -> GLANS PENIS
- Skin over glans penis is loose and retractable -> Prepuce / fore skin
- At the tip of glans penis a slit like urethral meatus is present
- Prepucial glands are present at the base of glans penis (neck of penis); these glands secretes white sebaceous
substance –> Smegma - Erection of penis is a purely vascular phenomenon
- Stimulus carried by PARASYMPATHETIC NERVES (S2, S3 and S4)
- During intercourse the sensory cells present in the skin of glans penis establish reflexes to induce EJACULATION
- The PENIS is the male external genitalia
- It is made up of special tissue that helps in erection of the penis to facilitate insemination.
- The enlarged end of penis called the GLANS PENIS is covered by a loose fold of skin called foreskin
SEMEN
- 2 to 5 ml in one ejaculation
- Alkaline viscous fluid (pH – 7.5)
- Have 200 to 300 million sperm in one ejaculation
- Semen = Seminal plasma + Sperm
- For normal fertility
• at least 60% normal sperm required
• at least 40% must have vigorous motility - Contains 60% seminal vesicle secretion + 30% prostate secretion + 10% sperm, vas deferens secretion, bulbourethral secretion
- Milky appearance of semen is due to prostatic secretion
- Viscosity is due to seminal vesicle secretion
- “Seminal plasmin” antibiotic discovered from semen ; it destroys vaginal bacteria
- Male with less than 35 million sperm / ml -> Sterile
- Semen replaced in 24 hours
- semen coagulated immediately after ejaculation