Accessory sex glands
- Seminal vesicles
- Secrete thick alkaline fluid
- Bulbourethral (Cowper’s) glands
- Add fluids to semen
- Prostate gland
- Secrete thin milky fluid
Ducts
- Epididymis
- Nutrition to sperms, become motile
- Vas deferens
- Continuation of tail of epididymis, secondary storage for sperms
- Ejaculatory ducts
- Union of ducts of vas deferens and seminal vesicles, opens into prostatic urethra
- Urethra
- Male urethra – muscular tube of 18 to 20 cm, conveys urine from internal sphincter to external sphincter
- Also exit for semen (sperms & glandular secretions)
Supporting structures
- Spermatic cord
- Suspend testis in scrotum, contains vas deferens, vessels & nerves of testis – pass through inguinal canal
- Scrotum
- Cuteneous fibromuscular sac
- Houses testis, epididymis and lower end of spermatic cord
- Maintains temperature lower than body, necessary for spermatogenesis
- Penis
- Male copulatory organ, common outlet for urine & semen
Gonads
- Pair of testis - Ovoid bodies suspended by spermatic cords into scrotum
- Weighs - 25 g
- 3 layers
- Tunica vasculosa (innermost)
- Tunica albuginea (middle)
- Tunica vaginalis (outermost)
Blood supply
- Artery – Testicular artery, Br. of abdominal aorta
- Vein – Pampiniform plexus of veins
- Lymph nodes – Lumbar & Pre-aortic nodes
- Nerve – Testicular plexus
- Testis is divided into many lobules by fibrous septa
- Lobules contain 2 compartments
- Seminiferous tubular compartment
- Intestitial compartment
Seminiferous tubular compartment
- Forms 80-90% of testicular volume
- Contains seminiferous tubules, which has two parts
- Convoluted part
- Straight part
- Terminal straight part is called rete testis and is continuous with epididymis
Histology of seminiferous tubules
- 3 layers
- Tunica propria
- Basement membrane
- Epithelial layer
- Germ cells (Spermatogenic cells)
- Supporting cells or sustenticular cells (Sertoli cells)
Sertoli cells
- Physical support & nutrition to maturing germ cells
- Phagocytic function
- Maintenance of blood-testis barrier
- Secretory function
- Mullerian duct inhibitory substance (MIS)
- Inhibin
- Androgen-binding protein
- Oestrogen
- Transport proteins
- Plasminogen activator
- Seminiferous tubular luminar fluid
Interstitial compartment
- Forms 10-20% of testicular volume
- Filled by loose connective tissue & Leydig cells
- Leydig cells have endocrine function of secretion of male sex hormone – testosterone
Functions of Testis
- Gametogenic function (Spermatogenesis)
- Endocrine function
Spermatogenesis
- Process of formation of spermatozoa from the primitive germ cells (spermatogonia)
- Average duration – 74 days
- At 32 deg. C
- Occurs in 4 stages
- Stage of proliferation
- Stage of growth
- Stage of maturation
- Stage of transformation
Phases of spermatogenesis
Phase of mitotic division of spermatogonia
1à2à4à8à16à32
Phase of formation of primary spermatocytes by mitotic
division
32 (44+X+Y) x 2 = 64 (44+X+Y)
Phase of formation of secondary speramatocyte by meiotic
division
64 (n) x2 = 128 (n) & 128 (n) x 2 = 256 (22+X or 22+Y)
Phase of formation of spermatid
256 (n) x 2 = 512 (n)
Phase of formation of spermatozoon
No
further division, undergoes changes in shape and orientation of its organelles
Semen
- Fluid ejaculated from male genital tract during orgasm
- Contains sperm, seminal fluid & secretion from prostate & bulbo-urethral gland
- Volume: 2.5ml - 3.5ml/ejaculation
- Colour - White opalescent
- Specific Gravity =1028
- pH=7.35-7.50
- Sperm count = 80 to100 million/ml
Endocrine function of testis
- Leydig cells – male sex hormones – androgens
- Sertoli cells – oestrogen, inhibin & activin
- Andrognes
- Testosterone
- Androsternedione
- Dihydrotestosterone
Functions of androgens
- Fetal period
- Sex differentiation in fetus and descent of testes
- Puberty
- External genitalia – pigmentation & enlargement
- Accessory sex organs - enlargement of seminal vesicles and growth of prostrate
- Development of male secondary sexual characters
- Psyche - male pattern of sexual behavior, initiates sexual drive
- Anabolic & growth promoting effects
- Nitrogen retention - rapid increase in stature
- Adults
- Hair growth – male pattern & baldness
- Psyche – behavioral attitudes & sexual potency
- Bone loss & osteoporosis prevented
- Speramtogeneisis
- Haematopoiesis
- Increases circulating levels of LDL
- Regulation of gonadotropin secretion
Applied Aspects
Hypergonadism
- Excessive secretion of male sex hormones – tumours of leydig cells
- Charecterised by
- Rapid growth of musculature of bones
- Height is less due to early closure of epiphysis
- Excessive development of sex organs and secondary sexual characters at an early age
- Overgrowth of breasts (Gynaecomastia)
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