1. Male Reproductive Physiology
بسم الله الرحمن الرحيم
Male Reproductive Physiology
Dr.Mohammed Sharique Ahmed Quadri
Assistant professor physiology
Al Maarefa College

2. Objectives
Describe the structure of the testis physiological functions of the major components of the male reproductive tract. 
Explain how the secretions of FSH and LH are regulated in the male and describe the actions of these hormones on the testis.
Describe spermatogenesis and the role of Sertoli cells, Leydig cells and the basement membrane in this process. 
Explain the hormonal control of spermatogenesis and describe the effects of androgens on the male accessory sex organs. 
Describe the composition of semen,  
Discuss the various factors that affect male fertility.

3. Male Reproductive Physiology
Testes
Development of testis occurs in abdominal cavity, Descent is usually complete by seventh month of gestation.
Descend into scrotum
Location provides cooler environment essential for spermatogenesis
Perform dual function
Produce sperm
Occurs within seminiferous tubules
Secrete testosterone
Produced by Leydig (interstitial) cells that lie in connective tissue between seminiferous tubules

4. Structure of Testis

5. Male Reproductive Physiology
Testosterone
Steroid hormone derived from cholesterol precursor molecule
It is synthesized from the cholesterol in the Leydig cells and also from the androstenedione secreted by the adrenal cortex
Testosterone secretion rate is 4-9mg/dL in normal adults and very small amount is secreted in women

6. Male Reproductive Physiology
Testosterone
Five categories of testosterone effects
Effects on Reproductive system before birth
Effects on Sex-specific tissues after birth
Other reproductive-related effects
Effects on Secondary sexual characteristics
Non-reproductive actions

7. Effects of Testosterone
Effects before Birth
Masculinizes the reproductive tract and external genitalia
Promotes descent of the testes into the scrotum
Effects on Sex-Specific Tissues after Birth
Promotes growth and maturation of the reproductive system at puberty
Enlargement and maturation of gonads,
Development of secondary sexual characteristics,
Achievement of fertility(Is essential for spermatogenesis)
Growth and maturation of the reproductive tract, and
Maintains the reproductive tract throughout adulthood

8. Effects of Testosterone(continues)
Other Reproduction-Related Effects
Develops the sex drive at puberty
Controls gonadotropin hormone secretion by negative feedback
Effects on Secondary Sexual Characteristics
Induces the male pattern of hair growth (e.g., beard)
A deep voice because of thickening of the vocal folds.
Thick skin
Promotes muscle growth responsible for the male body configuration.( as a result of protein-anabolic affect)

9. Effects of Testosterone(continues)
Nonreproductive Actions
Exerts a protein anabolic (synthesis) effect
Promotes bone growth at puberty
Closes the epiphyseal plates after being converted to estrogen by aromatase
Stimulates oil secretion by sebaceous glands (results in development of acne).
May induce aggressive behavior

10. Does males also have Estrogen?
Small amount produce by adrenal cortex
A portion of the testosterone secreted by the testes is converted to estrogen outside the testes by the enzyme aromatase, which is widely distributed but most abundant in adipose tissue

11. Spermatogenesis
Complex process by which diploid primordial germ cells (spermatogonia) are converted into motile haploid spermatozoa (sperm).
It takes 64 days for development of mature sperm from spermatogonium (several hundred million sperm may reach maturity daily)

12. Spermatogenesis Three major stages Mitotic proliferation Meiosis
Spermatogonia divide mitotically to give rise to two daughter cells
Sperm-forming daughter cell divides mitotically twice more to form four identical primary spermatocytes
Meiosis
Each primary spermatocyte forms two secondary spermatocytes yielding four spermatids after the second meiotic division
Theoretically, sixteen spermatozoa result from each spermatogonium that goes through process
Packaging
Production of motile spermatozoa from spermatids (Spermiogenesis).

13. Spermatogenesis

14. Spermiogenesis: Spermatids to Sperm

16. Spermatozoa Consists of four parts Head Acrosome Midpiece Tail
Consists primarily of the nucleus (contains DNA)
Acrosome
containing hydrolytic enzymes that allow the sperm to penetrate and enter the egg
Midpiece
Area where mitochondria are concentrated
Tail
Provides mobility for spermatozoa

17. Functions of Sertoli cells located in seminiferous tubules
Form blood-testes barrier
Provide nourishment
Phagocytic function
Secrete seminiferous tubule fluid which flushes released sperm from tubule into epididymis for storage and additional processing
Secrete androgen-binding protein
Site of action for testosterone & FSH to control spermatogenesis
Release inhibin,Acts in negative-feedback fashion to regulate FSH secretion
Also released Mullerian inhibiting factor ( fetal development)

18. Hypothalamic & pituitary Control on Testicular Function

19. Role of Accessory Sex Glans & Reproductive Tract
Epididymis and ductus deferens
Store and concentrate sperm
Increase sperm motility and fertility prior to ejaculation
Secret defensin , protect sperm from microorganisms

20. Role of Accessory Sex Glans &
Seminal vesicles
Sperm and seminal fluid mix in the ejaculatory duct and enter the prostatic urethra during ejaculation
Supply fructose f(energy source for sperms)
Contribute to 60% of the semen volume
Secrete fibrinogen
Supply prostaglandins
Promote smooth muscle contraction in both male and female reproductive tracts (enhances sperm transport)

21. Role of Accessory Sex Glans
Prostate gland
Contributes alkaline fluid that neutralizes acidic vaginal secretions( sperms are more viable in slightly alkaline environment)
Provides clotting enzymes and prostate-specific antigen(PSA)-fibrin degrading enzyme
Bulbourethral glands
Release lubricating mucus

22. Semen
Milky white, sticky mixture of sperm and accessory gland secretions
Viscous alkaline fluid containing fructose, coagulating enzyme , and prostaglandins
Provides a transport medium and nutrients (fructose), protects and activates sperm, and facilitates their movement
Average volume is ml per ejaculate
Normally 100 million sperm/ml of semen

23. Location and Functions of the Components of the Male Reproductive System

24. Abnormalities of testicular function
Cryptorchidism – descent of testes is incomplete one or less commonly both side, testes remain in the abdomen
Male hypogonadism:
Clinical picture depends on whether testicular deficiency develops before or after puberty.
causes:
Testicular disease(Hypergonadotrophic Hypogonadism)
Disorder of hypothalamus or pituitary (Hypogonadotrophic Hypogonadism)
Androgen secreting tumors : Leydig cell tumors (a rare condition) leads to precocious pseudopuberty in prepubertal boys

25. Don’t Forget the QUIZ on Saturday 12/05/2012

26. References Human physiology by Lauralee Sherwood, seventh edition
Text book physiology by Guyton &Hall,11th edition
Text book of physiology by Linda .s contanzo,third edition