MALE REPRODUCTIVE PHYSIOLOGY Dr. Amel Eassawi

OBJECTIVES  Describe the physiological functions of the major components of the male reproductive system.  Explain how the secretions of FSH and LH are regulated in the male and describe the actions of these hormones.  Describe spermatogenesis and the role of Sertoli cells, Leydig cells.  Explain the hormonal control of spermatogenesis and describe the effects of androgens on the male accessory sex organs.  Discuss the mechanisms of erection and ejaculation.  Discuss the various factors that affect male fertility. 2

MALE REPRODICTION SYSTEM 3

MALE REPRODUCTIVE SYSTEM Primary Sex Organs: Testes Functional Compartments: A.Seminiferous Tubules : Exocrine Function (spermatogenesis) B.Interstitial Tissue: Endocrine Function: Leydig cells (interstitial cells). Androgen Secretion (mainly testerone ) 4

TESTICULAR MORPHOLOGY 5

Male Reproductive SYSTEM Testosterone –Steroid hormone. –Synthesized from the cholesterol precursor 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

TESTOSTERONE BASED ACTIVITIES 7

TESTOSTERONE IN MALES 8 Effect of Testosterone 1. Effects before Birth 1.Masculinizes the reproductive tract and external genitalia. 2.Promotes descent of the testes into the scrotum 2. Effects on Sex-Specific Tissues after Birth Puberty Adulthood 1.Enlargement and maturation of gonads. 2.Development of secondary sexual characteristics. 3.Essential for spermatogenesis. 4.Growth and maturation of the reproductive tract. 5.Maintains the reproductive tract throughout adulthood

TESTOSTERONE IN MALES 9 Effect of Testosterone 3. Other Reproduction-Related Effects 1. Develops the sex drive at pubert. 2. Controls gonadotropin hormone secretion by negative feedback 4. Effects on Secondary Sexual Characteristics 1. Induces the male pattern of hair growth (e.g., beard). 2.A deep voice because of thickening of the vocal folds. 3. Thick skin. 4. Promotes muscle growth responsible for the male body configuration.( as a result of protein-anabolic affect)

TESTOSTERONE IN MALES 10 Effect of Testosterone 5. Non reproductive Actions1.Exerts a protein anabolic (synthesis) effect. 2.Promotes bone growth at puberty 3.Closes the epiphyseal plates after being converted to estrogen by aromatase. 4.Stimulates oil secretion by sebaceous glands (results in development of acne). 5.May induce aggressive behavior

ESTROGEN IN MALES 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). 2. It takes 64 days for development of mature sperm from spermatogonium (several hundred million sperm may reach maturity daily)

SPERMATOGENESIS 13 Spermatogenesis: Spermatids to Sperm

SPERMATOGENESIS Spermatozoa: Consists of four parts Head 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 14

FUNCTIONS OF SERTOLI CELLS 15 1.Form blood-testes barrier. 2.Provide nourishment and phagocytic function. 3.Secrete seminiferous tubule fluid which flushes released sperm from tubule into epididymis. 4.Secrete androgen-binding protein. 5.Site of action for testosterone & FSH to control spermatogenesis 6.Release inhibin, acts in negative-feedback fashion to regulate FSH secretion 7.Released mullerian inhibiting factor ( fetal development).

TESTICULAR CELL INTERACTIONS Sertoli cell products estradiol, inhibin, activin and other proteins modulate leydig cell activity Sertoli cell products modulate germ cell function Leydig cell testosterone modulate peritubular & Sertoli cell function Peritubular cell products influence Sertoli cell activity 16

LOCATION AND FUNCTIONS OF THE COMPONENTS OF THE MALE REPRODUCTIVE SYSTEM 17

MALE SEXUAL PERFORMANCE 18 Erection

MALE SEXUAL PERFORMANCE Mechanism of Penile Erection –Relaxation of trabecular smooth muscle leading to increased blood flow into cavernosal sinousoids –Engorged corpora cavernosa presses venules against tunica albuginea restricting venous outflow. Regulation of penile erection (smooth muscle tone) –Proerectile factors: parasympathetic input,  intracellular Ca +2,  PGE 1,  NO,  smooth muscle sensitivity to Ca +2 –Antierection factors: sympathetic input  intracellular Ca +2,  NE,  smooth muscle sensitivity to Ca +2 19

MALE SEXUAL PERFORMANCE 20 Components of the Male Sex Act 1. ErectionHardening of the normally flaccid penis to permit its entry into the vagina Parasympathetic induced vasodilatation of the penile artioles and mechanical compression of the veins. 2. Ejaculation A.Emission phase B.Expulsion phase Emptying of semen into urethra. Forceful expulsion of semen from penis. Sympathetic induced contraction of the smooth muscles of the walls ducts and accessory sex glands. Motor neuron induced contraction of the skeletal muscles at the base of the penis.

HUMAN SEXUAL RESPONSE CYCLE PHASES Phases include excitement, plateau, orgasm and resolution The resolution time for men is longer resulting in an increased refractory period to further stimulation 21

MALE SEXUAL PERFORMANCE 22 Erectile dysfunction or Impotence: Failure to achieve or maintain an erection suitable for sexual intercourse. Affect 50% of men between 40 and 70 years old. May be due to: 1. Psychological factors. 2. Physical factors. A. Nerve damage B. Medication that interfere with autonomic function C. Problem with blood flow to the penis. Sildenafil (Vigra): prescribed to treat erectile dysfunction. It does not produce an erection but it amplifies and prolongs an erectile response triggered by usual means of stimulation.

GYNECOMASTIA Defined as presence of any palpable breast tissue in men.  Due to increase in estrogen-androgen ratio.  Three classes physiological, pathological and idiopathic.  Three time period(Birth, Puberty, Old Age). Pysiological The breast enlargement of newborns, the transient gynecomastia of adolescence and breast development of aging men, which cannot be associated with a pathological condition are considered to be physiological. Pathological 1.Hypogonadism (Klinefelters). 2.Chronic liver diseases (cirrhosis, hepatitis). 3.Thyrotoxicosis. 4.Neoplasia. 5.Drugs (estrogen, testosterone) 23

ABNORMALITIES OF TESTICULAR FUNCTION 1. Cryptorchidism: descent of testes is incomplete, testes remain in the abdomen. Occurs in neonatal life. 1. Bilateral: Impaired Testosterone secretion and spermatogenesis. 2. Unilateral :Normal Testosterone and impaired spermatogenesis. 2. Male hypogonadism: Clinical picture depends on whether testicular deficiency develops before or after puberty. causes: –Testicular disease (Hypergonadotrophic Hypogonadism) – Disorder of hypothalamus or pituitary (Hypergonadotrophic Hypogonadism) 3. Androgen secreting tumors : Leydig cell tumors (a rare condition) leads to precocious pseudopuberty in prepubertal boys. 24

REFERENCES  Human physiology, Lauralee Sherwood, seventh edition.  Text book physiology by Guyton &Hall,11 th edition.  Text book of physiology by Linda.s Contanzo, third edition.  Physiology by Berne and Levy, sixth edition. 25