Reproduction

1. Reproduction

2. Male Reproductive Physiology The major organ involved in maintaining male reproductive function is the testis. A normal functioning testicle is required for 1)the production of mature sperm 2)and the synthesis of the major male reproductive hormone testosterone.

3. The Male Reproductive System Physiological functions of major components-

4. Section of human testis. Seminiferous epithelium * Blood–Testis Barrier * Spermatogenesis

5. Interaction between the Sertoli and Leydigcells.

6. Hypothalamic-pituitary-gonadal axis in the male Hypothalamus GnRH Anterior Pituitary LH and FSH Testes Testosterone

7. Gonadotropin Releasing Hormone (GnRH) • 10 AA peptide • Released in median eminence of hypothalamus • Secreted for a few minutes every 1-3 hours • Pulsatile (frequency and amplitude)

8. And Others Negative feedback Stress Sleep/wake cycle Hormones Temperature Hypothalamus GnRH RELEASE Change in amplitude Change in frequency

9. Gonadotroph GnRH Vesicles containing LH/FSH Also  LH and FSH synthesis PKC IP3 & DAG Release of LH/FSH via exocytosis Ca2+

10. Leydig Cell LH Increased testosterone production cAMP Via PKA cholesterol DNA transcription testosterone

11. Sertoli Cell FSH cAMP Via PKA Inhibin Aromatase ABP Growth Factors DNA transcription

12. At the target tissues *Synthesis Testosterone *Release *in the bloodstream Dihydrotestosterone (5 alpha reductase) Modulation of gene expression proteins

13. Physiological Action of Testosterone and Associated Androgens. An androgen is a substance that stimulates the growth of the male reproductive tract and development of secondary sex characteristics. It is important to realize that androgens affect most other tissues as well.

14. Penis and scrotum hCG Accessory Organs Testosterone Testicular descent Female suppression Fetal testes

15. Reproductive Organs Spermatogenesis Testosterone (Adult) Long bone fusion Secondary Sexual Characteristics Sex Drive

16. Body Hair and Baldness Deep voice Secondary Sexual Characteristics Acne Protein formation Muscle development Bone size and strength

17. Hypothalamus Some testosterone converted into estrogens GnRH Anterior Pituitary FSH LH Leydig cell Sertoli Cell Testosterone Inhibin

18. Formation of the Ejaculate and the Role of the Accessory Organs As the sperm passes through the epididymus it matures (due to dihydrotestosterone), and becomes more concentrated (fluid reabsorption). The sperm is then stored in the epididymus and vas deferens waiting for ejaculation. Sperm can remain viable here for up to 60 days as nutrition is supplied and inhibitory factors decrease their energy use. On ejaculation the sperm (and fluid) passes through the vas deferens, ejaculatory ducts and finally through the urethra. During this passage the fluid content is increased due to secretions from the accessory organs

19. Epididymus vas deferens 10% Sperm storage Seminal vesicles Sperm, fructose, prostaglandins, clotting precursors 60% Prostate gland 30% + alkalization, semen clotters And unclotters

20. The male sex act •The male must have an erection and ejaculate in order to complete the sex act. PSYCHOLOGICAL AND/OR PHYSICAL STIMULI Parasympathetic Activity Sympathetic Activity Via NO and/or ACh Vasodilation Erection

21. Ejaculation • Emission • Genital duct / accessory organ contraction (sympathetic stimulation) • Vas deferens, prostate, seminal vesicles • Mix with mucus in urethra producing semen • Expulsion • Semen expelled by rhythmic skeletal muscle contraction at base of penis

22. Hypogonadism • Non-functional testes in fetus • Lead to development of female sex organs • Loss of testes pre-puberty • Maintain infantile sex organs and characteristics • Bones less strong but longer • Maybe taller than other men

23. (cont) • Loss of testes post-puberty • Slight decrease in size of sexual organs • Slight increase in voice pitch • Loss of bone and protein build up • Slight loss of sexual desire • Less easy for erection • Ejaculation rarely occurs

24. Infertility • Sperm count • Should have ~ 120 million sperm / ml of semen • If below 20 million / ml are said to be infertile • Sperm morphology and motility • Abnormal shape of sperm • Lack of motility Impotence This is the inability to produce or maintain an erection. In most cases it is due to problems with blood flow.

25. An 8 year old boy visited his pediatrician, and his mother reported that he was in good health until about two weeks ago. He describes that his initial symptoms include a mild bifrontalheadache, which has become progressively worse. During the last few days, he developed nausea and bouts of occasional projectile vomiting accompanying the headaches. Furthermore, he recently noticed that he has tremendous difficulty when walking down the stairs from his bedroom to the kitchen and reported difficulties in sleeping. No family history of abnormal development or mental retardation exists. He has two perfectly healthy younger brothers. General Examination: This 8 year boy presents with pronounced pubic hair growth, a low pitched voice, enlarged genitalia, and acne on his forehead. Cardiac and respiratory examinations were unremarkable. Neurological Examination: Patient is alert and oriented x 3. No receptive or expressive aphasias were noted. Pupillary light reflex was intact bilaterally. Both the left and right optic discs appeared more pale than normal. Downward gaze (while the eyes were adducted) was impaired bilaterally.