Male reproductive system
- 1. The MALE Reproductive Systems Atul Prajapati PHM-19 Atul Prajapati
- 2. Male reproductive system • Gonads – testes – Produces sperm and secretes hormones • System of ducts – transport and stores sperm, assists in their maturation, and conveys them to the exterior – Epididymis, ductus deferens, ejaculatory ducts, and urethra • Accessory sex glands – adds secretions to semen – Seminal vesicles, prostate, and bulbourethral glands • Supporting structures – Scrotum supports testes and penis delivers sperm into female reproductive tract Atul Prajapati
- 3. Accessory sex glands – secrete most of liquid portion of semen • Seminal vesicles - About 60% of semen volume – Secrete alkaline, viscous fluid containing fructose, prostaglandins, and clotting proteins (different from blood) • Prostate - About 25% of semen volume – Secretes milky, slightly acidic fluid containing citric acid, several proteolytic enzymes, acid phosphatase, seminalplasmin (antibiotic) • Bulbourethral glands – Secrete alkaline fluid that protects passing sperm by neutralizing acids from urine in urethra – Mucus lubricates end of penis and lining of urethra Atul Prajapati
- 4. Accessory reproductive organs in males Atul Prajapati
- 5. Male reproductive system ducts – Spermatic cord • Ascends out of scrotum • Consists of ductus deferens as it ascends through scrotum, testicular artery, veins that drain testes and carry testosterone, autonomic nerves, lymphatic vessels, and cremaster muscle • Spermatic cord and ilioinguinal nerve pass through inguinal canal – Ejaculatory ducts • Formed by union of duct from seminal vesicle and ampulla of ductus deferens • Terminate in prostatic urethra • Eject sperm and seminal vesicle secretions just before release of semen into urethra – Urethra • Shared terminal duct of reproductive and urinary systems • Subdivided into prostatic urethra, membranous urethra, and spongy (penile) urethra • Ends at external urethral orificeAtul Prajapati
- 6. Reproductive system ducts in males – Ducts of testis • Pressure generated by fluid produced by Sertoli cells push sperm along seminiferous tubules into straight tubules, rete testis, efferent ducts in epididymis and then ductus epididymis – Epididymis • Consists of tightly coiled ductus epididymis • Stereocilia are microvilli that reabsorb degenerated sperm • Site of sperm maturation – acquire motility and ability to fertilize • Can store sperm for several months • Continues as ductus (vas) deferens – Ductus (vas) deferens • Conveys sperm during sexual arousal through peristaltic contractions • Can also store sperm several months Atul Prajapati
- 7. Internal structure of the penis Atul Prajapati
- 9. Male reproductive organs Atul Prajapati
- 10. Scrotum – Supporting structure for testes – Raphe – external median ridge – Scrotal septum – internally divides scrotum into two sacs, each with a single testis • Made up of subcutaneous layer and dartos muscle – Associated with each testis is the cremaster muscle – Normal sperm production requires a temperature 2-3°C below core body temperature • Cremaster and dartos muscle contracts or relaxes Atul Prajapati
- 12. Testes or testicles – Paired oval glands in the scrotum – Develops near kidney and descends through inguinal canals near 7th month of fetal development – Tunica vaginalis partially covers testes – Tunica albuginea – internal to tunica vaginalis • Extends inward forming septa that divide testis into lobules – Each of 200-300 lobules contains 1-3 seminiferous tubules • Sperm produced here through spermatogenesis Atul Prajapati
- 13. Internal and external anatomy of a testis Atul Prajapati
- 14. Seminferous tubule cells • Spermatogenic cells – sperm-forming cells – Spermatagonia (stem cell) develop from primordial germ cells that arise in yolk sac and enter testes in 5th week of development – Primary spermatocytes → secondary spermatocytes → spermatids → sperm cells → lumen • Sertoli cells or sustenacular cells– support cells – Tight junction form blood-testis barrier – prevents immune response against sperm cell surface antigens – Nourish spermatocytes, spermatids and sperm, phagocytize excess spermatid cytoplasm, control movements of spermatogenic cells, release sperm into lumen, produce fluid for sperm transport, secrete inhibin, regulate effects of testosterone and follicle-stimulating hormone (FSH) – Leydig (interstitial) cells found in spaces between seminiferous tubules • Secrete testosterone Atul Prajapati
- 15. Seminiferous tubules and stages of sperm production Atul Prajapati
- 16. Spermatogenesis – Takes 65-75 days – Begins with spermatogonia – diploid (2n) • Stem cells undergo mitosis to replace themselves and some continue development – Primary spermatocytes – diploid (2n) • Each duplicates its DNA and meiosis begins – Meiosis I – homologous pairs line up, crossing over occurs • Secondary spermatocytes (haploid or n) – 2 cells at end of Meiosis I – Each chromosome made up of 2 chromatids attached at centromere • Meiosis II – 2 chromatids separate – Spermatids – 4 haploid cells at end of meiosis II – Cells remain attached to each other by cytoplasmic bridges – Spermiogenesis – development of spermatids into sperm • Spherical spermatids transform into elongated sperm • Acrosome and flagella form, mitochondria multiply • Sertoli cells dispose of excess cytoplasm • Spermiation – release from connections to Sertoli cells • Not yet able to swim Atul Prajapati
- 17. Events in spermatogenesis Atul Prajapati
- 18. Sperm – Each day about 300 million sperm complete spermatogenesis – Head • Nucleus with 23 chromosomes (haploid or n) • Acrosome – vesicle filled with oocyte penetrating enzymes – Tail • Neck – contains centrioles forming microtubules that comprise remainder of tail • Middle piece – contains mitochondria • Principal piece – longest portion of tail • End piece – terminal, tapering portion of tail – Once ejaculated, sperm do not survive more than 48 hours in female reproductive tract Atul Prajapati
- 19. Parts of a sperm cell Atul Prajapati
- 20. Content of SEMEN • Sperm contains 200 separate protein +vitamin C, Calcium, Chlorine, Citric acid, Fructose, Lactic acid, Magnesium, Nitrogen, Potassium, Sodium, Phosphorus, Vitamin B12 and Zinc Atul Prajapati
- 21. Hormonal control of testes – At puberty, secretion of gonadotropin-releasing hormone (GnRH) increases – Stimulates anterior pituitary to increase secretion of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) – LH stimulates Leydig cells to secrete testosterone • Synthesized from cholesterol mainly in testes • Suppresses secretion of LH and GnRH via negative feedback • Enzyme 5 alpha-reductase converts testosterone into dihydrotestosterone (DHT) in external genitals and prostate – FSH acts indirectly on spermatogenesis • FSH and testosterone act on Sertoli cells to stimulate secretion of androgen-binding protein (ABP) • ABP binds testosterone keeping concentration high • Testosterone stimulates spermatogenesis • Sertoli cells release inhibin which inhibits FSH Atul Prajapati
- 22. Hormonal control of spermatogenesis Atul Prajapati
- 23. Androgens (testosterone and DHT) – Prenatal development • Testosterone stimulates male pattern of development or reproductive system ducts and descent of testes • DHT stimulates development of external genitalia – Development of male sexual characteristics • At puberty, they bring about development of male sex organs and development of male secondary sexual characteristics – Development of sexual function • Androgens contribute to male sexual behavior, spermatogenesis and sex drive (libido) – Stimulation of anabolism • Stimulate protein synthesis – heavier muscle and bone mass in men Atul Prajapati
- 24. Negative feedback regulates testosterone production Atul Prajapati
- 25. Semen and Penis • Semen – Mixture of sperm and seminal fluid – Typical volume 2.5-5 mL with 50-150 million sperm/mL – Slightly alkaline pH of 7.2-7.7 due to seminal vesicle secretions – Provides transport medium, nutrients, and protection – Coagulates after ejaculation due to clotting proteins • Penis – Contains urethra – Passageway for ejaculation of semen and excretion of urine – Body of penis – 3 cylindrical masses of tissue with erectile tissue – Glans penis – terminal opening is external urethral orifice • Prepuce or foreskin covers glans in uncircumcised men – Root of penis is attached portion – Erection – parasympathetic fibers release and cause local production of nitric oxide (NO) causing smooth muscle in arterioles to relax and dilate allowing large amounts of blood to enter penis Atul Prajapati
- 27. Erectile Dysfunction (ED) • Use of Papavarine injection: Prepartaion- Papavarine HCL as white crystalline + Dissolve in 30ml water and 120ml alcohol + edetate disodium 0.005%, add chlorobutanol (0.5%) as preservative Available as 30mg/ml Atul Prajapati
- 28. DRUGS BRAND NAMES Sildenafil citrate- brand name Viagra of PFIZER Tadalafil citrate- brand name Cialis and Adcirca Lilly ICOS, LLC, the joint venture of ICOS Corporation and Eli Lilly and Company. Also solr under name of Tadacip by the Indian pharmaceutical company Cipla Atul Prajapati