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MALE REPRODUCTIVE SYSTEM II

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MALE REPRODUCTIVE SYSTEM

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MALE REPRODUCTIVE SYSTEM II

  1. 1. MALE REPRODUCTIVE PHYSIOLOGY II Dr. Nilesh Kate (MBBS. MD) DR NILESH N KATE ASSOCIATE PROFESSOR ESIC MEDICAL COLLEGE GULBARGA.
  2. 2. ENDOCRINAL FUNCTIONS OF TESTES
  3. 3. MALE REPRODUCTIVE PHYSIOLOGY  Depends On Testosterone  Testicular Leydig Cells Secrete Testosterone  Sertoli Cells Secrets Inhibin, Oestrogen, And Activin.  Testes Descend And Pass Out Of Abdominal Cavity
  4. 4. TESTOSTERONE  Leydig cells -- interstitial connective tissue between seminiferous tubules.  Numerous in Newborn and after puberty  Childhood scanty  Decreases after 40 and absent in old age i.e. around 80 years of age.  Normal secretion 4-9 mg /day  Plasma testosterone 0.65 microgram %
  5. 5. DERIVATIVES OF TESTOSTERONE Insert fig. 20.14
  6. 6. TRANSPORT IN PLASMA  2 % in free form  98 % in bound to plasma proteins form  68 % --- albumin.  30% --- testosterone binding globulin i.e. sex steroid binding globulin . (SSBG)
  7. 7. ANDROSTENEDIONE  Steroid precursor for blood Oestrogen  2.5 mg/day DIHYDROTESTOSTERONE ■ Testosterone converted into Dihydro testosterone by 5 ά reductase. ■ Has more than twice biological activity.
  8. 8. FORMATRION OF ANDROGEN CHOLESTEROL PRGNENOLONE PROGESTERONE ANDROSENEDIONE TESTOSTERONE DIHYDROTESTOSTERONE DIHYDROTESTOSTERONE 17ά HYDROXY-PREGNENOLONE DEHYDROXYEPIANDROSYTERONE ANDROSENEDIONE KEY STEP IN TESTES
  9. 9. FUNCTIONS OF TESTOSTERONE Before birth At puberty In adults
  10. 10. TESTOSTERONE: BEFORE BIRTH  Effect on sex differentation in fetus Gonadal sex differentation Y chromosomes – TDF MIS Genital differentation internal genitalia External genitalia  Effect on descent of testes from abdomen to testis Cryptorchidism
  11. 11. Gonadal Differentiation 1. Genital Ridge 2. Bipotential Gonads 
  12. 12. BIPOTENTIAL GONADS testes ovaries TDF NO TDF TESTOSTERONE NO TESTOMIS NO MIS Degenerates MULLERIAN (Parameso) uterus and tubes epididymis, vas def.& ejaculatory ducts form WOLFFIAN (Meso) degenerates Genital differentiation
  13. 13. PUBERTY IN THE MALE  Usually 10-14 years old  Endocrine, physical, and behavioral growth.  Leydig cells “awake”
  14. 14. TESTOSTERONE: AT PUBERTY ■ EFFECTS ON EXTERNAL GENITALIA TESTOSTERONE – Enlargement of penis DHT – Scrotum size , pigmentation, Rugal folds ■ EFFECT ON ACCESSORY SEX ORGANS TESTOSTERONE -- SEMINAL VESICLES DHT -- PROSTATE SIZE AND SECREATIONS ■ MALE SECONDARY SEX CHARACTER Body hair – male pattern, beard growth Voice – Due To Larynx Enlargement, Low Pitch Muscle mass and shoulder girdle Changes in skin – thicker & darker.
  15. 15.  EFFECT ON PSYCHE Pshychological differtiation Libido – initiate sexual drive Aggressive behaviour  ANABOLIC AND GENERAL GROWTH PROMOTING EFFECT. Nitrogen retention - misuse Bone growth – Somatomedins C level Basal metabolic rate Water electrolyte balance
  16. 16. TESTOSTERONE: IN ADULTS  Hair Growth – Male baldness.  Psyche – behavioral attitude  Bone – prevent bone loss & osteoporosis.  Spermatogenesis  Haematopoiesis  Circulating and stored body fats :- LDL HDL  Gonadotrophins secretion Suppression of LHRH, LH.
  17. 17. Direct Gene Activation Receptor/hormone Complex mRNA Protein Aldosterone Cortisol Testosterone Estrogen Progesterone Thyroxine MODE OF ACTION OF ANDROGENS
  18. 18. CONTROL OF LH AND FSH SECRETION  Negative feedback:  Testosterone inhibits LH and GnRH production.  Maintain relatively constant secretion of LH and FSH.  Declines gradually in men over 50 years of age.  Testosterone converted to DHT, which inhibits LH.  Inhibin inhibits FSH secretion.  Aromatization reaction producing estradiol in the brain, is required for the negative feedback effects. Insert fig. 20.13
  19. 19. ENDOCRINE FUNCTION OF THE TESTES ■ Testosterone and its derivatives are responsible for initiation and maintenance of body changes in puberty. ■ Stimulate growth of muscles, larynx, and bone growth until sealing of the epiphyseal discs.  Promote hemoglobin synthesis.  Act in paracrine fashion, responsible for spermatogenesis. Insert fig. 20.15
  20. 20. Hormonal Control of Spermatogenesis  Formation of primary spermatocytes and entry into early prophase I, begin during embryonic development.  Spermatogenesis arrested until puberty.  Testosterone required for completion of meiosis and spermatid maturation.  Secrete paracrine regulators:  IGF-1.  Inhibin.  Transforming growth factor.  FSH necessary in the later stages of spermatid maturation.
  21. 21. ESTROGEN SECRETION  Sertoli and Leydig cells secrete small amounts of estradiol.  Receptors found in Sertoli and Leydig cells and accessory organs.  May be responsible for:  Negative feedback in brain.  Sealing of epiphyseal plates.  Regulatory function in fertility.
  22. 22. APPLIED ASPECTS Cryptorchidism Extirpation Hopogonadism in males Hopergonadism in males Male infertility Vasectomy
  23. 23. CRYPTORCHIDISM (Gk. kryptos – hidden + orchis - testis) ■ In 97% of male newborns, testes are present in the scrotum before birth. ■ In most of the remainder, descent will be completed during the first 3 months Postnatally. ■ However, in less than 1% of infants, one or both testes fail to descend.
  24. 24. CRYPTORCHIDISM  The condition is called Cryptorchidism and may be caused by decreased androgen (testosterone) production.  The undescended testes fail to produce mature spermatozoa and the condition is associated with a 3% to 5% incidence of renal anomalies.
  25. 25. EXTIRPATION  Removal of testes.  Before puberty --- ENUCHOIDISM  CHARACTERISED BY Permanent sterility Underdevelopment of external genitalia Underdevelopment of secondary sex character. Abnormal bone growth.
  26. 26. HOPOGONADISM IN MALES  Absent or deficient testicular hormone.  Due to – congenital non functioning of testes. Absent HCG. Cryptorchidism Extirpation of testes. Absent androgen receptors ■ Frohlich’s syndrome Obesity along with Enuchoidism
  27. 27. HYPERGONADISM IN MALES  Excessive secretion in tumors of Leydig cells.  Precocious pseudo puberty Rapid growth of muscles and bone Sex organs and secondary sex characters at early age. Also secretes Oestrogen so develops Gynecomastia.
  28. 28. INFERTILITY  Inability of sperm to fertilize ovum  Due to -- Androgen dysfunction with normal sperm count. -- Isolated dysfunction of sperm cell production -- Combined androgen and sperm cell production defects. -- Failure of deposition of sperm in female genital tract.
  29. 29. VASECTOMY  Permanent method for sterilization in males  Vas deferens cut and ligated
  30. 30. THANK YOU
  31. 31. Sunday, April 26, 2015

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