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Overview of Male Endocrinology


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Overview of Male Endocrinology

  1. 1. Biology 595EN Endocrinology October 28, 2003 Male Reproductive Endocrinology Kenneth L. Campbell Professor of Biology University of Massachusetts at Boston
  2. 2. This presentation is made possible by a grant entitled “Shortcourses in Endocrinology at Minority Undergraduate Institutions” from the National Institute of General Medical Sciences (NIGMS) to The Minority Affairs Committee of the Endocrine Society
  3. 3. What are endocrine systems for? <ul><li>Endocrine Functions </li></ul><ul><li>Maintain Internal Homeostasis </li></ul><ul><li>Support Cell Growth </li></ul><ul><li>Coordinate Development </li></ul><ul><li>Coordinate Reproduction </li></ul><ul><li>Facilitate Responses to External Stimuli </li></ul>
  4. 4. What are feedback systems? Feedbacks Generate Control Loops Negative These maintain hormonal balance & are often linked to homeostatic processes. If the multiplicative effect of the several links in a control loop is negative, the entire control loop is negative. Positive These cause physiologic changes in the system involved. If the multiplicative effect of the several links in a control loop is positive, the entire control loop is positive. -- + + +
  5. 5. How dynamic are these systems? Hormone, receptor, transducer & effector levels vary with time. Some change over short terms, others over long terms. Levels also vary with developmental stage, gender, & health status. testosterone_decline.gif After illus/i232_1.gif
  6. 6. Outline of Male Reproduction 1. Adult anatomy 2. Embryogenesis 3. Sex determination 4. Hormonal controls 5. Puberty 6. Testicular anatomy 7. Meiosis 8. Spermatogenesis 9. Contraception 10. Aging
  7. 7. Adult Male Anatomy
  8. 8. Male Embryogenesis
  9. 9. Male Germ Cell Migration
  10. 11. Sex Determination: Genetic
  11. 12. Sex Determination: Gonadal
  12. 13. Sex Determination: Internal Reproductive Tract
  13. 14. Sex Determination: External Reproductive Tract
  14. 15. Pituitary- Hypothalamic Associations anterior-pituitary.gif
  15. 16. How are the gonads controlled? LH © Kenneth L. Campbell, 1997. All rights reserved.
  16. 17. How are the gonads controlled? FSH © Kenneth L. Campbell, 1997. All rights reserved.
  17. 18. Inhibin Female Males lack inhibin A. Inhibin B is inversely correlated with FSH & spermatogenesis in normal adults.
  18. 19. Steroid Synthesis
  19. 20. Maturation: Hormonal
  20. 21. Leydig Cell Populations Lejeune, H, R Habert, JM Saez, Origin, proliferation and differentiation of Leydig cells, J Mol Endocrinol 20 :1-25, 1998.
  21. 22. Maturation: Tanner Stages
  22. 23. Testosterone in saliva in children & serum SHBG in adolescents & adults. The pubertal decrease in SHBG is less pronounced in women.
  23. 24. Testicular Anatomy
  24. 25. Meiosis: Males & Females Male Female
  25. 26. Spermatogenesis
  26. 27. Sperm Maturation Spermatozoa reach final shape in the testis, but they gain functional maturity while passing through the epididymus & female reproductive tract: activation of full motility, capacitation, in the vagina & cervix; final fertilizing ability after the acrosome reaction, usually near the egg.
  27. 28. Fertilization
  28. 29. Male Contraception <ul><li>Barriers </li></ul><ul><ul><ul><li>condoms </li></ul></ul></ul><ul><li>Vasectomy </li></ul><ul><li>Hormones </li></ul><ul><ul><ul><li>peripheral androgens +/- LHRH antagonists or agonists </li></ul></ul></ul>
  29. 30. Male Serum Hormone Age Profiles Male Aging & Reproductive Senescence
  30. 31. The ratio T/SHBG is the FAI, a Measure of free T. Adrenal androgens like DHEAS also decline with age.
  31. 32. Low Fertility in Gainj vs Other Groups
  32. 33. How is prolactin controlled?
  33. 35. FSH in Gainj Men
  34. 36. LH in Gainj Men
  35. 37. Many Gainj Men are Infertile
  36. 38. Support from: NSF, Umass/Boston, Sandia National Labs, Hybritech, Quidel, Monoclonal Antibodies Inc. (*in the lab at UMB) Acknowledgements Gainj Project The Gainj People Rees Midgley Al Hermalin Lora Myers Jim Wood Pat Johnson Ila Maslar Diana Lai Sam Refetoff Peter Smouse Peter Heywood Michael Alpers Brian Davison Yan Ren Lynne Shinto Diane Drinkwater Darryl Holman Bettina Shell Related Studies Kathy O’Connor Coralie Munro Susannah Barsom Ellie Brindle Cheryl Stroud Kai Orton Jodiann Thompson Yefim Proshchitskiy Yelena Filipova Matt Lopresti Oliver Schultheiss Cheryl Frederick Steve Monfort Malcolm Potts David McClelland (dec) Turkana Project All Turkana Subjects Mike Little Paul Leslie Ben Campbell Dhanesh Dookhran Kathy Whiteman Alexandra Evindar William Lukas Sandra Gray Jeanine Quigley Christine Sekadde -Kigondu Leah Kirumbi
  37. 39. Male Hormone Levels with Age