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Biology 595EN Endocrinology October 28, 2003 Male Reproductive Endocrinology Kenneth L. Campbell Professor of Biology University of Massachusetts at Boston.
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Biology 595EN Endocrinology October 28, 2003 Male Reproductive Endocrinology Kenneth L. Campbell Professor of Biology University of Massachusetts at Boston
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
What are endocrine systems for? • Endocrine Functions • Maintain Internal Homeostasis • Support Cell Growth • Coordinate Development • Coordinate Reproduction • Facilitate Responses to External Stimuli
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. + -- + +
How dynamic are these systems? www.antiaging.com/images/ testosterone_decline.gif After a248.e.akamai.net/.../pubs/mmanual_home/ illus/i232_1.gif 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.
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
Male Germ Cell Migration www.med.unc.edu/embryo_images/unit-genital/genital_gifs/genital008-1.gif www.med.unc.edu/embryo_images/unit-genital/genital_gifs/genital008-2all.gif
Sex Determination: Gonadal www.med.unc.edu/embryo_images/unit-genital/genital_gifs/genital010-1.gif
Pituitary- Hypothalamic Associations www.cushings-help.com/ anterior-pituitary.gif
How are the gonads controlled? LH © Kenneth L. Campbell, 1997. All rights reserved.
How are the gonads controlled? FSH © Kenneth L. Campbell, 1997. All rights reserved.
Inhibin europe.obgyn.net/nederland/mp/overgang/images/overgang14x.gif Female Males lack inhibin A. Inhibin B is inversely correlated with FSH & spermatogenesis in normal adults.
Steroid Synthesis arbl.cvmbs.colostate.edu/hbooks/pathphys/endocrine/basics/steroidogenesis.gif
Leydig Cell Populations Lejeune, H, R Habert, JM Saez, Origin, proliferation and differentiation of Leydig cells, J Mol Endocrinol 20:1-25, 1998.
Maturation: Tanner Stages a248.e.akamai.net/7/248/430/20020531071032/www.merck.com/pubs/mmanual_home/illus/i258 www.cuhk.edu.hk/proj/growthstd/images/bpuberty.gif www.cuhk.edu.hk/proj/growthstd/images/gpuberty.gif
Testosterone in saliva in children & serum SHBG in adolescents & adults. The pubertal decrease in SHBG is less pronounced in women. www.biomedcentral.com/content/figures/1471-2431-2-5-3-l.jpg
Testicular Anatomy trc.ucdavis.edu/mjguinan/apc100/modules/Reproductive/mammal/images/testis10.jpg
Meiosis: Males & Females Male Female
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.
Male Contraception • Barriers • condoms • Vasectomy • Hormones • peripheral androgens +/- LHRH antagonists or agonists
Male Serum HormoneAge Profiles www.dpcweb.com/documents/news&views/spring_02/the_aging_male.html Male Aging & Reproductive Senescence
The ratio T/SHBG is the FAI, a Measure of free T. Adrenal androgens like DHEAS also decline with age. www.dpcweb.com/documents/news&views/spring_02/the_aging_male.html
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 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 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) Support from: NSF, Umass/Boston, Sandia National Labs, Hybritech, Quidel, Monoclonal Antibodies Inc. (*in the lab at UMB)
Male Hormone Levels with Age www.dpcweb.com/documents/news&views/spring_02/the_aging_male.html