Hum. Reprod. Advance Access published online on July 8, 2005
Human Reproduction, doi:10.1093/humrep/dei174
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1 Department of Obstetrics and Gynaecology, University of Melbourne and Reproductive Services, Royal Women’s Hospital, Melbourne, Victoria 3053
* To whom correspondence should be addressed. BACKGROUND: Quantification of changes in semen may give insight into the testosterone (T)-induced disruption of spermatogenesis in man. METHODS: A model analogous to flushing of sperm from the genital tract after vasectomy was used to quantify the time course of semen changes in subjects participating in male contraceptive trials using 800 mg T-implant (n = 25) or 200 mg weekly intramuscular injection (IM-T; n = 33). A modified exponential decay model allowed for delayed onset and incomplete disruption to spermatogenesis. Semen variables measured weekly during a 91-day period after initial treatment were fitted to the model. RESULTS AND CONCLUSIONS: Sperm concentration, total count, motility and morphometry exhibited similar average decay rates (5 day half-life). The mean delay to onset of decline in concentration was 15 (IM-T) and 18 (T-implant) days. The significantly longer (P < 0.005) delays deduced for the commencement of fall in normal morphology (41 days), normal morphometry (40 days) and sperm viability (43 and 55 days), and the change of morphometry to smaller more compact sperm heads are consistent with sperm being progressively cleared from the genital tract rather than continued shedding of immature or abnormal sperm by the seminiferous epithelium. A significant negative relationship was found between lag time and baseline sperm concentration, consistent with longer sperm-epididymal transit times associated with lower daily production rates.
Received January 28, 2005
Revised May 15, 2005
Accepted June 6, 2005
Article
Time course of changes in sperm morphometry and semen variables during testosterone-induced suppression of human spermatogenesis
2 Prince Henry’s Institute of Medical Research, Monash Medical Centre, Clayton, Victoria 3168, Australia
C. Garrett, E-mail: garrettc{at}unimelb.edu.au
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