HEMIORCHIDECTOMY LEADS TO DRAMATIC AND IMMEDIATE ALTERATIONS IN PITUITARY FOLLICLE-STIMULATING-HORMONE SECRETION AND THE FUNCTIONAL-ACTIVITY OF THE REMAINING TESTIS IN THE ADULT MALE BONNET MONKEY (MACACA-RADIATA)

The aim of the present study was to examine the effect of hemiorchidec tomy (HO) on serum FSH, LH, testosterone (T), and inhibin (INH) concen trations as well as on the testicular volume (TV) and on changes in th e kinetics of germ cell turnovers in the remaining testis of adult mal e bonnet monkeys. Blood samples collected at 2200 h at various times b efore and after HO and testicular biopsies obtained at different perio ds were subjected to hormone analysis and DNA flow cytometry. Through serum T levels were lowered (p < 0.05) at 12 h after HO, T levels rapi dly returned to intact control concentrations by Day 5. While serum LH remained unaltered, serum FSH increased markedly within 2 days of HO and remained significantly (p < 0.05) elevated over the next 90 days. Though serum INH showed a significant decrease (p < 0.05) by 15 min of HO, it returned to approximately 80% of intact levels within one week . The TV of the remaining testis showed maximal increment by Day 30 (p < 0.05) of HO. DNA flow cytometric analysis 24 days after HO showed i ncreases (p < 0.05) in spermatogonia (2C) and primary spermatocytes (4 C). These cell types by Day 45 had transformed to round (1C) and elong ate (HC) (by 38%, p < 0.001) spermatids. Overall spermatogenesis (conv ersion of 2C to 1C and HC) showed significant enhancement at Days 110 and 175, suggesting that the spurt in spermatogenic activity is not co nfined to a single spermatogenic cycle. Hemiorchidectomy in the adult male bonnet monkey thus leads to 1) rapid compensation in serum T and FSH concentrations and 2) increased TV of the remaining testis. In kee ping with these alterations, the kinetics of germ cell turnover reveal ed dynamic changes.