CONICET | Buscador de Institutos y Recursos Humanos

The present study determined di.erences in the time course of sexual development in males selected for reduced (LS, low stress) or exaggerated (HS, high stress) plasma corticosterone response to brief restraint. Sexual development was assessed by examination of cloacal gland area (CAREA) and volume (CVOL), the proportion of individuals that produced cloacal gland foam (PICF), and the intensity of cloacal gland foam production (CFP) at 4, 5, 6, 8, 10, 14, and 16 wk of age. These intervals encompassed ages during which growing photostimulated quail would be expected to have: 1) no cloacal gland development and foam production (pre-pubescent), 2) partial development of the cloacal gland with some birds producing cloacal gland foam, and 3) full development of the cloacal gland with all birds producing foam (post-pubescence for all birds). Total testes weights (TW) were also measured at 6 and 16 wk of age. Mean CAREA and CVOL were similar in LS and HS quail at 4 wk of age. At 5 wk, LS quail showed a greater (P < 0.05) CAREA than HS ones and both cloacal gland size indices were consistently enhanced (P < 0.05) in LS quail thereafter. In addition, at 4 and 6 wk of age, a greater (P < 0.05) PICF was evident in LS birds. Beyond 8 wk, all birds were in foam production. CFP results generally mimicked those found for CA and CVOL (i.e., LS quail showed higher CFP than HS quail beginning at 6 wk of age), but these line di.erences were not statistically relevant. LS quail had higher (P< 0.10) TW than HS quail at both 6 and 16 wk. The results suggest that selection for reduced adrenocortical responsiveness in Coturnix is associated with an accelerated sexual development in males. Further, the enhanced reproductive development in LS males observed in juveniles remained extant at an adult age.

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