Annual circulating testosterone levels in captive and free \ x = req-\ ranging male armadillos ( Dasypus novemcinctus )

Mean circulating concentrations and seasonal changes in plasma testosterone over 3 years were similar in free-ranging and captive male armadillos. The highest concentrations were seen in the summer months, i.e. at the time of maximum breeding, but the relatively high values at other times and the inability of ACTH to restore dexamethasone-suppressed testosterone concentrations confirms that testicular function continues throughout the year. There was a gradual rise in plasma testosterone to adult levels from the 5th to the 9th month of life in captive\x=req-\ born males, indicating that sexual maturity is reached within the first year of life and that captivity is not deleterious to Leydig cell function.