Plasma Concentrations of Vitellogenin and Sex Steroids in Female Tuatara (Sphenodon punctatus punctatus) from Northern

摘要: Vitellogenesis in tuatara (Sphenodon punctatus) on Stephens Island, New Zealand, at the southern (coolest) end of the geographicał range of this species involves a prolonged period of about 3 years of the average 4-year reproductive cycle. These studies used a semiquan-titative electrophoretic assay for vitellogeni (Vg). In the preset study an ELISA was used to measure plasma levels of Vg in 138 female northern tuatara (Sp punctatus) on 11 islands at the warmest end of the tuatara's range. Blood samples were collected in late summer-early autumn, just prior to the expected time of ovulation in those females that would nest the following spring. Plasma Vg levels ranged from nondetectable to 2.9 mg ml but were not significantly correlated with plasma estradiol, testosterone, or progesterone levels. There was also no significant correlation among the three sex steroids. Plasma Vg and hormone levels were further …