Immunohistochemical evidence of seasonal changes of gonadotropes in male ruin lizard (Podarcis sicula campestris De Betta)

Abstract

The pars distalis from the pituitary gland of adult male ruin lizards (Podarcis sicula campestris De Betta), captured during the five periods of the annual sexual cycle (emergence from hibernation, reproductive period, summer regression, autumnal recrudescence, winter arrest), was studied immunohistochemically using specific antibodies against hFSHb, hLHb, oFSHb, and oLHb with the avidinbiotin complex (ABC) procedure to monitor the seasonal changes in shape, size and percentage area taken up from gonadotropes. FSH containing cells were specifically identified with anti-hFSHb and anti-oFSHb sera, whereas the LH cells were localized by anti-hLHb. The anti-oLHb serum showed cross-reactivity with the cells immunostained by the three above antisera (anti-hFSHb, anti-oFSHb, and anti-hLHb). None of the cells containing both gonadotropic hormones as shown by the doubleimmunostaining procedure. Generally, FSH cells were larger and more numerous than LH cells. FSH cells were elongated or pyriform in shape from spring to autumn, whereas they were round or oval during the winter stasis and until the emergence from hibernation. The size and the percentage area occupied by FSH cells showed an annual pattern with two distinct peaks in the reproductive and in the autumnal recrudescence periods. LH cells did not show seasonal changes in shape, being round or oval throughout the reproductive cycle, whereas their size and the area they occupied underwent seasonal variations. The LH cells reached the largest size during the reproductive period and the smallest size during the summer regression. The percentage area occupied by LH cells in the pars distalis peaked at the emergence from hibernation and during the summer refractory period, when FSH cells displayed their lowest values.