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

The pars distalis from the pituitary gland of adult male ruin lizards (Poda rcis sicula campestris De Betta), captured during the five periods of the a nnual sexual cycle (emergence from hibernation, reproductive period, summer regression, autumnal recrudescence, winter arrest), was studied immunohist ochemically using specific antibodies against hFSH beta, hLH beta, oFSH bet a, and oLH beta with the avidin-biotin complex (ABC) procedure to monitor t he seasonal changes in shape, size and percentage area taken up from gonado tropes. FSH containing cells were specifically identified with anti-hFSH be ta and anti-oFSH beta sera, whereas the LH cells were localized by anti-hLH beta. The anti-oLH beta serum showed cross-reactivity with the cells immun ostained by the three above antisera (anti-hFSH beta, anti-oFSH beta, and a nti-hLH beta). None of the cells contained both gonadotropic hormones as sh own by the double-immunostaining procedure. Generally, FSH cells were large r 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 win ter stasis and until the emergence from hibernation. The size and the perce ntage area occupied by FSH cells showed an annual pattern with two distinct peaks in the reproductive and in the autumnal recrudescence periods. LH ce lls did not show seasonal changes in shape, being round or oval throughout the reproductive cycle, whereas their size and the area they occupied under went 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 em ergence from hibernation and during the summer refractory period, when FSH cells displayed their lowest values.