Uraporn Vongvatcharanon, Pornpimol Kirirat, Jintamas Suwanjarat, and Piyakorn Boonyoung

pp. 437 - 445

Abstract

Pituitary gonadotrophs were studied in the adult female sand goby (Oxyeleotris marmoratus) during
its annual reproductive cycle, aiming at investigating the alteration of gonadotropic cell types and their
functions. The glands were divided into 3 groups according to maturity stages of the ovary: immature, mature
and gravid stages. All of the ovarian stages were found throughout the year except in November, when only
the gravid stage was identified. By using anti-chum salmon GTH Iβ and anti-chum salmon GTH IIβ antibodies for immunohistochemistry, strong anti-GTH IIβ reaction were observed in the proximal pars distalis
(PPD) of the pituitary gland in all stages and the number of cells was significantly increased in the gravid
stage (60.1±3.5 cell/mm²) compared to that of the immature (35.5±4.4 cell/mm²) and mature (48.3±7.2 cell/mm²) stages (P<0.05). In the immature and mature ovarian stages, a great number of vacuoles was observed
in areas of the PPD normally occupied by the gonadotrophs. The anti-GTH IIβ labeling gonadotrophs
exhibited patterns of activity, correlated with the ovarian maturity. Anti-GTH Iβ labeling gonadotrophs were
not observed in any stage, suggesting that GTH IIβ may be the only hormone regulating ovarian function
of the sand goby.