An immunocytochemical study of the pituitary gland of the white seabream (Diplodus sargus)

The adenohypophysis of the white seabream (Diplodus sargus) was studied usi ng histochemical and immunocytochemical techniques. The adenohypophysis was composed of rostral pars distalis, proximal pars distalis and pars interme dia. Prolactin (anti-chum salmon prolactin positive) and adrenocorticotropi c (anti-human ACTH positive) cells were found in the rostral pars distalis. Prolactin cells were organized into follicles, while ACTH cells were arran ged in cords around neurohypophyseal tissue branches that penetrated the ro stral pars distalis. In the proximal pars distalis, somatotropic (anti-chum salmon and anti-gilthead seabream growth hormone positive), gonadotropic ( anti-chum salmon beta -gonadotrophin II and anti-carp beta -gonadotrophin I I positive, but anti-chum salmon beta -gonadotrophin I negative) and thyrot ropic (anti-human beta -thyrotropin positive) cells were observed. Growth h ormone cells were restricted to the dorsal and ventral part of the proximal pars distalis. They were clustered or surrounded the neurohypophyseal bran ches. Only one type of gonadotrophin cell was identified and they were clus tered or isolated in the proximal pars distalis. Scattered groups of thyrot ropin cells were located throughout the proximal pars distalis. In the pars intermedia somatolactin (anti-chum salmon and anti-gilthead seabream somat olactin positive) and melanotropic (anti-alpha -melanotropic hormone positi ve) cells were localized. In addition, gonadotrophin cells surrounded the p ars intermedia or distributed evenly between somatolactin and melanotropic hormone cells. Somatolactin cells were periodic acid-Schiff negative and su rrounded the neurohypophyseal branches intermingled with melanotropic cells . These cells were also immunoreactive to anti-human ACTH antiserum.