Abstract
Immunocytochemical identification of the different cell types in the pituitary gland of Bagrus bayad was performed using antisera against mammalian (human and rat) and piscine hormones. The adenohypophysis was composed of rostral pars distalis (RPD), proximal pars distalis (PPD) and pars intermedia (PI). Prolactin and adrenocorticotrophic cells were located in the rostral pars distalis of the pituitary. Gonadotrophic and growth hormone cells were distributed in the proximal pars distalis, but gonadotrophic cells appear also at the border of the pars intermedia. Somatolactin cells, as well as alpha-melanotrophic cells were located in the pars intermedia of B. bayad pitui-tary. The prolactin (PRL) cells were distributed in the RPD stained with orange G and showed strong immunoreactivity with antiserum to chum salmon. The adrenocorticotrophic (ACTH) cells were lead hema-toxylin-positive (PbH+) and showed strong im- mu-noreactivity with anti-human ACTH; these cells bor-dered the neurohypophysis and grouped in islets be-tween PRL cells in the RPD. Growth hormone (GH) cells were densely distributed with the gonadotrophic (GTH) cells in the PPD. They were orange G positive and reacted with antiserum to chum salmon. GTH cells were located in the central area of the PPD and in the external border of the PI. These cells were Alcyan Blue and PAS positive, and immunostained with anti-chum salmon GTH Iβ and anti-chum salmon GTH IIβ. In addition, antiserum to rat thyrotropin stimulating hormone β (TSHβ) reacted positively to the GTH cells. These results suggest that GTH I, GTH II and TSH are synthesized in the same cells in the pituitary of B. bayad. The PI was composed mainly of PbH+ cells and a PAS+ cell adjacent to the neurohypophysis. The PAS+ cells from the PI bound specifically to anti-chum somatolactin. Anti-alpha- melanin stimulating hormone (MSH) stained only the PbH+ (alpha-melanotrophic) cells of the PI.
Highlights
The pituitary gland of teleosts has already been the subject of research for many years
The adenohypophysis was composed of rostral pars distalis (RPD), proximal pars distalis (PPD) and pars intermedia (PI)
The pituitary gland of B. bayad consists of the neurohypophysis, and the adenohypophysis, which showed the three major subdivisions typical of teleost; an anterior rostral pars distalis (RPD), a medium proximal pars distalis (PPD) and posterior pars intermedia (PI) (Figures 1 (a)-(c))
Summary
The pituitary gland of teleosts has already been the subject of research for many years. B. bayad (Forsskål, 1775) is an important food fish in tropical and semitropical waters. It grows fast and attains 112 cm in length with maximum weight of 12.5 kg [11]. During the past years with the development of industries and modern civilization, large amount of pollutants have been discharged into the Nile and the surrounding lakes. These pollutants affect the growth, health, and nutritional value of fishes and the distribution (i.e., survival) and reproduction of economically important fishes.
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