An anatomical and histochemical examination of the pituitary gland of carp (Cyprinus carpio)

Abstract

The present study was carried out for the purpose of studying the anatomical and the histochemical structure of the pituitary gland of the common carp, Cyprinus carpio. Anatomically, the shape of the gland has been observed to be round-oval, looking like an acorn. The pituitary gland consists of the adenohypophysis and neurohypophysis parts. Microscopically, the adenohypophysis consists of anterior (pars distalis) and posterior (pars intermedia) parts. The second lobe of the gland, called the neurohypophysis, is found in the core of the gland. Histologically, acidophilic prolactin cells stained red or orange and were dispersed in the rostral pars distalis (pro-adenohypophysis) of the adenohypophysis. Basophilic thyrotropin cells stained blue and were found in a small number in the same region. Adrenocorticotropin cells showed a chromophobic character; therefore, they did not get stained by the periodic acid-Schiff staining techniques. Gonadotropin cells were observed in the proximal pars distalis (meso-adenohypophysis) of the adenohypophysis. In the examined specimens, the faintly stained, elongated or pyramidal cells in the pars intermedia of the adenohypophysis were covering the neurohypophysis region. The neurohypophysial lobe was composed of unmyelinated nerve fibers and the pituicyte cells were located among the nerve fibers. Herring bodies were seen scattered in the neurohypophysis.