Prolactin and growth hormone cells in the reptile Chalcides chalcides

Prolactin (PRL) and Growth hormone (GH) cells are specific pituitary cells secerning PRL and GH respectively. These two hormones are members of a family of polypeptide which evolved from a common ancestral gene. Their molecular characteristics are indeed quite similar. Little is still known about PRL and GH cells in the reptiles. In order to develop our previous studies on the pituitary gland of the viviparous reptile Chalcides chalcides, in this paper we report the ultrastructural study of PRL and GH cells in this skink. Ultrathin sections of pituitary gland of C. chalcides females during the reproductive period were used. The immunodetection was performed by using the polyclonal anti-PRL and anti-GH antisera and the immunogold technique. PRL cells, present in the rostral and in the medial pars distalis, appeared pyriform or ovoidal, small in size with a mean diameter of 8,5(±1,2)x6,2(±0,9)μm. They showed a round nucleus and a large nucleolus. PRL cells were full of 250-350nm granules, in which was evident homogeneous material with a little area of higher density. GH cells were larger then PRL cells with a mean diameter of 10(±0,95)μm and were only observed in the caudal pars distalis. Their shape was generally globular with a peripheral and large nucleus. Unlike PRL cells, GH cells showed less numerous and smaller granules of 180-220nm. The immunogold labelling was limited in the secretory granules for both cellular types. It’s possible to conclude that, in the viviparous reptile, C. chalcides, the PRL and GH hormones, although structurally related, are secreted by two cellular types with ultrastructural characteristics quite different.