[Description of the hypophysis of the Saharian lizard Uromastix acanthinurus Bell 1825 (Sauria Agamidae): localization by immunofluorescence of various hypophyseal hormones]

Characterization of pituitary growth hormone and its receptor in the green iguana (Iguana iguana)

Pituitary growth hormone (GH) has been studied in most vertebrate groups; however, only a few studies have been carried out in reptiles. Little is known about pituitary hormones in the order Squamata, to which the green iguana (gi) belongs. In this work, we characterized the hypophysis of Iguana iguana morphologically. The somatotrophs (round cells of 7.6-10 μm containing 250- to 300-nm secretory granules where the giGH is stored) were found, by immunohistochemistry and in situ hybridization, exclusively in the caudal lobe of the pars distalis, whereas the lactotrophs were distributed only in the rostral lobe. A pituitary giGH-like protein was obtained by immuno-affinity chromatography employing a heterologous antibody against chicken GH. giGH showed molecular heterogeneity (22, 44, and 88 kDa by SDS-PAGE/Western blot under non-reducing conditions and at least four charge variants (pIs 6.2, 6.5, 6.9, 7.4) by isoelectric focusing. The pituitary giGH cDNA (1016 bp), amplified by PCR and RACE, encodes a pre-hormone of 218 aa, of which 190 aa correspond to the mature protein and 28 aa to the signal peptide. The giGH receptor cDNA was also partially sequenced. Phylogenetic analyses of the amino acid sequences of giGH and giGHR homologs in vertebrates suggest a parallel evolution and functional relationship between the GH and its receptor.

Immunocytochemical localization and ultrastructural study of gonadotroph cells in the female desert lizard Uromastyx acanthinura

The pars distalis from the pituitary gland of adult female desert lizards (Uromastyx acanthinura), captured during vitellogenesis (late may) and hivernal period, was studied with immunocytochemical methods using specific antisera against human FSH (hFSH) and LH (hLH). The immunostaining with anti-hLH and anti-hFSH allowed the identification of only FSH-like containing cells. The FSH-like immunoreactive cells were affected differently by a physiological stage and showed some heterogenous cytological characteristics. During vitellogenesis, four aspects of rostral FSH-like immunoreactive cells could be recognized. The expression of FSH-like in mainly immunoreactive cells was parallel to an intense synthetic activity and to the presence of ultrastructural features indicating an intense release of the hormone. This release was considerably altered in winter, the immunoreactive cells stored an important amount of secretion granules which increased in size and undergo a crinophagic process.

An immunohistochemical study of adenohypophyseal cells in the viviparous reptile Chalcides chalcides

The morphology of the hypophysis and the immunocharacteristics of the adenohypophyseal cells in the viviparous reptile Chalcides chalcides were studied by light microscopy, using conventional staining methods and an indirect antibody technique (ABC method), respectively. The general morphology of the C. chalcides hypophysis was comparable to that of other reptiles, showing three main regions: the pars distalis, the pars intermedia and the pars nervosa. The gland appeared as an elongated body in a cephalic-caudal direction and was almost completely enclosed in the sella turcica. For this reason, the hypophysis was studied in toto with the brain in decalcified specimens. The pars distalis accounted for most of the whole organ. The pars intermedia surrounded the pars nervosa as a goblet. The pars tuberalis was lacking. The immunohistochemical identification of the adenohypophyseal cells was performed using rabbit antisera against mammalian/synthetic hypophyseal hormones. Prolactin cells were clustered in small cellular cordons in the rostral pars distalis and in the medial pars distalis in both male and female specimens. Somatotropic cells were found in the caudal pars distalis. Corticotropic cells were observed in the medio-rostral pars distalis, as well as in the pars intermedia, where melanotropic cells were also present. Melanotropic cells were confined to the pars intermedia. Gonadotropic cells were mostly distributed in the ventral and lateral portions of the pars distalis, where they were found isolated or in small clusters. Thyrotropic cells were detected in the pars distalis with a distribution similar to that of the gonadotropic cells; however, atypically, they were also found in the pars intermedia. Therefore, the cytological characteristics of the adenohypophyseal cells appeared mostly conserved.

Immunohistochemistry and tinctorial affinity of adenohypophysial cells of the rat snake Ptyas mucosus (Colubridae)

Immunocharacteristics of the adenohypophysial cells of the rat snake Ptyas mucosus (Colubridae) were studied with an unlabeled antibody enzyme technique (PAP method) using rabbit antisera against mammalian/synthetic hypophysial hormones. Adenohypophysial cells were identified on the basis of their specific immunoreactivity with various heterologous antisera. As in other reptiles, there was regional localization of pars distalis (PD) cell types in this snake. The gonadotropic (GTH) cells were identified by their specific immunoreactivity with anti-porcine (p)LH beta serum and were distributed uniformly throughout the PD. The thyrotropic (TSH) cells, recognized by their specific immunoreactivity with anti-human (h)TSH beta serum, were found in the medial PD. The prolactin (PRL) and growth hormone (GH) cells were revealed by their specific immunoreactivity with anti-ovine (o)PRL and anti-hGH sera, respectively; the former were confined to the anterior two-thirds of the PD, and the latter were restricted to the posterior third of the PD. The corticotropic (ACTH) cells, identified by their specific immunoreactivity with the anti-ACTH1-24 serum, were localized in the anterior two-thirds of the PD. Though both ACTH and PRL cells were confined to the same area of the PD, they could be distinguished by their distinctive morphology and distribution pattern. Cells of the pars intermedia were revealed by their immunoreactivity to anti-alpha MSH (melanophore-stimulating hormone) and anti-ACTH1-24 sera. Among each adenohypophysial cell type, there was variation in the intensity of immunoreactivity and morphological features, which may be due to their heterogeneity, reflecting various stages of cellular activity. Unlike most other snake species, the occurrence of a rudimentary pars tuberalis in P. mucosus containing a few immunoreactive GTH and TSH cells appeared to be a novel finding. The occurrence of the PRL-like and TSH-like immunoreactivity seen in certain neuronal perikarya and fibers of the hypothalamus and median eminence conforms with earlier observations in other tetrapods. To resolve certain discrepancies in the literature, the tinctorial affinities of immunohistochemically identified adenohypophysial cell types of P. mucosus were studied using various conventional staining methods and were compared with those of other reptilian species studied earlier, including snakes of the family Colubridae.

Opiomelanocorticotropic-like hormones in Vipera aspis pituitary

By using immunohistochemical techniques (indirect immunofluorescence and PAP) adrenocorticotropic-like hormone (ACTH), alpha-melanocyte stimulating-like hormone (alpha-MSH), beta-lipotropic-like hormone (beta-LPH), and beta-endorphin-like (beta-EP) have been localized in the pituitary gland of newborn and adult Vipera aspis. The immunolocalization have been compared with the classical histochemical staining and the data show that the opiomelanocorticotropic-like cells resembles the B3 cells of the current literature. In the intermediate lobe both in adults and in newborns the same cells exhibit immunoreactivity for all the peptides considered, while in the rostral region of the pars distalis a difference has been observed between adults and newborns. In the adults, the cells immunostain for ACTH, beta-LPH, and beta-EP but not for alpha-MSH while in the newborns, the same cells show immunoreactivity for ACTH, beta-LPH, alpha-MSH but not for beta-EP. It has been hypothesized that in Vipera during maturation the pars distalis and the intermediate lobe can differently process the common precursor molecule.