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.

Seasonal variations in the ultrastructure and production of androgen-dependent proteins in the seminal vesicles of a Saharian rodent (Psammomys obesus).

The effects of seasonal variations and experimental deprivation and substitution of androgen in the seminal vesicles of the Saharian rodent Psammomys obesus were investigated. Cytological studies showed that, during the breeding season, epithelial cells had large amounts of rough endoplasmic reticulum (RER) and substantial apocrine secretion. During the non-breeding season, RER cisternae were no longer expanded and apocrine secretion was rare. Castration during the breeding season was followed by regression of the RER and the disappearance of apocrine secretion. Treating castrated animals and animals in the non-breeding season with testosterone for 15 days caused reactivation. Eight major proteins with molecular weights of 120, 78, 67, 41, 37, 34, 21 and 14.4 kDa were present in homogenates during the breeding season; six (92, 41, 36, 35, 21 and 14.4 kDa) were found in seminal vesicle secretions. During the non-breeding season, the very large amounts of the 21 kDa protein were greatly reduced; conversely the 45 kDa protein increased. Electrophoretic patterns of homogenates from animals castrated during the breeding season showed eight proteins differentially induced (37, 34, 21 and 18 kDa) or repressed (67, 45, 38 and 35 kDa) by testosterone, of which the 21 kDa protein decreased most dramatically after castration. The effects of castration were reversed by the administration of testosterone. During the non-breeding season, the synthesis of the four induced proteins was stimulated by testosterone treatment; conversely that of the 45 kDa protein was suppressed.

Tyrosine hydroxylase immunoreactivity in the retina of the diabetic sand rat Psammomys obesus.

The pattern of tyrosine hydroxylase (TH)-immunoreactivity, which labels dopamine neurons in the retina, is described in a diurnal sand rat Psammomys obesus. As in other rodent species, dopamine innervation is composed of large neurons located in the amacrine cell layer and sending processes mainly to sublamina 1 of the inner plexiform layer, where they form ring-like structures around unlabeled cell bodies. Thin varicose axon-like processes running to sublamina 3 are also present in significant number like in other diurnal animals. A few interplexiform cells are observed. Psammomys obesus rapidly develops hyperglycemia when held in captivity and fed normal synthetic laboratory rat diet, providing a model for the study of diabetes related impairment of dopamine metabolism in the retina. The pathomorphological analysis of TH-immunoreactivity was achieved in a population of diabetic Psammomys and compared with the normal. It indicates that moderate hyperglycemia induces a decrease of TH-immunoreactivity in dopamine dendrites only, while severe hyperglycemia can provoke dopamine neuron degeneration.