Cell types with secretory granules reactive to silver-methenamine after periodic-chromic oxidation in the anterior hypophysis of a lizard. An electron microscopic study.

The number of cell types that in reptilian pars distalis react with periodic acid-Schiff's leucofuchsin is a controversial question. The problem has been investigated at ultrastructural level in the teiid lizard Cnemidophorus lemniscatus (L) with the periodic acid-chromic acid-silver methenamine technique, which gives comparable results. Reactive cells were correlated with types extensively studied with conventional methods for electron microscopy in diverse experimental conditions. The three secretory cell types that have granules intensely stained by silver are considered to produce glycoprotein hormones. One is constituted of rounded cells with small spherical granules evenly stained; they abound in caudal and ventral regions, and may be assimilated to thyrotrophs. The other two types are assumed to be gonadotrophs. Rostral gonadotrophs are large cells with round granules of very different sizes; polymorphic bodies and the content of dilated endoplasmic reticulum appear slightly stained. Caudal gonadotrophs are elongate cells with small granules of irregular shape, which diversely take silver. A fourth secretory cell type, of rostral localization, has medium-sized rounded granules, uniformly stained but with lesser intensity than those of glycoprotein-producing cells; these elements are considered corticotrophs and often contain few granules. The scanty granules of folliculo-stellate cells, as well as the luminal substance of intercellular canaliculi, are rather strongly reactive; a certain secretory role of these cells is assumed.