Subcellular localization of gonadotropic hormones in pituitary cells of the castrated pig with the use of pre- and post-embedding immunocytochemical methods.

Pre- and post-embedding immunocytochemical methods based on the use of specific antibodies against beta-subunits of porcine LH and FSH were applied to determine the changes occurring in the anterior pituitary of the pig after gonadectomy. The results showed that (1) the total number of immunoreactive gonadotropes increased from 21-25% in control animals to 24-37% in castrated animals; (2) all gonadotropes contained both LH and FSH; (3) several types of immunoreactive LH/FSH cells were revealed; and (4) the two immunocytochemical methods used with dispersed cells localized the hormones in the same subcellular sites. However, the staining intensity in the different locations varied depending on the method applied. With the post-embedding method, a dense reaction product was found in the secretory granules but the cisternae of RER and the Golgi saccules were always slightly reactive. After the pre-embedding method, the staining intensity in the RER-cisternae and in the Golgi saccules was greatly increased. Thus, the two methodological approaches used in this study have permitted to visualize immunocytochemically the gonadotropic hormones not only at the sites of their storage but also along the intracellular pathway of the secretory material, i.e., at the site of its synthesis and during its passage via the Golgi zone.