An effective fixative for glucocorticoid receptors in fetal tissues

As a preliminary study in an autoradiographic study of glucocorticoid (GC) receptor localization in orofacial tissues of mouse fetuses, a search was made to determine the most effective fixative for preservation of the GC-receptor complex. Twelve-day-old mouse fetuses were administered tritiated triamcinolone acetonide (3H-TAC) intraamniotically and subsequently processed by one of the following three procedures: freeze-drying, prefixation with Karnovsky's fixative, or "the catechin fixative" (Karnovsky's fixative containing 1% D-catechin) and postfixation with osmium tetroxide. Light microscopic autoradiography and liquid scintillation counting of the specimens revealed that the catechin fixative gave the best results for fixation of the steroid-receptor complex and preservation of tissue structure. Light and electron microscopic autoradiographic studies of the time course of the localization of 3H-TAC in palatal shelves supported the catechin fixative as being the most effective in preservation of GC-receptor or ligand complexes.