Histochemical studies of mucosubstances and keratins of thymic corpuscles.

Keratin and prekeratin have been visualized histochemically by testing the reactivity of disulfide groups in the thymic corpuscles of the sheep. Rhesus monkey, rabbit and dog, and the reactivity of sulfhydryl groups in the sheep, Rhesus monkey, rabbit and rat. Ten to 50% of the thymic corpuscles showed keratinization by this method. Acidic mucosubstances were visualized histochemically in the Rhesus monkey, sheep and rat but not in the rabbit. Staining for vic-glycol groups was prominent in all species tested. Neuraminidase treatment with subsequent Alcian blue-periodic acid-Schiff (PAS) staining indicated the presence of sialomucins in the thymic corpuscles of the monkey and rat, but sialomucins were not demonstrated in the rabbit.