MOLECULAR ANATOMY OF A SKIN GLAND - HISTOCHEMICAL AND BIOCHEMICAL INVESTIGATIONS ON THE MUCOUS GLANDS OF XENOPUS-LAEVIS

The purpose of this study was to investigate the structure and chemica l composition of the mucous skin gland of Xenopus laevis by combined m orphological and biochemical techniques. Protein backbones of mucins w ere localized immunohistochemically in the gland with anti-peptide ant ibodies. Acid mucins were demonstrated by conventional histochemical t echniques and their terminal carbohydrate residues were localized by l ectin histochemistry. A dose correlation between antibody and lectin b inding of the same glycoproteins was achieved on Western blots from is olated skin gland mucins, indicating that the lectin-binding sites wer e due to defined mucin molecules. The cone cell, thought to be a degen erative cell in the past, contained mucin grannies with an electron-de nse core, strong PAS reactivity, a special lectin-binding pattern, and localization of integumentary mucins FIM-B.1 and FIM-C.1. These resul ts indicate that cone cells are a distinct cell type, elaborating and releasing particular mucins, and that functional heterogeneity of mucu s-producing cells exists in the mucous skin glands of X. laevis.