Keratinocyte Glycogen: An Ultrastructural Study of the Epidermal Response to Galactosamine and Glucose in Organ Culture

Abstract

D-galactosamine produces in vitro a striking change in the epidermis with the appearance of large PAS-positive cytoplasmic bodies. The effectiveness of galactosamine in eliciting this response was compared with glucose, glucosamine, and galactose. Explants of normal-appearing skin from 42 patients were maintained in organ culture with basal medium alone containing 100 mg% glucose or in media to which sugars had been added to give final concentrations of 1100 mg% glucose, 100 mg% glucose and 1000 mg% glucosamine, 100 mg% glucose and 1000 mg% galactose, or 100 mg% glucose and 100 mg% galactosamine. The explants were removed in 3–7 days, processed for light and electron microscopic examination and graded for the presence of PAS-positive material. Galactosamine alone produced a marked and consistent response in the epidermis which was statistically greater than the response to the other sugars. Contrary to previous report the PAS-positive bodies are diastase-labile and on ultrastructural examination are composed of 700–800 AU granules resembling the alpha, or rosette, form of glycogen a form of glycogen not normally present in the epidermis. Glycogen induced by the presence of glucose alone appeared in the form of 300–400 AU particles normal for epidermis.