Dermal cysts of the rhino mouse develop into unopened sebaceous glands

The rhino mouse (hr(rh)hr(rh)) is a mutant strain characterized by a wrinkled and hail less skin with epidermal utriculi (pseudocomedones) and dermal cysts, The epidermal cysts have been extensively studied, The present work focused on the dermal cysts, By electron microscopy it was found that they appear on day 20 after birth and that they originate from a a pool of undifferentiated epithelial cells of the deepest part of the initial follicular unit, Progressively, the number of cells ire these islets increased and a central cavity was formed, Peripheral cells differentiated into sebocyte-like cells and outer root sheath cells, Staining with Oil Red O solution indicated accumulation of lipid material in the central cavity, The dermal cysts of the adult rhino moose were isolated and purified ire several steps including enzyme digestion, centrifugation, and separation on Nylex sieves, The integrity of the isolated cysts was confirmed by histology and electron microscopy, Study of their keratin polypeptide pattern by gel electrophoresis indicated that they express the mouse keratins 5, 14, 6 and 17, Neutral Lipid analysis of the dermal cyst contents showed that they were mainly composed of cholesterol esters, wax esters, lipid fractions which migrate between triglycerides sand cholesterol esters but very small amounts of triglycerides, cholesterol and ceramides. In conclusion, the present results demonstrate that dermal cysts of the rhino mouse have strong similarities with sebaceous glands and outer root sheath cells, These structures earn easily be isolated and could therefore serve as a 'closed sebaceous gland' model to study the physiology or differentiation of the sebaceous gland, or the effects of pharmacological agents.