RESUMO
Various concentrations of vitamin A acid were applied to experimentally induced comedones. All concentrations produced non-cohesive hyperkeratinization, which loosened the cohesive horny mass induced by oleic acid and expelled it from the follicle within 7 days. The highest concentration (0.1%) produced the greatest degree of non-cohesive desquamation in the shortest time. In follicles treated with the acid, the cell membrane of horny cells was thin and ruptured easily to produce a non-cohesive debris. Desmosomes were scarce and desmosomal bodies (fusiform electron-dense bodies) and tight junctions between horny cells were not seen in follicles treated with the acid. The acid also produced hyperplasia of the epithelial wall and an apparently increased mitotic rate. A 0.025% concentration of the acid increased the number of membrane coating granules by about 70% in all regions of the follicle.
Assuntos
Acne Vulgar/tratamento farmacológico , Tretinoína/uso terapêutico , Vitamina A/análogos & derivados , Acne Vulgar/induzido quimicamente , Acne Vulgar/patologia , Animais , Membrana Celular/ultraestrutura , Desmossomos/ultraestrutura , Masculino , Microscopia Eletrônica , Coelhos , Pele/ultraestruturaRESUMO
Membrane coating granules (MCGs) may be required for normal keratinization. Comedone formation is associated with abnormal keratinization, and so the MCGs in sebacaous follicles were counted during experimental comedogenesis in the rabbit. During induced comedo formation with 50% oleic acid in paraffin oil, the numbers of MCGs decreased significantly; first, at the epidermis and mouth of the follicle and then later, at the follicular canal and common sebaceous duct. The maximum decrease of about 40% was reached by the 6th day in these regions. Throughout the treatment, the MCG count in the individual sebaceous ducts remained fairly constant.
Assuntos
Acne Vulgar/patologia , Cabelo/ultraestrutura , Animais , Membrana Celular/ultraestrutura , Grânulos Citoplasmáticos/ultraestrutura , Queratinas , Microscopia Eletrônica , CoelhosRESUMO
Cohesion between horny cells was studied in experimentally induced comedones, from the rabbit's external ear canal. It occurred in two different ways: initially, by the persistence of desmosones and desmonosmal bodies (fusiform electron dense bodies), which loosely held the horny cells together; later, and to a lesser extent, by tight junctions, which tightly bound the horny cells together. A gradual decrease in the numbers of membrane coating granules was observed.
