RESUMO
Analysis of melanins and melanosomes in eight hair and skin samples taken of adult pigmented Argentine llamas (Lama glama L.) has been carried out. In each sample, eumelanins, pheomelanins and alkali-soluble melanins were identified. The total amount of melanins and the amount of eumelanins both decreased from black to reddish brown colour, while pheomelanins were found to be present in small quantities in each sample. Eumelanosomes were round and oval-shaped, displaying transverse striations clearly visible at low magnification. Dark brown samples revealed all four melanosomes stages. Stages I and II melanosomes appeared as large, asymmetrical vacuoles containing numerous microvesicles randomly scattered within an amorphous proteinaceous material (vesiculo-globular bodies). Stage III melanosomes had microgranular melanin deposits in the microvesicles and in the matrix. The fully melanized melanosomes (stage IV) were primarily round-shaped, showing an irregular outline and the electron-dense pigment was arranged to form large clusters. In light brown melanocytes, numerous melanosomes at different maturation stages could be found. Premelanosomes appeared ovoid, containing amorphous proteinaceous material and spotty and microgranular deposits. Mature melanosomes were fully melanized, homogeneously electron-dense, ovoid granules.
