FUNDAMENTOS: O processo de envelhecimento tecidual é evidente nas modificações visíveis na pele, resultando em importantes implicações psicológicas para o indivíduo e crescente interesse científico. OBJETIVOS: O presente trabalho objetivou analisar as alterações da pele normal com o envelhecimento mediante estratégias de histomorfometria e autofluorescência. MÉTODOS: Foram coletadas amostras de pele do abdômen de 18 cadáveres, incluindo cinco indivíduos jovens (menos de 20 anos), sete indivíduos com idade intermediária (20-60 anos) e seis indivíduos idosos (mais de 60 anos). Foram feitos cortes histológicos em parafina seguidos de coloração pela Hematoxilina-Eosina (H&E) e pelo tricrômio de Van Gieson-elastina. Avaliaram-se a espessura da epiderme e derme, e a superfície de contato epidermo-dérmica. Investigaram-se ainda as modificações qualitativas do aparelho colágeno-elástico, considerando sua disposição espacial na derme. Espécimes corados em H&E também foram utilizados para autofluorescência. RESULTADOS: A espessura da epiderme e derme do grupo idoso foi significativamente diminuída (p<0,05) em relação aos demais grupos. Os grupos idoso e intermediário exibiram acentuada redução na superfície de contato epiderme-derme (p<0,05). Detectaram-se a perda da distribuição em rede das fibras elásticas com sua progressiva fragmentação, alterações da compactação do colágeno e espessamento da membrana basal com o envelhecimento. CONCLUSÃO: O envelhecimento leva à redução da espessura da derme e epiderme, bem como ao aplanamento da junção dermo-epidérmica. As mudanças da pele ao longo da vida nem sempre seguem um perfil linear, mostrando drásticas alterações nas últimas décadas de vida. O método de autofluorescência mostrou-se um instrumento valioso no estudo da complexa relação espacial das fibras elásticas e colágenas.

BACKGROUND: Age-related changes are easily recognized by examining the skin and lead to important psychological implications, motivating increased scientific interest. OBJECTIVES: This study aimed to analyze, by histomorphometric and autofluorescence approaches, the aged-related alterations in normal human skin. METHODS: Normal abdominal skin samples were taken from eighteen cadavers, including five young subjects (below 20 years old), seven subjects with intermediate age (20-60 years old) and six elderly subjects (over 60 years old). Paraffin-embedded sections were prepared and stained by Hematoxylin and Eosin (H&E) and Van Gieson-elastin trichrome. Afterwards, the H&E specimens were also used for autofluorescence technique. RESULTS: The thickness of elderly epidermis and dermis was reduced compared to middle-aged and young age groups (p<0.05). The elderly and middle-aged groups also showed a marked reduction in the epidermal-dermal contact surface (p<0.05) in comparison to the young group. In addition, we detected a loss of the distribution in the elastic fiber network in the elderly with progressive fragmentation, as demonstrated by Weigert's stain for elastin and poor fluorescent contrast. CONCLUSION: The thickness of the epidermis, dermis, and epidermal-dermal interface contact surface decreased in the aged skin. The changes throughout life in the normal skin did not follow a continuous linear profile, showing drastic alterations especially in the last decades. Autofluorescence approach proved to be an important additional tool for studying the complex relation-ship between the elastic and collagen fibers.

The Argentinean Chaco region has been considered the center of origin of Drosophila buzzatii in South America because it contains most of the chromosomal polymorphism detected in natural populations. Two hypotheses have been put forward to explain the distribution of D. buzzatii in Brazil, one proposing that it has only recently passively colonized Brazil via human dispersal and the other suggesting that D. buzzatii has actively migrated to Brazil some time ago. Data from chromosomal inversions support recent colonization, whereas data from allozymes and mtDNA variation indicate that D. buzzatii has been in Brazil longer, favoring an active dispersal hypothesis. In our present work we analyzed data on 56 South American flies, mostly from Brazil, sequenced for the 5’ end of the mtDNA COI gene. The combined use of many neutrality tests and phylogeographic methods (e.g. nested clade analysis) indicated high gene flow throughout most of the range of D. buzzatii, although significant population structure was still detected. The high nucleotide diversity in the Northeast region of Brazil and the results from the nested clade analysis suggest that D. buzzatii has been in Brazil longer than proposed by the passive dispersal hypothesis. Our data indicate that D. buzzatii has been distributed throughout Brazil and Argentina since the Quaternary, though more data from different localities and markers need to be gathered to determine how the occupation of South America by D. buzzatii has occurred.