The aim of this study was to evaluate the influence of the depth of the dermis on the measured collagen and elastin levels and to establish the correlation between the amount of these two extracellular matrix (ECM) components and age. Multiphoton Microscopy (MPM) that measures the autofluorescence (AF) and second harmonic generation (SHG) was used to quantify the levels of elastin and collagen and to determine the SAAID (SHG-to-AF Aging Index of Dermis) at two different skin depths. A 50 MHz ultrasound scanner was used for the calculation of the Sub Epidermal Non Echogenic Band (SENEB). The measurements of the skin mechanical properties were done with a cutometer. All measurements were performed on two groups of 30 healthy female volunteers. The MPM showed a decrease of the quantity of collagen and elastin as a function of depth of the dermis as well as age. The SAAID was lower for the older skin in the deeper dermis. Ultrasound imaging revealed a significant decrease of SENEB as a function of aging. The mechanical properties confirmed a loss of cutaneous elasticity and firmness. Although multiphoton microscopy is a powerful technique to study the characteristics of the dermis and its age-related damage, the location of the measurements (depth) remains very

The cellular composition of 46 pyogranulomas experimentally induced with Corynebacterium pseudotuberculosis in sheep was determined by immunohistochemistry. Lesions localized in inoculation sites or draining lymph nodes consisted of macrophage and lymphocyte layers distributed around a necrotic center and surrounded by a fibrous capsule. In immature lesions, T cells of the CD4+ subset predominated, whereas in mature lesions proportions of CD8+ T lymphocytes and cells expressing the gamma/delta chains for the T cell receptor increased. Numerous pyogranuloma cells expressed the interleukin-2 receptor. In addition to these general characteristics, a large individual variability in the proportions of macrophage and T cell subsets was observed for lesions of the same age, in particular for epithelioid macrophages. This heterogeneity suggests a different cellular pattern in relation to the persistence or the elimination of bacteria by the host.

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