35 - Evaluating Dermatoglyphs as Proxy of Mechanoreceptor Densities in a Macaque Model

Poster Board Number: 35
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Abstract Body : Precision touch is fundamental for allowing humans and non-human primates to interact with their external environment. Two types of mechanoreceptors are particularly important for precision touch: tactile epithelial cells (e.g., Merkel cells) and tactile corpuscles (e.g., Meissner corpuscles). Previous research suggests that dermatoglyphic (fingerprint) features such as papillary ridge widths may be useful morphometric proxy for the densities of these mechanoreceptor types. However, much of this work relies on relationships between dermatoglyphics and behavioral sensitivity rather than histologically-measured mechanoreceptor densities. In this study, we investigated the relationships between mechanoreceptor densities and papillary ridge widths in the fingers of nine young adult macaques (Macaca mulatta) from the Cayo Santiago Primate Research Station in Puerto Rico). We collected fingerprints and skin samples from the fingertips of the first and second digits. We predicted that as papillary ridge width increases, the density of mechanoreceptors will decrease. We used ImageJ to quantify average papillary ridge width from 20 randomly sampled locations for each fingerprint. Next, we embedded skin samples in paraffin blocks and stained sections with hematoxylin and eosin. We counted the number of tactile epithelial cells and tactile corpuscles in six sections across 100 um and quantified their densities using established methods. Consistent with our prediction, we found negative correlations between average papillary ridge widths and mechanoreceptor densities (tactile epithelial cells: r2 = -0.65, p = 0.043; tactile corpuscles: r2 = -0.60, p = 0.066). We also found significant differences in average ridge width between the first and second digits. Our results suggest that papillary ridge width in fingerprints may be a useful proxy for the density of tactile corpuscle and tactile epithelial cells in young, healthy individuals.