Dear Colleagues, Our new micr- macrovibrissal paper in phocids in now published in Brain, Behavior and Evolution and can be found at the following link: http://www.karger.com/Article/Abstract/447551 Thanks, Christopher Marshall Mattson*, E.E., MARSHALL, C.D. 2016. Follicle Microstructure and Innervation Vary Between Pinniped Micro- and Macrovibrissae. Brain Behavior and Evolution. DOI:10.1159/000447551) Abstract Histological data from terrestrial, semiaquatic, and fully aquatic mammal vibrissa (whisker) studies indicate that follicle microstructure and innervation vary across the mystacial vibrissal array (i.e. medial microvibrissae to lateral macrovibrissae). However, comparative data are lacking, and current histological studies on pinniped vibrissae only focus on the largest ventrolateral vibrissae. Consequently, we investigated the microstructure, medial-to-lateral innervation, and morphometric trends in harp seal (Pagophilus groenlandicus) vibrissal follicle-sinus complexes (F-SCs). The F-SCs were sectioned either longitudinally or in cross-section and stained with a modified Masson's trichrome stain (microstructure) or Bodian's silver stain (innervation). All F-SCs exhibited a tripartite blood organization system. The dermal capsule thickness, the distribution of major branches of the deep vibrissal nerve, and the hair shaft design were more symmetrical in medial F-SCs, but these features became more asymmetrical as the F-SCs became more lateral. Overall, the mean axon count was 1,221 ± 422.3 axons/F-SC and mean axon counts by column ranged from 550 ± 97.4 axons/F-SC (medially, column 11) to 1,632 ± 173.2 axons/F-SC (laterally, column 2). These values indicate a total of 117,216 axons innervating the entire mystacial vibrissal array. The mean axon count of lateral F-SCs was 1,533 ± 192.9 axons/ F-SC, which is similar to values reported in the literature for other pinniped F-SCs. Our data suggest that conventional studies that only examine the largest ventrolateral vibrissae may overestimate the total innervation by ∼20%. However, our study also accounts for variation in quantification methods and shows that conventional analyses likely only overestimate innervation by ∼10%. The relationship between axon count and cross-sectional F-SC surface area was nonlinear, and axon densities were consistent across the snout. Our data indicate that harp seals exhibit microstructural and innervational differences between t heir microvibrissae (columns 8-11) and macrovibrissae (columns 1-7). We hypothesize that this feature is conserved among pinnipeds and may result in functional compartmentalization within their mystacial vibrissal arrays. ------------------------------------------------------ Christopher D. Marshall, Ph.D. Professor Department of Marine Biology 200 Seawolf Parkway Building 3029, Room 253 Texas A&M University Galveston, Texas 77553 Phone: (409) 740-4884 Fax: (409) 740-5001 Email: marshalc@tamug.edu (please note the difference in the spelling of my last name) Website: www.marinebiology.edu/Marshall -- Great things are not done by impulse, but by a series of small things brought together. - Vincent van Gogh