Fig. 4: Organization of elephant trunk whisker follicles.

Virtual longitudinal microCT section of a a dorsal African elephant trunk follicle-sinus-complex (FSC). The follicle was stained in 1% iodine for 48 h. The surrounding tissue was cropped, and whisker contrast was selectively adjusted in some areas to maintain visibility and avoid saturation. b a lateral Asian elephant trunk FSC, conventions as in a. c a rat δ whisker FSC. The FSC was stained in 1% iodine for 24 h. d Micrograph of a hematoxylin-eosin stained longitudinal section of a lateral adult African elephant trunk FSC (scale bar = 1 mm). e Micrograph of hematoxylin-eosin stained transversal sections of a lateral adult African elephant trunk FSC. Approximate planes of the sections are indicated in d with dotted lines (scale bar = 500 µm). f As d but for a lateral adult Asian elephant trunk FSC (scale bar = 1 mm). Note that the whisker partially broke during cryosectioning and embedding. g As e but for a lateral newborn Asian elephant trunk FSC (scale bar = 100 µm). h Volume rendering of an Asian newborn elephant trunk microCT scan with single FSCs and their respective whiskers segmented on the trunk tip and a proximal trunk piece. FSCs are color-coded depending on their lengths. Left, view of the whole scan. Right, Volume rendering of the proximal trunk piece. i Follicle length in the lateral and ventral trunk and the trunk tip of an Asian newborn elephant (Hoa’s Baby, see Table 1). One-way ANOVA, P < 0.001, post hoc Scheffé test for pairwise comparison (*P < 0.05, ***P < 0.001). Error bars indicate the standard deviation. RRC Rete ridge collar, MS Mesenchymal sheath, C Vibrissal capsule, S Vibrissal shaft, RoS Root sheath, VSS Vascular sinus spaces, DVN Deep vibrissal nerve.