Comparative analysis of Meissner's corpuscles in the fingertips of primates

Abstract

Meissner's corpuscles (MCs) are tactile mechanoreceptors found in the glabrous skin of primates, including fingertips. These receptors are characterized by sensitivity to light touch, and therefore might be associated with the evolution of manipulative abilities of the hands in primates. We examined MCs in different primate species, including common marmoset (Callithrix jacchus, n = 5), baboon (Papio anubis, n = 2), rhesus macaque (Macaca mulatta, n = 3), chimpanzee (Pan troglodytes, n = 3), bonobo (Pan paniscus, n = 1) and human (Homo sapiens, n = 8). Fingertips of the first, second and fourth digits were collected from both hands of specimens, dissected and histologically stained using hematoxylin and eosin. The density (MCs per 1 mm(2) ) and the size (cross-sectional diameter of MCs) were quantified. Overall, there were no differences in the densities of MCs or their size among the digits or between the hands for any species examined. However, MCs varied across species. We found a trend for higher densities of MCs in macaques and humans compared with chimpanzees and bonobos; moreover, apes had larger MCs than monkeys. We further examined whether the density or size of MCs varied as a function of body mass, measures of dexterity and dietary frugivory. Among these variables, only body size accounted for a significant amount of variation in the size of MCs.

Keywords: Meissner's corpuscles; body mass; dietary frugivory; digital dexterity; primates.

Figure 1

MCs of a rhesus macaque (Macaca mulatta). MCs are indicated by red arrows.

Figure 2

MCs of Callithrix jacchus (A), Papio anubis (B), Macaca mulatta (C), Pan troglodytes (D), Pan paniscus (E) and Homo sapiens (F).

Figure 3

Meissner's corpuscles (MCs) density per mm² and MCs size across digits for each primate species. Error bars indicate SEM. One-way anova showed no differences in MCs density or size among the digits or between the hands for any species examined (all P values non-significant). See text for more details.

Figure 4

Comparison of Meissner's corpuscles (MCs) density (A) and size (B) among the primate species. Box-plots indicate the 25th percentile, the median and the 75th percentile; the whiskers indicate the range. Non-parametric Kruskall–Wallis one-way anova showed significant species differences in both the density and the size of MCs. Bonferroni-adjusted post hoc pairwise comparisons revealed significant differences between the species (solid line) or differences that approached statistical significance (dotted lines).

Figure 5

Comparison of Meissner's corpuscles (MCs) density (A) and size (B) between apes (humans and two chimpanzee species) and monkeys (marmosets, baboons and rhesus). Box-plots indicate the 25th percentile, the median and the 75th percentile; the whiskers indicate the range. Independent samples t-test revealed a significant difference between these groups in MCs size but not density.

Figure 6

Relationships between Meissner's corpuscles (MCs) density (A), size (B) and body mass (kg). Body mass data are taken from Smith & Jungers (1997). The regression line and the confidence intervals are derived from ordinary least-squares regression analysis. See text for more details.

Figure 7

Relationship between Meissner's corpuscles (MCs) density (A) and size (B), and either dexterity or dietary frugivory. The dexterity index was originally developed by Heffner & Masterton (1975) on the basis of the anatomy of the hand described by Napier & Napier (; see also Napier, 1961). The dietary frugivory was compiled from available data. See text for more details.