Having compared the microanatomy of the toes of a terrestrial to two climbing species, adaptations were found in the flexor tendons and in the integument. In contrast to Crocidura russula, both Muscardinus avellanarius and Micromys minutus have a tendon-locking mechanism (TLM) that is engaged when the middle phalanx is bent. A ventral thickening of the flexor tendon is situated deep to a thickened portion of the ventral tendon sheath. When twigs or stalks are grasped, the TLM allows less muscular energy to be expended. In C. russula glands are restricted to the terminal pads, but in the climbing species they occur in the sole of the toes as well. In the reed-living M. minutus knob-shaped integumental thickenings, together with the digital pads, stabilize the grip. In contrast the arboreal M. avellanarius often climbs thick branches and shows adaptations for pressing the sole of the feet against the surface. Thereby the tendon attached to the plantar integument of the toes transfers the muscle force directly to the bark. Unlike the other digits on the forefeet of both climbing species, no TLM is present in the anterior digit. In M. minutus this short digit is twisted towards the palm and, with the carpal pads, provides an abutment against the grasping fingers. In M. avellanarius the anterior digit has very thin tendons and is that much reduced in length that it is completely integrated into the digital pad where it acts, at best, as a lateral support of the pad.

The foot pads of ®ve rodents were studied by means of gross morphology and histology. The secretory portions of the glands are placed caudad to the openings of the ducts in species that mostly walk on the ground. This way the secretions are pressed out during walking by rolling on the foot pads craniad. In climbing species, the secretory portions are placed underneath the openings of the ducts and lead to secretion delivery during climbing by grasping. With their small and¯at pads with few glands, digging species have a rather smooth and dry volar aspect to work in a shovel-like way. In contrast, climbing species have large and soft foot pads with a lot of glands. The thickness of the corni®ed layer is positively correlated with the density of glands and increases strikingly from digging to climbing species. Although scent production is possible for these glands, this points to a function of the secretions in connection with the corni®ed layer. In climbing species, the secretions of glands can moisten the skin and thereby heighten the friction between volar and climbing surface to prevent the animal from slipping. The density of glands per unit of surface is doubled in the ridged skin of Muscardinus avellanarius in comparison with the coned skin in Micromys minutus. While M. minutus mainly climbs by grasping stalks of reed and can tighten the grip by increasing the grasping force, M. avellanarius often climbs by pressing the volar aspect on to the bark, whereby friction is increased by the moistened skin.

The foot pads of ®ve rodents were studied by means of gross morphology and histology. The secretory portions of the glands are placed caudad to the openings of the ducts in species that mostly walk on the ground. This way the secretions are pressed out during walking by rolling on the foot pads craniad. In climbing species, the secretory portions are placed underneath the openings of the ducts and lead to secretion delivery during climbing by grasping. With their small and¯at pads with few glands, digging species have a rather smooth and dry volar aspect to work in a shovel-like way. In contrast, climbing species have large and soft foot pads with a lot of glands. The thickness of the corni®ed layer is positively correlated with the density of glands and increases strikingly from digging to climbing species. Although scent production is possible for these glands, this points to a function of the secretions in connection with the corni®ed layer. In climbing species, the secretions of glands can moisten the skin and thereby heighten the friction between volar and climbing surface to prevent the animal from slipping. The density of glands per unit of surface is doubled in the ridged skin of Muscardinus avellanarius in comparison with the coned skin in Micromys minutus. While M. minutus mainly climbs by grasping stalks of reed and can tighten the grip by increasing the grasping force, M. avellanarius often climbs by pressing the volar aspect on to the bark, whereby friction is increased by the moistened skin.