Radio-ulnar deviation of the primate carpus: an X-ray study.

The lack of contact between the ulna and first row of carpals characterizes the wrist morphology of hominoids as compared to other primates. This distinctive feature--generally interpreted as a significant synapomorphy between humans and other hominoids--was a priori considered to be an indication of an increased capacity for ulnar deviation, allowing a greater diversity of hand movements. This X-ray study aimed to test this hypothesis by comparing the shifting of the carpals throughout radioulnar deviation in eight extant genera endowed with ulno-carpal contact or lacking it. The results show that the amplitude of ulnar deviation is not directly correlated with the presence or absence of an ulno-carpal contact: most ulnar deviation takes place at the antebrachio-carpal joint in those primates that lack an ulno-carpal contact (hominoids), instead of at the mid-carpal joint in primates whose ulna articulates with the triquetral (cercopithecoids, platyrrhines, most strepsirrhines). Analysis of the X-ray suggests that the loss of ulno-carpal contact improved the ability to supinate at the radio-ulnar joints, with correlated unfitness for palmigrade/semidigitigrade walking. This evolutive change, associated with a considerable reduction of the share of body weight carried on the forelimbs, likely cleared the way for either knuckle walking or bipedalism and handiness.

Effects of fixation and preservation conditions on immunohistochemical profiles of the skeletal muscle fibers in Japanese macaques.

Effects of fixation and preservation conditions of muscle tissues on immunohistochemical profiles are investigated. Samples of the hind limb and epaxial muscles were removed from 4 adult female Japanese macaques (Macaca fuscata) fixated with 10% formalin and preserved in the same solution under different conditions for 6 months to 4 years and 6 months. Sections were stained with indirect immunofluorescence and avidin-biotin peroxidase complex methods using an antibody against fast myosin (Mouse Monoclonal Anti-skeletal Myosin-Fast, clone MY-32, Sigma) as a primary antibody. Clear responses to the antibody were demonstrated in the samples from the specimens fixated by injection or immersion with 10% formalin and preserved in the same solution for 6 months to 1 year and 6 months. Distribution patterns of the fibers reacting to the antibody coincided with that of the fast twitch fibers determined using enzyme-histochemical techniques in these samples. Clear responses to the antibody were not demonstrated in the samples from the specimen repeatedly rinsed in water for gross anatomical dissections during the preservation period. The results of this study warrant applications of immunohistochemical techniques to the study of fiber type composition in muscle samples from specimens fixated with formalin and preserved in the same solution for a long term.