THE ULTRASTRUCTURE AND FUNCTION OF THE TUBERCLES ON THE BACK OF NEOPHOCAENA PHOCAENOIDES IN THE CHANGJIANG RIVER IN CHINA

There is a longitudinal string of tubercles, arranged in one to three rows, on the surface of the dorsal skin of Neophocaena phocaenoides in the Changjiang River. On the basis of our histological research, the tubercles are the projecting hillocks of the epidermis extending higher than the surface of the skin. In the tubercular area, the papillae insert deeply into the epidermis. Their height is 70—80% of the epidermis in the adults, 84.5% in 1ihe newborn animals. In recent study, we found that a lot of the encapsulated nerve endings similar to the pacinian corpuscle in human skin and some kinds of bundles of myelinated nerve fibres are present in the tubercular skin. According to these findings, we could refer the tubercles to a sensory organ rather than a structure for preventing the calf from slipping off.