Spheno-occipital synchondroses were studied histologically in eight human fetuses ranging from 100 mm CRL to term. Cartilage canals were present in all seven specimens over 110 mm CRL. With age the canals grew longer and wider and the larger ones developed some branching. The histologic structure, external morphology and spatial arrangement of these cartilage canals were described. Some attributes of cartilage canals were reviewed from available data in the literature and their significance for the present findings discussed. It was suggested that the canals, containing blood vessels and connective tissue elements, actively invade the cartilage of the synchondrosis. It was suggested further that they probably serve as a source of nutrition or as an extension of the perichondrium (and a source of prospective chondroblasts) or both.