The development of the stria vascularis in the human foetus

The development of the stria vascularis in the human cochlea was studied in step sections of 81 human foetal temporal bones. The stria vascularis prim ordium can be identified as a ridge of epithelial cells on the lateral wall of the cochlear duct. The first signs of differentiation appear at the 11t h week, but it is not until the 17th-18th week that the typical trilaminar structure is observed. The appearance of similar cells with notched nuclei in both marginal and mesenchymal layers at this stage suggests the possibil ity that some of the intermediate cells may be of epithelial origin. By the 21st week, the overall appearance resembles that of the adult structure. T his occurs 1 week after the opening of the tunnel of Corti, and possibly ma rks the onset of cochlear function.