Further contributions about the use of the horseradish peroxidase (HRP) in the ultrastructural study of the olivary neurons of cat.

In order to recognize with E.M. the specific aspect of HRP in olivary neurons of cat, we have used newborn animals twenty-four, forty-eight hours old. The observation of these neurons has allowed us to see a numerous series of dense bodies various in size and density; these bodies have never been found in similar neurons from adult cats or from newborn cats not treated with HRP. These structures could represent the equivalent of an intraneuronal storage of enzyme, whose presence had been confirmed by O.M.