[Postnatal development of the tectorial membrane's marginal net of the rabbit. Correlations with the typical marginal structures of the adult squirrel monkey].

To date the structure of the marginal net of the tectorial membrane has not been sufficiently described, its function is unclear and can only be understood after further detailed analysis. The limiting factor in these experiments is that mostly the applied routine preparation techniques always unspecifically change the tectorial membrane. The preparation techniques have now been modified so far that the induced changes can be kept at a minimum. Examinations were carried out parallely with the stereo microscope, the light microscope, the scanning and transmission electron microscopes; results were compared and ensured. 1. The normal structure of the marginal net of the adult squirrel monkey was compared with that of the adult rabbit. The similarity suggests to study for the first time the development of the marginal net in the embryologically more easily accessable rabbit by means of scanning electron microscope. 2. The refined preparation technique enables a reproducable investigation of the tectorial membrane in a lifted off state and subsequently in a large area even in a not lifted off state. 3. During the various steps of preparation the marginal zone is deformed much stronger than the rest of the membrane. 4. In the squirrel monkey a distinctly developed marginal net seems to be combined with the presence of a fourth row of other hair cells. To this conclusion leads the following observation: the impressions of the sensory cell hairs on the bottom side of the tectorial membrane are found predominately in the cross connections of the marginal net. 5. The marginal net of the rabbit shows a development from basal to apical. Thereby the hair cells are covered with fibres of the tectorial membrane up to the Hensen's cells. 6. On the fifth day characteristic holes are growing in the marginal area and the fibres withdraw from the Hensen' cells. This development proceeds in the rabbit more than in the squirrel monkey, the emerged net structure is reduced to the advantage of the marginal band. 7. A new technique allows the same spot to be observed by the scanning as well as the transmission electron microscopes. The interdental cells examinated in this way showed a strong activity of synthesis in the "3d" stage.