II. Ultrastructural development of the early rat otocyst

Various methods of dissection, fixation, osmication, sectioning and staining were tested in order to develop an acceptable technique for preparing 9, 10, 11, and 12 day old rat otocysts for electron microscopic study. The general problems associated with embryonic tissue difficult handling, high water content and poor stainability are discussed, and concrete methods of preparation which significantly decrease these diffculties are proposed. The specific fixation and sectioning requirements of rat otocyst are also described in the elaboration of a method which will be used in subsequent studies of the organogenesis of rodent ear.