Secretory phenomena at the ependyma of the sulcus hypothalamicus Monroi of the fetal rat. A histochemical and electron microscopic study

In a localized area above the sulcus hypothalamicus Monroi ventriculi tertii of the rat ependymal structures are observed, which only occur between the 18th and 20th day of gestation. They were investigated with the aid of lightmicroscopic, ultrastructural and histochemical technics. The surface of the ventricular wall is rendered irregular by protrusions and deposits. Neurosecretory stains and histochemical examination give no positive results. Apical parts of the ependymal cells are fingershaped, dome-like and of spheric appearance. The equipment of the protrusions with organels is variable. Some of them contain a fine granular ground plasma, polyribosomes and occasional profiles of the endoplasmatic reticulum. Others are impacted with optic empty or substantial vacuols. Vacuols merging in the cellular membrane evacuate their content into the ventricular space. Multivesicular bodys engorged with vesicles are together with those, which lie empty in the ventricular cavity. Empty, buddle like and frequently folded membrane protrusions suggest that cellular content has been delivered into the ventricle.