STRUCTURE OF THE ROOF OF THE 4TH VENTRICLE IN PIGEON AND CHICK BRAINS BY LIGHT AND ELECTRON-MICROSCOPY

Abstract

The hindbrains and meninges of pigeon and chick were examined by light microscopy and EM. Serial section histology of the skull with the brain and meninges intact showed that the caudal end of the roof of the 4th ventricle consists of an extensive membranous pouch which projects caudally and dorsally into the subarachnoid space. EM showed that selected areas of the membranous pouch in the pigeon consist of 2 components: ependymal cells and pial tissue. The membrane ependymal cells are squamous, adjacent cells being linked by intermediate junctions. At the junction with the surface of the medulla the ependymal cells are continuous with the ventricular ependyma, and at the choroid plexus they are continuous with the choroid plexus epithelium. These results are discussed in relation to the fluid spaces in and around the hindbrain.