Supraependymal neurons overlying the periventricular region of the third ventricle of the guinea pig: A correlative scanning—transmission electron microscopic study

Abstract

The frequency of occurrence, distribution and morphology of supraependymal neurons associated with the third ventricular wall of the guinea pig were investigated by correlative scanning and transmission electron microscopy. Each of the specimens was located on the ciliated ventricular wall between the inferior border of the thalamus and the non-ciliated ependyma associated with the median eminence. Prominent clusters of neuronal perikaria in association with massive process bundles were observed in 7 of the 31 specimens examined. In those specimens lacking prominent neuronal networks a more diffuse array of independent nerve fibers was sometimes seen on the ependymal surface. Neuronal perikaria exhibited numerous surface protrusions and were covered by a rich meshwork of crisscrossing, varicosed fibers. Many of these cells were associated with multiple processes of varying diameters and lengths which either coursed independently over the ventricular surface or formed fasciculated bundles. As process bundles traversed the ependymal surface, individual processes branched off and either terminated within the ventricular lumen or penetrated the subjacent ependymal lining. Fibers also made contact with adjacent supraependymal neuronal elements. Correlative transmission electron microscopic observations indicate that both the perikaria and processes of such supraependymal networks possess ultrastructural features characteristic of neurons. The morphological characteristics of the intraventricular neuronal networks suggest that they may be engaged in functional interactions with the cerebrospinal fluid, with adjacent supraependymal neuronal elements and with the subjacent neuropil.

Scanning and transmission electron microscope studies of the supraependymal neurons in the third ventricular wall of the arctic lamprey,Lampetra japonica.

“…In addition, the general configuration and surface fine structure of the supraependymal neurons in the lamprey are similar to those in other vertebrates (EVAN et al, 1976 b;SCOTT et al, 1976;MITCHELL and CARD, 1978;VIGH-TEICHMANN et al, 1979;RICHARDS et al, 1980).…”

“…The sites of occurrence of the supraependymal neurons VIGH and VIGH-TEICHMANN, 1973;PAULL et al, 1974;SCOTT et al, 1976;MITCHELL and CARD, 1978;VIGH-TEICHMANN et al, 1979;RICHARDS et al, 1980). In addition, the general configuration and surface fine structure of the supraependymal neurons in the lamprey are similar to those in other vertebrates (EVAN et al, 1976 b;SCOTT et al, 1976;MITCHELL and CARD, 1978;VIGH-TEICHMANN et al, 1979;RICHARDS et al, 1980).…”

“…The neuronal elements in the cerebral ventricles have been reported in different vertebrates from cyclostomes to mammals (LEONHARDT and PRIEN, 1968;HONMA, 1969;VIGH and VIGH-TEICHMANN, 1973;PAULL et al, 1974;EVAN et al, 1976 a, b;SCOTT et al, 1976;MITCHELL and CARD, 1978). In general, these elements are divisible into two categories: the supraependymal neurons and the cerebrospinal fluid (CSF)-contacting subependymal neurons with an intraventricular process.…”

Epiplexus cells in the embryos of the turtle, Trionyx sinensis.

“…So far, supraependymal neurons as described by MITCHELL and CARD (1978) in the guinea pig have not been identified in the present materials using the combined scanning and transmission electron microscopy.…”

Hypothalamic neuroendocrine correlates of cutaneous burn injury in the rat: i. scanning electron microscopy

“…A groups stain exclusively with antisera against the enzyme wealth of literature has served to describe the cerebral yenprobe tyrosine hydroxylase, but not dopamine beta hytricular surfaces of the rat [13,14,20,22,28,30,38,56], the droxylase or phenylethylamine-N-methyltransferase. hamster [6], the guinea pig [26], the cat [9], the rabbit [51],…”