Licht- und elektronenmikroskopische Untersuchungen des gro�en Epithelwulstes und seiner Beziehungen zu der sich entwickelnden Membrana tectoria im Ductus cochlearis von Meerschweinchenfeten

Abstract

In early stages of fetal development (36th day, 3rd turn) the thickening of the epithelium at the basal side of the cochlear duct forms two ridges. Later in fetal development the laterally situated lesser epithelial ridge forms the major part of the organ of Corti, whereas the medially situated greater epithelial ridge contributes only a small part to this organ. The medial part of the greater ridge consists of the columnar inner supporting cells, which bear a border of closely packed microvilli at their upper surface. Up to the time of the opening of the internal spiral sulcus in the 48th day of fetal development, there is a close spacial relationship between microvilli and filaments of the tectorial membrane. We conclude that the inner supporting cells contribute to the formation of the tectorial membrane. However, thus far we cannot entirely exclude a different possibility, that the inner supporting cells absorb material of the tectorial membrane. During the opening of the sulcus spiralis internus the inner supporting cells become considerably smaller, some of them undergo complete destruction by cytolysis, with pyknosis and karyorrhexis.

Licht- und elektronenmikroskopische Untersuchungen zur Entwicklung der Stria vascularis im Ductus cochlearis von Meerschweinchenfeten

“…Auch an anderen Stellen des Ductus cochlearis wurden während der Entwicklung vorübergehend Glykogenein lagerungen beobachtet [Falbe-Hansen, 1967;Chody nicki, 1968;Thorn, 1975;Thorn et al, 1977Thorn et al, , 1978 und als Energiespeicher für die Differenzierungsvorgänge gedeutet [Chodynicki, 1968;Thorn, 1975].…”

Early identification of inner pillar cells during rat cochlear development

“…On the basis of the number of cell layers, the dorsal epithelium of the cochlea can be divided into two distinct ridges of cells separated by a depression: the greater epithelial ridge (GER) and the lesser epithelial ridge (LER; von Kölliker 1879;Weibel 1957;Thorn et al 1978;Kelley and Bianchi 2002). The GER occupies approximately two thirds of the dorsal wall of the duct on the modiolar border, whereas the LER comprises the remaining third on the striolar edge.…”