Morphology of Supraependymal Cells and Their Occurrence in the Cerebral Ventricles of Sheep and Goats. a Scanning Electron Microscopy Study

Raj to v a V.: Morphology 0/ Supraependymal Cells and their Occurrence in the Cerebral Ventricles o/Sheep and Goats. A Scanning Electron Microscopy Study. Acta vet. Brno 1995, 64:17-21. Occurrence and external morphology of supraependymal cells (SECs) were studied in 14 Merino sheep and 24 crossbred goats of both sexes. This type of supraependymal structures in both small ruminant species occurred only in the upper part of the third cerebral ventricle. In sheep they were recorded only during physiological estrus and gravidity in the recessus infundibuli. In male goats, the infundibular recessus surface was covered with SECs only during the mating period (autumn months) whereas in female goats they were present during all phases of the ovarian cycle but also after hormonal stimulation. On the surface of the eminentia mediana surface in goats (independent of sex) supraependymal cells occurred only in animals after gonadectomy. Occurrence of supraependymal cells in the third cerebral ventricle seems to be connected with the activity of the gonads, or their higher centres. Differences between sheep and goats were found in the structure of the external surface of the ependymal lining of the upper part of the third cerebral ventricle. Central nervous system, ventriculus tertius, ependyma, sheep, goat Structures found on the surface of the ependymal lining of the cerebral ventricles belong among its regional characteristics. They protrude into the ventricular lumen and are denoted as supraependymal structures to which supraependymal cells also belong. They were first discovered by K 0 I mer (1921) using light microscopy, and later by electron microscopy in differentlocations of the cerebral ventricles, in numerous animal species (C I e men t i and Mar in i 1972; S cot t et al. 1973, 1974; Co ate s 1973ab; Bra w e r et al. 1974; B Ie ieretal. 1975; M e s tre s andB reip oh11976; J en ne s et al. 1977; M i tc hel and Car d 1978). K 0 Z low ski et al. (1972, 1973) reported brief data on the supraependymal cells in sheep. The present paper deals with the description of supraependymal cells in sheep and goats, to compare them, and then show differences between them. Materials and Methods Thirty eight animals, 14 Merino sheep and 24 crossbred goats of both sexes were used. The animals were divided in one control and two experimental groups. The control ewes were killed during the anestrous or estrous phases of the ovarian cycle, female goats in the period of anestrus, proestrus, estrus and luteal phase. One pregnant ewe and one goat (d 80 of pregnancy) were also included in the control group. Males of both species were killed during the "rest" period in April, and during the mating period (October, November). In experimental group I, hormone preparations were administered to adult experimental ewes and goats as follows: During the anticipated period of estrus (April) hormone preparations: (40 JLg synthetic LH-RH together with 250 JLg synthetic Gn-RH, i.m., at 30 min intervals) were administered. The same group of female goats was given 20 mg synthetic progesterone in vaginal sponges. The animals were killed 26 hours after the last i.m. injection, or 16 days after insertion of vaginal sponges. In experimental group 2, mature females and male goats were gonadectomized; artificial cryptorchids were made of two male goats. The animals of this group were killed 2 months following gonadectomy. Also one testicular hermaphrodite, acquired incidentally, was included in this group. After exsanguination, the heads of all animals were rinsed in 0.2 mol/l phosphate buffer, preliminarily fixed by perfusion of Kamovsky solution. After the brains were removed, the samples were fixed using 3 % glutaraldehyde solution in 0.2 mol/l cacodylate buffer (the temperature of all solutions was 4 QC). After processing (M u r a k am i et