| Abstract: | The ependyma in the infundibular region of the third cerebral ventricle was studied. Ageline sponges (20 mg per animal) were applied to nine ewes. On the thirteenth day after the removal of sponges, 750 I. U. PMSG was administered intramuscularly to three ewes, 1000 I. U. PMSG to another three, and the remaining three ewes were left without this treatment. Six ewes were the control. After embedding in paraffin, the material obtained from four control sheep and all the test sheep was stained with haematoxylin-eosine, material from another two control animals was impregnated by the method after Golgi-Cox. The ependyma in the infundibular region of anoestric ewes has a single layer and is cubic to cylindrical; it is only in the recessus infundibuli that it forms two to four layers. After the administration of Ageline, or in combination with PMSG, ependyma can be observed to react within the whole infundibular region of the third cerebral ventricle, but the most expressive reaction is recorded in the caudal part of the middle third of infundibulum where a transient type of cells (between ependymal cells and tanycytes) was found in the control animals after impregnation (they have cilia and one to two short and one long processes). After Ageline administration, ependymal cells in the middle third stretch out like in the anoestric period. The administration of 20 mg Ageline and 750 I. U. PMSG gave rise to low digital excrescences, the ependyma is undulated (pseudo-stratified) or contains small deposits of multiplied cells. After the administration of 20 mg Ageline and 1000 I. U. PMSG, the middle third contained, besides subependymal serous infiltrate, also large digital excrescences, probably filled with a serous fluid, and the surface of the subependyma and ependyma is eroded, containing proliferated deposits of ependymal cells of different thickness. Everywhere proliferation occurs, the surface layer of ependymocytes is desquamated into the cerebrospinal fluid. The histological picture described in the present paper probably suggests an increased secretory activity of ependymal cells after the administration of hormonal preparations. It is confirmed by these results that ependyma is involved in the hypothalamo-hypophyseal control of the sexual activity of sheep. |
