Ultrastructural characterization of glial cells in the rat pineal gland with special reference to the pineal stalk

Abstract

In the present study the "interstitial" cells of the superficial pineal gland and the nonparenchymal cells of the pineal stalk in Sprague-Dawley rats were examined ultrastructurally with the aim of defining the cells more closely. The "interstitial" cells of the superficial pineal gland do not represent a homogeneous cell population. The most abundant cell type is the mononuclear phagocyte, most easily recognized by its dark appearance and its content of primary and conspicuous secondary lysosomes. Astrocytes can be distinguished by the typical appearance of their nuclei (i.e., a thin continuous rim of heterochromatin adjacent to the nuclear membrane), identical to that of astrocytes in the CNS. Depending on the absence or presence of glial filaments and their amount, a spectrum of astrocytic cells is present. Mature astrocytes with filaments throughout their cytoplasm are rare. Immature glial cells with few or no filaments predominate. In the vicinity of blood vessels pericytes are present. In view of the fact that the "interstitial" cells could generally be identified it is suggested to abandon the term interstitial for the cells in question. In the pineal stalk mature astrocytes predominate; they have some features in common with pinealocytes, i.e., the presence of intergrade endoplasmic reticulum and grumose bodies (lysosomes). Other unusual features are a relative abundance of coated pits and vesicles. Oligodendrocytes are restricted to the proximal part of the stalk, near the deep pineal, where myelinated axons are abundant. More distally a few Schwann cells were seen.

Central GABAergic innervation of the mammalian pineal gland: A light and electron microscopic immunocytochemical investigation in rodent and nonrodent species

“…Electron microscopic observations on the pineal gland of the rat (Luo et al, 1984) and guinea pig have shown that myelinated and unmyelinated fibers from the habenular and posterior commissures enter the proximal portion of the gland and that these fibers reach the distal portion through the intermediate portion in the rat. 2.…”

Eri̇şki̇n İnsan, Köpek, Tavşan Ve Siçan Pi̇neal Organlarinin Işik Mi̇kroskobu Düzeyi̇nde Kiyasli İncelenmesi̇

“…Bu hücreler ışık mikroskobunda pinealositlere göre daha kü-çük ve koyu boyanan çekirdekleriyle ayırdolunurlar (7,16,24). Bu hüc-reler daha çok astrositlere benzetilmektedir (17,18,22,24). Bazı araştır-macılar fibröz astrositler olduklarını iddia etmektedirler (13,16).…”

“…Bu hücreler dışında bağ dokusu bölmelerine bağlı olarak organ, içinde bağ dokusu hücreleri de gözlenmektedir (13,17,23). Bu araştırma-da da bağ dokusu bölmelerinde bağ dokusu hücreleri, özellikle insanda daha fazla olarak görüldü.…”

Ultrastructural localization of acetylcholinesterase in the guinea pig pineal gland

“…This agrees with the heterogeneity of pinealocytes reported by other investigators. Evidence for such morphological heterogeneity was seen in the staining properties of pineal parenchyma1 cells (Tapp and Blumfield, 1970) and in the varying electron densities of light and dark pinealocytes (Arstila, 1967;Benson and Satterfield, 1975;Luo et al, 1984). Based on ultrastructural variations (Pevet, 1977;Pevet and Kuyper, 1978) and a possible link to photoreceptor cells (Pevet et al, 19771, two mammalian pinealocyte populations (I and 11) were identified.…”