Cytochemical Analysis of Calcium Distribution in the Superficial Pineal Gland of the Mongolian Gerbil

Abstract

The potassium pyroantimonate-osmium method was employed to determine the distribution of cations in the superficial pineal gland of the Mongolian gerbil. The reaction product in the glands was presumed to be calcium following the use of both the chelator EGTA and x-ray microanalysis. A gradient of reaction product was found in the pineal with the highest concentrations occurring in and around the pineal concretions (PC). The periphery of mature PC demonstrated a heavy precipitate as did the surrounding pinealocytes. PC-associated pinealocytes contained reaction product in many organelles, including small vesicles that appeared to be opening in the direction of the concretions. The vacuoles of the pinealocytes contained various concentrations of precipitate. The results obtained in the present investigation have led to a hypothesis on the formation of pineal concretions: a pinealocyte vacuole is formed, calcium is transported to the vacuole, the cation content of the vacuole increases, and the cations precipitate into an immature concretion. Fibrillar material and an amorphous substance located within the pinealocyte vacuole appear to form cation containing vesicles that contribute to the periphery of the developing PC, resulting in the continued growth of the concretion.

Immunohistochemical localization of synaptophysin (p38) in the pineal gland of the Mongolian gerbil (Meriones unguiculatus)

“…The possibility should also be considered that at least some small vesicles in the gerbil pinealocyte are involved in the transport of calcium, which plays a pivotal role in the genesis of pineal concretions. Thus, Welsh (1984) has localized calcium cations electron-microscopically in clear vesicles of various size (30 nm-300 nm diameter), which may well correspond to the vesicles described in the present study. The calcium-loaded vesicles are thought to transport the cations to intracytoplasmic vacuoles.…”

“…The latter have also been evident in this investigation. It is within these vacuoles that calcified concretions develop (Welsh and Reiter 1978;Welsh 1984). These morphological phenomena of many mammalian pineal glands are still poorly understood.…”

Synaptophysin – a common constituent of presumptive secretory microvesicles in the mammalian pinealocyte: A study of rat and gerbil pineal glands

“…Such a role has been proposed for microvesicles in neurohypophyseal axon terminals (Pow and Morris, 1991) which have been shown to contain several synaptic vesicle membrane antigens including synaptophysin (Navone et al, 1989). Interestingly, calcium cations have been localized in small clear vesicles of gerbil pinealocytes in an earlier cytochemical study by Welsh (1984). WhPtever their functions, it can be inferred that accumulations of synaptophysin-positive microvesicles in pinealocyte processes indicate release sites for pineal secretory products.…”

Morphofunctional aspects of the mammalian pineal gland

“…It should be noted that detailed studies of pineal concretions in the human are very difficult for various reasons. However, observations of the formation of pineal concretions in the pineal gland of the Mongolian gerbil (Japha et al, 1974(Japha et al, , 1976Welsh and Reiter, 1978) and the discovery of their similar chemical composition to the human pineal concretions (Krstic and Golaz, 1977) stimulated a number of authors to use the gerbil as a model for studying pineal calcification mechanisms in various experimental conditions (Japha et al, 1974(Japha et al, , 1976Reiter et al, 1976;Lewinski et al, 1983;Vaughan et al, 1983;Champney et al, 1985) as well as for ultracytochemical studies (Welsh, 1984;Krstic, 1985Krstic, , 1986.…”