Corpora Arenacea Research Articles

MORPHOLOGY AND MINERAL COMPOSITION OF PINEAL GLAND CONCRETIONS IN VULPES LAGOPUS L., 1758 (MAMMALIA: CARNIVORA)

Mammalian pineal gland is known to often contain the calcified concretions (brain sand, corpora arenacea, acervuli, concrements), which biological significance, mineral and chemical composition are not full studied. Previous studies reported about chemistry, shape, size and structure of these biominerals from human and rodent pineal gland. The present study addresses to the morphology, mineral and chemical composition of calcified concretions in pineal gland of blue fox Vulpes lagopus L. (Mammalia: Carnivora). We used routine histological methods as well as scanning electron microscopy coupled with energy-dispersive detector and Raman spectroscopy. Results suggest that the process of mineralization of pineal gland most likely is not age-associated. Our data concerning the location and mineral composition of calcium concretions in blue fox pineal gland are in agreement with those obtained by other researchers on rodent and human pineal glands. Calcified concretions were located in capsule, protruding septae and parenchyma of pineal gland. Two morphological types of concrements were distinguished including mulberry-like and irregular elongated structures. The acervuli of mulberry-like structure were presented by hydroxylapatite and calcite, and the irregular elongated aggregates were composed of only hydroxylapatite. The last one has not been previously recorded in the calcified concretions of the mammals. Present findings give the first insight into the morphology, mineral and chemical composition of calcium concrements in pineal gland of blue fox.

Taxonomic and Ethnical Dispersion of the Phenomenon of Pineal Concretions in the Gerontological Context

Pineal gland (PG), or epiphysis, is involved in the organization of biological rhythms and adaptive reactions of the organism through the hormone melatonin. It is shown that various factors can influence the morphology and functional activity of the gland. Calcified concretions (corpora arenacea, brain sand) are unique biomineral structures of the PG, the causes of the formation and possible functional significance of which remain unclear until now. Currently, concrements have been found in several species of birds, in many mammals as well as humans; they are absent in fish, amphibians and reptiles. In this review, we have collected the available literature data on the composition, mechanisms of formation, and the possible factors affecting the accumulation of concretions in the epiphysis. Despite the fact that the generally accepted point of view is the age-dependent nature of the accumulation of pineal calcium deposits, the available data on the PG mineralization lead to the conclusion that, most likely, there is a multifactorial mechanism for the formation of concrements. In addition, the nature and crystallinity of the inorganic tissue of the pineal concretions suggest that corpora arenacea is rather a regulated and physiological than pathological type of petrification. The existence of contradictory data on the connection between the formation of brain sand and the change in the functional activity of the PG during seasonal endocrine changes and in the process of aging makes the study of deposits as the necessary and requiring in-depth investigation.

Gross and histopathological pitfalls found in the examination of 3,338 cattle brains submitted to the BSE surveillance program in Brazil

ABSTRACT: This study stems from the findings during the gross and histopathological exam of 3,338 cattle brains as part of the bovine spongiform encephalopathy (BSE) active surveillance program of the Brazilian Ministry of Agriculture, Livestock, and Supply from 2001 to 2005. The work was carried out in the Veterinary Pathology Laboratory of the Federal University of Santa Maria which at the time (2001-2007) was the national reference laboratory for the diagnosis of BSE and other transmissible spongiform encephalopathies. Both gross and histopathological aspects are described. Several gross aspects were annotated: anatomic normal structures not commonly recognized (non-lesions), lesions of no clinical significance, postmortem changes and artifacts; all these can amount to important pitfalls that distract the pathologist during the routine gross examination of the central nervous system (CNS). Accordingly, equivalent pitfalls were described in the histological examination. Non-lesions observed were the pineal body, embryo remnants such as the external germinal layer of the cerebellum, subependymal plates, and clusters of neuroblasts in the basal ganglia; or circumventricular structures such as area postrema, subcomisural organ, and melanosis in the leptomeninges and vessel walls. Lesions with little or no clinical importance included age-related changes as lipofuscin, hemosiderin, mineralization and hyalinization of vessel walls within the brain and meninges. Corpora amylacea and corpora arenacea were detected respectively in astrocyte processes and the pineal body. Cytoplasmic neuronal vacuolization was observed in the red nucleus and habenular nucleus. Sarcocystis sp. without a correspondent inflammatory reaction was rarely observed. Included within findings with no clinical manifestation were axonal spheroids and perivascular mononuclear cuffings. Changes in the CNS due to killing, sampling and fixation methods can obscure or distract from the more critical lesions. The ones related to the process of killing included hemorrhages caused in cattle destroyed by a captive bolt. Artifacts related to sampling and handling of CNS tissue consisted of inclusion of bone sand in the neural tissue from sawing the calvarium; dark neurons produced by excessive handling of the brain, and micro-organisms that contaminated the tissues during sampling or histological processing. Postmortem autolytic or putrefactive changes observed included vacuolar changes in the myelin sheath, clear halos surrounding neurons and oligodendrocytes, clusters of putrefaction bacilli within vessels or dispersed throughout the brain tissue associated or not to clear halos. One interesting, and somewhat frequent, postmortem autolytic change found in the bovine brain was the partial dissolution of the granule cell layer (GCL) of the cerebellum, also referred to as conglutination of the GCL or as the French denomination “état glace”. Due to the shortage of comprehensive publications in the subject, this review is intended to address the main pitfalls that can be observed in the brain of cattle hoping to help other pathologists avoiding misinterpret them.

Morphological and Immunohistochemical Studies on the Pineal Gland of the Donkey (Equus asinus).

The pineal glands of donkey were light beige to dark brown, fusiform structure. It lies at the pineal recess caudal to the splenium of the corpus callosum and caudodorsal to the third ventricle, just in front of the rostral colliculi and in between the para hippocampal gyrus. The pineal gland was supplied from the caudal choroidal artery and branches from artery of corpus callosum. The venous drainage by the pineal veins flow- ing into the cerebral vein. The glial fibrillary acidic protein (GFAP) and S100 protein immu- noreactivity was restricted to glial cells. They showed a heterogeneous pattern of immunostaining for (GFAP) and S100. It was conspicuous around the large pineal cyst and corpora arenacea, where the pinealocytes formed clusters, widely separated by aggregations of GFAP and S100 immunoreactive glial cells and their processes. They were also striking around blood vessels. At the periphery of the gland, only a relatively few GFAP and S100 positive cell bodies and/or processes were seen in the marginal portions of the parenchyma. S100 immunoreactive cells showed similar morphological characteristics to those of GFAP-reactivity, but their immunoreactivity was denser. Immunolabeling of the pinealocyte marker synaptophysin was intense, especially in pinealocytes at perivascular space. Several highly synaptophysin-positive blotch of variable extent were a conspicuous fea- ture in pinealocyte throughout the gland. While it was less dense in the vicinity of the pineal cyst and corpora arenacea. The intercellular differences in the degrees of synaptophysin immunostaining may, therefore, reflect different states of a specific cellular activity. The presence of synaptophysin in pinealocytes of the normal pineal, highlights the paraneuronal nature of these cells.

Comparative histology of pineal calcification.

The pineal organ (pineal gland, epiphysis cerebri) contains several calcified concretions called "brain sand" or acervuli (corpora arenacea). These concretions are conspicuous with imaging techniques and provide a useful landmark for orientation in the diagnosis of intracranial diseases. Predominantly composed of calcium and magnesium salts, corpora arenacea are numerous in old patients. In smaller number they can be present in children as well. The degree of calcification was associated to various diseases. However, the presence of calcified concretions seems not to reflect a specific pathological state. Corpora arenacea occur not only in the actual pineal tissue but also in the leptomeninges, in the habenular commissure and in the choroid plexus. Studies with the potassium pyroantimonate (PPA) method on the ultrastructural localization of free calcium ions in the human pineal, revealed the presence of calcium alongside the cell membranes, a finding that underlines the importance of membrane functions in the production of calcium deposits. Intrapineal corpora arenacea are characterized by a surface with globular structures. Meningeal acervuli that are present in the arachnoid cover of the organ, differ in structure from intrapineal ones and show a prominent concentric lamination of alternating dark and light lines. The electron-lucent lines contain more calcium than the dark ones. There is a correlation between the age of the subject and the number of layers in the largest acervuli. This suggests that the formation of these layers is connected to circannual changes in the calcium level of the organ. The histological organization of the human pineal is basically the same as that of mammalian experimental animals. Pineal concretions present in mammalian animal species are mainly of the meningeal type. Meningeal cells around acervuli contain active cytoplasmic organelles and exhibit alkaline phosphatase reaction in the rat and mink, an indication of a presumable osteoblast-like activity. Using Kossa's method for the staining of calcium deposits, a higher calcium concentration was detected in the rat pineal than in the surrounding brain tissue. Since in parathyroidectomised rats calcified deposits are larger and more numerous than in controls, the regulation of the production of acervuli by the parathyroid gland has also been postulated. In most of submammalian species, the pineal organs (pineal-, parapineal organ, frontal organ, parietal eye) are photoreceptive and organized similarly to the retina. Acervuli were found in the pineal of some birds. The pineal organs of lower vertebrates (fish, amphibians, reptiles) exhibit a high calcium content by ultrastructural calcium histochemistry (PPA-method). However, concrements are not formed. The accumulation of Ca2+ seems to depend on the receptor function of the organ. Comparing pineal and retinal photoreceptors in the frog, the photoreceptor outer segments of pinealocytes as well as retinal cones and rods show a large amount of Capyroantimonate deposits. In dark adapted animals calcium ions are present in both sides of the photoreceptor membranes of the outer segment, whereas calcium is shifted extra-cellularly following light adaptation. Overviewing the data available about the pineal calcification, we can conclude that a multifactorial mechanism may be responsible for the calcification. The pineal of higher vertebrates is not just a simple endocrine gland, rather, its histological organization resembles a folded retina having both hormonal and neural efferentation. Mammalian pinealocytes preserve several characteristics of submammalian receptor cells and accumulate free Ca2+ on their membranes (1). In the thin walled retina and in the similarly organized pineal of submammalian species, the diffusion of extracellular calcium is probably easy and there is a lesser tendency to form concrements. (ABSTRACT TRUNCATED)

Two components of the pineal organ in the mink (Mustela vison): their structural similarity to submammalian pineal complexes and calcification.

The pineal complex in the mink (Mustela vison) consists of a larger ventral and a smaller dorsal pineal. Both organs contain pinealocytes, neurons, glial cells, nerve fibers and synapses in an organization characteristic of nervous tissue. The cellular elements are arranged circularly around strait lumina. These lumina correspond to the photoreceptor spaces of submammalian pineals. A 9 + 0-type cilium marks the receptory pole of the pinealocytes which may form an inner-segment-like dendrite terminal in the pineal lumina. The cilia correspond to outer segments which form photoreceptor membrane multiplications in the pineal of submammalians and in certain insectivorous and mustelid mammals (bat, hedgehog, ferret). Axonal processes of the pinealocytes contain synaptic ribbons and terminate on intrapineal neurons of both organs. This pattern represents a neural efferentation of the pineal nervous tissue. The axonal processes of pinealocytes also form neurohormonal endings which pierce the perivascular limiting glial membrane in the ventral as well as in the dorsal pineal. The upper pineal ("epipineal") of the mink may correspond to the parapineal, frontal, or parietal organs of submammalian pineal complexes. Both pineals are encapsulated by the meningeal tissue of the brain stem. Afferent vasomotor axons of the meninges innervate smooth muscle cells of pineal arterioles. There are corpora arenacea in the pineal arachnoid and in the pineal nervous tissue, primarily in the ventral pineal. The localization of calcium ions detected around the membrane of pineal cells by pyroantimonate cytochemistry suggests membrane activity as the source of the calcium ions. The accumulation of calcium by the pinealocytes may be due to their neurosensory character. The mink is the first animal described to have both intrapineal and meningeal concrements like the human pineal.

Meningeal calcification of the rat pineal organ. Finestructural localization of calcium-ions.

The surface of the pineal organ of the rat is covered by a leptomeningeal tissue, the continuation of the corresponding meningeal layers of the diencephalon. The pineal leptomeninx consists of stratified arachnoid and of pia mater cells which follow the vessels into the pineal nervous tissue. The pineal arachnoid contains electron-lucent and electron dense cells differing from each other in their cytoplasmic components. Corpora arenacea of various size and density occur among these arachnoid cells and can grow into the pineal organ alongside pia mater tissue. Acervuli often form groups in circumscribed meningeal "calcification foci". Concrements are absent or rare in the 1- and 2-month-old animal, while they are usually present in the 4- and 6-month-old rats. The electronmicroscopic localization of Ca-ions was studied in 2- and 4-month-old rats by potassium pyroantimonate cytochemistry. In the 4-month-old animals, arachnoid cells containing a varying amount of Ca-pyroantimonate deposits were found first of all around corpora arenacea, but there were also cells free of deposits in the close vicinity of the acervuli. Deposits were preferentially localized to the cytoplasm of electron dense arachnoid cells and to the cell membrane of electron-lucent cells. Most of the precipitates occurred in locally enlarged intercellular spaces. Here, microacervuli were found in 4-month-old animals suggesting that a calcium-rich environment was responsible for the appearance of the concrements. Intermediate stages between the small acervuli and large concentric corpora arenacea may indicate an appositional growth of the acervuli in the calcification foci.(ABSTRACT TRUNCATED AT 250 WORDS)

The pinealocyte forming receptor and effector endings: Immunoelectron microscopy and calcium histochemistry.

The pinealocytes--the main cellular elements of the pineal organ--are polarized, displaying a (photo)receptor and an axonic effector cell pole. The receptor endings are of two main types: they bear rod-type or cone-type outer segments characterized by the presence of immunoreactive opsin-, S-antigen- and vitamin A-binding sites. The effector pole may form ribbon-containing synapses on the secondary pineal neurons, and/or neurohormonal terminals on the basal lamina of the pineal nervous tissue. Applying potassium pyroantimonate (PPA) to electron-microscopic histochemistry, we found in the frog that both effector terminals and photoreceptor outer segments contained a large amount of Ca-pyroantimonate deposit similar to retinal cones and rods. Rods and rod-like pinealocytes contained more deposits than cones. The higher concentration of calcium on the cell membranes of dark pinealocytes in the rat may be connected with their rod-like character. In the frog, a high amount of calcium seemed to be concentrated in the photoreceptor effector terminals, especially around their synaptic ribbons, and in myeloid bodies of the pineal ependyma and retinal pigment epithelium. Calcium was richly found in or around corpora arenacea in the human and rat pineal. It is suggested that the formation of concrements may be connected with the high demand of Ca-exchange of pinealocytes for their receptor and effector membrane functions. In the rat, lymphocytes were found to migrate through the wall of the vena magna of Galen and to closely contact pinealocytes, presumably to receive immunological information as an additional pineal output.

Hereditäre Drusen der Bruchschen Membran

The left eye of a 71-year-old patient who had suffered from choroiditis guttata was removed immediately after death by enucleation. Histopathological studies revealed numerous nodular (hard) drusen, a wide variety of senile alterations of the pigment epithelium and Bruch's membrane, and the presence of multiple corpora arenacea in the subarachnoid space of the optic nerve. A new hypothesis concerning the development of hereditary drusen is advanced, postulating a disturbance of the lysosomal enzyme/inhibitor balance.

Age‐related changes in the intact and sympathetically denervated gerbil pineal gland

The pineal gland of four-month-old gerbils contains numerous calcareous deposits (corpora arenacea or concretions). Also, the tissue appears vacuolated due to the presence of a number of large rounded spaces. The deposits are usually associated with or lying within these "vacuoles". By eight months of age, the number of both the corpora arenacea and the "vacuoles" are increased over those present in the pineals of four-month-old gerbils. Bilateral superior cervical ganglionectomy at one month of age prevents the formation of both the concretions and "vacuoles". The cells in the sympathetically denervated pineal glands are smaller than those in pineal glands of animals that possess intact superior cervical ganglia.

The Ultrastructure of the Gerbil Pineal Gland Under Normal and Experimental Conditions

Multilayered concretions (corpora arenacea), which have been found in the pineal gland of numerous species, may be indicative of the intensity of the secretory processes of the pineal gland. Concretions in the pineal gland of the gerbil (Meriones unguiculatus) occur by the age of 2 months and are a consistent feature in the adult animal. We feel the gerbil pineal provides a good system for examining pineal calcification under controlled conditions.The ultrastructure of the pineal gland of the gerbil was examined in 1 to 18 month old gerbils which had been maintained in a controlled light environment (LD 14:10). Other gerbils used for this study had been maintained either in constant light environment, had been superior cervical ganglionectomized, or had been blinded by bilateral optic enucleation.

Histophysiological evidence for the secretion of polypeptides by the pineal gland.

Histophysiological examinations of the bovine and monkey pineal gland indicate that this organ may be involved in the secretion of polypeptides. Using various histochemical procedures designed to identify peptide-secreting cells, granules and/or droplets of presumptive secretory product were identified within cellular processes, within the walls of blood vessels and associated with multilayered corpuscles (corpora arenacea). In bovine pineal tissue, the stained material was found most often in what appeared to be pinealocyte processes, as perivascular granules and associated with multilayered corpuscles. In the monkey pineal the stainable material was more distinct; this was probably due to the earlier fixation of the glands after death of the animals. In this species, the presumptive secretory material was found in nerve fibers, occasionally in glial cell and pinealocyte processes and within and around the walls of capillaries. In nerve fibers, the stained material sometimes resembled Herring bodies of the posterior pituitary gland. Similar material appeared to be located in capillary endothelial cells and within multilayered corpuscles. In pineal tissue of both species, calcium was detectable histochemically within multilayered corpuscles. Although tinctorially different, the presumptive neurosecretory material was similar to that found in the posterior pituitary gland. As a working hypothesis, we propose that polypeptides may be released from cells in conjunction with a carrier protein and that the mechanism of secretion of the polypeptide into the vascular system may involve its exchange for calcium. The calcium is then theoretically deposited in the multilayered corpuscles.