The subcellular distribution of zinc in dog prostate studied by x-ray microanalysis

Synchrotron radiation X-ray fluorescence microscopy reveals a spatial association of copper on elastic laminae in rat aortic media

Copper, an essential trace metal in humans, plays an important role in elastic formation. However, little is known about the spatial association between copper, elastin, and elastin producing cells. The aorta is the largest artery; the aortic media is primarily composed of the elastic lamellae and vascular smooth muscle cells, which makes it a good model to address this issue. Synchrotron radiation X-ray fluorescence microscopy (SRXRF) is a new generation technique to investigate the spatial topography of trace metals in biological samples. Recently, we utilized this technique to determine the topography of copper as well as other trace elements in aortic media of Sprague Dawley rats. A standard rat diet was used to feed Sprague Dawley rats, which contains the normal dietary requirements of copper and zinc. Paraffin embedded segments (4 μm of thickness) of thoracic aorta were analyzed using a 10 keV incident monochromatic X-ray beam focusing on a spot size of 0.3 μm × 0.2 μm (horizontal × vertical). The X-ray spectrum was measured using an energy-dispersive silicon drift detector for elemental topography. Our results showed that phosphorus, sulfur, and zinc are predominately distributed in the vascular smooth muscle cells, whereas copper is dramatically accumulated in elastic laminae, indicating a preferential spatial association of copper on elastic laminae in aortic media. This finding sheds new light on the role of copper in elastic formation. Our studies also demonstrate that SRXRF allows for the visualization of trace elements in tissues and cells of rodent aorta with high spatial resolution and provides an opportunity to study the role of trace elements in vasculature.

Immunohistochemical localization of metallothionein in the rat prostate gland during postnatal development

Immunocytochemical and electrophoretic techniques were used to investigate the presence of metallothionein, a metal-binding protein, in the dorsolateral and ventral lobes of the developing rat prostate. Male rats aged 7 and 14 days were injected subcutaneously with 6 and 20 mg/kg body weight of cadmium and zinc, respectively, or with saline for controls, 24 h prior to tissue sampling. Immunohistochemical localization of metallothionein was observed in the epithelial tissues of the dorsolateral prostate from 7 and 14 day-old animals and in 1 day-old untreated rats. This staining pattern did not appear to be significantly affected by cadmium or zinc treatment. In contrast, metallothionein localization in the ventral prostate decreased with age but demonstrated a slight response to metal-ion treatment in the 7 day-old animals. Electrophoretic and immunoblot analysis confirmed the presence of metallothionein in the control and metal-induced prostate samples from neonatal rats. Lobe-specific differences in localization suggest a functional significance for metallothionein, independent of inducible protein.

Ultracytochemical localization of calcium in the superficial pineal gland of the Mongolian gerbil

In order to demonstrate fine localization of Ca2+ in the superficial pineal gland of Meriones unguiculatus, the pyroantimonate technique was employed. Control experiments were performed with EGTA and analysis of obtained reaction product using an energy-dispersive x-ray microanalysis. Precipitates of calcium antimonate were formed almost exclusively in swollen clear pinealocytes, in and along their cell membranes, over their nuclei, in mitochondria, the Golgi apparatus, endoplasmic and integrade reticulums, acervuli, in vesicles surrounding synaptic bars, cytoplasmic matrix, and flocculent extracellular material. It has been concluded that the swollen pinealocytes represent a degenerative cell form probably occurring by impairment of plasmalemmal Ca2+-ATPase's ability to eliminate Ca2+ ion from the cell, with consecutive increase of calcium in the cytoplasmic matrix, followed by increase of intramitochondrial Ca2+ concentration, gradual arrest of mitochondrial function, depolymerization of cytoskeletal microtubuli, loss of the cell form, and cell death. Decrease of function of pinealocyte plasmalemma seems to be related to aging.

The effects of estradiol-17 beta on the ultrastructure and subcellular distribution of zinc in the prostatic epithelium of castrated rats

Male Sprague-Dawley rats, previously castrated for a 7-day period, were maintained on either a low or high dose of estradiol-17 beta for 3 days. Some areas of the prostatic epithelium in the lateral lobe exhibited the ultrastructural characteristics of the untreated, intact animals in response to the small dose of estrogen. The ventral lobe by comparison was not similarly affected. This stimulation in the lateral prostate was not reflected by comparable changes in the subcellular distribution of zinc.

The distribution of zinc in the prostate of rhesus and cynomolgus monkeys determined by electron microscopy and x-ray microanalysis

The distribution of zinc in the prostate of the mature rhesus monkey is described. High levels of zinc were located in the nuclei of epithelial and basal cells in both lobes of the gland, while elevated concentrations of the metal were also found in secretory granules and along lateral cell membranes. A similar zinc distribution pattern was observed in the 2 lobes of the gland, but in general organelles in the cranial region had a higher content of the metal. In whole tissue, however, a 15 times greater zinc content was measured in the caudal lobe. This difference could be explained in terms of the high levels of the metal present in secretory granules and luminal secretion in the caudal lobe. A similar ultrastructural appearance and distribution of zinc was observed in the prostate of the cynomolgus monkey (Macaca fascicularis).

Ultrastructural and analytical studies on the prostate of castrated rats

Rat lateral and ventral prostate tissue was studied using ultrastructural and analytical techniques in adult animals castrated for periods of 3 to 20 days. As in previous reports involution of the prostatic epithelium following testosterone deprivation resulted in alterations of the amount, distribution, and conformation of the endoplasmic reticulum, Golgi, and lysosomes in addition to some nuclear changes. Although the fundamental changes were similar in both lobes there were specific effects on the individual lobes. Reductions in the subcellular levels of zinc were more pronounced in the lateral prostate, particularly with respect to the secretory and stromal concentrations of the metal. Despite low concentrations of circulating testosterone, secretory activity was still evident after a 20-day castration period and would appear to reflect a different sensitivity in the lateral lobe to the lowered testosterone level or stimulation by other hormones when compared to the ventral lobe. The significance of the subcellular distribution pattern of zinc during the experimental periods is discussed in relation to the possible functional significance of the metal in prostatic tissue.

Ultrastructural localization of zinc in the hyperplastic prostate

The localization of zinc was investigated in specimens of hyperplastic prostate by means of light microscopy, electron microscopy, and x-ray microanalysis. After fixation in glutaraldehyde plus hydrogen sulfide, representative sections were developed with sulfide-silver while, for comparison, other sections were not developed. Aggregation of the silver precipitation was seen on the secretory vacuoles of the developed sections. None of the deposits were detected on the nucleus, lysosomes, Golgi apparatus, or other cytoplasmic organelles. X-ray microanalysis was performed on these sections of hyperplastic prostate. X-ray energy spectrum analysis of the undeveloped sections revealed that the concentration of zinc on the electron-dense materials in the secretory vacuoles corresponded to the deposits of silver granules. The present investigation provides direct proof of the localization of ionized zinc in the cytoplasm of the hyperplastic prostate.

Ultrastructural and histochemical aspects of prostatic secretion in dog

The reaction of canine prostatic epithelium was studied ultrastructurally and histochemically (acid phosphatase, zinc) in mature Beagle-dogs 15 minutes after intravenous application of pilocarpine (1 mg/kg body weight). In the normal prostate we found only merocrine secretion with exocytosis of secretory granules. Exocytosis persisted after stimulation with pilocarpine, but was quantitatively greatly increased. Apocrine or holocrine types of secretion were neither found under resting conditions nor under extreme functional stress of the glandular epithelium. Histochemically a distinct decrease of the activity of acid phosphatase and of zinc in the apical part of the epithelium has developed, which corresponds to the ultrastructurally obvious loss of secretory granules.

Sodium and calcium localization in cells and tissues by precipitation with antimonate: a quantitative study

Komnick's antimonate technique, which was devised to localize Na+ in cells and tissues, was studied quantitatively. Some modifications, as well as its application to Ca2+ localization, were also investigated. We combined measurements of Na+ and Ca2+ retention in plant roots during the various procedures, electron microscopy, autoradiography, and semiquantitative X-ray microanalysis. We were able to show that (at least in barley roots) antimonate does not precipitate at all with Na+, irrespective of the Na+ content of the tissue or the method of antimonate application. (Even during precipitative freeze dissolution or after freeze drying, no Na+ is precipitated.) By means of Komnick's antimonate technique Ca2+ is trapped within the tissue, but only after serious dislocation. Perspectives for reliable localization of diffusible ions in cells and tissues, by precipitation simultaneously with conventional fixations, are bad.