Histochemical localization of zinc in the feline tapetum

Summary High resolution electron microscopy of ultrathin sections confirms the presence of a membrane surrounding the tapetal rods in the cat. Cats depleted of taurine exhibit disruption and disorganization of this membrane, probably the first stage of more severe tapetal degeneration. Histochemical localization of zinc shows it to be present on the periphery of the tapetal rods. The amount of zinc present on the periphery of the tapetal rods of taurine depleted cats was greatly reduced. Taurine in feline tapetum, confirmed by autoradiography and direct measurement, was also greatly reduced in taurine-depleted cats. We conclude that both taurine and zinc are localized on the periphery of the tapetal rods and that they contribute to the stability of the membrane. We have also confirmed earlier reports that the cat tapetal rods contain riboflavin and no detectable cysteine.Presented in part at the International Symposium Taurine-Questions and Answers Mexico City, November 16–19, 1980     

Hereditary abnormality in tapetum lucidum of the Siamese cats

Summary Gross examination showed a weaker reflection (less shining) of the tapetum lucidum of the Siamese cats compared with common cats. Toluidine blue sections revealed that many tapetal cells were weakly stained and giving vacuolated appearance under high magnification. Further examination with electron microscope showed that those weakly stained cells were filled with disrupted tapetal rods. In these affected cells, the arrangement of the tapetal rods was no longer regular. The membranes of the tapetal rods were either enlarged or disrupted. Some of them appeared to be myelin-like structures. The cores of the tapetal rods were either empty or filled with electron-dense materials which may be the remnant of the original cores. The severity of this type of abnormality or degeneration in the tapetum varied from lavers to layers. Those layers closer to the retina showed a greater number of cells with degeneration. Quantitative analysis of histochemical detection of zinc showed a significantly smaller amount of zinc in tapetal rods of the Siamese cats as compared with common cats. Less zinc and disruption of the regular arrangement of the tapetal rods may result in weaker reflection of light by Siamese cat tapetum. In four of the nine Siamese cats studied, this type of abnormality was observed. It suggests that it is a hereditary disorder of relatively high frequency.     

Histochemical demonstration of zinc ions in human epididymis using autometallography

Summary A recently described autometallographic technique, allowing demonstration of chelatable zinc in human biopsy material, was applied to cryostat sections from biopsies of human epididymis. Sections from the rat epididymis were used as control materials to examine the quality of the method compared with a previously used autometallographic method. The human epididymis exhibits heavy staining in the head of the epididymis and only small amounts of zinc in the body and tail of the organ. The zinc staining was found in the apical part of the ciliated cells and in the lumen. The present technique can be used to localize zinc ions at ultrastructural levels. Zinc grains were localized in lysosome-like bodies and secretory granules of the ciliated cells. The luminal staining was present as free, evenly dispersed zinc grains or attached to sperm cells and stereocilia in the lumen. The large differences in staining patterns along the epididymal tract in humans and rats suggest that zinc ions are important for the maturation of sperm cells This revised version was published online in November 2006 with corrections to the Cover Date.     

Histochemical demonstration of some dehydrogenases and NAD-H diaphorase in cat Pacinian Corpuscles

Summary Using histochemical methods for G-6-P-DH, NAD-HD, M-DH, S-DH, L-DH and G-DH the author has examined the participation and distribution of these enzymes in Pacinian Corpuscles of male cats. The reactions for G-6-P-DH, L-DH, M-DH and NAD-HD show similarity regarding the intensity and the character of intrareceptoral distribution. The nerve fibre and its ending show the highest activity. Three other zones might be differentiated round them. The first zone situated in close proximity to the axon coincides with the inner core of the Corpuscles and shows higher activity than the others (second and third zones). The activity of the latter ones diminishes towards the periphery of the receptor.The reaction for S-DH is strongly expressed at the nerve fibre and its ending and weaker at the inner core of the Corpuscles.The reaction for G-DH is moderately expressed in the inner core whereas the nerve fibre and the outer core show the feeble activity.The author discusses the obtained results in relation to the necessity of energy and the ways it is obtained for the excitation of the axonal membrane.     

Histochemical demonstration of zinc in rat epididymis using a sulphide-silver method

Summary We studied the histochemical distribution of zinc in rat epididymis using a sulphide-silver method. In the supranuclear cytoplasm of the principal cells that line the epididymis of rats, varying amounts of sulphide-silver-reactive zinc were visualized. In adult mating rats, significant amounts of zinc were found in the proximal portion of the epididymis, whereas in non-mating, mature and immature young rats, this heavy metal was most prominent in the distal portion of this organ. In all of the rats studied, zinc was sparsely distributed in the intermediate portion of the epididymis. From these results, it can be assumed that the zinc present in the epithelial lining of rat epididymis plays an important role in the maturation of spermatozoa. The present results represent a useful contribution to our understanding of the functional morphology of rat epididymis.Dedicated to Professor Dr. T.H.Schiebler on the occasion of his 65th birthday     

Histochemical demonstration of zinc in rat epididymis using a sulphide-silver method

We studied the histochemical distribution of zinc in rat epididymis using a sulphide-silver method. In the supranuclear cytoplasm of the principal cells that line the epididymis of rats, varying amounts of sulphide-silver-reactive zinc were visualized. In adult mating rats, significant amounts of zinc were found in the proximal portion of the epididymis, whereas in non-mating, mature and immature young rats, this heavy metal was most prominent in the distal portion of this organ. In all of the rats studied, zinc was sparsely distributed in the intermediate portion of the epididymis. From these results, it can be assumed that the zinc present in the epithelial lining of rat epididymis plays an important role in the maturation of spermatozoa. The present results represent a useful contribution to our understanding of the functional morphology of rat epididymis.     

The tapetum lucidum in the eye of the big-eye Priacanthus arenatus Cuvier

The big-eye Priacanthus arenatus Cuvier contains a tapetum lucidum or reflector which lies in the inner region of the choroid. It extends over the entire surface of the fundus, and it consists of several layers of reflecting cells. The cells contain many layers of thin guanine crystals, and there is about 0.5 mg of guanine in a square cm of tapetum. The retina is duplex, and rods are small and very numerous. The tapetum of the big-eye is compared with those of selachians and sturgeons, which it much resembles.     

Histochemical and cytochemical demonstration of Ca++-ATPase activity in the stellate cells of the adenohypophysis of the guinea pig

The histo- and cytochemical localization of Ca++-ATPase activity in the adenohypophysis of the guinea pig was studied utilizing a newly developed method (Ando et al. 1981). An intense reaction was observed in the wall of the blood vessels and between non-secretory cells (stellate cells) and endocrine cells of the pars distalis. Under the electron microscope the Ca++-ATPase reaction product was located extracellularly in relation to the plasmalemma of the stellate cells. This reaction was dependent on Ca++ and the substrate, ATP, and reduced by the addition of 0,1 mM quercetin to the standard incubation medium. Preheating of the sections before incubation completely inhibited the enzyme activity. When Mg++ in different concentrations were substituted for Ca++ in the incubation medium the reaction was always reduced. Both Ca++ and Mg++ in the incubation medium also reduced the reaction. The plasmalemma of the endocrine cells contains no demonstrable amount of Ca++-ATPase activity. The function of the Ca++-ATPase activity is discussed in relation to the regulation of the extracellular Ca++ concentration which seems to be important with respect not only to the secretory process of the endocrine cells but also to the metabolism of the adenohypophysis.     

Histochemical and cytochemical demonstration of Ca++-ATPase activity in the stellate cells of the adenohypophysis of the guinea pig

Summary The histo- and cytochemical localization of Ca⁺⁺-ATPase activity in the adenohypophysis of the guinea pig was studied utilizing a newly developed method (Ando et al. 1981). An intense reaction was observed in the wall of the blood vessels and between non-secretory cells (stellate cells) and endocrine cells of the pars distalis. Under the electron microscope the Ca⁺⁺-ATPase reaction product was located extracellularly in relation to the plasmalemma of the stellate cells. This reaction was dependent on Ca⁺⁺ and the substrate, ATP, and reduced by the addition of 0,1 mM quercetin to the standard incubation medium. Preheating of the sections before incubation completely inhibited the enzyme activity. When Mg⁺⁺ in different concentrations were substituted for Ca⁺⁺ in the incubation medium the reaction was always reduced. Both Ca⁺⁺ and Mg⁺⁺ in the incubation medium also reduced the reaction. The plasmalemma of the endocrine cells contains no demonstrable amount of Ca⁺⁺-ATPase activity. The function of the Ca⁺⁺-ATPase activity is discussed in relation to the regulation of the extracellular Ca⁺⁺ concentration which seems to be important with respect not only to the secretory process of the endocrine cells but also to the metabolism of the adenohypophysis.