Fine structural and enzyme histochemical observations on the dorsal tail tubercle of Mertensiella caucasica (Urodela,Amphibia)

Summary Dorsal tubercle and skin of Mertensiella caucasica have been investigated with the electron microscope and enzyme histochemical methods. The epidermis of the tubercle consists of 8–9 cell layers, that of normal dorsal skin of 5–6. The tubercle is filled with large mucous glands which are surrounded by an almost complete layer of smooth muscle cells (myoepithelial cells). Their glandular cells undergo cyclical changes and are characterized by specific secretory granules, which differ from those of the relatively small mucous glands of the normal dorsal skin.In the connective tissue of the tubercle a relatively rich supply of nerve fibres has been found, which in part contain synaptic and dense core vesicles or accumulations of mitochondria. In the normal dorsal skin nerve fibres occur less frequently.The following enzymes have been demonstrated in the mucous glands of the tubercle: SDH, acid phosphatase, unspecific esterases, E 600 resistant esterase.The tubercle seems to stimulate the female cloaca chemically and mechanically.     

An investigation of ageing in human costal cartilage

Summary Changes in human costal cartilage with increasing age (2–81 years) have been studied in the optical and electron microscope using routine and histochemical techniques.Concurrent with increasing age, chondrocytes undergo degeneration which is characterized initially by the accumulation of lipidic material within cells and, subsequently, by the formation of a halo around degenerating chondrocytes. The halo material is composed of electron dense bodies, amorphous material, and collagen fibrils. Both electron dense bodies and the amorphous material are of cellular origin and they have similar histochemical responses.Using histochemical techniques in the optical and in the electron microscope, it has been shown that chondroitin sulfate decreases with increasing age, while a hyaluronidase resistant material (presumably keratan sulfate) increases, initially in the central zone, and subsequently in the peripheral zones. Hyaluronidase resistant material is minute or absent in the central zone of aged cartilage.The genesis of collagen fibrils progresses from thin unbanded collagen-like fibrils in the pericellular lacunae of chondrocytes in young specimens to thick fibrils (sometimes in excess of 0.5 ) with a period of 640 Å in ageing cartilage. Aggregation of collagen fibrils seems to be related at least initially to the preponderance of matrix granules and beaded filaments which have been shown to originate intracellularly in vacuoles formed in degenerating mitochondria. Both of these structures contain glycosaminoglycans and, with increasing age, glycosaminoglycans decrease while collagen fibrils aggregate. In old age, the amorphous material, and possibly the content of disrupting electron dense bodies, seem to give origin to some collagen fibrils. This and other mechanisms of formation of collagen fibrils have been observed and they are discussed.Calcification of the matrix increases with increasing age and this agrees with previous findings.Supported by grants from the Italian National Research Council. — The authors are indebted to Miss Giuliana Silvestrini and to Mr. Lucio Virgilii for their expert and extensive technical assistance. — To Dr. A. Ascenzi, Director 1° Istituto di Anatomia e Istologia Patologica, and to Dr. C. Cavallero, Director, 2° Istituto di Anatomia e Istologia Patologica, Università di Roma, the senior author would like to express his appreciation for the use of equipment and facilities pursuant to this investigation, while on sabbatical leave from the University of California, Irvine, College of Medicine. — We wish to extend our thanks to the Italian National Research Council for supporting this study.On sabbatical leave from the University of California, Irvine, College of Medicine.     

Neurosecretion in the external and internal zone of the median eminence of the cat and dog

Summary The immunoglobulin-enzyme bridge technique, in association with rabbit antiporcine neurophysin-II has been applied to the median eminence of the dog and cat in order to study the distribution of neurophysin-like antigens throughout this area of the brain and correlate the findings with the corresponding distribution of neurosecretory material (NSM) as revealed by the crotonaldehyde fuchsin stain.Neurophysin and NSM were both present in the hypothalamo-supraoptico-neurohypophysial system—the pathway taken by oxytocin, vasopressin and neurophysin from the hypothalamus to the posterior pituitary lobe.Whereas the tuberoinfundibular tract of the median eminence was almost devoid of NSM, the presence of neurophysin-like material was clearly evident using immunoperoxidase histochemistry. The significance of a protein in the external median eminence possessing determinants cross-reactive against anti-neurophysin serum is discussed.This work was financed by a grant from the Medical Research Council of New Zealand.     

Histological, fine-structural and histochemical differences in the testicular glands of gobiid and blenniid fishes

The testicular gland (t.g.) is a glandular tissue situated adjacent to the testis of blenniid and several gobiid species. In the present study the t.g. of Blennius pavo Risso and Gobius niger L. were compared by histological and histochemical methods. In B. pavo the spermatozoa have to cross the t.g. to reach the vas deferens and thus they come into contact with the gland cells, whereas in G. niger the vas deferens is situated between the testis and the t.g. The fine structure and histo-chemistry of the t.g. cells reveal that in B.pavo the cells of the t.g. have exocrine as well as endocrine functions. The t.g. cells of B. pavo contain large amounts of lipids, form a secretion containing acid mucopolysaccharides, show positive reaction for acid phosphatase, and some cells stain for 3β-HSD and G6PD. The function of the t.g. of G. niger is exclusively endocrine. Characteristics of the gland cells of this species are well developed smooth ER and tubulovesicular or paracristal-line mitochondria. The stainings for 3β-HSD, G6PD and UDPGD give strong positive results in the whole t.g., indicating the presence of steroids and steroid glucuronides.     

Allelic polymorphism in the hamster oviductin gene is due to a variable number of mucin-like tandem repeats

Oviductins are high-molecular-weight glycoproteins specifically secreted by the oviduct. These proteins bind to the zona pellucida of the ovulated oocyte and remain associated with the embryo during its transit in the oviduct. They may be involved in fertilization and early embryonic development. In order to explore their putative biological function, the cDNA sequence corresponding to oviductin in the golden hamster was determined. We found that the deduced amino acid sequence of this heavily O-glycosylated protein presents characteristics typical of mucins, including serine- or threonine-rich tandem repeats. Analysis of several cDNA clones and of genomic DNA revealed the presence of a single copy gene with two frequent alleles differing in the number of repeats. Comparison with oviductin sequences from other mammals indicates a high degree of conservation amongst species, except for the repeat region which shows divergence, notably in the number of repeats. Based on its biochemical and genetic properties, hamster oviductin can now be classified as a secretory mucin. This concept provides a new insight in the elucidation of its biological role: oviductin could possibly provide the oviduct and the oocyte with a protective coating ensuring normal tubal function and embryonic development. © 1995 wiley-Liss, Inc.     

Fine structure and lectin histochemistry of the apical surface of the free neuromast of Lampetra japonica

The surface coat, ciliary process, and microvilli of the lamprey neuromast were examined with electron microscopy after tannic acid prefixation and lectin histochemistry. The neuromast was found to exist in the form of a dermal mound with a furrow in the middle. On the bottom of the furrow, the hair cell was characterized by a kinocilium and 15–20 stereocilia, arranged along the longitudinal axis of the furrow. Spanning structures were demonstrated between the kinocilium and stereocilia as well as between stereocilia. The surface coat, enhanced by tannic acid prefixation, was particularly rich over the surface of the supporting cell; by contrast, it was thin over the hair cell. Some lectins (PNA, GS-I, SBA, WGA) showed affinity to the surface coat of the supporting cell as well as the hair cell, and the others (RCA-I, MPA, ConA) showed affinity only to the supporting cell. These differences in the structure and affinities of the surface coat suggest an extracellular milieu highly specialized for the hair cell in this particular form of the mechanoreceptor.     

Nitric oxide synthase in the rat carotid body and carotid sinus

The participation of nitric oxide synthase (NOS) in the innervation of the rat carotid body and carotid sinus was investigated by means of NADPH-diaphorase histochemistry and NOS immunohistochemistry using antisera raised against purified neuronal NOS and a synthetic tridecapeptide. NOS was detected in 23% of neurons at the periphery of the carotid bodies. Some negative neurons were surrounded by NOS-positive terminals. NOS-containing varicose nerve fibres innervated the arterial vascular bed and, to a lesser extent, the islands of glomus cells. These fibres persisted after transection of the carotid sinus nerve and are probably derived from intrinsic neurons. Large NOS-positive axonal swellings in the wall of the carotid sinus were absent after transection of the sinus nerve, indicating their sensory origin. The results suggest a neuronal nitrergic control of blood flow, neuronal activity and chemoreception in the carotid body, and an intrinsic role of NO in the process of arterial baroreception.     

Distribution of NADPH-diaphorase activity in rat paravertebral,prevertebral and pelvic sympathetic ganglia

Summary Paravertebral (superior cervical and stellate), prevertebral (coeliac-superior mesenteric, inferior mesenteric) and pelvic (hypogastric) sympathetic ganglia of the rat were investigated by enzyme histochemistry to ascertain the distribution of nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-diaphorase) activity. In the paravertebral ganglia the majority of the sympathetic neuronal perikarya contained lightly and homogeneously distributed formazan reaction product but there was a range of staining intensities amongst the neuron population. In contrast, in the prevertebral ganglia, intense NADPH-diaphorase staining was present in certain neurons. Firstly, a population of neurons of the coeliac-superior mesenteric ganglion complex were surrounded by densely NADPH-diaphorase-positive baskets of fibres and other stained fibres were seen in interstitial nerve bundles and in nerve trunks connected to the ganglion complex. Secondly, in both the inferior mesenteric ganglion and hypogastric ganglion there were many very intensely NADPH-diaphorase positive neurons. Stained dendritic and axonal processes emerged from these cell bodies. In both ganglia this population of neurons was smaller in size than the lightly stained ganglionic neurons and commonly had only one long (presumably axonal) process. The similarity of these highly NADPH-diaphorase-positive neurons with previously described postganglionic parasympathetic neurons in the hypogastric ganglion is discussed.     

Ultrastructural localization of carbohydrates in Reichert's membrane of the mouse

In the present investigation, we examined the role of trophoblast and parietal endoderm cells in the synthesis of carbohydrate-containing components of Reichert's membrane. To eliminate the function of Reichert's membrane as a filter between maternal and embryonal tissues we carried out our examination under in vitro conditions. Parietal yolk sac from mouse embryos on day 9 post coitum (p.c.) were cultivated for 0 to 5 days. Because tannic acid enables a complex formation between carbohydrates and osmium we chose the fixation with this acid for the ultrastructural study. Electron microscopy showed that for assembly of Reichert's membrane, trophoblast cells produce and then release components that were detected as tannic acid-positive granules both in the Reichert's membrane and in the vacuoles of the trophoblast cells. To localize specific carbohydrates we used postembedding-gold-lectin histochemistry on LR-Gold^R-embedded tissues. Strong binding sites for the lectins WGA (Triticum vulgare), RCA I (Ricinus communis) and Con A (Canavalia ensiformis) were observed in Reichert's membrane and trophoblast cells but not in the parietal endoderm cells. The LTA (Lotus tetragonolobus)-binding pattern was positive in the membrane and its adjacent cells but that of the LFA (Limax flavus) was negative in the parietal endoderm cells and very weak in Reichert's membrane and trophoblast cells. Our results demonstrate that trophoblast cells are involved in the construction of Reichert's membrane through the production and release of specific glycoconjugates.     

硫酸铝钾对小鼠肝损害的实验研究

本文主要观察硫酸铝钾——饮用水净化剂引致小鼠肝酶组化,超微结构和组织结构的变化。动物30只,分为正常组、硫酸铝钾大、小剂量组。实验结果:硫酸铝钾10mg/kg/日(大剂量组)与5mg/kg/日(小剂量组)动物用药10天、80天均可使肝SDH酶活性降低;肝细胞线粒体肿胀、嵴断裂和溶解。在光学显微镜下用药80天后大部分肝细胞肿胀,胞浆疏松淡染、肝小叶内可见呈小灶状分布的炎性细胞浸润,主要为淋巴细胞及浆细胞,门管区偶见少许炎性细胞,但肝小叶和门管区未见结缔组织增生。为此,硫酸铝钾作为净水剂,不宜用量过大。