Lectin cytochemistry was carried out to elucidate the role of stratum intermedium cells and papillary layer cells in amelogenesis, especially in the process of sugar incorporation and on membrane characteristics according to their cytodifferentiation.
Regarding the lectin-reaction on the plasma membrane, little or at best a weak reaction of Con A, UEA-I, PNA, MPA and WGA was seen in stratum intermedium cells from the late differentiation stage to the early secretory stage of ameloblasts. Lectinstainability in the stratum intermedium increased in accordance with the cytodifferentiation of ameloblasts. At the active secretory stage of ameloblasts, lectins intensely stained the plasma membranes of stratum intermedium cells. The plasma membranes of papillary layer cells at both stages of ruffle-ended and smoothended ameloblasts were stained by same lectins as well.
The results therefore suggest that: 1) stratum intermedium cells bring about changes in the glycolipids and glycoproteins of their plasma membranes in accordance with the cytodifferentiation of ameloblasts; 2) they regulate the transport of mineral and/or organic materials between ameloblasts and extracellular fluid via highly charged plasma membranes generated by glycocalyx; 3) the cell-cell interaction of stratum intermedium cells with ameloblasts, in which carbohydrate-protein (endogenous lectin) interaction plays a significant role, is important for the cytodifferentiation of these cells. Regarding the papillary layer cells, the results suggest that they also regulate the transport of minerals by their charged plasma membranes and participate in the removal of the enamel matrix.

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In order to elucidate the cytochemical properties of rat podocyte's membranes, the authors studied the constituents and distribution of glycocalyx and membrane cholesterol. Chromic-phosphotungstic acid (Cr-PTA) stain combined with enzyme digestive tests was used for the glycocalyx analysis. A digitonin fixation method was applied for the detection of membrane cholesterol. On the whole surface of podocytes, glycocalyx showed a strongly positive reaction to Cr-PTA. In normal rats, the reactivity on the urinary surface above the slit membrane of the podocyte foot processes was decreased after treatments with neuraminidase, hyaluronidase and heparitinase. The reactivity on the basal surface below the slit membrane disappeared only after treatment with chondroitinase ABC. In Puromycin Aminonucleoside nephrosis (PAN) rats, the foot processes were effaced extensively. Though a highly positive reactivity of Cr-PTA was observed on the urinary surface of the podocytes, the basal surface reacted weakly. The positive reaction of the urinary surface was not affected by the treatments with neuraminidase, hyaluronidase and heparitinase, but the weak reaction of the basal surface disappeared completely through chondroitinase ABC treatment. The distribution of membrane cholesterol was clearly revealed by the digitonin fixation method, showing digitonin cholesterol complexes of localized trilamellar structures. In normal rat podocytes the complexes were found on the urinary surface, with only a few on the basal surface. In PAN rats the complexes were seldom noticed either on the urinary or basal surfaces. The heterogeneous distribution of glycocalyx and membrane cholesterol seen in normal rat podocytes are changed remarkably under nephrotic condition.

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The differentiation of the collagenous dermis has been followed by electron microscopy in larvae of three anuran species. Events can be divided into five phases, depending on the organization of the cellular elements. Initial secretion of collagen appears to be from the epidermis but fibroblasts are present from early stages. Apart from secretion, there is phagocytosis of fibrils by fibroblasts, seen most frequently when the operculum is formed and at metamorphosis. In most larval stages, the dermis consists of regular plies of collagen fibrils, penetrated by processes from underlying fibroblasts and crossed by nerves, with a cellular layer defining the deep face. In Rana, these cells contain enormous vacuoles and have been called “compartmented cells”, but the vacuoles are absent in Bufo and Xenopus. Just before metamorphosis, fibroblasts and chromatophores migrate into the dermis, and establish a stratum laxum. A few plies of larval collagen fibrils are left under the epidermis, the bulk of the larval dermis becomes the stratum compactum. During larval life, the hypodermis contains chromatophores, blood capillaries and wandering leucocytes. The dermis gains a blood circulation only at metamorphosis, when subdermal lymph sacs and vertical smooth muscles are established.

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The effect of oral administrations (20 or 40mg/kg body weight/day, for 21 days) of gossypol tetraacetic acid on the testis of the Parkes strain mouse was investigated. Gossypol treatment did not affect the body weight or testicular weight, but caused a significant depression in the weight of the seminal vesicle. Histologically, the testes in mice treated with gossypol possessed regressed seminiferous tubules showing the exfoliation of germ cells, the occurrence of giant cells, a disorganization of the germinal epithelium, the degeneration of germinal elements, intraepithelial vacuolation and dislocation of the Sertoli cells into the luminal portion. However, the effect of gossypol was not uniform, and normal features were also observed in the majority of the tubules in the testes of the gossypol-treated mice. When quantitatively analysed, the frequency of regressed seminiferous tubules was significantly higher in the testes in the treated mice than the controls. The results suggest that the gossypol treatment induces non-uniform regressive changes in the seminiferous tubules in the mouse testis.

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The growth rate of calcium carbonat (CaCO₃) crystals in the endolymphatic sac was modulated, and morphological changes in this organ were observed by light and electron microscopy. When calcium chloride (CaCl₂) was given to the tree frog for a short period (3 days to 2 weeks), CaCO₃ crystal production was accelerated. Epithelial cells enlarged, their rough endoplasmic reticulum (rER) and Golgi apparatus developed, and dense material increased around CaCO₃ crystals and/or in the endolymphatic lumen. In addition, multiluminal endolymphatic chambers appeared in some frogs. On the other hand, as the CaCl₂ loading period lengthened and CaCO₃ crystal formation decreased or stopped, the epithelial cells became flat and extended with scanty cytoplasm, and the rER and Golgi apparatus decreased in number and size. Furthermore, the amount of dense material around CaCO₃ crystals and in the lumen decreased. These findings suggest that the rER, Golgi apparatus and dense material have key roles in the production of CaCO₃ crystals.

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The pyroantimonate technique and a new demineralization method were employed to visualize pyroantimonate-precipitable calcium in the endolymphatic sac of the tree frog. The precipitate was determined to contain calcium (Ca) by EGTA extraction and X-ray microanalysis. The precipitate was mainly localized around calcium carbonate (CaCO₃) crystals when frogs were not loaded with calcium chloride (CaCl₂). When crystalline growth was accelerated by loading with CaCl₂, the precipitate increased in amount, especially around the crystals and in the basement membrane (lamina rara and reticular lamina). Various degrees of precipitation were found in epithelial cells; however, neither epithelial granules nor mitochondria seemed to have a significant amount of precipitate. This study demonstrates that Ca ion accumulates around those crystals where a dense material is located. The dense material probably has an affinity for the Ca ion, and plays an important role in crystal formation. However, the transport pathway for the Ca ion into the endolymphatic lumen is still obscure.

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The subcellular localization of calciumactivated neutral protease requiring a millimolar calcium concentration (m-CANP) was examined by light and electron microscopy in various tissues of the rabbit, using an immunoperoxidase method with a monoclonal antibody (1C6D1). In skeletal muscles, specific staining for m-CANP was recognized on collagen fibrils (ca 40nm in diameter) with a periodic banding pattern. In the lung, dense reaction products were precipitated on elastic fibers under the bronchial epithelia. In the aorta, tunica intima and adventitia were intensely stained. Dense reaction products were observed on collagen fibrils and elastic fibers. Basal laminae, on the other hand, were not stained by anti m-CANP antibody in these tissues. These findings suggest that m-CANP may be involved in the regulation of the structure and function of the extracellular matrix.

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Responses of odontoblasts and pulp capillaries to cavity preparation were investigated in the upper first molar teeth of rats, using light and transmission electron microscopy. At 100 days of age, the blood vessels of the pulp formed a subodontoblastic network consisting of continuous capillaries at a short distance from the odontoblast layer. Cavity preparation caused the displacement of some odontoblasts into the dentinal tubules, while others were separated from the predentin by rapid inflammatory exudation after drilling. The subodontoblastic capillary network under the injured dentin was shifted inwards together with the separated odontoblasts. The endothelium of the shifted capillaries showed a remarkable increase of pinocytotic vesicles, an event thought to be closely related to the formation of the exudative lesion.
By one day after cavity preparation, most of the damaged odontoblasts had degenerated. Many cells with high nucleus/cytoplasm (N/C) ratios and prominent nucleoli accumulated around the subodontoblastic capillaries, some of which had many endothelial fenestrae facing these cells. These cells were suggestive of newly differentiating odontoblasts receiving nutritional supply from the capillaries.
Three days after cavity preparation, newly differentiating odontoblasts took the place of the degenerated odontoblasts. They began to produce reparative dentin by five days after cavity preparation. Capillaries were located beneath the newly differentiating odontoblasts, but endothelial fenestrae gradually decreased in number.
During the active reparative dentin formation, capillaries remained closely beneath the new odontoblast layer. Although the rate of reparative dentin deposition was not significantly lower than that in the primary dentin formation, one could not recognize an invasion of capillaries into the odontoblast layer nor a remarkable increase of endothelial fenestrae, both of which are common in active primary dentin formation. The results suggest that the function of capillaries differs between primary and reparative dentin formation.

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The auditory teeth in the spiral limbus of the cochlear duct are located under the limbal portion of the tectorial membrane and separated by furrows lodging the interdental cells. In this study, the shape, arrangement and distribution of the auditory teeth in the cochlear duct of adult mice were examined by scanning electron microscopy after removing the tectorial membrane and the interdental cells with chemical maceration methods.
The auditory teeth appeared on the top face of the spiral limbus between the edge of the vestibular lip and the Reissner membrane. The teeth on the vestibular lip side possessed elongated upper plates and formed a continuous row resembling the keyboard of a piano; the teeth were separated by radially oriented parallel slits. The elongated teeth decreased in length from the base to the apex of the cochlear duct. The teeth on the Reissner membrane side showed star-shaped upper plates separated by slits and gaps. The population density of the star-shaped teeth decreased from the base to the apex, widening the gaps to hold the interdental cells. The upper plates of the teeth occupied about 75% of an extent of the tooth zone in the hook and first basal half turn, and about 55% in the apical turn.
The regional differences of the auditory teeth are considered to be closely related to local functions of the tectorial membrane and the interdental cells.

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The multiaxonal nerve endings, consisting of a bundle of axons, were reexamined in the muscle spindles of the adult Chinese hamster. In addition to the frequent occurrence of the multiaxonal endings innervating the nuclear bag fibers in the equatorial region (DESAKI and UEHARA, 1988), these endings were also occasionally distributed not only in the equatorial region of the nuclear chain fibers, adjacent to annulospiral sensory endings, but also in the polar region of the same muscle fiber. They were derived from non-myelinated stem nerves becoming varicose along their course. Terminal axons composing the endings were almost naked, except at the initial muscle-contact portion, where they were surrounded by Schwann cell processes. They contained a significant number of clear synaptic vesicles and large granulated vesicles, and were closely apposed to each other and to the muscle cell surface without an interposing basal lamina. Some terminal axons formed synaptic contacts with each other and with the muscle cell surface. These structural features, including their wide distribution, suggest that the multiaxonal endings may belong to the autonomic nerves rather than the fusimotor nerves.

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Capsaicin was injected subcutaneously (50mg/kg) into 10 mice on days 2 or 3 after birth, and 12h, 3 and 5 days later the distribution and structure of degenerated primary afferent central axons or terminals (C-terminals) in the lumbar spinal dorsal horn were examined by electron microscopy. Degenerated terminal axons with dense or lamellar bodies or higher electron density were conspicuous 12h after treatment with capsaicin. Severely degenerated unmyelinated axons, including dense or lamellar bodies engulfed by microglial cells, were numerous in the most superficial (marginal) layer, but rarely seen in the substantia gelatinosa. Two types of primary afferent central terminals in the substantia gelatinosa showed various extents of degeneration: small dark C-terminals (CI-terminals) with densely packed agranular synaptic vesicles, and large light ones (CII-terminals) with less dense agranular synaptic vesicles and a few granular synaptic vesicles. Thus, many central axon terminals of dorsal root ganglion (DRG) neurons that are sensitive to capsaicin enter the marginal layer and substantia gelatinosa.
Degenerated primary afferent central axons or terminals markedly decreased in the superficial dorsal horn 3 and 5 days after capsaicin treatment, still, there were many degenerating DRG neurons at this time as shown by our previous study. Previously we also reported that fewer slightly degenerating unmyelinated dorsal root axons and small DRG neurons appear at 12h and larger DRG neurons degenerate later than smaller ones after treatment with capsaicin. As a result, the discovery of many severely degenerated terminal axons in the superficial dorsal horn soon after treatment supports the idea that capsaicin first acts on the central terminals and that this is followed by damage to larger DRG neurons.

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