Identification of neutrophils in the nonsensory epithelium of the vomeronasal organ in virus-antibody-free rats

Cells infiltrating the nonsensory epithelium of the vomeronasal organ of virus-antibody-free rats exhibited surface immunoreactivity for ₂-microglobulin and immunoglobulin (Ig) E. They were further characterized by using immunohistochemical techniques with antibodies to cell-specific markers or histochemical techniques for immunocytes with surface receptors for IgE. Localization of intracellular granules immunoreactive for lactoferrin and CD18, a leukocyte adhesion molecule, unequivocally identified these cells as neutrophils. The low number of IgA-and IgG-immunoreactive B lymphocytes, T lymphocytes, and accessory immunocytes in the vomeronasal organ as well as the rest of the nasal cavity confirmed the absence of infection. We hypothesize that the operation of the vomeronasal pump induces repeated episodes of transient focal ischemia followed by reperfusion, which results in release of neutrophil chemoattractants and modulation of adhesion factors that regulate the extravasation and migration of neutrophils into the nonsensory epithelium. The distribution of immunoreactivity for interleukin 8 suggests that it is not the primary neutrophil chemoattractant in this system while that of CD18 suggests its active involvement in neutrophil extravasation. In addition to their role in immune surveillance, neutrophils may stimulate ion/water secretion into the vomeronasal lumen, affecting the perireceptor processes regulating stimulus access and clearance from the sensory epithelium.     

Intraepithelial blood vessels in the vomeronasal neuroepithelium of the rat

Summary Epithelial-vascular relationships are established during the development of the vomeronasal neuroepithelium of the rat. Special attention is given to the fine structure of the endothelial wall of intra-epithelial vessels, to ultrastructural aspects of the neuronal-vascular relationships, and to the appearance of inclusion bodies in the neuronal cells adjacent to these vessels. The neuronal perikarya surrounding the blood vessels are filled with highly developed smooth endoplasmic reticulum. Possible functional implications of the vascularization of the neuroepithelium of the vomeronasal organ in mediating olfacto-endocrine relationships are discussed. It is suggested that the intra-epithelial blood vessels are at least supportive and nutritive in nature, while their implication in an olfacto-endocrine connection remains obscure.On sabattical leave: Visiting Professor, Department of Anatomy, University of Kentucky, Lexington, Ky., USA     

The cell coat of the olfactory epithelium proper and vomeronasal neuroepithelium of the rat as revealed by means of the Ruthenium-red reaction

Summary The apical cell coat of the olfactory epithelium proper and the vomeronasal neuroepithelium of the rat was investigated electronmicroscopically by means of the Ruthenium-red reaction. In the olfactory epithelium proper, the cilia of receptor cells and microvilli of supporting cells possess a cell coat measuring approximately 10 nm in thickness. In the vomeronasal neuroepithelium, the apical cell coat is thicker than in the olfactory epithelium proper. On microvilli of vomeronasal receptor cells the cell coat varies in thickness from 15 to 20 nm, and on microvilli of supporting cells it measures approximately 75 nm. The functional implications of these findings are discussed.A portion of this study was presented at the 6^th European Anatomical Congress in Hamburg. This publication is dedicated to Prof. E. KlikaSupported by the Deutsche Forschungsgemeinschaft (Br 358/5-1).     

Ultrastructural study of neurovascular contacts in the median eminence of the rat

Summary In the median eminence of the rat axons of the supraoptic-paraventricular-hypophyseal tract with elementary neurosecretory granules (150–200 m) traverse the internal zone. Terminals containing dense core vesicles 60–120 m in diameter end on the portal capillaries of the median eminence. A unique organisation of the primary portal capillaries is shown. Endothelial cells have many fenestrae. The pericapillary space has numerous extensions all of which represent a special zone around the endothelial tube. The fine structural organisation and function of the neurovascular contacts in the median eminence are discussed.     

Distribution of different cell types within the rat thymus in the neonatal period of life

Summary This study attempted to define reciprocal positions of cell types within the thymus. Random or non-random contacts between specific cell types were analyzed by means of graph theory. For analysis, thymus blocks were sectioned serially and, then, thymus cells were categorized into types, based on morphological criteria. The distribution of individual cell types within the cortex, cortico-medullary zone and medulla was presented in form of a map. In the analysis, three types of epithelial cell, characteristic of each thymus zone, macrophages, Langerhans-like cells and lymphocytes were found in non-random relations to one another. Moreover, characteristic groups of cells associated with one another were also demonstrated.This study was supported by the Polish Academy of Sciences     

Differential binding patterns of three antibodies (VOBM1, VOBM2, and VOM2) in the rat vomeronasal organ and accessory olfactory bulb

Immunohistochemical properties of monoclonal antibodies raised against the rat vomeronasal epithelium were examined in adult rats. Three monoclonal antibodies, VOBM1, VOBM2, and VOM2, reacted specifically to the luminal surface of the sensory epithelium of the vomeronasal organ. In addition, the reactivities of VOBM1 and VOBM2 were detected in the vomeronasal nerve layer and the glomerular layer of the accessory olfactory bulb. Electron-microscopic study revealed differential patterns of the immunoreactivity of the three antibodies to the microvilli of vomeronasal sensory epithelium. VOBM1 immunoreactivity was found on the microvilli of the supporting cells, whereas VOBM2 immunoreactivity was found on those of the sensory cells. VOM2 immunoreactivity was observed on the microvilli of both the sensory and supporting cells. These results suggest that the three antibodies recognize different antigens on the vomeronasal sensory epithelium. In particular, VOBM2 antibody appears to react to an antigen specific to the microvilli of the vomeronasal sensory cells.     

Ultrastructural evidence for sinusoid spaces and coupling between pituicytes in the rat

Summary The pericapillary palisade of the rat neurohypophysis was examined by means of thin-section and freeze-etch electron-microscopy. Special attention was given to pituicyte processes intermingled with neurosecretory terminals. These processes are identified by the presence of lipid droplets and ribosomes.Extracellular spaces are conspicuously enlarged in circumscribed regions between fingerlike protrusions of pituicyte processes. Neurosecretory axons seem to have free access to these enlarged spaces. Zonulae occludentes often combined with small gap junctions are found at the border of these sinusoid spaces. Gap junctions and occasionally intermediate junctions are seen between pituicyte processes. The topographic relationship and the functional significance of these structural features remain to be further elucidated.Supported by Grants of the Dr. Eric Slack-Gyr Foundation, Zürich, the Swiss National Foundation for Scientific Research Nrs. 3.823.72, 3.774.72, 3.712.72 and 3.045.73, the EMDO-Foundation and the Hartmann-Müller-Foundation for Medical Research at the University of Zürich. A short account has been presented at the meeting of the Union of Swiss Societies for Experimental Biology, April 1975 (Experientia 1975, in press).     

A freeze-fracture study of the papillary layer of the rat incisor enamel organ

After tooth enamel has been secreted it undergoes maturation or hardening. This process is mediated by ruffled and smooth-ended ameloblasts and associated papillary layer cells. The cells of the papillary layer are characterized by large numbers of mitochondria, coated vesicles, microvilli, and gap junctions. These features have led numerous investigators to speculate that the papillary layer is an ion-transporting epithelium. We have conducted freeze-fracture studies of the rat papillary layer in order to better characterize the surface features of these cells. The cell membranes of the papillary cells contained large numbers of intramembrane particles of various sizes ranging from 4 to 9 nm in diameter. Gap junctions were present at the cell surface and in the cytoplasm in the form of annular gap junctions. The intramembrane particles or connexons of both types of gap junctions were about 8-9 nm wide and were either packed randomly or present in the so-called 'crystallized' state. At the interface between smooth-ended ameloblasts and papillary layer cells, a well-developed zonula occludens was present along the basal surfaces of the ameloblasts and several large gap junctions were formed between the two cell types. The capillary network associated with the papillary layer was characterized by a thin endothelium containing large numbers of fenestrations.     

Lectin histochemical localization of galactose,N-acetylgalactosamine,and N-acetylglucosamine in glycoconjugates of the rat vomeronasal organ,with comparison to the olfactory and septal mucosae

The localization of -D-galactose, N-acetyl-D-galactosamine, and N-acetyl-D-glucosamine sugar residues of glycoconjugates in the vomeronasal organ, olfactory mucosa, and septal organ in the nasal mucosae of rats was investigated using lectinohistochemical techniques combined with bright-field, epifluorescence, and confocal laser scanning microscopy. Glycoconjugates in the mucomicrovillar complex of the vomeronasal organ contained all the sugar residues investigated, whereas glycoconjugates in the mucociliary complex of the olfactory mucosa and septal organ contained only N-acetyl-D-glucosamine. Vomeronasal receptor neurons expressed glycoconjugates with terminal -D-galactose and -N-acetyl-D-galactosamine, and N-acetyl-D-glucosamine residues, whereas olfactory and septal receptor neurons expressed glycoconjugates with only N-acetyl-D-glucosamine residues. Secretory granules of glands of the vomeronasal organ contained glycoconjugates with terminal -D-galactose and N-acetyl-D-galactosamine, and N-acetyl-D-glucosamine, whereas those of the Bowman's glands and glands of septal organ contained glycoconjugates with only internal N-acetyl-D-glucosamine residues. The results demonstrate that the glycoconjugates expressed by vomeronasal receptor neurons and glands contain terminal -D-galactose and -N-acetyl-D-galactosamine sugar residues that are not expressed by analogous cells in the olfactory mucosa and septal organ.     

Ultracytochemistry of the synaptic ribbons in the rat pineal organ

Summary The synaptic complexes of the rat pinealocytes are neither cholinergic nor adrenergic. In the synaptic vesicles, a neurotransmitter carrier substance of lipid nature reacting with OsO₄-Zn I₂ mixture (similar to that present in both cholinergic and adrenergic vesicles) was not found.In addition, there were no indications of glucose-6-phosphatase or thiamine-pyrophosphatase activity in the synaptic vesicles. Thus, it appears that the synaptic vesicles do not originate from the rough or smooth endoplasmic reticulum.The synaptic ribbons do not contain carbohydrates, are of protein nature and possess some chemical resemblance to microtubules and microtubular bouquets.Appropriate ultracytochemical reactions have not shown detectable quantities of sodium and calcium ions in pinealocyte synaptic complexes.Grateful acknowledgment is made to Mr. P.-A. Milliquet for technical assistance and to Dr. T. Jalanti (C.M.E., Lausanne) for his help in the use of the X-ray microanalyser.Dedicated to Professor Dr. med. G. Töndury on the occasion of his 70th birthday.     

Fine structure of the vomeronasal organ in the grass lizard, Takydromus tachydromoides

The squamates are composed of many taxa, among which there is morphological variation in the vomeronasal organ (VNO). To elucidate the evolution of chemoreception in squamate reptiles, morphological data from the VNO from a variety of squamate species is required. In this study, the morphology of the VNO of the grass lizard Takydromus tachydromoides was examined using light and electron microscopy. The VNO consists of a pair of dome-shaped structures, which communicate with the oral cavity. There are no associated glandular structures. Microvilli are present on the apical surfaces of receptor cells in its sensory epithelium, as well as on supporting cells, and there are centrioles and ciliary precursor bodies on the dendrites. In addition to ciliated cells and basal cells in the non-sensory epithelium, there is a novel type of non-ciliated cell in T. tachydromoides. They have constricted apical cytoplasm and microvilli instead of cilia, and are sparsely distributed in the epithelium. Based on these results, the variation in the morphology of the VNO in scincomorpha, a representative squamate taxon, is discussed.     

Freeze-fracture and deep-etching studies on zymogen-granule membranes of the rat pancreas

Summary Whole pancreatic zymogen granules or their membrane fraction were examined by freeze-fracture or deep-etching under different experimental conditions. The granules were fixed for different time periods, or not fixed, and were cryoprotected with glycerol or DMSO; 3% glutaraldehyde followed by 30% glycerol were finally chosen for giving the best resolution and the highest density of intramembrane particles (IMP). IMP are present on the PF and EF leaflets. Their number decreases with the duration of the fixation. Several granules exhibit IMP-free blebs.Incubation of the granules with protamine sulfate causes an aggregation of IMP and of the rough-textured background on the EF leaflet. A second fracture plane can be formed and has been shown by deep-etching to be intercalated between PF and EF. Deep-etching has also shown that particles attached to the perimeter of the granules and of the blebs are, in fact, large nodules on the PS face which partially extend onto the blebs and do not aggregate with the IMP after protamine treatment. Fusion is also indicated between membrane vesicles. Freeze-fracture of the purified membrane fraction seems to indicate the formation of an IMP cap during the lysis of the granule. Moreover, large nodules remain present on the PS face on these membrane fractions but the majority disappear after washing at pH 11.2 with Na₂CO₃ and EDTA.Supported by a research grant from the Medical Research Council of Canada (F.L.) (J.S.H.)     

Roles of the main olfactory and vomeronasal systems in the detection of androstenone in inbred strains of mice

We investigated the role of the main olfactory and accessory olfactory systems (MOS and AOS respectively) in the detection of androstenone. We used the following experimental approaches: behavioral, surgical removal of the vomeronasal organ (VNX) followed by histochemical verification and Fos immunohistochemistry. Using a Y-maze paradigm we estimated sensitivity of NZB/B1NJ and CBA/J mice to androstenone. CBA mice were 2,000-fold more sensitive to androstenone than NZB mice. VNX caused a 4- to 16-fold decre...     

Specific arrangements of membrane particles at sites of exo-endocytosis in the freeze-etched neurohypophysis

Summary Images have been obtained from freeze-etch replicas of neurohypophyses which are consistent with the view that orderly arranged aggregates of membrane particles occur in regions where fragments of membrane are being added to and taken away from the plasma membrane during secretion. Aggregates of particles included rosette-like and necklace-like patterns similar to those described by other authors at sites of exocytosis and endocytosis.Dedicated to Prof. W. Bargmann at the occasion of his 70th birthday. A short account has been presented at the 8th International Congress of Electron Microscopy (Dreifuss, Akert, Sandri and Moor, 1974).This work was supported by grants from the Swiss National Foundation for Scientific Research Nos. 3.257.74, 3.368.0.74, 3.774.72 and 3.045.73; the Hartmann-Müller Foundation for Medical Research in Zürich and the Dr. Eric Slack-Gyr Stiftung.     

Vasopressin- and oxytocin-containing fibres in the pineal gland and subcommissural organ of the rat

Summary Vasopressin and oxytocin were specifically demonstrated in the rat brain using the unlabelled antibody-enzyme method and purification of the first antiserum. Vasopressin and oxytocin fibres extend via the subcommissural organ or habenular commissure into the pineal stalk and terminate in the anterior part of the pineal organ. In addition, immediately adjacent to the subsommissural organ many vasopressin-containing fibres run caudally toward the central grey. These results are discussed in relation to the proposed presence of vasotocin in the pineal gland.This study was supported by the Foundation for Medical Research, FUNGOThe authors wish to thank Dr. D.F. Swaab and Prof. J. Ariëns Kappers for their suggestions and critical remarks     

A simple operation method on removal of the vomeronasal organ of the rat

The vomeronasal organ (VNO) of the rat was removed completely using the following operation procedure. The mouth of the anesthetized rat was opened. A midline incision was made in the plate of the upper jaw, the tissue was retracted and a hole was drilled at both the anterior and posterior points of attachment of the VNO. The location of these holes allowed removal of the bone to which the VNO is attached together with the VNO itself.     

棕色田鼠与沼泽田鼠犁鼻器和副嗅球的组织结构

用组织学方法研究了棕色田鼠(Microtus mandarinus)、沼泽田鼠(M．fastis)副嗅球和犁鼻器的结构及其在两种鼠间的差异，以此探讨两种田鼠的进化机制与适应功能。两种田鼠的犁鼻器位于鼻腔前端鼻中隔基部的两侧，呈管状结构；沿着犁鼻器的长轴犁鼻管呈现不同的形态学特征，犁鼻管直接开口于鼻腔，从前向后沿着长轴旋转，中间管壁(犁鼻粘膜)变成底部，侧面管壁(假覆层上皮)变成犁鼻管顶壁，最终犁鼻管变小成为一个腺体的分支，不同部位具有不同的组织学特征。通过选取中间相似部位对两种田鼠进行比较研究，发现棕色田鼠犁鼻粘膜比沼泽田鼠厚，而其长度却短于沼泽田鼠。棕色田鼠副嗅球颗粒细胞带宽和僧帽细胞带宽均大于沼泽田鼠，而带长却小于沼泽田鼠。相关分析发现，犁鼻器和副嗅球形态有一定的对应关系，这可能和两个结构之间存在着神经投射有关。棕色田鼠幼体的犁鼻粘膜、神经细胞核、假覆层上皮、血管面积均小于成体[动物学报49(2)：248—255，2003]。     

Luliberin and somatostatin fiber-terminals in the subfornical organ of the rat

Summary With the aid of light- and electron- microscopic immunocytochemistry, somatostatin- and luliberin (LRF)-positive fibers can be demonstrated in the rat subfornical organ (SFO). Each of the neurohormones has a specific location: LRF in the lateral parts of the organ, and somatostatin in the center of the posterior zone. Common to both neurohormone-containing fibers is the pattern in which they reach the organ as well as the fact that their terminals are located in the perivascular spaces of fenestrated vessels, i.e., within the limited neurohemal regions of the organ. Since injection of India ink of different colors demonstrates that the capillary bed of the SFO is connected with the central capillaries of the choroid plexus, the question arises as to whether the neurohormones released in the area of the SFO influence the choroid plexus.Supported by the Deutsche Forschungsgemeinschaft (Grant Nr. Kr 569/3) and Stiftung Volkswagenwerk     

Transplantation of the rat pineal organ to the brain: pinealocyte differentiation and innervation

Summary The pineal organ of neonatal rats was transplanted to the frontal part of the cerebral cortex or the cerebral interhemispheric fissure of an isogenic adult rat to determine whether pineal differentiation and pinealopetal innervation are affected by aberrant neuronal influences. Transplants were fixed for immunohistochemistry at 1, 2 and 6 months after transplantation. When treated with an anti-serotonin antibody, cells in transplants from both locations showed intense immunoreactivity and a morphology comparable to intact pinealocytes, indicating that the transplanted pinealocytes had differentiated normally. Tyrosine hydroxylase immunohistochemistry revealed that new catecholamine fibers of central nervous origin extended only into the periphery and not into the core of transplants grafted within the cortex. However, numerous catecholamine fibers were found in transplants placed in the interhemispheric fissure. These fibers were often accompanied by blood vessels, suggesting that they derived from sympathetic ganglia. Serotonin fibers, which are densely distributed in the cerebral cortex, were seldom found to enter transplants from both locations. These observations indicate that pineal cells express their characteristic properties even when transferred to a foreign milieu and that they do not receive novel innervation from the central nerves that normally do not innervate the intact pineal body; the transplant thereby retains the property of selective pinealopetal innervation.