Andrés S. Mendoza

Morphological studies on the rodent main and accessory olfactory systems: The regio olfactoria and vomeronasal organ

The present study on the main olfactory system (MOS) and the accessory olfactory system (AOS) documents the functional morphology of the rodent olfactory region and that of the vomeronasal organ (VNO) using light and electron microscopical techniques. Special attention is given to the cytoarchitecture of the sensory epithelia, i. e. the olfactory epithelium (OE) of the regio olfactoria and the neuroepithelium of the VNO (VNO-NE). Both sensory epithelia consist of a pseudostratified columnar epithelium composed of three types of cells, i. e. receptor cells, supporting cells and progenitor cells. Even at the light microscopical level, however, distinctive morphological features can be distinguished which illustrate important differences between the two sensory epithelia. For example, the height of the respective epithelia differs considerably, the VNO-NE is approximately 170 microns tall and the OE is only about 90 microns. The receptors of the VNO-NE lack olfactory knobs which are typically found in the sensory cells of the OE. The perikarya of the receptor cells of the VNO-NE are very large when compared to those of the sensory cells of the OE. In contrast to the OE, blood vessels are found within the neuroepithelial layer of the VNO. The progenitor cells of the OE are located in a clearly distinguishable cell layer which is lacking in the rodent VNO-NE. The differences between the two epithelial layers become more obvious at the electron microscopical level. The olfactory knobs of the sensory cell dendrites of the OE reach the nasal cavity with numerous cilia. These olfactory hairs, on average 11 per knob, consist of a short proximal segment and a long and thin distal segment. This distal segment runs parallel to the epithelial surface and is embedded in the neuroepithelial mucosal layer. The dendrites of the receptor cells of the VNO-NE reach the lumen of the VNO with numerous branched microvilli which are also embedded in the mucous layer. Horizontal ultrathin sections through the apical portion of the OE reveal that each supporting cell completely envelopes several dendrites. This glia-like relationship is not found in the corresponding layer of the VNO-NE. The sensory cell perikarya of the OE contain only a few endoplasmatic reticulum (ER) profiles while the receptor cells of the VNO are characterized by an extensive smooth endoplasmatic reticulum (SER). In contrast to the fila olfactoria, numerous axons within the vomeronasal nerve show ellipsoidal varicosities without synaptic vesicles which may indicate the existence of at least two vomeronasal nerve fibers.(ABSTRACT TRUNCATED AT 400 WORDS)

The vomeronasal organ of the New World monkey Saguinus fuscicollis (Callitrichidae). A light and transmission electron microscopic study

The vomeronasal organ (VNO) of the New World monkey Saguinus fuscicollis (Callitrichidae) is located at the base of the most distal portion of the nasal septum opening into the nasal portion of the ductus nasopalatinus which also communicates with the oral cavity. The lumen of the VNO is limited medially and laterally by a neuroepithelium which is devoid of intraepithelially located blood vessels and composed of receptor, supporting and basal cells. Ultrastructural analysis of the VNO of Saguinus fuscicollis reveals morphological features which lead one to postulate the functional capacity of this organ in these primates. A possible mechanism through which scent marks may be incorporated into the VNO is discussed.

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

SummaryThe 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.

The cell coat of the developing olfactory epithelium in the chick

SummaryDuring development of the olfactory epithelium in the chick embryo, the cell coat is revealed by treatment with Ruthenium red. On day 4 of incubation the developing sensory epithelium displays a thicker apical and basal cell coat than the neighbouring head ectoderm. The lateral cell coat is of equal thickness in both epithelia. The apical cell coat of the olfactory epithelium increases in thickness from day 4 to day 19 of embryonic life, finally attaining a thickness of about 55 nm.

Lektinhistochemische Untersuchungen an der Regio olfactoria und am vomeronasalen Organ von Ratte und Goldhamster

Summary The present investigation describes the lectin-binding properties of the regio olfactoria ( RO ) and thevomeronasal organ ( VNO ) of the rat and golden hamster. Especial attention is paid to the lectin-binding properties of the chemosensory epithelia as well as to the reactions of their specific glands. The following lectins were used: wheat germ agglutinin ( WGA ), horseshoe crab agglutinin ( LPA ), gorse agglutinin ( UEA I ), peanut agglutinin ( PNA ), soybean agglutinin ( SBA ), and horse gram agglutinin ( DBA ). Lectin-binding procedure was performed on paraffin sections of the RO and VNO using the peroxidase-antiperodixase method. Comparisons of the lectin-binding properties of the surface of the main olfactory epithelium ( MOE ) with that of the neuroepithelium ( NE ) of the VNO as estimated by the intensity of staining demonstrate that in both species differences exist between the lectin-binding properties, of the MOE and VNO-NE. Moreover, some reactions of the MOE and VNO-NE differ from species to species.

The morphology of xenotransplanted human breast carcinoma MX-1 growing in nude mice. A light and transmission electron microscopic study.

The present investigation is concerned with the morphological features of the human breast carcinoma MX-1, transplanted subcutaneously into nude mice. Three weeks after transplantation the tumor tissue is clearly distinct from the dermis. Solid tumor cell groups are separated incompletely by thin connective tissue septa, giving rise to a lobular appearance. The tumor cells are characterized by very irregularly formed nuclei with three or more nucleoli. The cytoplasm of these cells displays some lysosomes, the cisternae of the rough endoplasmic reticulum, mitochondria and a variable number of ribosomes. The Golgi fields are frequently observed, particularly near the nucleus. The cells are connected to each other by desmosomes, which also persist during mitotic activity. Ductular formations can occasionally be seen. The ultrastructure of the blood vessels discloses the morphological features necessary for the regulation of blood flow. Capillaries present a sinusoidal aspect with distended and narrow lumina. Interruptions of the endothelial wall, however, were not observed. This morphological appearance was found in all the MX-1 tumors investigated, reflecting the stable growth of this tumor cell line in nude mice.

Storage lesion of human platelets as revealed by ultrathin sections and freeze-fracture replicas

We report the ultrastructural changes occurring in human platelets during eight days of storage. Extension of pseudopodia is frequently observed, but a concentration of organelles in the centre of the platelets is found only in a minor fraction (∼5%). Striking changes can be observed in both the granules and the open canalicular system. In fresh platelets, the latter often has the form of stacked membranes that have no lumen, but these membranes separate and spread with increasing storage time. However, the openings of this system on the outer surface of the platelet remain unchanged. Some of these features differ from the morphological description of platelets activated by thrombin or ADP, and suggest that the storage lesion is the result of a prolonged weak activation that leads to an incomplete release reaction within the first five days.

Postnatal changes in the ultrastructure of the rat olfactory epithelium: the supranuclear region of the supporting cells

SummaryThe present electron-microscopical study reports ultrastructural changes occurring in the supranuclear region of the supporting cells of the rat olfactory epithelium during the first 16 days of postnatal life. These changes are concerned with the enclosure of receptor cell dendrites and an increase in the amount of smooth endoplasmic reticulum, which has a specific distribution in the supporting cell. An increase in microvillous projections at the free cell surface is also observed. Moreover, this report demonstrates that the cytoarchitecture of the apical portion of the olfactory epithelium at the 16th day of postnatal life is similar, with respect to the relationship between supporting cells and receptor cell dendrites, to that of adult animals.

Treatment with the anti-tumor drugs, cis-platin and mafosfamide, does not affect the structure of prekinetochores in a human breast cancer cell line. An immunofluorescence study using human anticentromere autoantibodies

The goal of the present article was to determine whether a nuclear parameter, centromere structure of interphase cells, could serve as an indicator to assess cellular damage caused by anti-tumor drugs. These were cis-platin and mafosfamide, which are widely used for the management of solid tumors. To visualize the centromeres, we probed treated and untreated cells of a human breast cancer cell line, MX-1, with a human anti-centromere serum. The serum was obtained from a scleroderma patient and detects antigens associated with prekinetochores of the decondensed chromosomes. The DNA was simultaneously displayed by a specific fluorescent dye. The cells were grown on coverslips, incubated for 1 h in a drug-containing medium, transferred into a drug-free medium and observed 24 h later. Since the efficiency of many anti-tumor drugs increases with the temperature, two different temperatures, 37 and 42 degrees C, were used. The analysis revealed that the treatment did not visibly alter the labeling pattern. We conclude that chromosome structure remains largely intact and is not suitable for the cytological evaluation of the efficiency of anti-tumor drugs. This is in contrast with, for example, the microtubular cytoskeleton and mitochondria, which were extensively damaged under the conditions applied here (compare Wolf et al. 1995). Independent of the drug and the temperature selected, the nuclear lumen of mononucleated and multinucleated cells contained small fluorescent spots. Double dots corresponding to the sister centromeres in the G2 phase of the cell cycle were rare. In addition to the voluminous nuclei, some cells possessed micronuclei in the lateral cytoplasm and these were regularly labeled by the autoantibodies. A small subset of the mononucleated MX-1 cells had unusually large nuclei. It is reasonable to assume that they are polyploid. The fluorescent spots marking the prekinetochores were very large in these cells. This may indicate that the chromosomes remain associated after replication.

The Effect of Ifosfamide on Tumor Oxygenation at Different Temperatures

In MX1 human breast cancer xenografts grown on the hind paw of thymusaplastic nude mice the effect of ifosfamide on tumor oxygenation, tumor pH and the concentration of lactic acid have been determined at mean tumor temperatures of 32 degrees C, 37 degrees C and 41 degrees C. For histological studies tumors were shock-frozen or fixed with formalin or glutaraldehyde. Treatment with Ifosfamide (250 mg/kg b.w.) reduced intratumoral laser Doppler flow, oxygenation and pH. This suggests that ifosfamide or its metabolites may have an effect on tumor vasculature.