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PubMed1997

Lymphatic system of the mouse diaphragm: morphology and function of the lymphatic sieve.

BACKGROUND: The diaphragm has a unique system that collects peritoneal fluid and carries it into the lymphatic system. However, our understanding of the morphology and function of this system is still incomplete. METHODS: Twelve C57BL/6 mice of 13 to 25 weeks of age were used without regard to sex. In one series of experiments, the diaphragm was isolated and fixed 10-15 minutes after injection of india ink into the peritoneal cavity and then the peritoneal mesothelium was peeled off from the submesothelial connective tissue. The lymphatic vessels attached to the mesothelial strip were examined by scanning electron microscopy. The diaphragm was also observed in plastic-embedded semithin and ultrathin sections. In another series of experiments, the diaphragm was stained by 5'-nucleotidase histochemistry (Wachstein and Meizel, 1957a. Am. J. Clin. Pathol., 27:13-23), and several microdrops of india ink were placed on the peritoneal or pleural surface to reveal the profile of the lymphatic vessels. RESULTS: The lymphatic vessels on the peritoneal side of the diaphragm were flattened. They usually ranged from several to 100 microns in width and from close to zero to a few micrometers in thickness. In other words, they formed extremely flat lumina, differing from the more usual tubular lymphatic vessels. Several lymphatic vessels extended radially and parallel to one another from the central tendon to the thoracic wall, with numerous connecting branches, forming an area of lymphatic vessels. The india ink that had been injected intraperitoneally and the staining with 5'-nucleotidase revealed that there were seven to nine such lymphatic areas in one hemisphere of the diaphragm. The lymphatic areas spread in parallel with the peritoneal surface of the diaphragm and all the areas together appeared to occupy more than half the surface area of the sternocostal part of the diaphragm. Each area was a relatively distinct functional unit with respect to the draining of india ink. Microdrops of india ink placed on the pleural surface did not enter the lymphatic vessels, while those placed on the peritoneal surface immediately entered the peritoneal lymphatic vessels and migrated to the pleural lymphatic vessels via the transmuscular lymphatic branches. CONCLUSIONS: The peritoneal lymphatic vessels of the diaphragm have extremely flat lumina that spread in parallel with the peritoneal surface of the diaphragm and form a lymphatic sieve that covers approximately half or more of the surface area of the sternocostal region for drainage of fluid and particulate matter from the peritoneal cavity. The lymphatic system has been characterized by the presence of openings (= stomata) to the peritoneal cavity and the amplitude of the lumina (= lacunae). However, the fundamental characteristic of the system is the extremely flat lumen (= vadum), which facilitates the formation of the lymphatic sieve.

Animals↗
PubMed1975

Eccrine sweat gland tumor of clear cell origin involving the eyelids.

A 47-year-old patient with an unusual tumor involving the right upper and lower eyelids has been followed for almost 6 years. The tumor has remained localized to the eyelids and has recurred locally following attempts at complete or partial excision. The morphological features of the tumor as seen by ordinary light microscopic methods were puzzling, and resulted in a variety of pathologic diagnoses. Light microscopic examination of plastic-embedded semithin sections, and electron microscopic examination indicate that this is a hitherto undescribed eccrine sweat gland tumor of clear cell origin. Its infiltrative growth pattern and tendency to local recurrence suggests that it may be a low-grade malignant neoplasm.

Eyelid Neoplasms↗
PubMed1979

Terminal deoxynucleotidyl transferase positive lymphoblastic lymphoma: a study of 15 cases.

The investigation was undertaken to define the features of lymphoblastic lymphoma. Fifteen lymph node biopsies from a group of 82 specimens studied for the enzyme terminal deoxynucleotidyl transferase (TdT) fulfilled morphological criteria for this diagnosis. These criteria required a diffuse infiltrate of relatively uniform, immature lymphoid cells with basophilic cytoplasm; round, oval or lobulated nuclei with evenly dispersed chromatin; rare or inconspicuous nucleoli; and numerous mitotic figures. Examination of 1-micron thick, plastic-embedded, Giemsa-stained tissue sections revealed convoluted nuclei in more than 50% of neoplastic cells in four cases: in six specimens there was an admixture of cells with grooved, hyperlobulated, and round nuclei, and in five the round or oval nuclei were non-convoluted. Specimens from all 15 patients were positive for TdT by fluorescent antibody and biochemical assays. The percentage of cells from involved nodes reacting by indirect immunofluorescence with an antiserum against bovine TdT ranged from 4 to 90% (mean of 52%), and the mean level of biochemically measured enzyme activity was 8.7 units/g of tissue (range of 1.9 to 27.5). Cytochemical stains for acid phosphatase were positive in 13 of the 15 cases. In eight samples more than 50% of cells formed rosettes with sheep erythrocytes, while the E rosettes varied from 14 to 38% in the other seven. The percentage of cells with complement receptors varied widely (range of 6 to 80), but cells bearing surface immunoglobulin or IgGfc receptors were not increased. All patients presented with supradiaphragmatic lymphaedenopathy, eight with an anterior mediastinal mass. Two-thirds of the patients were male, and the mean age was 20 years (range 4 to 46 years). None were leukemic at the time of diagnosis, but eight patients subsequently developed acute lymphoblastic leukemia. Involvement of the central nervous system was observed in four of the 15, and of the testes in two. Ten patients have died of their disease with a median survival of 8 months (range 4 to 20), and five are alive 3--8 months after diagnosis. We observed no differences in clinical findings at presentation, incidence of mediastinal involvement or leukemic dissemination, content of TdT, acid phosphatase staining, or immunologic cell surface characteristics between the convoluted and non-convoluted types of lymphoblastic lymphoma. Distinctive morphologic, cell surface, biochemical, and clinical features of lymphoblastic lymphoma can be identified irrespective of the presence or absence of convoluted nuclei.

Acid Phosphatase↗
PubMed1982

Dark epithelial cells in preneoplastic lesions of the human respiratory tract.

Dark epithelial cells, previously identified in preneoplastic lesions of rat tracheae induced with chemical carcinogens, were observed in similar lesions in human airways and investigated using plastic-embedded material from the lungs of 21 autopsy cases. The lesion types and the percentage of dark cells in their basal layers were as follows: squamous metaplasia without atypia = 13 +/- 3%, squamous metaplasia with slight atypia = 13 +/- 3%, squamous metaplasia with moderate atypia = 26 +/- 5%, squamous metaplasia with severe atypia = 27 +/- 4%, and carcinoma in situ = 34 +/- 11%. Notwithstanding a technical complication caused by differences in fixation and embedding procedures, it was possible to detect an increase in the number of dark cells in human preneoplastic lesions that was directly proportional to the degree of atypia. This increase points to the importance of these cells in neoplastic development and indicates that, regardless of their nature, the number of dark cells can be used as an indicator of the degree of atypia.

Animals↗
PubMed1990

Macrophage invasion and phagocytic activity during lens regeneration from the iris epithelium in newts.

Following removal of the lens through the cornea, early stages of lens regeneration from the dorsal iris of the adult newt, Notophthalmus viridescens, were studied using light and electron microscopic observations on sectioned, plastic-embedded irises. Specimens were fixed in Karnovsky's fixative every 2 days from 0 to 12 and 15 days after lentectomy. Infiltration of the iris epithelium by macrophages and their phagocytosis of melanosomes and small fragments of iris epithelial cells were observed. These macrophages were characterized by coarse nuclear chromatin, numerous mitochondria, free ribosomes, granular endoplasmic reticulum, Golgi complexes, vesicles, lysosomes, and phagosomes containing ingested melanosomes. Lamellipodia of varying length projected from their surface. Most of the cells lying on or close to the posterior surface of the iris could be identified as macrophages by these criteria. During this period, there was enlargement of the intercellular spaces within the iris epithelium. The iris epithelial cells near the margin of the pupil elongated, lost their melanin pigment and some associated cytoplasm, and acquired abundant free polyribosomes to form a lens vesicle of depigmented cells.

Animals↗
PubMed1992

Expression of sarcomeric myosin in the presumptive myocardium of chicken embryos occurs within six hours of myocyte commitment.

The distribution of sarcomeric myosin heavy chain (MyHC) has been examined immunocytochemically in the presumptive myocardial cells of chicken embryos (stages 6-10) prior to the onset of the heart beat. Embryos were stained with monoclonal antibody MF20, a reagent which recognizes all chicken sarcomeric MyHCs (Bader et al., 1982), and then examined both in whole mount by immunofluorescence and in semithin, plastic-embedded sections following immunoperoxidase labeling. We observed that myosin could be detected as early as stage 7 (0-2 pairs of somites) in 29% of the 31 embryos examined, and by stage 8 (4 pairs of somites) more than 80% of the embryos were MF20+. Every embryo with 5 pairs of somites (stage 8+) labeled strongly with MF20. Labeling was first detected at stage 7 to 7+ as a diffuse fluorescent signal within pleomorphic cells of the splanchnic mesoderm located in two crescent-shaped regions bordering each side of the anterior intestinal portal (AIP). With progressive development, the two crescent-shaped regions merged at the apex of the AIP, and as the two heart tubes began fusion at stage 9, the MyHC+ regions extended cranially and medially. By somite stages 9-10, the myosin-positive cells completely encircled the heart tube. From stages 7 to 9 the myosin signal had no sarcomeric distribution; i.e., there were no MyHC striations nor periodic repeats evident in the presumptive myocytes until late stage 9 and stage 10. Semithin sections revealed that myosin was first distributed in apical regions of the myocytes, adjacent to the pericardial coelom. The implications of these findings for myocyte determination, differentiation and morphogenesis are discussed.

Animals↗
PubMed1986

Comparative evaluation of bone marrow aspirate particle smears, biopsy imprints, and biopsy sections.

Bone marrow aspirate particle smears, biopsy imprints, and biopsy sections were compared to determine the accuracy of the three samples in assessing for overall cellularity, differential cell count, megakaryocyte density, iron stores, and tumor infiltration. Aspirate particle smears and biopsy imprints were stained by Wright-Giemsa method. Aspirate particle smears were also stained with Prussian-blue. Biopsy sections were 1 1/2-2 micron thick and were prepared from non-decalcified plastic embedded samples and stained with combined Prussian-blue-hematoxylin-eosin, and Giemsa. One hundred-eight sets of specimens from 99 patients were examined. In 20 cases, chi-square analysis showed a comparable degree of cellularity (p less than 0.001) and megakaryocyte density (p less than 0.001) among the three preparations. Differential count comparison by regression analysis indicated that mean percentages of neutrophilic cells in the proliferation compartment were comparable in the three groups (p less than 0.01). A better correlation was obtained among the three groups in the percent neutrophilic cells in the maturation-storage compartment, normoblasts, eosinophils, and plasma cells (p less than 0.001). Lymphocytes in the aspirate smears correlated with the biopsy imprints (p less than 0.01) but not with the biopsy sections (p greater than 0.05). Monocytes did not correlate in any of the groups (p greater than 0.05). In 47 cases, chi-square analysis of iron stores in the aspirate particle smears correlated well with those in the biopsy sections (p less than 0.001). Fifty-two marrows that were done for staging nonhematological malignancies revealed malignant cells in 21 cases, biopsy sections were positive in all, biopsy imprints were positive in 19 (90%), and aspirate particle smears were positive in 7 (33%). Thirty-six marrows done for staging non-Hodgkin's lymphoma showed malignant cells in 13 cases. Twelve (92%) biopsy sections, three (23%) biopsy imprints, and nine (69%) aspirate particle smears contained lymphoma cells. In conclusion, a satisfactory evaluation of marrow samples for diagnostic studies can be achieved by examination of biopsy sections along with aspirate particle smears or biopsy imprints. Any of the three marrow preparations alone is not sufficient for accurate diagnosis in all cases. The biopsy imprint is an accurate modality for identifying nonhematological tumor metastasis in the bone marrow.

Biopsy↗
PubMed1992

Selective accumulation of aluminum and iron in the neurofibrillary tangles of Alzheimer's disease: a laser microprobe (LAMMA) study.

We report the results of an examination of the elemental content of neurofibrillary tangle-bearing and neurofibrillary tangle-free neurons identified within the hippocampus of 10 subjects with Alzheimer's disease and 4 neuropathologically intact age-matched control subjects. The study employed laser microprobe mass analysis (LAMMA), a technique that provides extremely sensitive multielement detection in plastic-embedded, semithin-sectioned tissues. Evidence for the selective accumulation of aluminum within the neurofibrillary tangle-bearing neurons was obtained in all 10 subjects with Alzheimer's disease. The site of aluminum deposition within these cells was the neurofibrillary tangle itself, and not the "nuclear region," as we previously reported. Iron accumulation was also detected within neurofibrillary tangles. Evaluation for the accumulation of other elements within the tangle-bearing neurons failed to reveal any other metallic element as being consistently present. In addition, probe sites directed to neurons identified in snap-frozen cryostat sections from 2 subjects with Alzheimer's disease revealed similar spectra with prominent aluminum-related peaks, confirming that our findings are not related to exogenous contamination through fixation, embedding, or other procedures prior to analysis. This study further confirms the association of aluminum and neurofibrillary tangle formation in Alzheimer's disease.

Aluminum↗
PubMed1992

Comparative techniques for determining cellular iron distribution in brain tissues.

Iron is essential for a number of normal brain functions and accumulates in high concentrations in specific regions of the brain. In pathological states, it may further accumulate in these and other areas that are typically low in iron content. The contribution of excess iron to potential central nervous system damage through its ability to donate an electron and to promote oxygen free radical formation has made the nature, location, extent, and process of iron deposition in the brain important areas of investigation. Nevertheless, there is relatively little information currently available on the cellular and subcellular distribution of iron in the central nervous system in either normal or diseased states. We describe and compare a number of the currently available techniques by which iron can be detected within the cellular components of the brain. Histochemical approaches, primarily in the form of the Perls' stain, yields information only on iron in its ferric state and is a relatively insensitive technique. Electron microscopy with x-ray spectrometry can provide positive identification of iron but has limitations regarding morphological verification of the specific cells being probed and also has a relatively high lowest detection limit. Secondary ion mass spectrometry and proton-induced x-ray spectrometry are both expensive, highly complex techniques with greater detection sensitivity, but they have problems identifying the cellular components being analyzed. Finally, laser microprobe mass analysis combines histological localization and identification of probe sites in plastic-embedded histological sections with detection limits in the single part per million range.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1975

Pathways of clearance in mouse lungs exposed to iron oxide aerosols.

The history of particle clearance was studied in lungs of mice serially sacrificed at intervals up to 14 months following single exposures to an aerosol of submicronic, particulate, iron oxide used as a similitude for atmospheric dust. Clearance was followed by light microscopy in unstained and Prussian blue stained frozen and plastic embedded sections, as well as by electron microscopy, where iron oxide can be recognized by its form. Related problems were investigated through histochemical demonstration of acid phosphatase activity in pulmonary lysosomes and Prussian blue staining of various tissues after administration of iron compounds by gastrointestinal and vascular routes. The iron particles settle extensively but not uniformly on pulmonary alveolar surfaces. Clearance is centripetal and involves two mechanisms, an extracellular mechanism fed by fluid currents sweeping across the surfcace, and cellular mechanism principally involving alveolar macrophages. In the early post exposure period both actively remove deposited particles predominantly through the pulmonary airways. By 24 hours uncleared residues have become ingested and clearance thereafter results mainly from cellular action. Macrophages enter bronchial passages where they sometimes continue to pursue normal activities. A chronic phase of clearance begins when deposited particles become sequestered in macrophages of pulmonary connective tissues. These cells are reached by several routes, not least by crossing the bronchial epithelium. Particle clearance from these macrophages is very slow, and residue-containg cells eventually congregate in lymphoid tissues surrounding major bronchi. These findings are discussed as they help to develop an overall picture of clearance from the lungs and as they bear on related topics, such as functional roles of alveolar and pulmonary connective tissue macrophages and the pathogenesis of chronic bronchial disease.

Acid Phosphatase↗
PubMed1982

Carbonic anhydrase histochemistry in rabbit and mouse kidneys.

The presence of carbonic anhydrase activity in rabbit and mouse kidneys was examined using a histochemical procedure with plastic embedded sections stained by the modified version of the cobalt-phosphate method (Hansson, 1967, 1968; Ridderstrale, 1976). Proximal convoluted tubules (S1 and S2 segments) in both species were strongly positive for carbonic anhydrase activity on the membranes of the luminal, lateral, and basal surfaces. The apical cytoplasm beneath the brush border and the nuclei also stained positively for carbonic anhydrase. The S3 segment (pars recta) of the proximal tubule in the rabbit was positive on the luminal membrane, with somewhat less intensity seen on the lateral and basal surfaces. This segment in the mouse was completely negative. The first part of the thin limbs of long-looped nephrons exhibited strong staining in the mouse. Faint luminal staining was present on descending thin limbs of short-looped nephrons in the mouse. In the rabbit, both the medullary and cortical ascending thick segments of the limb of Henle were completely negative. In contrast, the medullary and cortical ascending thick limbs in the mouse kidney showed staining on all plasma membranes. The intercalated cells in the cortical and medullary portion of the collecting tubules stained positively for carbonic anhydrase in both species. The principal cells of the collecting duct in the cortex were negative in the rabbit and faintly positive in the mouse. The principal cells in the upper medullary collecting tubules in both species stained intensely along the luminal, lateral, and basal cell membranes. The papillary collecting ducts were largely negative in both the rabbit and the mouse. Some interstitial cells in the rabbit in the region of the papillary tip were strongly positive. We conclude that there is a marked difference in carbonic anhydrase activity within and between the renal tubular segments of the rabbit and the mouse. In addition, these distinct differences that exist between the two species correlated with known physiological roles in ion transport.

Animals↗
PubMed1987

Electron microscopic immunostaining of nerve growth factor: secretagogue stimulated submandibular glands.

Immunocytochemical localization of nerve growth factor (NGF) was assessed on thin sections of plastic-embedded male mouse submandibular glands by electron microscopy. Both control and secretagogue-stimulated glands were examined. NGF was localized in granules of both granular convoluted tubule (GCT) cells and transition cells. The latter were intermediate in morphology between GCT cells and striated duct cells. Both large and small granules were immunostained in GCT cells; however, considerable variability in immunostaining intensity was observed in both sizes of granules but especially in the small granules of transition cells. Rough endoplasmic reticulum (RER) in both cell types exhibited NGF immunoreactivity. No Golgi-associated immunostaining was observed. Following alpha-adrenergic stimulation with phenylephrine, NGF-containing granules were sharply reduced because of extensive degranulation. Pools of immunostained secretory material suggested intracellular fusion of NGF-containing granules. Immunostaining was also observed on membrane fragments found within large vacuoles in GCT cells. Evidence of NGF secretion after beta-adrenergic or cholinergic stimulation was less dramatic. In isoproterenol-stimulated GCT cells there was evidence of fusion of small, apical, NGF-stained granules. These cells also possessed heavily immunostained apical membrane blebs. Pilocarpine-stimulated cells exhibited pleomorphic immunostained apical granules but less apical membrane immunostaining. Abundant basal lysosomes appearing in GCT cells after pilocarpine stimulation did not stain for NGF.

Animals↗
PubMed1991

Ultrastructure of the human erythrocyte cytoskeleton and its attachment to the membrane.

We attached paraformaldehyde-fixed human erythrocyte ghosts to coated coverslips and sheared them to expose the cytoskeleton. Quick-freeze, deep-etch, rotary-replication, or tannic acid/osmium fixation and plastic embedding revealed the cytoskeleton as a dense network of intersecting straight filaments. Previous negative stain studies on spread skeletons found 5-6 spectrin tetramers intersecting at each actin oligomer, with an estimated 250 such intersections/microns 2 of membrane. In contrast, we found 3-4 filaments at each intersection and approximately 400 intersections/microns 2 of membrane. Immunogold labeling verified that the filaments were spectrin, but their lengths (29-37 nm) were approximately one-third that of extended spectrin dimers. The length and diameter of the filaments were sufficient to accommodate spectrin dimers, but not spectrin tetramers. Our results suggest that, in situ, spectrin dimers may associate as hexamers and octamers, rather than tetramers. We present several explanations that can reconcile our observations on intact cytoskeletons with previous reports on spread material. Extracting sheared ghosts with solutions of low ionic strength removed the cytoskeleton to reveal projections from the cytoplasmic surface of the membrane. These projections contained band 3, as shown by immunogold labeling, and they aggregated to a similar extent as intramembrane particles (IMP) when the cytoskeleton was removed, suggesting a direct relationship between these structures. Quantification indicated a stoichiometry of 2 IMP for each cytoplasmic projection. Cytoplasmic projections presumably contain other proteins besides band 3 since further treatment with high ionic strength solutions extracts peripheral proteins and reduces the diameter of projections by approximately 3 nm.

Actin Cytoskeleton↗
PubMed2001

Layer V in cat primary auditory cortex (AI): cellular architecture and identification of projection neurons.

The cytoarchitectonic organization and the structure of layer V neuronal populations in cat primary auditory cortex (AI) were analyzed in Golgi, Nissl, immunocytochemical, and plastic-embedded preparations from mature specimens. The major cell types were characterized as a prelude to identifying their connections with the thalamus, midbrain, and cerebral cortex using axoplasmic transport methods. The goal was to describe the structure and connections of layer V neurons more fully. Layer V has three sublayers based on the types of neuron and their sublaminar projections. Four types of pyramidal and three kinds of nonpyramidal cells were present. Classic pyramidal cells had a long apical dendrite, robust basal arbors, and an axon with both local and corticofugal projections. Only the largest pyramidal cell apical dendrites reached the supragranular layers, and their somata were found mainly in layer Vb. Three types departed from the classic pattern; these were the star, fusiform, and inverted pyramidal neurons. Nonpyramidal cells ranged from large multipolar neurons with radiating dendrites, to Martinotti cells, with smooth dendrites and a primary trunk oriented toward the white matter. Many nonpyramidal cells were multipolar, of which three subtypes (large, medium, and small) were identified; bipolar and other types also were seen. Their axons formed local projections within layer V, often near pyramidal neurons. Several features distinguish layer V from other layers in AI. The largest pyramidal neurons were in layer V. Layer V neuronal diversity aligns it with layer VI (Prieto and Winer [1999] J. Comp. Neurol. 404:332--358), and it is consistent with the many connectional systems in layer V, each of which has specific sublaminar and neuronal origins. The infragranular layers are the source for several parallel descending systems. There were significant differences in somatic size among these projection neurons. This finding implies that diverse corticofugal roles in sensorimotor processing may require a correspondingly wide range of neuronal architecture.

Animals↗
PubMed1979

Spiral ganglion cell counts in an age-graded series of rat cochleas.

Spiral ganglion cells in the cochleas of Sprague-Dawley rats in various age groups were counted in order to assess the extent and location of cell degeneration with age. Cells in every tenth section of serially sectioned plastic embedded cochleas were counted in the light microscope. The median cell number for the 1- to 2-month-old animals was 15,800 cells. This number was first seen to be significantly reduced (-14%) in the 23-month-old animals. At 27 to 29 months the ganglion cell number was reduced by 20%, while at 33 to 34 months there was a 17% loss. Losses were found throughout the length of the ganglion with the greatest losses at the lower basal and apical ends. In the oldest group, these losses amounted to 28% and 33%, respectively. Type II ganglion cells first showed a significant decrease in number in the 27- to 29-month-old group, when a 32% loss was seen. The same loss was seen in the 33- to 34-month-old group. Unlike the type I cells which are lost throughout the length of the ganglion, type II cells were not significantly reduced in number at the basal end, but decreased by as much as 42% in the middle and apical regions.

Age Factors↗
PubMed1981

Neurogenesis in the 3-month-old rat visual cortex.

Newly formed neurons in the adult mammalian neocortex have been reported by several investigators using light microscopic radioautography, but these reports have not been confirmed by electron microscopy--probably because their rarity precludes any reasonable chance of observing these cells with electron microscopic radioautography. To overcome this problem I have used a recently developed method that allows serial thin sectioning and subsequent electron microscopic examination of plastic-embedded sections previously prepared for light microscopic radioautography. Ninety-day-old rats were injected with 4.3 microCi per gm body weight of [H3] thymidine and allowed to survive for 30 days. In the light radioautographs, labeled cells were found in layer IV of the visual cortex, and analysis of electron micrographs of selected examples of these labeled cells clearly demonstrated their neuronal nature wit synapses along their cell bodies and dendrites. In order to quantify the relative frequency of labeled neurons, the number of labeled cells seen in the light microscopic sections was expressed as a percentage of the total number of neurons found in sections through the entire thickness of the visual cortex; the percentage was 0.011%, or about 1 in 10,000. The results of this study are in agreement with evidence of neurogenesis of granular neurons in the adult rat olfactory bulb and dentate gyrus (Kaplan and Hinds, '77). Thus, it has now been confirmed that relatively small labeled neurons and their synapses are found in at least 3 brain regions (olfactory bulb, dentate gyrus, and visual cortex) in a normal adult rodent.

Animals↗
PubMed1981

Age- and position-dependent effects of monaural acoustic deprivation in nucleus magnocellularis of the chicken.

The effect of a moderately severe monaural conductive hearing loss on the development of neuronal size in the avian nucleus magnocellularis (NM) was investigated. NM is considered to be the homologue of the mammalian anteroventral cochlear nucleus and receives large calyceal synaptic endings from the cochlear nerve. Silicone plastic earplugs which produce a 40 dB broadband conductive hearing loss were placed in one external auditory canal of chick embryos on the 18th day of incubation. After hatching, all animals were housed in communal brooders and sacrificed at 4, 10, 25, and 60 days of age. Nissl-stained sections from paraffin- and plastic-embedded brains were used to sample neuronal cross-sectional areas in NM on the deprived and nondeprived sides of the brain. These samples were obtained separately in each brain from three posterior-to-anterior percentage quartiles within NM. Statistical analyses of these data showed that the severity of deprivation-induced cell size changes in NM varied as a function of both age and position. In the 4- and 10-day groups, no significant deprived-versus-nondeprived differences in neuronal size were seen in any area of the nucleus. At 25 days after hatching, only the third posterior-to-anterior quartile (i.e., 50-74%) showed a significant difference; this difference was also significantly greater than those in the second and fourth quartiles at this age. By 60 days, all three sampled areas in NM showed highly significant differences (averaging 12%) in mean neuronal cross-sectional area. Cell size values from the deprived and nondeprived sides of 60-day-old experimental animals were also compared with values from 60-day-old control subjects. Whereas the deprived NM cells were significantly smaller than controls, there was no evidence for a reliable hypertrophy in the nondeprived cells. Thus, the principal effect of the acoustic deprivation produced was to retard continued growth of the deprived neurons after 4 days of age.

Animals↗
PubMed1984

Partial characterization of lectin binding sites of retinal photoreceptor outer segments and interphotoreceptor matrix.

We have used cytochemistry together with exoglycosidase digestion and polyacrylamide gel electrophoresis to partially characterize lectin binding sites of the interphotoreceptor matrix and of photoreceptor outer segments. In order to obtain uniform access of reagents to all regions of the preparation, we have used a procedure in which plastic sections are etched with sodium ethoxide prior to cytochemical analysis. Neuraminidase pretreatment of plastic-embedded sections of Xenopus laevis eyecups leads to a loss of wheat germ agglutinin binding and a concomitant appearance of Ricinus communis agglutinin binding to the interphotoreceptor matrix. In contrast, wheat germ agglutinin binding to the outer segments is not altered by the neuraminidase pretreatment. These results suggest that wheat germ agglutinin binding sites of interphotoreceptor matrix are sialoglyconjugates and that outer segment binding sites are not sialoglycoconjugates. Enzyme digestions followed by lectin cytochemistry of matrix polypeptides separated by polyacrylamide gel electrophoresis do not identify a likely candidate to give rise to the cytochemical staining patterns. Lectin cytochemistry of retinas from which the interphotoreceptor matrix has been extracted do not show a loss of wheat germ agglutinin binding sites to the matrix. These results suggest that the major wheat germ agglutinin binding sites in the interphotoreceptor matrix are to as yet unidentified sialoglycoconjugates.

Animals↗