A scanning electron microscopic study of the human ovarian surface epithelium: characterization of two cell types

The surface of the ovary has two types of epithelial cells. We have called these A and B cells and they are found in their own respective zones (A and B). To assess the scanning electron microscopic features of these cell types, 65 ovarian samples were collected from biopsies taken from 35 women with normal ovaries. Biopsies included developing follicles, corpora lutea and ovarian capsules. Type A cells were cuboidal and sometimes tall, with a mean diameter of 6.49 microns, and a mean density of microvilli of 6.48/microns 2. Type B cells, on the other hand, were flat squamous cells with broader and flat apices with mean diameters and microvillus density of 11.71 microns and 3.88/microns 2 respectively. The A and B zones were common to all surfaces including the distending follicle. Type A cells overlying the distended surface of a follicle had a mean diameter of 7.03 microns compared to a mean of 6.05 microns for the capsular surface. Type B cell diameters and the microvillus density of both types were more variable and did not differ significantly over any of the surfaces. We suggest that previous human studies which identified flattening of cells over the distending follicle were probably observing B cells. The relationship of the B zones to papillae and surface bridges on the ovarian surface, and the association of these with ovulation sites, suggests that B cells are probably metaplastic cells derived in response to chronic surface injury with ovulation.     

Quantitation of structural features characterizing weight- and less-weight-bearing regions in articular cartilage: A stereological analysis of medical femoral condyles in young adult rabbits

The structural organization of articular cartilage from the medial femoral condyle of young adult rabbits has been examined after processing according to an improved fixation procedure. By using recently developed stereological methods, a quantitative analysis of chondrocyte number, surface area, volume, and matrix volume per cell was carried out in the light microscope; at the electron microscopic level, quantities of cytoplasmic components within chondrocytes (including organelles) were estimated. These measurements were made for each of the four zones from the (articular cartilage) surface down to the tidemark, and the results (for each zone) were compared between weight- and less-weight-bearing regions. In general, articular cartilage revealed considerable heterogeneity in structure throughout its depth. The number of cells per unit volume is maximal beneath the surface and decreases towards the tidemark. The size of chondrocytes, and the mean matrix volume surrounding each, increases from the surface toward the deeper zones. Comparison between weight- and less-weight-bearing regions reveals striking differences. The numerical volume density of cells in the superficial zone of regions bearing high physiological load is less than half of that in less-weight-bearing regions, chondrocyte death being principally responsible for this reduction. A comparison between the midzones of weight- and less-weight-bearing areas reveals that the former is characterized by a decrease in cell density and an approximately threefold increase in cell size in relation to the latter. The increase in cell volume is attributable principally to an accumulation of intermediate filaments and glycogen particles, and represents an adaptation to increased functional requirements. Near the tidemark, numerical volume densities of chondrocytes in both weight- and less-weight-bearing locations are similar, but the larger cell size in the former still persists.     

Quantitation of structural features characterizing weight- and less-weight-bearing regions in articular cartilage: a stereological analysis of medial femoral condyles in young adult rabbits

The structural organization of articular cartilage from the medial femoral condyle of young adult rabbits has been examined after processing according to an improved fixation procedure. By using recently developed stereological methods, a quantitative analysis of chondrocyte number, surface area, volume, and matrix volume per cell was carried out in the light microscope; at the electron microscopic level, quantities of cytoplasmic components within chondrocytes (including organelles) were estimated. These measurements were made for each of the four zones from the (articular cartilage) surface down to the tidemark, and the results (for each zone) were compared between weight- and less-weight-bearing regions. In general, articular cartilage revealed considerable heterogeneity in structure throughout its depth. The number of cells per unit volume is maximal beneath the surface and decreases toward the tidemark. The size of chondrocytes, and the mean matrix volume surrounding each, increases from the surface toward the deeper zones. Comparison between weight- and less-weight-bearing regions reveals striking differences. The numerical volume density of cells in the superficial zone of regions bearing high physiological load is less than half of that in less-weight-bearing regions, chondrocyte death being principally responsible for this reduction. A comparison between the midzones of weight- and less-weight-bearing areas reveals that the former is characterized by a decrease in cell density and an approximately threefold increase in cell size in relation to the latter. The increase in cell volume is attributable principally to an accumulation of intermediate filaments and glycogen particles, and represents an adaptation to increased functional requirements. Near the tidemark, numerical volume densities of chondrocytes in both weight- and less-weight-bearing locations are similar, but the larger cell size in the former still persists.     

Morphometric study of normal and adenomatous pituitary somatotrophs in humans

Somatotrophs from ten pituitary adenomas were evaluated morphometrically by light and electron microscopy using the following parameters: a) nuclear, cytoplasmic and cell volumes; b) volume density, total volume, surface density, total surface and surface/volume ratio of secretory granules, mitochondria, rough endoplasmic reticulum and Golgi apparatus, and c) the number of secretory granules and mitochondria per micron3 of cytoplasm and per cell. The results were compared (p less than 0.05 and p less than 0.10) with those obtained from somatotrophs identified in five normal pituitaries. The data obtained indicate that: a) in the adenomas, the number of secretory granules per cell cannot be accurately evaluated from their apparent number in sectioned cell profiles; b) there are two basic sub-types of adenomatous somatotrophs defined according to the mean secretory granule diameter; cells in which granule diameter is inferior to 180 nm exhibit distinct morphological features such as nuclear pleomorphism, the presence of gross bundles of intermediate sized filaments or fibrous bodies in the cytoplasm and a variable number of secretory granules. Adenomas constituted mainly by these cells were found in younger patients, suggesting the more aggressive nature of these tumours, thus warranting close clinical follow-up of such patients; and c) in both types of adenomatous cells, the organelles directly involved in the secretory process, i.e., the rough endoplasmic reticulum and Golgi apparatus, are larger than in the control cells; however, the ratio between the surfaces of these two compartments does not differ among the three groups studied.     

Stereologic analysis of monocytes and their subcellular organelles in patients with acute monocytic and myelomonocytic leukemia

The stereologic characteristics of monocytes from patients with acute nonlymphocytic leukemia containing a monocytic component (FAB M4 and M5), and the monocytes from normal individuals were determined by morphometric analysis. The cells studied were monocytic cells beyond the promonocyte stage of development, as defined by ultrastructural criteria. Parameters evaluated included cell and nuclear volumes and surface areas, mitochondrial and myeloperoxidase (MPO)-positive secretory granule volume and numerical density as well as volume and number of the organelles/cell. Peripheral blood and bone marrow monocytes of leukemic patients could not be distinguished by their cell or organelle stereologic characteristics. Monocytes from patients with both M4 and M5 acute leukemia had relatively large cell and nuclear volumes. Mitochondrial volume density and volume/cell were also high in monocytes from leukemic patients (M4; 21 microns 3/cell, M5 20 microns 3/cell) as compared with monocytes from normal individuals (8.5 microns 3/cell). On the other hand, MPO-positive secretory granule stereologic parameters in monocytes from leukemic patients were indistinguishable from those of normal individuals. A small number (3 of 18) patients showed very low monocyte MPO-positive granule volume densities. There was a slight positive correlation between MPO-positive granule volume density and patient survival time. No relationship between mitochondrial characteristics and survival was noted.     

Electron microscopic, biochemical and physiological studies of Bifidobacterium pseudolongum SS-24 and Bifidobacterium thermophilum SS-19

Comparative studies of physiology, biochemical characteristics, and morphology by electron microscopy were conducted on Bifidobacterium pseudolongum SS-24 isolated from dogs and Bifidobacterium thermophilum SS-19 isolated from swine. Both B. pseudolongum and B. thermophilum grow unusually rapidly in the rumen fluid medium of Scott and Dehority, and reached a maximum of optical density after only 6 to 7 h of incubation. B. pseudolongum and B. thermophilum showed similar patterns of results for 21 biochemical characteristics tested, with a difference found only for N-acetyl-glucosaminidase. Scanning electron micrographs revealed that B. pseudolongum produced extensive amounts of extracellular material. The cell walls of B. pseudolongum and B. thermophilum were totally different. Transmission electron micrographs of ruthenium red-stained preparations of B. pseudolongum showed a very thick (ca. 0.2 microns) Gram-positive cell wall, whereas B. thermophilum was found to have a thin (ca. 0.05 microns) Gram-positive cell wall.     

Avian lower intestine adapts to dietary salt (NaCl) depletion by increasing transepithelial sodium transport and microvillous membrane surface area.

A tissue sampling scheme for tandem assessments of whole-organ physiology and ultrastructure was applied to the lower intestine (coprodaeum) of White Plymouth Rock hens on low- and high-NaCl diets. The objective was to correlate net amiloride-sensitive Na transport determined using the Ussing chamber with the plasma membrane surface areas due to microvilli at the epithelial cell apex. Hens kept on the low-NaCl diet for 3-4 weeks displayed a substantial increase in short-circuit current and in total microvillous membrane surface area. The latter rose from a group mean +/- S.E.M. of about 90 +/- 9.7 cm2 to one of 200 +/- 38 cm2 per organ. An increase in epithelial cell membrane contributed to, but did not fully explain, the increase in microvillous area. No differences in mean cell height or mean cell volume were found but the average cell in the low-NaCl birds was better developed in possessing a greater surface area of microvilli. On the high-NaCl diet, the epithelium was 33 +/- 2.7 microns tall and contained about 270 +/- 15 million cells. Each cell had a volume, on average, of 540 +/- 59 microns 3 and a microvillous surface of 32 +/- 2.6 microns 2. After NaCl depletion, there were 420 +/- 75 million cells and the average microvillous surface was 49 +/- 5.3 microns 2 per cell. The morphological adaptations alone do not explain the increased net Na transport found on the low-NaCl diet. Of cardinal importance is greater density of open Na channels in apical cell membranes.     

Application of stereological analysis of cell volume to isolated myocytes in culture with and without adrenergic innervation.

A three-dimensional analysis to evaluate structural changes in cultured cardiac myocytes following adrenergic innervation was performed using stereological techniques formerly limited to cells in tissue and organs. Cell volumes were calculated for two groups of cells at 96 hours in culture: isolated myocytes and myocytes innervated with adrenergic neurons. Relative and absolute volumes of the nucleus, cytoplasm, and cell were quantified by systematically sampling sections throughout the cell and by point count sampling techniques. Volumetric estimates were similarly determined for the mitochondria, sarcomeres, and other cellular components in the cytoplasm. Data were analyzed with ANOVA and randomized block design to control for variation among the cultures. Adrenergic innervation produced a 44% increase in cell volume, X +/- SEM, (3,344 +/- 196 microns3 to 4,816 +/- 400 microns3, P = 0.007). The absolute volume of mitochondria significantly increased after innervation (521 +/- 42 microns3 to 744 +/- 54 microns3, P less than 0.01). Absolute sarcomere volume did not change significantly (750 +/- 92 microns3 to 642 +/- 1061 microns3, P = 0.14). Other cellular components, defined as all cytoplasmic components except mitochondria and sarcomeres, significantly increased with innervation (1,739 +/- 166 microns3 to 3,097 +/- 338 microns3, P = 0.02). The relative volume of the nucleus and the cytoplasm in the cell remained unchanged following innervation. However, the relative volume of mitochondria decreased by 6%, the percent of the cytoplasm occupied by the sarcomeres decreased by 44%, and the volume occupied by the other cellular components increased by 22%. These findings support the use of stereological analysis as a means to quantify cell volumes of cultured myocytes.(ABSTRACT TRUNCATED AT 250 WORDS)     

A quantitative analysis of rat adrenal chromaffin tissue: Morphometric analysis at tissue and cellular level correlated with catecholamine content

A morphometric analysis of normal Wistar rat adrenal medulla following perfusion fixation and Araldite embedding, was correlated with catecholamine levels on fresh tissue, measured by high-performance liquid chromatography. The mean volume of whole adrenal is 13.2 mm³ and the mean medullary volume 1.3mm³. Volume density estimates showed that the medulla is composed of 63% chromaffin tissue with an adrenaline to noradrenaline storing cell ratio of 4.4:1. The vasculature occupies 20%, neuronal tissue 5% and interstitial tissues 12% of the medulla. A comparison was made of cell volumes, cell numbers and volume and surface density estimates of cytoplasmic organdies in adrenaline and noradrenaline storing cells. The mean cell volume of adrenaline storing cells at 1300 μm³ is larger than that of noradrenaline storing cells at 980 μm³. A single adrenal medulla contains4.4−5.7 × 10⁵ adrenaline cells and1.5−1.9 × 10⁵ noradrenaline cells. Chromaffin granules account for approximately 30% of the volume of the cytoplasm; the numerical density of granules at different sites in the cell was calculated for adrenaline cells. The volume density of mitochondria (4%) and the surface density of mitochondrial membranes (the ratio of outer to inner membrane being approximately 1:2.3) were similar in both cell types. Rough endoplasmic reticulum was the only organelle to show a significant difference in volume and surface density between the two cell types. Adrenaline storing cells have stacks of rough endoplasmic reticulum which have two to three times the surface and volume densities of that found diffusely scattered throughout noradrenaline cells. The adrenaline content of an adrenaline storing cell is0.14 × 10⁻⁶ μM and that of a granule 3.0 × 10⁻¹² or3.8 × 10⁻¹² μ moles depending on the method of calculation. The noradrenaline content of noradrenaline storing cells can only be calculated on the assumption that all noradrenaline is stored in this cell type though it is likely that some is contained within adrenaline cells. Based on this assumption the noradrenaline content is0.17 × 10⁻⁶μ moles per cell and5 × 10⁻¹² μ moles per granule. The present study provides baseline morphometric data on the rat adrenal medulla at tissue and cellular level correlated with amine levels in adrenaline and noradrenaline storing cells and granules.     

Early morphologic changes in cat heart muscle cells after acute coronary artery occlusion.

The left descending coronary artery (LAD) was occluded in 16 open-chest cats for 10, 20, 40, or 60 minutes (four cats in each group). In addition, four sham-operated cats served as controls. Specimens for electron microscopy were obtained from the normal and ischemic zones, guided by in vivo injection of fluorescein, and verified by blood flow measurements with microspheres. The ultrastructure of 2,400 heart muscle cells and nuclei was studied. Fractional volumes of main cell components, mitochondrial surface density, and mitochondrial surface: volume ratio were calculated in 480 micrographs. After 10 minutes of ischemia we observed signs of sarcolemmal fragility, mitochondrial swelling, and lipid droplet accumulation. After 20 minutes of ischemia sarcolemmal fragmentation, chromatin clumping or margination and a maximal cytoplasmic edema were evident. The fractional volume of mitochondria was equally increased in ischemic zones of all groups. In both normal and ischemic zones there was a tendency toward smaller fractional volumes of lipid droplets during ischemia. In the normal zone there was mild cytoplasmic edema and slight mitochondrial swelling 10 minutes after occlusion as compared with the sham group. The present study demonstrates that a large proportion of cardiac myocytes undergoes severe damage within 20 minutes of coronary occlusion.     

The interstitial cells of Cajal of the rat stomach. A light and electron microscope study

Interstitial cells of Cajal (ICC), presumed to have a smooth muscle-like nature and to play a pacemaker role, are usually identified for their peculiar ultrastructural features and specific location throughout the gut muscle wall. A Zinc-Iodide-Osmium (ZIO) impregnation for ICC identification under the light microscope has been proposed. However, controversies as to certain ICC identification under both light and electron microscopes are still present, due to their ultrastructural features somewhat similar to the fibroblast ones and the low specificity of the ZIO-staining. The rat stomach has been studied. Some specimens have been routinely processed for electron microscopy, some others have been ZIO-impregnated and further routinely processed for both light and electron microscopy, in order to assure that all the cells presumed to be ICC for their ZIO-staining affinity are the same cells identified as ICC with routine electron microscope procedures, and not fibroblasts. The routine electron microscope examination made it possible to identify within the rat gastric muscle coat two cell populations, one with the same location and morphology as those reported in literature for the gastric ICC, and a second one with a similar location, but showing undoubted fibroblastic features. ZIO-staining, under both light and electron microscopes, revealed ZIO-stained cells distributed within the muscle coat in a manner identical to that of the ultrastructurally identified ICC. Under electron microscope examination, this cell type only was fully impregnated by the zinciodide deposits, whereas all other cell types, including fibroblast-like cells, were devoid of them. These data confirm that ICC can be electively ZIO-stained and that these cells and fibroblasts are two distinct cell types, as ultrastructural and physiological reports had previously suggested.     

Immunocytochemical localization of four hormones in the pancreas of the garter snake, Thamnophis sirtalis

Insulin, glucagon, somatostatin, and pancreatic polypeptide (PP) were localized in the pancreas of the common garter snake, Thamnophis sirtalis, by light and transmission electron microscopic (TEM) immunocytochemistry. Colloidal gold-protein A was used for TEM localization and the peroxidase--antiperoxidase complex technique was used for light microscopy. The glucagon-containing A cells and the insulin-positive B cells were the most numerous cell types. The somatostatin-containing D cells made up about 15% of the endocrine cells. PP-positive F cells were a minor cell type. The only topographic arrangement of the cells within the endocrine-rich areas that was apparent was the peripheral localization of the D and F cells. Cells of a specific cell type were sometimes grouped together. At the electron microscopic (EM) level, the gold particles (indicating the presence of hormone) were localized nearly exclusively over the secretory granules of the reactive cells. The alpha-granules were the largest found and were predominantly electron dense with a moderately electron-dense periphery. PP-containing granules were the smallest. The somatostatin-reactive delta-granules were round and moderately electron opaque. The beta-granules were heterogeneous in appearance. The morphognomy of the secretory granules of the major endocrine cell types is qualitatively similar to that of mammals. Whether or not the quantitative and/or associative differences contribute to the marked metabolic differences between reptiles and mammals, remains to be determined.     

Electron microscope study of PNH red cells and AET-treated normal red cells (PNH-like cells)

The morphology of red cells damaged by 2-aminoethylisothiouronium bromide (AET) has been compared to that of PNH cells by transmission and scanning electron microscopy. The main features of the effect of AET as demonstrated by the scanning electron microscope were spherical and deformed cells, with surface craters and relatively large pits. The transmission electron microscope revealed loss of surface structure, an unusual amount of irregularly shaped electrondense material and fine pits in the cell membranes. The paroxysmal nocturnal haemoglobinuria cells showed, by transmission electron microscope, electron-dense material scattered over the cell and fine pitting; by scanning electron microscope, larger craters were seen and swellings protruded from the cell surface. Although the AET changes were not identical with the natural abnormality of paroxysmal nocturnal haemoglobinuria, the two types of cells were sufficiently similar to each other to support the proposition that AET cells have many of the characteristics of paroxysmal nocturnal haemoglobinuria.     

A light and electron microscopic study of the effects of surface topography on the behavior of cells attached to titanium-coated percutaneous implants

Previous studies using light microscopy have demonstrated that micromachined grooved surfaces inhibit epithelial (E) downgrowth and affect cell orientation at the tissue/implant interface. This study investigates the ultrastructure of the epithelial and connective-tissue attachment to titanium-coated micromachined grooved, as well as smooth control, implant surfaces. V-shaped grooves, 3, 10, or 22 microns deep, were produced in silicon wafers by micromachining, replicated in epoxy resin, and coated with 50-nm titanium. These grooved, as well as smooth, titanium-coated surfaces were implanted percutaneously in the parietal area of rats and after 7 days processed for electron microscopy. The tissue preparation technique used in this study enabled us to obtain ultrathin sections with few artifacts from the area of epithelial and connective-tissue attachment. The histological observations demonstrated that E cells closely attached to, and interdigitated with, the 3-microns and 10-microns grooves. In contrast, E cells were not found inside the 22-microns-deep grooves and made contact only with the flat ridges between the grooves. As a general rule, fibroblasts (F) were oriented parallel to the long axis of the implants and produced a connective tissue capsule with 3-microns and 10-microns-deep grooved surfaces as well as smooth surfaces. On the 22-microns-deep grooved surfaces, however, F inserted obliquely into the implant. The attachment of F to the titanium surface was mediated by two zones; a thin (approximately 20 nm), amorphous, electron dense zone immediately contacting the titanium surface, and a fine fibrillar zone extending from the amorphous zone to the cell membrane. As oblique orientation of F has been associated with the inhibition of epithelial downgrowth, micromachined grooved surfaces of appropriate dimensions have the potential to improve the performance of percutaneous devices.     

Intercellular communication between rat anterior pituitary cells

Cell-to-cell communication within the rat anterior pituitary was investigated in 60-day-old male rats with immunohistochemistry, scanning electron microscopy, freeze-fracture electron microscopy, and conventional transmission electron microscopy. A dense cytoreticular network of cytoplasmic processes from the folliculostellate cells was found to contain immunoreactive S-100 protein and was observed throughout the anterior pituitary. Nonimmunoreactive cells, which were granular, were situated in the center of each network. Almost all of the granulated cells were situated in close proximity to the folliculostellate cells. Scanning electron microscopy revealed that the gland consisted of microlobules enclosed by a basal lamina. On the surface of the microlobules were blood vessels whose branches invaded its internal structures. Cytoplasmic processes from folliculostellate cells projected outside the microlobule. Freeze-fracture electron microscopy demonstrated the presence of numerous intramembranous particles on the P-face of the plasma membrane. Scattered on the cell surface were groups of particles forming gap junctions. Meshworks of ridges which were representations of tight junctions were also observed near clusters of microvillous fragments. Clusters of particles forming small gap junctions were located between the meshworks of tight junctions. Small gap junctions were clearly observed by conventional electron microscopy between junctional complexes in a manner similar to that seen by freeze-fracture electron microscopy. Slender cytoplasmic processes of folliculostellate cells came in contact near the basal lamina and were adjoined by small gap junctions. The ratio of nongranular cells which contained gap junctions to those in which the junctions were absent was about 1:1. The size of the gap junctions ranged from 50 nm to 3 microns. No gap junctions were observed along the plasma membranes of the granular cells. The significance of an intercellular communication system within the anterior pituitary gland of the rat is to establish a mechanism for rapid transmission of information in an organ which lacks direct innervation.     

Mathematical study of size distribution of alveolar mononuclear cells (CMA) in man]

The mathematical study using the Wicksell transformation of the size distribution of the mononuclear alveolar cells has shown two different populations among the alveolar macrophages obtained from 4 adult men. These two types of cells could be also found out and described by electron microscopy. The large cells (14 microns in diameter) looked like the "alveolar macrophage ", with many phagolysosomes. The small cells (7 microns in diameter), less numerous (1/3 of the whole population) resembled monocytes. These data in man are compared to those found in rabbits and the role ot two kinds of cells is discussed.     

Ultrastructure of the interstitium in the rabbit kidney

Kidneys from six male New Zealand white rabbits were fixed by perfusion, and the interstitium of all zones was studied by light and electron microscopy. The volume and amount of the basic components varied not only between cortex and medulla, but within each zone itself. Two main cell types were found in the cortical interstitium, the first appeared to be morphologically identical with a fibroblast, although it contained frequent surface depressions. The second cell type was of the mononuclear series, the most frequent of which was characterized by abundant free ribosomes and was frequently wrapped by processes of fibroblasts. Although collagenous fibrils, basement membrane-like material, and flocculent electron-dense material have previously been described in the interstitium of other animal species, this paper describes the presence and distribution of microfibrils approximately 150 Å in diameter with electron-lucent cores throughout the entire kidney interstitium and discusses the distribution of globular deposits which may represent glycosaminoglycans in the various zones of the kidney.     

Electron microscopy of surface structures ofBlastocystis sp. from different hosts

Samples ofBlastocystis sp. obtained from humans, monkeys, pigs and chickens were examined by scanning electron microscopy and transmission electron microscopy to compare surface structures. The surface coat ofBlastocystis sp. cells from each host species showed some morphological variations, but these were not sufficiently different to allow judgement to be made on speciation. The surface structure morphology appeared similar for samples ofBlastocystis sp. from the same host species. The surface coat of the cultured human isolate ofB. hominis was much thinner than that of cells from fresh human faecal material, and the cell surface appeared to be smoother and without the small projections seen in the fresh forms. Bacteria were frequently found in association with the surface coat ofBlastocystis sp. from all fresh faecal material. Possible functions of the surface coat, especially in relation to protection against osmotic shock, are discussed.     

The adrenal cortex in spontaneously hypertensive rats. A quantitative ultrastructural study.

The adrenal cortex of spontaneously hypertensive rats (SHR) has been examined by quantitative morphologic techniques for electron microscopy. The volume and surface area of smooth endoplasmic reticulum and the volume of Golgi apparatuses in zona glomerulosa cells of SHR was significantly greater than those of Wistar-Kyoto strain (W/KY) normotensive controls; the volume of lipid droplets and nucleus was significantly less in SHR than in W/KY animals. A stimulation of the zona glomerulosa in SHR may well be attributable to the elevation in systolic blood pressure. A distinct lipid-free subglomerulosa was observed in the adrenal gland of W/KY rats; the cell volume was similar to that of the zona glomerulosa although the cells showed a significantly greater volume of mitochondria and surface area of mitochondrial membranes and greater volume of smooth endoplasmic reticulum and lysosomes. In the zona fasciculata, cell volume, volumes and surface area of mitochondria and smooth endoplasmic reticulum, and volume of lipid droplets were significantly lower in SHR than in W/KY rats. The volume of the Golgi apparatus was greater in SHR than in W/KY rats. Glycogen particles were observed in focal areas of some zona fasciculata cells. The adrenal cortex of another strain of normotensive Wistar rat (W/CFN) was compared with that of the W/KY and SHR. Although the relative adrenal weights of SHR and W/KY animals were identical, the weight of that in W/CFN was significantly smaller. The volume of the zona glomerulosa of SHR was significantly greater than that of W/KY although the volume of the zona glomerulosa in W/CFN was significantly greater than the other two groups. The volume of nucleus and lipid droplets of zona glomerulosa in W/KY was significantly greater than that in the S/CFN; the volume of the cell, mitochondria, smooth endoplasmic reticulum, lipid droplets, and lysosomes, and the surface area of smooth endoplasmic reticulum and mitochondrial membranes of W/KY animals was significantly greater than those of W/CFN animals. It is concluded that the W/CFN rat is not an appropriate control for spontaneously hypertensive rats.     

Allometric relationships of cell numbers and size in the mammalian lung.

Allometric studies have shown that lung volume, alveolar surface area, and diffusing capacity increase proportionally with body weight across a broad range of mammalian species. Changes in the number of cells and in average cell size and surface areas with increasing body weight have not been defined. We speculated that cell size is determined more by cell function than by species and body weight. To test this hypothesis, nine species ranging in size from shrew (2 to 3 g) to horse (510 kg) were studied. Random sites from the distal alveolar region of each species were analyzed using morphometric techniques. Six to 10 nuclei from each of the major classes of parenchymal lung cells were three-dimensionally reconstructed to determine their average diameter, volume, and surface area. To calculate the cell density, nuclear profiles were counted using electron microscopy. The number of cells per lung increased with body mass and lung volume with a slope of 1.01 (r2 = 0.99). The lung is unique among organs in the diversity and function of individual cell types, such as mechanical, sensory, secretory, transporting, and circulating cells. Excluding the circulatory cells, the lung has greater than 60 different cell types, making it an ideal organ for examining the varieties in cell characteristics across different species. Up to 6-fold differences in size were found between different lung cell types within a single species; however, for cells having secretory functions, such as type II cells, there was no detectable change in cell size with increasing lung surface area or body mass.(ABSTRACT TRUNCATED AT 250 WORDS)