bluuebunny/crossref_metadata_2025 huggingface dataset:
Modification of the phenotypic expression of murine dystrophy: A morphological study
Authors: Bourke Dianna L. , Ontell Marcia
Published: February 2005

The extensor digitorum longus muscles of 4–6‐week‐old normal mice (129 ReJ) and dystrophic mice (129 ReJ dy/dy) were orthotopically transplanted. Grafted muscles were examined 1, 3, 7, 14, 20, 50, and 100 days post‐transplantation. The myofibers of both types of grafts underwent a similar time course of necrosis and regeneration. Other than during the initial necrotic response, no evidence of necrotic myofibers was found in either type of grafted muscle. At 100 days post‐transplantation, the grafted normal and dystrophic muscles were essentially similar, except that the dystrophic graft was of smaller size. Based on a comparison of the number of myofibers found at the 100‐day grafts' widest girths [631 ± 59 SEM, for normal grafts (Bourke and Ontell, 1984); 631 ± 74 SEM, for dystrophic grafts], it is suggested that the regenerative capability of traumatized 4–6‐week‐old dystrophic muscle is similar to that of traumatized normal muscle. At 100 days post‐transplantation, the grafted dystrophic muscle appeared “healthier” than untraumatized muscle from age‐matched dystrophic mice, having less variation in myofiber diameter, better fascicular organization, and less connective tissue. The transplantation system demonstrates the possibility of modifying the expression of genetic programming of myopathic disorders using environmental manipulation.
Dynamic features of duct epithelial cells in the mouse pancreas as shown by radioautography following continuous 3H‐thymidine infusion
Authors: Tsubouchi Susumu , Kano Eiichi , Suzuki's H.
Published: February 2005

The possibility of turnover of the epithelial duct cells was examined in the adult mouse pancreas by radioautography following continuous administration of 3H‐thymidine for periods varying from 1 h to 60 days. One hour after an injection of 3H‐thymidine, the label observed in small and large ducts was low but increased with the duration of the continuous infusion of 3H‐thymidine and reached a level of about 67% cells labeled after 60 days. The rate of duct cell labeling was estimated from the regression line of the labeling index vs. time in four types of ducts classified according to their inner diameter and the presence of the adventitia and was given as 0.60% cells per day in small (adventitia‐free) ducts (π 4–12 μm), 0.89%, 1.02%, and 1.23% cells per day in large (adventitia‐including) ducts (π 15–29, 30–49, and 50–160 μm respectively). In contrast, the labeling index of aciner cells after a 60‐day infusion indicated an addition of only 0.02–0.07% per day, and that of islet cells 0.14–0.22% per day.

It is known that most parenchymal cells belong to either expanding or renewing cell populations. The acinar cells of the pancreas have been shown to constitute an expanding population, a conclusion confirmed by the low addition of cells observed in the present work. However, the relatively high rate of cell addition in the duct epithelia indicates that they may turn over in a period of 2.7 months in the case of large ducts and 5.6 months in the case of small ducts. It is proposed that the added cells replace cells carried away by the flow of pancreatic juice.
Focal tight junctions between mesenchymal cells of fetal dermis
Authors: Riddle Clara V.
Published: February 2005

This freeze fracture study shows the presence of focal tight junctions (maculae occludentes) between the mesenchymal cells in the connective tissue matrix of embryonic and fetal dermis. The overall outline of these unique junctions varies from circular to very angular. The junctional elements are most frequently present in a groove on the E fracture face. The corresponding P fracture face has ridges delineating the junction. These intercellular junctions may provide a means of informational or metabolic coupling between cells, may serve a structural role as scaffolding in the deposition and orientation of extracellular materials, or may be involved in the early stages of angiogenesis.
A method for explantation of selected areas of the neural retina
Authors: Carri Néstor G. , Ebendal Ted
Published: February 2005

A method of obtaining explants of selected areas of the embryonic neural retina is described. Small plugs of the tissue are sucked into a glass capillary tube connected to a micrometer syringe via flexible tubing. The plugs of tissue are separated into their components (neural retina, pigmented layer, and mesenchyme). Retinal explants so obtained have similar shape and size. Polarity of the explants is easily determined. The procedure is simple, rapid, and precise. The method is suitable for studies of retina based on explanted or transplanted tissue.
Ultrastructure of the secretory response of male mouse submandibular gland granular tubules
Authors: Hazen‐Martin Debra J. , Simson J. A. V.
Published: February 2005

The organization and fine structure of granular convoluted tubule cells (GCT) from male mouse submandibular glands have been examined in controls and in animals injected with adrenergic and cholinergic secretagogues. Control submandibular glands exhibited a single population of GCT cells with numerous homogeneous granules filling the apical two‐thirds of the cytoplasm. A zone of transition cells, exhibiting characteristics of both GCT and striated duct cells, was found between the agranular intercalated duct and GCT segments. These transition cells possessed apical granules of variable size as well as prominent basal striations.

Dramatic changes in the morphology of GCT cells followed administration of the α‐adrenergic agent, phenylephrine. The extensive degranulation involved formation of “secretory pools” of fused granules and release of secretory material into the lumen. The appearance of numerous smooth vesicles near luminal membranes suggested extensive membrane retrieval. Intracellular membrane‐limited aggregates of membrane fragments suggested that much of the retrieved membrane was destined for degradation. Rough endoplasmic reticulum was highly dilated but there was no indication of increased size or activity of the Golgi complex.

Ultrastructural evidence indicated that the secretory responses to isoproterenol, a β‐adrenergic agent, and to pilocarpine, a cholinergic agent, were much more modest, but it is clear that some secretory response to these agents does occur. The other cell types of the duct and tubule system did not exhibit comparable morphological changes in response to the agents used.
A proposed alveolar model for adult human lungs: The regular dodecahedron
Authors: Linhartová Alena , Caldwell William , Andersondr Augustus E.
Published: February 2005

In an endeavor to delineate an alveolar configuration that would reasonably mirror the natural state, polygonal shapes of normal alveoli were tabulated in histologic sections from inflation‐fixed specimens of 16 men aged 16–48 years. The resulting alveolar population varied from three‐ to ten‐sided polygons with a preponderance of tetragons, pentagons, and hexagons. These observations were compared with the possible combinations of polygonal sections through various polyhedral models proposed by other workers and the five classical regular polyhedrons. The potential types of sections through the regular dodecahedron, i.e., a twelve‐sided shape with faces consisting of pentagons, seemed to fit best with present findings, and this is suggested as an idealized configuration that might be useful in various geometric determinations, e.g., estimates of alveolar surface area and volume.
The development of the syrian hamster cheek pouch
Authors: Hardy Margaret H. , Vrablic Olga E. , Covant Howard A. , Kandarkar Shripad V.
Published: February 2005

The objective of this study was to provide a detailed account of the morphogenesis and early cytodifferentiation of the hamster cheek pouch. Although the newborn “cheek pouch” is used for in vitro studies of the effects of retinoids and carcinogens, its rudimentary structure has not been adequately described. Complete paraffin serial sections of the heads of 14‐ and 15‐day fetuses were cut in three planes to determine the location and shape of the earliest pouch rudiments. Complete paraffin serial sections were prepared from pouch rudiments dissected from hamsters at birth and at daily intervals from 3 to 12 days postnatal. Semithin Epon sections were examined by light microscopy and ultrathin sections by transmission electron microscopy. The pouch can appear in the fetus as two solid epithelial ingrowths from the lining of the oral cavity. They are the margins of an ingrowing sheet of oral epithelium which becomes leaflike at about the time of birth, as it grows caudad into the tissue of the cheek. The central cells of the ingrowth accumulate large quantities of glycogen before differentiating as a stratum spinosum 5 days after birth. Within the stratum spinosum, groups of cells containing keratohyalin granules initiate the stratum granulosum. Keratinized cells appear within the stratum granulosum areas. Spaces appear between keratinized cells, and the spaces coalesce to form the pouch cavity between 7 and 12 days postnatal. Soon afterward, this cavity opens to the oral cavity to make a pouch, and the ultrastructure of the cheek pouch epithelium closely resembles that of the adult.
Computer‐assisted morphometry using video‐mixed microscopic images and computer graphics
Authors: Curcio Christine A. , Sloan Kenneth R.
Published: February 2005

A microcomputer system has been developed for collection and analysis of morphometric data from video images of histological sections. Microscopic fields of view are visualized on a video monitor and are overlaid with computer‐generated graphics by means of a video mixer. Planimetric data are entered by drawing on a digitizing tablet while observing the drawn image superimposed on the tissue. Programs are available to calculate various geometric parameters, count objects in a field, perform descriptive statistics, and measure volume and surface area of a solid from a series of cross sections. A program for point‐counting stereology presents single points for scoring within a user‐defined reference area. The potential applications of interactive graphics in morphometry are discussed.
An ultrastructural study of the papillary layer and its vascular bed in the kitten enamel organ
Authors: Sasaki Takahisa , Garant Philias R.
Published: February 2005

Ultrastructure and three‐dimensional architecture of the papillary layer and associated capillaries in the enamel organ of 2–3‐month‐old kittens were examined by means of routine thin sections, freeze‐fracture, and scanning electron microscopy of the tissues digested by HCl‐collagenase and of vascular corrosion casts. Outwardly, the papillary layer formed gently sloping upheavals, but did not show prominent papillary ridges. The papillary cells were characterized by a high concentration of intramembranous particles on the plasma membrane P‐face, by numerous hemi‐annular gap junctions between the cell process of one papillary cell and the cell body of another host cell, and by annular gap junctional vesicles in the subsurface cytoplasm. Some annular gap junctions appeared partially degenerated. These findings led us to speculate that these annular gap junctions are produced by the endocytosis of gap junctional membranes from the cell surface into the subsurface cytoplasm.

Capillaries were distributed on the enamel organ within shallow furrows between the papillary upheavals. A part of these capillaries penetrated deeply into the enamel organ but did not contact the ameloblasts. The endothelial walls of the capillaries were pierced with many endothelial fenestrations, especially when facing the papillary layer. The endothelial cell also contained numerous micropinocytotic vesicles throughout its entire cytoplasm. These findings suggest that the papillary cells and associated capillaries are highly specialized for transport of solutes and molecules between the vascular region and the enamel organ during the phase of enamel maturation.
Glucose 6‐phosphatase activity in pregnant and lactating mammary glands of the mouse
Authors: Shugyo Yoshihiko , Watanabe Jun , Kanamura Shinsuke , Kanai Kazuo
Published: February 2005

Glucose 6‐phosphatase activity was studied in the secretory epithelial cell and other cell types composing alveoli of the mammary gland (cytochemical study) and in the whole mammary gland (biochemical study) of pregnant and lactating mice.

The reaction product for the enzyme activity was seen in the endoplasmic reticulum and nuclear envelope in secretory epithelial cells from all animals examined days 7 and 14 of pregnancy, and days 0, 3, 10, and 20 of lactation. The amounts of the reaction product appeared scarce at day 7 of pregnancy, moderate at day 14 of pregnancy and day 0 of lactation, and abundant at days 3 and 10 of lactation. The reaction product, however, became generally scarce at day 20 of lactation. Biochemical activity was relatively low at days 7 and 14 of pregnancy and days 0 and 20 of lactation, while it was high at days 3 and 10 of lactation.

The increased activity is probably related to functions of secretory epithelial cells in the lactating gland.
Clinical and anatomical observations of a two‐headed lamb
Authors: Fisher Kenneth R. S. , Partlow Gary D. , Walker Anne F.
Published: February 2005

The clinical and anatomical features of a live‐born diprosopic lamb are described. There are no complete anatomical analyses of two‐faced lambs in the literature despite the frequency of conjoined twinning in sheep.

The lamb had two heads fused in the occipital region. Each head had two eyes. The pinnae of the medial ears were fused. Caudal to the neck the lamb appeared grossly normal. The lamb was unable to raise its heads or stand. Both heads showed synchronous sucking motions and cranial reflexes were present. Nystagmus, strabismus, and limb incoordination were present. The respiratory and heart rates were elevated. There was a grade IV murmur over the left heart base and a palpable thrill on the left side. Each head possessed a normal nasopharynx, oropharynx, and tongue. There was a singular laryngopharnyx and esophagus although the hyoid apparatus was partially duplicated. The cranial and cervical musculature reflected the head duplications. The aortic trunk emerged from the right ventricle just to the right of the conus arteriosus. A ventricular septal defect, patent foramen ovale, and ductus arteriosus were present along with malformed atrioventricular valves. Brainstem fusion began at the cranial medulla oblongata between cranial nerves IX and XII. The cerebella were separate but small. The ventromedial structures from each medulla oblongata were compressed into an extraneous midline remnant of tissue which extended caudally to the level of T2. The clinical signs therefore reflected the anatomical anomalies. A possible etiology for this diprosopus might be the presence early in development of an excessively large block of chordamesoderm. This would allow for the formation of two head folds and hence two “heads.”.
Phenytoin‐induced connective tissue growth in the rat
Authors: Dill R. E. , Jones R. G. , Davis W. L.
Published: February 2005

Rats were treated daily for 9 days with 100, 50, or 25 mg/kg phenytoin i.p. This treatment resulted in a significant increase in the thickness of the connective tissue capsules of the liver, spleen, and pancreas, and of the subepithelial connective tissue of the mesentery but not the epicardium or visceral pleura of the lung where exposure to the drug was via the vascular route. Many areas of connective tissue growth exhibited obvious proliferation of fibroblasts and in some areas contained seemingly large numbers of macrophages and an increase in vascularity. It was demonstrated by electron microscopy that the macrophages occasionally were seen in intimate contact with the fibroblasts.

Our observations clearly showed that intraperitoneal exposure of visceral connective tissues of the rat to phenytoin rapidly resulted in a dose‐related proliferation of that tissue. The presence of numerous macrophages leads to the suggestion that macrophage‐derived growth factor could be responsible for the increased growth.
Cell‐cell matrix interactions in induced lung injury: III. Long term effects of X‐irradiation on basal laminar proteoglycans
Authors: Rosenkrans Wayne A. , Penney David P.
Published: February 2005

The lungs of male LAF1 mice were locally irradiated with doses of 5, 9, and 13 Gy. The animals were killed at times corresponding to the appearance of histologically identifiable fibrosis or, for 13 Gy, at the LD50 for these doses and strain of mouse: 63, 36, and 28 weeks postirradiation (PI) respectively. Lungs were excised, incubated in buffer alone, or partially digested with enzymes for determination of relative glycosidase resistance, fixed with ruthenium red/Triton X‐100 for demonstration of basal laminar anionic sites, and processed for electron microscopy. Sham‐irradiated and untreated control groups (0 Gy, 0 times) were also processed. Tissue was examined ultrastructurally and alterations in both alveolar and capillary basal laminar anionic sites were quantitated. In each of the doses examined the number of anionic sites surpassed normal levels; however, the glycosidase resistance of the regenerated laminae at these late time points was not significantly altered from controls. This contrasts with the marked increase in the glycosidase resistance of laminae regenerating from radiation damage (4–12 weeks PI) reported earlier. The increased numbers of anionic sites were compared to expected values derived from models based on compensatory synthesis and continued accumulation and indicate close correlation with certain aspects of the compensatory synthesis model but not with others. The effects on basal laminar permeability, basal laminar thickening, and fibrotic induction are discussed.
Immunohistochemical localization of calbindin‐D28k during the development of the rabbit nephron
Authors: McIntosh James E. , Bourdeau James E. , Taylor Alan N.
Published: February 2005

Specific antibodies raised against a 28‐kilodalton chick intestinal calcium‐binding protein (calbindin‐D28k) were used to localize the protein immuno‐cytochemically in the developing rabbit kidney. Kidneys taken from rabbits between the 13th embryonic and 17th postnatal day were examined. Calbindin‐D28k was observed in the mesonephric duct and the ureteral bud on the 13th embryonic day. During subsequent involution of the mesonephros, the ampullae of the metanephric ureteral buds contained calbindin‐D28k. The protein was gradually lost from the ureters and the deep interstitial collecting ducts. Calbindin‐D28k was never present in the renal vesicles derived from the nephrogenic blastema, but it was present in the connecting tubule segments during formation of the arcades. The last finding supports the belief that the connecting tubule is derived from the ureteral bud.
Alterations in muscle spindle morphology in advanced stages of murine muscular dystrophy
Authors: Ovalle William K. , Dow Pierre R.
Published: February 2005

Muscle spindles in the soleus of 1‐year‐old dystrophic mice of the C57BL/6J dy2J/dy2J strain were studied by microscopic and morphometric methods, and comparisons were made with those in age‐matched normal tissue. Transverse epon sections were cut through various regions of an individual receptor, and subsequent 90° reorientation enabled longitudinal examination of the same spindle. In dystrophy, alterations were detected in the outer capsule and consisted of a significant increase in its overall thickness in equatorial regions. Perineurial proliferation accompanied histiocyte and collagen infiltration. Within the equator, intrafusal fibers and sensory terminals appeared unaffected by dystrophy. Alterations in the intrafusal fibers were restricted to polar zones where the mean diameters of chain and bag fibers were significantly reduced. Polar chain fibers exhibited a greater degree of atrophy in dystrophy with a 40% diminution in size. Ultrastructural changes in intrafusal fiber polar regions were less pronounced compared to the surrounding dystrophic muscle. Mitochondrial alterations in affected intrafusal fibers included intramatrix inclusions and glycogen deposition. Vacuolization of the sarcoplasmic reticulum and subsarcolemmal tubular aggregates were also observed in polar regions of dystrophic chain fibers. Regional variation in spindle involvement in advanced murine dystrophy provides evidence that the equatorial contents of this receptor are sequestered from the deleterious effects of the disease. Capsular thickening in the equator may be an adaptive response, preventing the intrafusal fibers from undergoing the moderate change and atrophy observed at their polar ends.
Morphology and glycoprotein synthesis of uterine glandular epithelium in human basal plate at term: An ultrastructural and autoradiographic study
Authors: Nelson Michael D. , Ortman‐Nabi Judith , Curran Edward M.
Published: February 2005

This study describes the morphologic features of uterine glandular epithelium in human basal plate at term and identifies this epithelium as an active site of glycoprotein synthesis. Wedge biopsies were obtained from the basal plate at the time of repeat cesarean section from 11 normal pregnant patients at term. Biopsy specimens were either processed immediately for microscopic examination or incubated in vitro with 25μCi/cc of 3H‐galactose or 3H‐leucine. Tissues incubated with tritiated compounds (2‐hour pulse ± 3‐hour chase in nonradioactive medium) were either processed for light microscopic autoradiographic analysis or extracted for determination of trichloroacetic‐acid‐precipitable tritiated macromolecules in tissues and medium. Profiles of cuboidal‐columnar glandular epithelium were identified in the decidual component of the basal plate region adjacent to spiral arterioles and perpendicular to the inner layers of myometrial muscle. Autoradiographic and biochemical studies identified the glandular epithelium, as well as large decidual cells, to be major sites of incorporation of both 3H‐galactose and 3H‐leucine and to be prime sources for secretion of tritiated macromolecules that appeared in the medium during in vitro incubation of basal plate tissue. Ultrastructurally, the glandular epithelium was noted to rest on a basal lamina, to have lateral cell membranes with numerous desmosomes, and to exhibit an apical surface with microvilli projecting into a luminal space. Cytologic features of the cells included abundant profiles of rough endoplasmic reticulum, multiple mitochondria with lamellar cristae, a well‐developed perinuclear but nonpolarized Golgi apparatus, and nuclei containing predominantly euchromatin. Lipid droplets and glycogen deposits were present in some cells. This study indicates that uterine glands persist throughout human gestation in the basal plate and that these glands continue to be active in glycoprotein synthesis and secretion.
The distribution of 3H‐proline in alveolar bone of the mouse as seen by radioautography
Authors: Johnson Roger B.
Published: February 2005

Previous studies of the turnover of alveolar bone collagenous proteins have devoted little attention to the variable patterns in this process caused by bone remodeling. The present study seeks to document changes resulting from physiologic tooth movements in the incorporation and removal of the 3H‐proline label within the interdental septum of alveolar bone. One week following 3H‐proline injection, three zones could be distinguished: (1) the appositional band, (2) new bone, and (3) old bone. Radioautography demonstrated that formation of new bone on the distal wall of the septum entrapped fibers of the periodontal ligament to create Sharpey's fibers. At the alveolar crest, new bone entrapped transseptal fibers to form transalveolar Sharpey's fibers. Grain counts were made within each area and over the total septum and were compared statistically. The data strongly suggested regional variations in protein remodeling. Counts from old and new bone were significantly different from the total septum or the appositional band (P < .001). Regression lines were drawn to represent incorporation and removal of the isotope; slopes were calculated and compared statistically. The rate of incorporation and removal was significantly greater in the appositional band and in the total septum in comparison to old bone (P < .001). The rates of incorporation and removal in the appositional band, old bone, and total septum were significantly different (P < .001). Half‐life of the labeled protein of old bone was 16.78 weeks; in the appositional band, 7.66 weeks; and in the total septum, 7.64 weeks. These data suggest that regional variations in collagen remodeling must be considered in a study of interdental bone and that the total septal grain counts are not indicative of the remodeling in the component zones.
Rabbit endocervical epithelium: Morphometric analysis of secretory cell populations
Authors: Chilton Beverly S. , Sowinski J. M. , Barnes H. , McAllister C. J.
Published: February 2005

In this report we quantitated ultrastructural changes in two cytologically distinct secretory cell populations from the rabbit endocervix. Type I and type II cells from estrous animals differ only in the presence of one or more empty cytoplasmic vacuoles in type II cells. Comparing type II cells from 5‐day pseudopregnant (PSP) rabbits with type II cells from estrous controls, there is no increase (P>.05) in the average vacuole volume. When type I and type II cells from PSP animals are compared to cells from estrous controls, there is a decrease (P<.01) in the average cell volume, a decrease (P<.01) in the average nuclear volume, and a decrease (P<.01) in the average granule volume. This reduction in the granule content of secretory endocervical cells was correlated with a dramatic decrease in protein glycosylation into the microsomal fraction. Serum estradiol concentrations for estrous (13.7 ± 1.0 pg/ml) and PSP (18.1 ± 1.5 pg/ml) animals were comparable. However, the 36‐fold increase in serum progesterone concentrations for PSP (12.04 ± 1.7 ng/ml) animals compared to estrous (0.33 ± 0.1 ng/ml) animals may be responsible for the decrease in protein glycosylation.
Neuronal development in the trigeminal mesencephalic nucleus of the duck under normal and hypothyroid states: I. A light microscopic morphometric analysis
Authors: Narayanan Y. , Narayanan C. H.
Published: February 2005

Light microscopic morphometric procedures were used in order to examine the effects of propylthiouracil (PTU) on the development of the mesencephalic nucleus of the trigeminal nerve in the duck. A single vascular injection of a 0.2% solution of PTU was administered at a dosage of 2 μl/gm embryo weight on embryonic day nine (E9). Control embryos received a similar dose of Ringer's solution. The following parameters of cytodifferentiation of cells of the mesencephalic nucleus of V were studied: somal area profiles, nuclear area, and nuclear cytoplasmic ratios. In addition, the frequency of beak clapping was recorded from E16. Significant differences were observed in somal area profiles in the experimental group at E16 and E18 and in nuclear area profiles from E16 through hatching. Beak activity in the experimental embryos was drastically reduced. It is concluded that PTU induces a retardation in the differentiation of cells of the mesencephalic nucleus of V which may lead to behavior deficits as evidenced by reduction of beak activity. These observations provide a basis for the study of interactions between thyroid hormone and specific neuronal systems in the emergence of an adaptive function.
Maturation antigen of the mouse sperm flagellum: II. Origin from holocrine cells of the distal caput epididymis
Authors: Feuchter F. A. , Green M. F. , Tabet A. J.
Published: February 2005

During epididymal transit, the mouse sperm flagellum acquires a surface glycoprotein (SMA4) from epididymal fluid that functions as a sperm antiagglutinin. To determine the origin of this molecule, testes and epididymides of male mice were sectioned for light microscopy and stained with wheat germ agglutinin (WGA)‐peroxidase, a probe that has been used previously to examine the biology of SMA4. WGA reactivity was localized to the cytoplasm in a small population of cells in the distal caput epididymis. Testis cells and principle cells of the caput were nonreactive with WGA, while stereocilia were stained on principle cells in the corpus and cauda. The WGA‐positive cells in the distal caput were identified as holocrine cells on the basis of morphology, distribution, and PAS+ reaction. At high magnification, intense WGA reactivity was due to the presence of numerous apical granules in the cytoplasm. The location of the cells in distal caput coincided exactly with the region of tubule in which sperm first acquired SMA4 on their flagellae. These data suggest that holocrine cells near the junction of caput and corpus epididymis are the source of the sperm antiagglutinin SMA4.
Immunoultrastructural studies of human NK cells: II. Effector‐target cell binding and phagocytosis
Authors: Kang Yuan‐Hsu , Carl Mitchell , Watson Lorrita P. , Yaffe Lyn
Published: February 2005

The binding of NK cells to a target cell appears to be a necessary step for NK cell‐mediated cytolysis. In this report, we demonstrated effector‐target binding by immunoelectron microscopy by using monoclonal antibodies against NK cells (Leu‐7, Leu‐11a) and T‐cell subsets (Leu‐2a/T8, Leu‐3a/T4). The surfaces of NK and K562 cells were characterized by antitransferrin receptor antibody and various lectins. In addition, the controversial phagocytic activity of NK cells was studied by incubation of peripheral blood mononuclear cells with opsonized Staphylococcus aureus and labeling with anti‐Leu‐7 or anti‐Leu‐11a antibody. Results showed that only Leu‐11a+ cells displayed a broad cell‐to‐cell contact with the target by a shallow intercellular interdigitation of cytoplasmic projections, while Leu‐7+, Leu‐2a+, or Leu‐3a+ cells showed only a partial contact with target without interdigitation. The Leu‐11a+ cells were frequently observed in small clusters and in close association with monocytes. Cluster formation and association with monocytes were not observed in other NK and T‐cell immunophenotypes. In Leu‐11a+ cells conjugated with target cells, membrane‐bound granules, small vesicles, parallel tubular arrays, Golgi apparatus, endoplasmic reticulum, and small vacuoles were evident and concentrated toward the target. The surface of NK cells was intensely stained for glycoprotein by chromic acid‐phosphotungstic acid, whereas target cells were not stained. Transferrin receptors were stained only on the surface of target cells. Only the lectins RCA and UEA labeled the surfaces of both NK and target cells. Phagocytic vacuoles containing cell debris or fragments and ingested bacteria were found in the cytoplasm of Leu‐11a+ cells but not in Leu‐7+ cells. NK cells were also found within the cytoplasm of K562 target cells. All these findings suggest that Leu‐11a+ cells are the true functional NK cells involved in NK cell‐mediated cytolysis, phagocytosis, and emperipolesis. Therefore, the NK cell is probably “a phagocyte in lymphocyte's clothing.” The presence of peroxidase in the small vesicles of NK cells and endocytotic vesicles of target cells at the effector‐target contact area indicates that cytolytic enzymes or factors derived from NK cells may be transported into the target by endocytosis.
Differential technique to stain nerve cells and fibers in methacrylate sections
Authors: Toliva J. , Tolivia D.
Published: February 2005

A simple method for the simultaneous staining of nerve cells and fibers, applicable to sections of pieces embedded in methacrylate, is described. Sections of 12 μm in thickness were attached to slides and stained for 10–18 hours in the following solution: 0.03% thionin, 0.5% formaldehyde, 0.5% acetic acid in distilled water. They were then rinsed in acetic water (0.5% acetic acid) for 30 seconds, washed in distilled water, dehydrated through 96% and absolute ethanol, cleared in eucalyptol, and mounted in Eukitt.
Endothelial vesicular system in rapid‐frozen muscle capillaries revealed by serial sectioning and deep etching
Authors: Noguchi Yasuo , Shibata Yosaburo , Yamamoto Torao
Published: February 2005

Endothelial plasmalemmal vesicles were examined in serial sections and in deep‐etch replicas of rapid‐frozen rat muscle capillary endothelium. Numerous fused vesicles were observed in both preparations. The morphology of the vesicles in rapid‐frozen capillaries differed from that in the chemically fixed ones; rapid‐frozen vesicles were spherical rather than ovoid, and the necks of caveolae and the connecting portion of fused vesicles were wider than those of chemically fixed ones. In the serial sections, true free vesicles were rarely identified (1.6%). In the deep‐etch replicas, some of the cytoplasmic surface of vesicles had a mulberrylike appearance and intracytoplasmic fine fibrils appeared to connect the vesicles either to other vesicles or to the plasmalemma proper. Two transendothelial channels were found among 250 capillary profiles. Almost all endothelial “vesicles” proved to be invaginations of the surface membrane, and chemical fixatives did not seem to induce any substantial membrane fusion. These observations suggest that transendothelial transport of large macromolecules across continuous capillary endothelium is carried out mainly by diffusion through transendothelial channels.
Acetylcholinesterase in prenatal rat heart: A marker for the early development of the cardiac conductive tissue?
Authors: Lamers Wouter H. , Korstschot Anita Te , Los Johannes A. , Moorman Antoon F. M.
Published: February 2005

In rat embryos, acetylcholinesterase (AChE, EC 3.1.1.7) activity is present in a continuous sleeve of mycocytes that extends from the myocardium that is adjacent to the atrioventricular endocardial cushions via the ventricular trabeculae to the outflow tract. No activity is found in the atrial roof, in the ventricular walls and in the interventricular septum except for its subendocardial surface. AChE‐positive cells are first identified in 11‐day rat embryos, while the prototypical distribution is best demonstrable in 13‐day embryos. Part of the AChE‐positive cell system is identifiable as a precursor of the adult conduction system by topographical criteria in 16‐day fetuses and by morphological criteria in 20‐day fetuses. At birth (2 days later), AChE activity has disappeared from the cardiac myocytes except for a ring of tissue at the atrial side of the atrioventricular junction. These findings suggest that the embryonic heart can be divided into an upstream mycardium that has no AChE activity and a downstream myocardium that is characterized by the presence of AChE. Furthermore they suggest that an acetylcholine‐dependent mechanism may be responsible for the retardation of the depolarization wave in the downstream parts of the heart. Finally they show that the adult conduction system is formed by a transdifferentiation of part of a far more extensive embryonic precursor system.
Distribution of basement membrane antigens in cryopreserved early embryonic hearts
Authors: Kitten Gregory T. , Markwald Roger R. , Bolender David L.
Published: February 2005

The early embryonic heart is composed of two cylindrical epithelial layers, an inner endothelium and an outer myocardium. The cardiac jelly (CJ), an acellular accumulation of extracellular matrix (ECM), fills the space between the two epithelia. During development of the heart, a portion of the endothelial cells of the atrioventricular (AV) region differentiate into mesenchyme cells in a temporally and spacially specific manner. Although contiguous with those in the AV region, endothelial cells lining the ventricle never form mesenchyme in situ. At present, the mechanisms controlling the biphasic differentiation of the endothelium and the subsequent migration of cardiac mesenchymal cells are poorly understood.

Although the CJ lies between two epithelial and is spatially equivalent to a basement membrane (BM), it has not traditionally been considered to be organized into a BM‐like structure. The potential significance of this observation to developmental biology lies in the possibility that BM or their individual componetns (i.e.), fibronectin (FN), laminin (LM), type IV collagen, and heparin sulfate proteoglycan (HSPG) may function as the regulatory site of epithelial differentiation and morphogenesis.

A cryofixation technique was developed in order to determine the in situ immunohistochemical distribution of the BM components in the CJ. Results indicated that the CJ exists as the fusion between a larger myocardially derived BM having a lamina densa and an extended reticular lamina and an attenuated, endothelial‐associated BM composed only of a lamina densa. Except for FN, the individual BM components were not all present during early stages, but instead appeared in a sequential manner, suggesting that all components of an adult‐type BM are not required to initiate the assembly of a structural and functional BM during development. In the AV canal and outflow tract (OT), FN appeared as a progressively expanding gradient of material with the greates density nearer the myocardium.
Morphometric analysis of neuronal soma size within the motor nucleus of a transplanted murine skeletal muscle
Authors: Klueber Kathleen M.
Published: February 2005

Since the number of motor neurons supplying a muscle graft is reduced, the peripheral field for the surviving motor neurons would be enlarged. This possible change in motor unit size may result in morphologic changes in the size of motor neurons within the motor neuron pool of the graft. The extensor digitorum longus (EDL) muscle from 19 transplanted and 17 age‐matched normal 129 ReJ female mice were injected with horseradish peroxidase in order to examine the cell size distributions of the motor neuron pools supplying these muscles. Computer‐assisted morphometric analysis of cell sizes within the motor neuron pool to the transplants indicated a singnificant shift in cell size, with the largest areas ranging between 630 and 1250 μm2. A number of the alpha neurons supplying the grafts were twice the average cell size for the control population (X = 592 μm2). The increase in the number of large motor neurons indicates an hypertrophy of neurons reinnervating the grafts. The long‐term graft is reinnervated by a decreased population of motor neurons (X = 7), which vary in size from small to very large, reflecting both changes in the possible source of the nerve reinnervating the graft as well as alteration in the size of the motor unit, respectively.
Extraocular muscles in the microphthalmic rat
Authors: Tanaka Koichi , Otani Katsumi , Sugita Shoei
Published: February 2005

The extraocular muscles in a mutant microphthalmic strain of rat were studied. The eyeball of this strain of rat is reduced to about a third in diameter of that of the normal rat. Nevertheless, in the orbit of the mutant rat, every one of the extraocular muscles was identified; their origins and courses were the same as in the normal rat, but differences existed in the insertions. These insertions could be classified into three groups: Group A (retractor bulbi): like normal insertion into the eyeball. Group B (superior rectus and superior oblique): attachment of tendonlike insertions to each other; these muscles come from opposite directions and form a loop. Group C (lateral, medial, and inferior rectus and inferior oblique): insertion into connective tissue surrounding the reduced eyeball.

The volume of each muscle of the mutant rat was smaller than that of the normal rat; moreover, significant differences existed in the degree of reduction in the volume of each muscle group classified according to the change of insertion. In the group A muscle the volume was only 33% of the normal volume, whereas group B was 74% and group C was about half of normal.
Isoflurane as an anesthetic for experimental animal surgery
Authors: Raper Steven E. , Barker Mary E. , Burwen Susan J. , Jones Albert L.
Published: February 2005

Isoflurane is an inhalational anesthetic agent associated with no known hepatic toxicity. Despite this fact, isoflurane has not been widely utilized as an anesthetic agent in studies of liver structure and function in experimental animals. For this reason, livers from rats treated with pentobarbital or diethylether were compared to those from rats treated with isoflurane to determine differences in biochemical and morphologic parameters.

Liver from pentobarbital‐treated rats showed a significant decline in glutathione‐S‐transferase activity compared to liver from isoflurane/O2 or ether‐treated rats. Liver microsomes from isoflurane/O2‐treated rats retained more cytochrome‐C(P450)‐reductase activity than did those from pentobarbital‐treated, ether‐treated, or decapitated rats. Despite these biochemical alterations, morphometric analysis of liver from isoflurane/O2 and pentobarbital‐treated rats showed no quantitative or qualitative differences in liver structure or organelle volume densities. Neither were differences detected in uptake and distribution of 125I‐epidermal growth factor when analyzed by electron microscopic autoradiography. These data show that isoflurane with supplemental O2 has no effects on hepatic structure and fewer effects on hepatic function than other anesthetics and may be a better experimental anesthetic than any currently in use.
Fiber‐type composition of selected hindlimb muscles of a primate (cynomolgus monkey)
Authors: Acosta Luis , Roy Roland R.
Published: February 2005

The distribution of fiber types in selected leg and thigh muscles of three male Cynomolgus monkeys were determined. Almost all fibers could be classified as fast‐glycolytic (FG), fast‐oxidative glycolytic (FOG), or slow‐oxidative (SO) according to the qualitative histochemical staining scheme described by Peter et al. (1972). Most muscles showed regional variations in fiber‐type distributions, i.e., the percent SO was higher and the percent FG was lower in the deep, compared to the superficial, regions of the muscle. Exceptions were the soleus and plantaris muscles, which contained similar distributions of fiber types throughout their cross sections. In the extensor compartment of the leg, a layering of fiber types from deep to superficial were evident in the triceps surae and plantaris complex with the deepest muscle, the soleus, having primarily SO fibers. A similar layering arrangement was observed in the extensor compartment of the thigh, with the deepest muscle, the vastus intermedius, having a much larger proportion of SO fibers than the other muscles in the quadriceps complex. These results indicate that Cynomolgus monkey hindlimb muscles, unlike human leg muscles (Saltin and Gollnick: Handbook of Physiology, L.D. Peachey, ed. American Physiological Society, MD, pp. 55–631, 1983) have a regional distribution of fiber types similar to that observed in many subprimate mammals. Further, the presence of compartmentalization of fiber types within the cross section of several of the muscles studied is suggestive of structure‐function interrelationships related to motor control.
Effects of salt loading on the fractional volume of atria‐specific granules in dahl salt‐sensitive and salt‐resistant rats
Authors: Hansen John T. , Haywood J. R. , Howell Andrew
Published: February 2005

The cardiac atria are known to play a role in blood volume homeostasis, secreting a peptide that induces a potent natriuresis and diuresis. This peptide is atrial natriuretic factor (ANF), and its primary site of storage is within atria‐specific granules found in atrial cardiocytes.

Since salt loading results in an increase in circulating levels of ANF, our aim was to determine if the atria‐specific granule population in the cardiocytes of Dahl rats would decrease accordingly. To this end, the fractional volume of the atria‐specific granules was determined by ultrastructural morphometric analysis in the Dahl salt model of hypertension. This analysis was performed on the right atria of Dahl salt‐resistant (DR) and salt‐sensitive (DS) rats fed either a low‐salt (0.4%) or high‐salt (8%) diet for 12 weeks prior to sacrifice. DR and DS rats fed a low‐salt diet had significantly reduced plasma sodium levels and osmolalities, and a significantly lower mean arterial blood pressure than did rats fed a high‐salt diet. The fractional volume of atria‐specific granules was significantly lower in salt‐loaded DR (P<0.01) and DS (P<0.025) rats than in their respective low‐salt controls. This significant decrease in atrial granules corresponds to the reported decrease in the storage of atrial ANF in salt‐loaded rats, and provides a morphological verification of the biochemical studies. Moreover, these results, in combination with a growing body of physiological data, lend support to the hypothesized role of ANF in the regulation of water–electrolyte balance, which may play an important role in cardiovascular pathophysiological states related to hypertension.
Postnatal development of the vallate papilla and taste buds in rats
Authors: Hosley Mark A. , Oakley Bruce
Published: February 2005

The postnatal maturation of the vallate papilla and its taste buds was quantitatively investigated in rats by light microscopy. Specifically, we measured postnatal increases in the size of mature vallate taste buds and the vallate papilla, increases in the thickness of the gustatory epidermis, and increases in the number of mature taste buds and taste cells per bud. Mature taste buds, defined as those having a taste pore, are rare at birth but proliferate rapidly during the first postnatal month until an average of 610 mature taste buds has accumulated by 90 days. Throughout this postnatal period, mature taste buds adjust to the developmental thickening of the epidermis by continuously increasing in length. Mature taste buds also increase in width, in part due to a threefold increase from 10 and 45 days in the number of taste cells per bud. From 10 to 21 days there is an average daily net increase of three cells per mature taste bud. The maturational increase in taste buds and cells may contribute to the functional changes in taste nerve responses known to occur over the course of several generations of taste receptor cells. The dimensions of the vallate papilla and the surface area of the gustatory epithelium increase logarithmically with age. Although mature taste buds continue to increase in number until 90 days, both taste bud density (178/mm2) and the number of cells per mature taste bud (70–75 cells) reach ceilings by 45 days. Thus, density‐dependent factors appear to control vallate taste bud maturation. The immaturity of lingual taste buds in newborn rats supports the view that odor, rather than taste, is the chemosensory signal that guides suckling in altricial rodents.
Differences in glycocalyx composition between cells of the cortical thick ascending limb of Henle and the macula densa revealed by lectin‐gold cytochemistry
Authors: Rielle Jean‐Charles , Brown Dennis , Orci Lelio
Published: February 2005

The glycocalyx composition of cells from the macula densa and the cortical thick ascending limb of Henle was examined in rabbit kidney by means of the lectin‐gold technique. A quantitative evaluation at the ultrastructural level showed that macula densa cells had a considerably greater affinity for Helix pomatia lectin than adjacent cells of the thick ascending limb. Wheat germ lectin and concanavalin A bound equally well to both cell types. This difference in plasma membrane glycocalyx composition may be an important aspect of the functional differentiation of cell types in this specialized nephron segment.