Structure of taste buds in foliate papillae of the rhesus monkey,Macaca mulatta

Taste buds in foliate papillae of the rhesus monkey were examined by electron microscopy. Three distinct cell types were identified. Type I cells were narrow elongated cells containing an oval nucleus, bundles of intermediate filaments, several Golgi bodies, and characteristic apical membrane-bounded dense granules. These cells exhibited morphological variations: some had a moderately dense cytoplasm, perinuclear free ribosomes, and flattened sacs of rough endoplasmic reticulum; others had a more lucent cytoplasm, dilated irregular rough endoplasmic reticulum, lysosome-like dense bodies, and lipid droplets. Type II cells typically contained a spherical, pale nucleus, a prominent nucleolus, supranuclear and infranuclear Golgi bodies, mitochondria with tubular cristae, and one or two centrioles. This cell type, too, showed some variation in the relative amounts of ribosomes and smooth endoplasmic reticulum, which varied inversely with each other. Type III cells were characterized by a clear apical cytoplasm essentially devoid of ribosomes and containing microtubules. In a few type III cells, the peri- and infranuclear regions contained many ribosomes and some rough endoplasmic reticulum. In most Type III cells, there were large numbers of dense and clear vesicles in the peri- and infranuclear regions; some of the vesicles were grouped in synapse-like arrangements with adjacent nerves. The morphological variations exhibited by all three cell types could be accounted for by age differences in each of the cells. This would be consistent with the notion that cell renewal occurs in each of the three cell populations.     

Phagocytosis by hemolymph cells of the land slug, Incilaria fruhstorferi Collinge (Gastropoda: Pulmonata)

Phagocytosis by hemolymph cells of the land slug, Incilaria fruhstorferi Collinge, were studied with the scanning electron microscopy (SEM) and the transmission electron microscopy (TEM). The fate of foreign materials, i.e., sheep red blood cells (SRBC) and latex beads, introduced into the hemocoel of the slug were followed. Certain hemocytes named as Type I cell were involved in spontaneous cyto-adherence while both Type II and III cells were not observed to adhere to foreign materials. SRBC and latex beads (luminal diameter 0.79 micron) were phagocytosed and latex beads (luminal diameter 15.8 micron) were engulfed by Type I cells. In vitro phagocytosis experiments showed that SRBC formed the rosette structure surrounding a Type I cell and both SRBC and latex beads (luminal diameter 0.79 micron) were swallowed by Type I cells in vivo. The plate-like structures with long fine fibers attached the latex beads. The latex beads were often seen deep in the aggregates of plate-like structures.     

Hemolymph cells and the platelet-like structures of the land slug, Incilaria bilineata (Gastropoda: Pulmonata)

3 morphologically distinct hemolymph cell-types, Types I, II and III, were found by light and electron microscopy of hemolymph from the land slug, Incilaria bilineata. In addition, vast numbers of the platelet-like structures were present in the collected hemolymph. Type I cells were macrophage-like, Type II cells were lymphocyte-like and Type III cells were fibroblast-like. Among these hemolymph cells, only Type I cells could recognize foreign materials and phagocytose them. Type I cells, whether from circulating hemolymph or from the heart-kidney region (regarded as a hemopoietic organ), could be maintained for only 4 d in cultivation because the cells gradually divided within 3 or 4 d. Thus, the platelet-like structures appear to be derived from Type I cells, which readily fragmentize and function by clamping onto foreign materials.     

Macro-orchidism: light and electron microscopic study of four cases.

A hormonal and quantitative light microscopy study of one man with macro-orchidism associated with mental retardation and fragile X chromosome (case no. 1) and three men with idiopathic macro-orchidism (cases no. 2 to 4) is reported. Hormonal study revealed slightly increased follicle-stimulating hormone serum levels in cases no. 1 to 3. The testes from cases no. 1 (orchidoepididymoectomy specimen) and 2 (testicular biopsy) presented interstitial edema and three different tubular patterns that were arranged in a mosaic-like manner. Type I tubules had an increased diameter (less than 220 microns), dilated lumen, and thin seminiferous epithelium usually consisting of Sertoli cells, spermatogonia, primary spermatocytes, and sometimes a few spermatids. Type II tubules had a normal diameter (180 to 220 microns) and germ cell development varied between complete spermatogenesis and Sertoli-cell-only tubules. Type III tubules had decreased diameter (less than 180 microns), atrophic seminiferous epithelium, and thickened tunica propria. The appearance of the nuclei of the Sertoli cells in the three types of tubules could be either mature or immature. Some of the mature Sertoli cells presented a granular cytoplasm. A few of these granular cells grouped together, forming nests that protruded into the tubular lumen. The testicular biopsies from cases no. 3 and 4 only presented type II tubules that contained both mature and immature Sertoli cells. Quantitative study revealed that the large testicular size was principally due to an increased tubular length in all four cases. Although the seminiferous tubule lesions and interstitial edema suggest an obstructive process, the testicular excretory ducts (studied in case no. 1) appeared normal or only slightly dilated. It is possible that the seminiferous tubule lesions (dilated lumen and germ cell depletion) might be secondary to the Sertoli cell lesions (granular cytoplasm and nuclear immature-like pattern.     

免疫组化电镜示垂体LH细胞

应用免疫组化电镜显示垂体黄体生成素(LH)细胞的形态特徵、超微结构以及反应阳性颗粒的分布状况等,并按此将LH细胞分为四型。一、二型细胞内大小分泌粒均含有LH;三型细胞长(?)的150 nm及200 nm颗粒显免疫反应阳性,且部分胞膜和微绒毛顶部界膜内外附着致密细粒;四型细胞出现反应阴性颗粒,仅在rER膜囊外显有直径30～40 nm黑色细粒。LH细胞的分泌可能以外排、分子渗透和局部分泌三种方式排出LH。     

A Golgi study on the dorsal nucleus of the lateral lemniscus in the mouse

The dorsal nucleus of the lateral lemniscus (DLL) in the mouse was studied using the rapid Golgi method. Three types of neurons were observed in the DLL. Type I neurons had a piriform or triangular cell body with a mean diameter of 14 by 19 micron, and emitted 3-5 primary dendrites. The cell bodies of type II neurons were either spindle or piriform in shape and were, on the average, 17 by 26 micron in diameter with 2-4 primary dendrites. Type III neurons had polygonal or triangular cell bodies which were 24 by 31 micron in average diameter and there were 4-6 primary dendrites. The axons of the DLL neurons most frequently traveled medially or ventromedially, and only a few could be followed dorsally among the fibers composing the lateral lemniscus (LL). The afferent fibers of the DLL were separated into three groups: ascending afferents, descending afferents and afferents from the medial aspect. The ascending afferents were collaterals of the LL fibers distributed mainly in the inferior colliculus. The descending afferents were also collaterals arising from the descending LL fibers. The afferents from the medial aspect ran across the tegmental area to distribute in the DLL. In addition, numerous LL fibers gave off terminal collaterals to the DLL. The ascending or descending nature of these LL fibers was not determined. Thus, the DLL is considered to be one of the commissural relay nuclei in the auditory system.     

Morphology of the bovine epididymis

The epididymis of the bull was divided into six regions, and morphological differences between regions were studied. The epithelium of all regions contained four cell types: principal and basal epithelial cells, and intraepithelial lymphocytes and macrophages. The epithelium of regions II–V also contained a few apical cells. Principal cells of all regions possessed an endocytotic apparatus including stereocilia underlain by canaliculi, coated vesicles, and subapical vacuoles (up to 1 μm in diameter); however, large vacuoles with a flocculent content and multivesicular bodies (up to 5 μm in diameter) were most numerous in regions II, III, and IV. The unique features of principal cells of region I were the presence of well-developed Golgi bodies, few lipid droplets, and whorls of smooth endoplasmic reticulum in the supranuclear cytoplasm. Numerous mitochondria, distended cisternae of rough endoplasmic reticulum, and dense granules characterized the infranuclear cytoplasm of the principal cells of regions II–VI; however, these features were more developed in region V. Apical cells were characterized by the apical location of the nucleus, many mitochondria in the apical cytoplasm, and few microvilli at the luminal border. Basal cells with few cytoplasmic lipid droplets were present throughout the length of the epididymis but appeared more numerous in region V. Intraepithelial lymphocytes were present at all levels of the epithelium but were never seen in the lumen. Intraepithelial macrophages containing heterogenous granules, eccentric nuclei, and pseudopods were invariably seen near the basal area of the epithelium in all regions. These observations are discussed in an effort to define the role of each cell type in the epididymal epithelium.     

Biophysical studies of the cellular elements of the rabbit carotid body

The carotid body is a major sensor of oxygen partial pressure in the arterial blood, and plays a role in the control of respiration. Despite extensive investigation of the structure, the cellular basis of the transduction mechanism remains poorly understood. We have developed a preparation of freshly dissociated cells from the rabbit carotid body, in which two cell types may be identified using morphological criteria. The preparation allows application of the patch clamp technique to characterize the properties of the cells which have otherwise proved difficult to study in situ. Carotid bodies of rabbits were dissociated using a combination of enzymatic and mechanical procedures. The dissociated preparation obtained consisted of clusters of spherical or ovoid cells of 12-15 microns in diameter and a distinct population of spherical cells of 8-10 microns diameter. Electron microscopic techniques were used to identify the cells present in the preparation. Again two populations of cells could be distinguished. A population of cells 10-12 microns in diameter, often found in clusters, possessed the dense-cored vesicles characteristic of Type I cells, while a population of smaller cells (diameter 5-7 microns) had peripherally condensed nuclear chromatin and fine cytoplasmic surface extensions characteristic of Type II cells. Patch clamp study of the cells showed that they represent two electrophysiologically distinct populations. The larger cells, corresponding to Type I cells, were found to be excitable, generating fast, sodium-dependent action potentials that were recorded both in the cell attached and whole cell recording configurations. The smaller Type II cells did not generate action potentials. Voltage clamp study of Type I cells allowed definition of a range of voltage-gated currents. These included an inactivating, tetrodotoxin-sensitive inward sodium current, a high threshold sustained inward calcium current, and outward potassium currents. A component of the outward current showed a dependence on voltage-gated calcium entry, and was blocked by cobalt or cadmium. Of the calcium-dependent current, a component was sensitive to apamin, and the remaining current was blocked by tetraethylammonium. Type II cells showed only a high threshold outward potassium current. These studies have thus revealed an electrophysiological differentiation that parallels the morphological differentiation of the cells of the carotid body. The Type I cell is essentially neuron-like in its properties, while the Type II cell appears to have properties resembling those of glial elements elsewhere in the nervous system.(ABSTRACT TRUNCATED AT 400 WORDS)     

The liver hemopoietic environment: II. Peroxidase reactive mouse fetal liver hemopoietic cells

Through the combined use of peroxidase cytochemistry and examination at the ultrastructural level, the present study has identified liver hemopoietic foci containing three forms of erythropoietic cells, two forms of myelopoietic cells, and a population of peroxidase nonreactive cells within the extravascular compartments of mouse fetal liver. The nonreactive cells were 10 μm in diameter, displayed no peroxidase activity and were designated type I cells. This cell had an irregular nucleus, small profiles of rough endoplasmic reticulum (RER), a considerable population of monoribosomes and a few polyribosomes. The incidence of this cell type decreased significantly from 50% at 12 days gestation to approximately 10% of the hemopoietic cells at 17 days gestation. Type I cells could not be classified into a hemopoietic lineage and may represent undifferentiated hemopoietic stem cells. Three forms of erythropoietic cells, designated types II, III, and IV, were identified. These cells had a diffuse cytoplasmic peroxidase reaction, no peroxidase positive membrane-bound organelles, and were approximately 7 μm in diameter. They corresponded to the more classically defined proerythroblast, polychromatophilic erythroblast, and nucleated normoblast, respectively. Types II and III had moderate cytoplasmic reactions, whereas type III, in addition, had a slight nuclear reaction. Type IV cells had a very dense cytoplasmic reaction but no nuclear reaction. Of the myelopoietic cells detected, one form had a slightly reactive Golgi and a few reactive granules. The other form possessed a clearly positive nuclear envelope (NE), RER, Golgi, and a population of reactive granules. The phagocytic sinusoidal lining cells (Kupffer cells) were peroxidase negative in contrast to similar cells in the rat. A population of peroxidasepositive granules was detected in fetal liver developing hepatocytes at 17 days gestation and increased in number with age. The morphology and organization of these various cell types in the liver hemopoietic environment are discussed.     

The morphology of neurons in trigeminal nucleus oralis projecting to the medullary dorsal horn (trigeminal nucleus caudalis): a retrograde horseradish peroxidase and Golgi study

This study demonstrates that trigeminal nucleus oralis, the most rostral subdivision of the spinal trigeminal nucleus, contains four morphologically distinct types of small neurons which project to the medullary dorsal horn (trigeminal nucleus caudalis) via descending intratrigeminal pathways. Using the retrograde transport of horseradish peroxidase following injections in the medullary dorsal horn, labeled small neurons with cell bodies ranging from 8-15 microns in diameter are found principally in the ventrolateral portion of the trigeminal nucleus oralis. Most neurons are labeled ipsilaterally throughout the entire rostrocaudal extent of the ventrolateral portion of the trigeminal nucleus oralis, but a few cells are also labeled contralaterally. From this aspect of the present study it can be concluded that a specific portion of the trigeminal nucleus oralis, i.e. the ventrolateral part, contains numerous small neurons which send descending projections to the medullary dorsal horn that could affect synaptic activity there. Utilizing both the methods of Golgi and retrograde horseradish peroxidase labeling four distinct types of small descending medullary dorsal horn projection neurons can be distinguished in the ventrolateral portion of the trigeminal nucleus oralis on the basis of their morphology and the distribution of their axons and dendrites. All four neuronal cell types are present throughout the entire rostrocaudal extent of the trigeminal nucleus oralis. Type I neurons are the most frequently labeled descending medullary dorsal horn projection neurons. They are concentrated in the medial 500-550 microns of the ventrolateral portion of the trigeminal nucleus oralis and display dendritic trees which occupy spherical domains approaching 300 microns in diameter. The unmyelinated axons of many of these cells arise either directly from the cell body or a primary dendrite and give rise to a single collateral within 50 microns of their site of origin. This collateral generates a fine axonal plexus within a portion of the dendritic arbor of the parent cell while the parent axon, without branching further, travels a short distance in the ventrolateral portion of the trigeminal nucleus oralis and enters a deep axon bundle. Type II neurons are the second most frequently labeled descending medullary dorsal horn projection neuron. They generate medial and lateral dendritic arbors which together span nearly the entire medial 500-550 microns of the ventrolateral portion of the trigeminal nucleus oralis. An unmyelinated axon emerges from the cell body and within 10-30 microns of its origin gives rise to two collaterals.(ABSTRACT TRUNCATED AT 400 WORDS)     

Choline acetyltransferase- and substance P-like immunoreactive elements in fetal striatal grafts in the rat: a correlated light and electron microscopic study.

Fetal striatal neurons were transplanted into the ibotenic acid-lesioned rat striatum. Three months after transplantation, the graft tissue was processed for choline acetyltransferase- and substance P-like immunoreactivity and was subsequently examined at the light and electron microscopic levels. The study demonstrated that choline acetyltransferase- and substance P-like-immunoreactive neurons were homogenously present throughout fetal striatal grafts, although in decreased numbers compared with those in the normal rat striatum. The majority of the choline acetyltransferase-immunoreactive neurons had fusiform, oval, or polygonal somata with somatic diameters greater than 20 microns and contained deeply invaginated nuclei surrounded by copious cytoplasm. In addition, choline acetyltransferase-immunoreactive neurons with somatic diameters between 10 and 20 microns were also demonstrated. The grafts' substance P-like-immunoreactive neurons, which had somatic diameters between 10 and 25 microns and had oval or polygonal perikarya, could be classified into two types based on their ultrastructural characteristics. Type I neurons contained an unindented nucleus which was surrounded by a thin rim or moderate amount of cytoplasm, whereas Type II immunoreactive neurons contained an indented nucleus which was surrounded by copious cytoplasm. Choline acetyltransferase- and substance P-like-immunoreactive dendrites in the grafts' neuropil were contacted by multiple unlabeled axon terminals. In addition, choline acetyltransferase- and substance P-like-immunoreactive axon terminals forming symmetric contacts with unlabeled dendrites were present within the graft. The study demonstrated that many of the neuroanatomical features of choline acetyltransferase- and substance P-like-immunoreactive elements found in the normal rat striatum are present in mature fetal striatal grafts.     

Bovine circumvallate taste buds: taste cell structure and immunoreactivity to alpha-gustducin

The taste buds of bovine circumvallate papillae were investigated under light and electron microscopy both by histological and immunohistochemical methods. Taste buds existed in the inner epithelium of the trench of the papillae. Under electron microscopy, two types of taste cells, type I and type II, could be classified according to the existence of dense-cored vesicles and cytoplasmic density. Type I had electron-lucent cytoplasm and possessed many electron-dense cored vesicles in the apical cytoplasm. It was considered that the electron-dense materials of the vesicles were released and constituted the pore substance. This type of cell possessed long and thick apical processes in the taste pore. Type II had denser electron cytoplasm compared with that of type I and possessed many electron-lucent vesicles in the apical cytoplasm. This type of cell possessed microvilli in the taste pore. To know the immunoreactivity to alpha-gustducin in bovine circumvallate taste buds, we used the immunoblotting method and the immunohistochemical method. The alpha-gustducin reaction band at 40 kDa was displayed in the specimen of Western blots. The immunohistochemical property of the antiserum to alpha-gustducin was investigated by using the avidin-biotin complex (ABC) method and the 1.4-nm gold and silver enhancement methods. A subset of taste cells showed the immunoreactivity under light microscopy. The electron microscopic specimens with the 1.4-nm gold and silver enhancement method revealed that only type II cells exhibited the alpha-gustducin immunoreactivity.     

Coloration of cytologic thick sections containing biomaterials with silver methenamine. Usefulness for scanning electron microscopy

Prostheses implanted in hard tissues cannot be processed for electron microscopic examination or microanalysis in the same way as those in other tissues. For these reasons, we have developed a method allowing light and electron microscopic studies as well as microanalysis of the interface between bone and biomaterials after the sections glycoproteins have been stained with silver methenamine. Silver can be evidenced by SEM in back scattered mode. MATERIALS AND METHODS: Tranverse sections of a human femur containing an HA-coated prostheses were obtained with a diamond saw and ground to a thickness of 50-100 microns. The sections were stained in a microwave oven using a 1% silver methenamine solution. They have been examined by back-scatter SEM operated at 25 KV. EDS has been performed on cellular inclusions and extracellular bone matrix. RESULTS: Type I and III collagen fibers, and reticulin fibers were stained. The mineralized matrix was heavily colored. At the cell level, the nuclear and cytoplasm membranes, the chromatin and ribosomes were shown. The characteristic peaks of the Ag spectrum are distinct from those of the elements used in orthopaedic biomaterials and did not impair their identification.     

Mononuclear cells in the extraembryonic and intraembryonic coelom of the mouse embryo: a semithin light microscopic cytometry

Mononuclear cells in the extraembryonic and intraembryonic spaces of mice were examined qualitatively and quantitatively by semithin light microscopy. At 9 and 10 days of gestation, the extraembryonic serous cavities contained a small number of mononuclear free cells. These cells had an elongated or kidney-shaped nucleus and the cell surface showed many villous projections. The cytoplasm occasionally contained small lucent vesicles but no phagocytic vacuoles. The average cell diameter was 8.4 +/- 0.9 microns and N-C ratio, 0.51 +/- 0.21. Cell larger than 10 microns in diameter constituted only 0.4% of the total. In vitelline vessels at 9 days, mononuclear cells bearing a close morphological resemblance to extraembryonic free cells were observed. At 12 days of gestation, extraembryonic and peritoneal cavities contained mature macrophages and a few small mononuclears which had the same morphological features as those in the extraembryonic coelom and vitelline vessels.     

The oculomotor and trochlear nuclei in the one humped camel (Camelus dromedarius).

Literature on the organization of the oculomotor and trochlear nuclei of large animals is scanty. There were no reports on the organization of the oculomotor and trochlear nuclei of the camel, hence this study. Nine brains were used for the study. The brainstems were double-embedded in celloidin and paraffin and were cut serially at 24 microns and stained with toluidine blue. Light microscopic studies of the nuclei showed that the principal oculomotor nuclei were not subdivided and were composed of large multipolar nerve cell bodies that had a mean length of 30 +/- 5 microns. The nucleus was 2.4 mm long, 0.7 mm wide and 1.1 mm high. The Edinger-Westphal nucleus was small and was made up of elongated oval cell bodies that had a mean length of 33 +/- 5 microns and a mean diameter of 10 +/- 2 microns. The trochlear nucleus was located caudal to the oculomotor nucleus from which it was separated by a gap. The nerve cell bodies of the trochlear nuclei were similar to those of the oculomotor nuclei. The cell bodies had a mean length of 20 +/- 2.5 microns and a mean width of 18 +/- 3 microns. The caudal central nucleus was indistinct. It was concluded, that the oculomotor and trochlear nuclei of the camel are similar in their general organization to those of other animals but differences exist in the development and organization of the component parts.     

Morphological and cytochemical characterization of female Anopheles albimanus (Diptera: Culicidae) hemocytes.

Hemocytes of 2- to 3-d-old female Anopheles albimanus Wiedemann are described by morphology, cytochemistry, and functional criteria. Supplemented Grace's insect medium in a modified Foley's perfusion method was used to obtain hemolymph from An. albimanus. Morphological analysis indicated 3 types of hemocytes were present, prohemocytes, plasmatocytes, and granular cells. Prohemocytes were small round cells with a high nuclear/cytoplasmic ratio. Plasmatocytes were the most abundant cell types in the hemolymph, and appeared as small to large and spindle-shaped cells with round or elongate nucleus, variable number of vacuoles, small granules, and pseudopodia. Granular cells were small to large and round with a large number of cytoplasmic granules, vacuoles, and numerous filopodia. Ultrastructurally, prohemocytes were undifferentiated with abundant free ribosomes and with few small electron-dense granules. Plasmatocytes were rich in mitochondria, rough endoplasmic reticulum, free ribosomes, small electron-dense granules, numerous peripheral vacuoles and with an important organelle polarization. Granular cells contained numerous large electron-dense granular inclusions and vacuoles. Cytochemical studies showed that plasmatocytes and granular cells have cationic bactericidal proteins. Only granular cells showed phenoloxidase and probably lysosomal activities. In vitro functional studies demonstrated that both plasmatocytes and granular cells were able to attach to glass slides, and only plasmatocyte had phagocytic activity and motility. These results characterize the hemocytes of An. albimanus and suggest that plasmatocytes and granular cells may have a role in defense responses to foreign organisms.     

Fine structure of the taste bud in guinea pigs. I. Cell characterization and innervation patterns

Guinea pig taste buds were observed by transmission electron microscopy with special reference to cell types and innervation. The taste bud comprised four distinct cell types: basal, type I, type II, and type III cells. Basal cells, residing at the baso-lateral region of the taste bud without extending to the taste pore, were considered precursors of the other types of cells. The rest were all spindle-shaped cells reaching apically to the taste pit. Type I cells were characterized by the darkest appearance of the cytoplasm, apically possessing large, electron-dense granules and basally enveloping intragemmal nerves. This cell type, intervening between the other types of cells, was postulated to be sustentacular in nature. Type II cells, the largest and lightest cells in the taste bud, possessed a conspicuous stack of smooth endoplasmic reticulum above the nucleus. Due to their intimate and specialized relationships with nerves, the type II cells were presumed to receive an efferent innervation. Type III cells made synaptic contacts with nerves and contained dense-cored vesicles, which accumulated in the synaptic areas. This finding strongly suggests a gustatory function for the cells. The occurrence of such numerous peptidergic-type granules gathering to gustatory synapses as demonstrated in this report has not been recorded in previous papers on mammalian taste buds. The nerve terminals on the type III cell also contained synaptic vesicles, thus suggesting a reciprocal synapse here. The taste bud often included degenerating cells which were demonstrated to be phagocytosed by extrinsic cells identified as macrophages.     

Ultrastructure of a spiral micro-organism from pig gastric mucosa ("Gastrospirillum suis")

The ultrastructural features of a helical-shaped bacterium occurring in the stomach of pigs, within the mucus on the mucosal surface of antral pits, were examined. The bacterial cell had three to eight spiral turns, flattened and truncated ends and was approximately 4.0 microns long and 0.6 microns wide. In some sections, up to six flagella, about 22 nm in diameter, were seen arising from each pole. The cytoplasm contained sparse, irregular granules, numerous ribosomes and large single-layered membrane-bound granules. In the flagella insertion area, there was a highly electron-dense component, the "polar membrane". This micro-organism differed from similar bacteria described in cats, dogs and monkeys, and may cause inflammation in the antral mucosa of pigs similar to Helicobacter pylori infection in man. Furthermore, it was morphologically similar to the spiral micro-organism distinct from H. pylori which has been described recently in human antral mucosa from patients with gastritis and may be of potential significance as a pathogen in man. The name "Gastrospirillum suis" is proposed for this bacterium.     

Intravascular macrophages in normal calf lung. An electron microscopic study

Intravascular macrophages were found commonly in sections of calf lung capillaries. These cells were large with many pseudopodia of various sizes. The cell membrane was covered with an electron-opaque coat which remains between adjacent pseudopodial walls and results in structures suggesting “micropinocytosis vermiformis.” The cytoplasm of the macrophage was electron-lucent and contained endoplasmic reticulum, numerous mitochondria, free ribosomes, Golgi zones, dense bodies and vesicles of many sizes. These macrophages showed phagocytic activity. During erythrophagocytosis, a dense layer initially appeared at the red blood cell periphery. This layer moved toward the center together with the erythrocyte membrane as phagocytosis progressed. Simultaneously, the electron opacity of the red blood cell decreased until the cell was completely dispersed within the macrophage. This erythrophagocytosis occurred relatively seldom. The possibility that intravascular macrophages are the pre-cursors of alveolar macrophages is discussed.     

Ultrastructural studies of the development of feline calicivirus in a feline embryo cell line

The ultrastructural changes in a feline embryo continuous cell line infected with feline calicivirus at a multiplicity of infection of approximately 1 were studied. Virus was found only in the cytoplasm and was observed as single particles, as extensive, non-regular accumulations, as paracrystalline arrays, and as single or multiple linear arrays associated with microfbrils. Mature virus particles were readily distinguished from ribosomes in that they were larger (35nm diameter) and consisted of a central, electron-dense core 20 nm diameter surrounded by a less electron-dense coat. Other changes ovserved in infected cells included rounding of the cell and nucleus and loss of pseudopodia. There was extensive production of smooth-membrane bound vesicles in the cytoplasm. Virus accumulations of each type, but especially paracrystalline arrays, were frequently closely associated with collections of these vesicles. The cisternae of the endoplasmic reticulum and the space between the two layers of the nuclear membrane was distended. By Feulgen staining and light microscopy, as well as electron microscopy, it was established that nuclear chromatin undergoes profound changes consisting of condensation usually into a single, rounded, central mass.