Fine structure of the dorsal lingual epithelium of the Japanese lizard, Takydromus tachydromoides.

The histology and the ultrastructure of the dorsal lingual epithelium of the Japanese lizard, Takydromus tachydromoides, were investigated by light and transmission electron microscopy. The epithelium of the anterior and middle portions of the tongue showed "orthokeratinization," being composed of a thick layer of keratinized cells. The epithelium of the posterior portion of the tongue showed "parakeratinization" and "nonkeratinization." Most of the nonkeratinized cells contained large numbers of secretory granules.     

Fine structure of the dorsal lingual epithelium of the crab-eating monkey, Macaca irus.

Light and electron microscopic observations of the dorsal lingual epithelium of the crab-eating monkey, Macaca irus, revealed three different regions: the epithelium on the anterior side of the filiform papillae, the epithelium on the posterior side of the filiform papillae, and the interpapillar epithelium. Whereas the basal and suprabasal cells are similar throughout, differences characterize the intermediate and surface layers. Keratohyalin granules appear predominantly in the intermediate layer of the epithelium on the anterior side of filiform papillae. In the epithelium on the posterior side of the filiform papillae, no keratohyalin granules are seen and, instead, tonofibrils are prominent. The cells begin to be significantly flattened. In the interpapillar epithelium, no keratohyalin granules and tonofibrils are seen, and the tonofilaments occupy almost the entire cytoplasm of the cells of the intermediate and surface layers, with the cells having larger volumes in these layers.     

Fine structure of the Herbst corpuscles in the lingual mucosa of the finch, Lonchura striata.

The ultrastructure of Herbst corpuscles in the lingual mucosa of the finch, Lonchura striata var. domestica, was examined by light and electron microscopy. Numerous Herbst corpuscles were found at the top of connective tissue papillae just beneath the dorsal epithelium. The Herbst corpuscle was composed of an outer capsule, inner core and central axon. The central axon was discoid in shape and immunoreactive for NSE-antiserum. The central axon was surrounded by compactly stacked layers of thin lamellae of lamellar cell processes. Since these lamellae did not completely encircle the axon as seen in cross sections, they displayed a symmetrical longitudinal cleft dividing the inner core into bilateral halves. Numerous axonal spines were seen to extend from the Y-axis of the axolemma into the cleft and occasionally into the cytoplasmic invagination of the lamellar cell body in the inner core. A number of clear and dense-cored vesicles were seen in the axoplasm near the base of axonal spines. Further, the omega-shaped coated invaginations were occasionally found on the axolemma near those places. These findings suggest that the area nearby the axonal spine in the central axon of the Herbst corpuscle is a site active both metabolically and functionally.     

Neutral endopeptidase degrades endothelins in guinea pig tracheal epithelial cells

Inflammation Research -     

Fine structure of the dorsal lingual epithelium of the domestic, newborn kitten, Felis catus.

The tip and the body of the tongue of the domestic kitten, Felis catus, were examined by light and transmission electron microscopy. On the tip of the tongue, no filiform papillae were observed, but the connective tissue papillae of the lamina propria were recognized. On the lingual body, there were filiform papillae composed of an anterior, a posterior and interpapillar epithelium. Under the transmission electron microscope, the epithelium on the tip of the kitten tongue was found to be of the stratified squamous type. The epithelium contained no cells filled with keratin fibers. In the lingual body, the interpapillar epithelium contained very few keratohyalin granules, and no cells with keratin fibers. In the epithelium on the anterior side of the filiform papillae, numerous keratohyalin granules appeared in the intermediate layer. In the surface layer, a thin layer of typical keratinized cells was visible. In the epithelium on the posterior side of the filiform papillae, a thick layer of keratinized cells was located on the surface layer.     

Fine structure of the dorsal lingual epithelium of the lizard,Gekko japonicus (Lacertilia,Gekkonidae)

Three different types of lingual papilla were observed by scanning electron microscopy on the dorsal lingual epithelium of the lizard Gekko japonicus. Dome-shaped lingual papillae were located at the apex. Flat, fan-shaped lingual papillae were seen in the widest area of the lingual body. Long, scale-like lingual papillae were arranged on the latero-posterior dorsal surface. At higher magnification, microvilli and microridges were seen to be widely distributed over the surface of the papillae. By light microscopy, the epithelium of the dome-shaped papillae was composed of single, columnar epithelial cells filled with secretory granules. The tip of the epithelium of the fan-shaped and scale-like papillae was composed of stratified squamous epithelial cells without granules. The major part of the epithelium of these two types of papilla, except the tip area, was also composed of single, columnar epithelial cells with secretory granules. By transmission electron microscopy, a nucleus without a defined shape was seen to be located in the basal part of each of the single, columnar epithelial cells. Rough-surfaced endoplasmic reticulum and Golgi apparatus were well developed around the nucleus. The other, major part of the cytoplasm was filled with the spherical secretory granules, a large number of which had very electron-dense cores and moderately electron-dense peripheral regions. In the stratified squamous epithelium, a nucleus, which tended to be condensed on the free-surface side, was located in the center of each cell. Mitochondria, endoplasmic reticulum, and vesicles were observed in the cytoplasm.     

Ultrastructural evidence for an innervation of epithelial enterochromaffine cells in the guinea pig duodenum

The innervation of the duodenal enterochromaffine cells (E.C.) of the guinea pig was studied at the electronmicroscopic level. Pretreatment with 5-OH-dopamine was performed to visualize catecholaminergic (CA) nervous elements. Near the basement membrane of all examined E.C. in the crypts, bundles of unmyelinated nerve processes were observed, only partly ensheathed in a Schwann cell cover. At least 4 types of processes could be observed. 1) Boutons containing only small clear vesicles, probably cholinergic fibres; 2) boutons with small clear vesicles, and in addition large (200 nm) granules with a dense matrix (P-type-fibres); 3) boutons with small electron-dense vesicles, probably CA-fibres; and 4) processes with few vesicles but having the appearance of dendrites. No typical synaptic arrangements were observed, but the minimal distance between the E.C. and the nerve bundles was 150 to 250 nm, thus well within the functional limits of the “autonomic gap”. Thus, epithelial E.C. may be influenced by several types of nervous elements, including CA-fibres.     

Three-dimensional architecture of the connective tissue core of the lingual papillae in the guinea pig

Summary The three-dimensional structure of the connective tissue core (CTC) of the lingual papillae of the guinea pig was studied by means of scanning electron microscopy, after fixation with Karnovsky's fixative and after removal of the epithelial cell layers by long-term treatment with hydrochloric acid. The CTC of four types of lingual papillae was revealed. (a) Filiform papillae distributed over the anterior part (comprising about one half of the tongue) are characterized by having a few long connective tissue protrusions arranged transversely to the long axis of the tongue, while large conical papillae distributed on the intermolar prominence (intermediate part comprising most of the posterior half of the tongue) have more numerous and longer connective tissue protrusions, forming a bundle. (b) Fungiform papillae scattered among the filiform papillae are restricted to the anterior part of the tongue and possess connective tissue components in the form of a fist-like structure. (c) Foliate papillae are found in lateral and posterior locations. At both sites they contain slender epithelial crypts. Removal of the epithelia reveals wide grooves which correspond to the epithelial crypts. The rims of these grooves are surrounded by numerous small protrusions.     

Ultrastructural development of guinea pig cytomegalovirus in cultured guinea pig embryo cells.

The ultrastructural development of guinea pig cytomegalovirus (GPCMV) in guinea pig embryo cells was studied using electron microscopy. Tubular structures were found in nuclei of virus infected cells, followed by the appearance of intranuclear inclusions containing virus nucleocapsids. While some nucleocapsids were enveloped at the inner nuclear membrane, others were released into the cytoplasm where they were associated with, or within, dense matrix which was subsequently enveloped by cytoplasmic membranes to form enveloped dense virions. Dense bodies without virus capsids were formed in the cytoplasm and enveloped in a similar manner. An involvement of the nuclear pores in the release of unenveloped virus capsids from the nucleus to the cytoplasm was postulated. Evidence that the enveloped dense virions and dense bodies shared common envelope antigen(s) was obtained by immunoelectron microscopy. The similarities and differences in the ultrastructural development of GPCMV and other cytomegaloviruses are discussed.     

Production of arachidonic and linoleic acid metabolites by guinea pig tracheal epithelial cells

Pulmonary epithelial cells may be responsible for regulating airway smooth muscle function, in part by release of fatty acid-derived mediators. Incubation of isolated guinea pig tracheal epithelial cells with radiolabeled arachidonic acid (AA) leads to the production of 5- and 15-hydroxyeicosatetraenoic acid (5- and 15-HETE) and smaller amounts of leukotriene (LT) B₄ and C₄ and 12-hydroxyheptadecatrienoic acid (HHT). Epithelial cells also are able to release linoleic acid (LA) metabolites. Incubation with radiolabeled linoleic acid leads to the formation of 9- and 13-hydroxyoctadecadienoic acid (9- and 13-HODE). The biological significance of these mediators produced by epithelial cells is discussed.     

Factors influencing metabolism of arachidonic acid in guinea pig gastric mucosa

The metabolism of [14C]arachidonic acid in whole homogenates of gastric corpus mucosa in the guinea pig was characterized. Identity of labeled products was validated by comigration against standards in multiple chromatographic systems and by selective synthesis inhibition. At near-physiological conditions, homogenates converted arachidonic acid to the cyclooxygenase products prostaglandins F2, E2, and D2, 6-keto-prostaglandin F1 alpha, and thromboxane B2 (in descending order of magnitude) and to a lipoxygenase product cochromatographing with 12-hydroxyeicosatetraenoic acid. However, dramatic qualitative and quantitative changes in this product profile were noted with relatively small changes in incubation temperature, substrate concentration, and especially pH. Whole homogenates generated more prostaglandin and in different proportions than did the microsomal fraction from an equal mass of mucosa. No catabolism of prostaglandin products was observed in whole homogenates. Tissue preparation and storage also influenced prostaglandin synthesis activity. These in vitro observations may have important implications for future studies of prostaglandin generation in small gastric mucosal biopsies.     

The response of guinea pig airway epithelial cells and alveolar macrophages to environmental stress

Cells lining the respiratory tract form an interface between the organism and the external environment and are repeatedly exposed to physical, chemical, and metabolic stresses. We examined the response of cultured guinea pig tracheal epithelial cells and alveolar macrophages to various forms of stress, including clinically and environmentally relevant metabolic stresses such as ozone and acid exposure. Classic stress treatments such as heat shock and sodium arsenite treatment induced the synthesis of 28, 32, 72, 73, 90, and 110 kD stress proteins similar to those observed in other cell types. In contrast, no significant changes in the pattern of protein synthesis were detected after exposure to ambient concentrations of ozone, although ozone exposure caused significant cytotoxicity to both cell types. Another potent oxidant, hydrogen peroxide, similarly did not induce appreciable stress protein synthesis. However, surface acidification of tracheal epithelial cells and alveolar macrophages caused the induction of 72 and 78 kD stress proteins. While stress proteins may play a role in the response of respiratory cells to certain injuries such as hyperthermia and surface acidification, they may not be important in the defense against ozone or other forms of oxidative injury.     

Annulate lamellae in guinea pig Sertoli cells

Unilateral torsion of the spermatic cord was surgically induced in 24 Hartley strain guinea pigs. Groups of six animals were sacrificed 4, 8, 12, and 16 months after the surgery and testes were excised. Nine animals has severely damaged testes. Extensive study on the Sertoli cells of each of these nine animals was carried out after testicular tissues were processed for electron microscopy following the usual procedure. The majority of the affected seminiferous tubules contained a single layer of Sertoli cells without any differentiating germ cells. The Sertoli cells were vacuolated and contained highly lobulated nuclei. Each nucleus contained a nucleolus. The Sertoli cells contained an elaborate annulate lamellae system. The membranous portion of the annulate lamellae was associated with the rough and smooth endoplasmic reticulum. Close association of the annulate lamellae with the lysosomes and lipid droplets was found to be a consistent feature. Although it was not possible for us to predict the functional significance of these annulate lamellae, the present investigation clearly established for the first time, the presence of an annulate lamellae system in the Sertoli cell of a rodent species.