Comparative features of the mucous glands in the gastroduodenal junction in guinea pigs and chinchillas: microanatomy and histochemistry

Background: Mucous glands from the gastroduodenal junction are briefly represented by glandular cells in the stomach and by Brunner’s glands in the duodenum. The aim of the study was to describe the main histological/histochemical features of the gastroduodenal junction in guinea pigs and chinchillas. Results: The material was represented by tissue samples collected from the stomach and duodenum processed by paraffin technique. Histological sections were stained by Goldner’s trichrome stain, while mucous content was identified by Periodic acid–Schiff (PAS) stain (for neutral mucosubstances) and Alcian blue stain (for acid mucosubstances). In guinea pig, the pyloric glands were positive for both mucus types, whereas in chinchillas a low amount of mucin was identified. The Bruner glands, in guinea pigs displayed a weak reaction for the both mucin types. In chinchillas, the Bruner glands showed a significantly higher amount of PAS and Alcian blue-positives mucosubstances types. As observed, a higher amount of neutral mucus was identified in the pyloric glands in guinea pigs comparing to chinchillas. Contrariwise, chinchillas displayed a suggestively higher amount of mucus in Bruner glands comparing to guinea pigs. Conclusions: Concluding, this is the first report describing the comparative features of the mucous glands in the two rodents, with detailed histological and histochemical features.

Cryptosporidium muris-like Infection in Stomach of Cynomolgus Monkeys (Macaca fascicularis)

Protozoa were present in routine sections of the gastric fundus of 15 cynomolgus monkeys ( Macaca fascicularis) that were being studied in three toxicity studies with novel immunosuppressive agents. Upon detailed light microscopic and ultrastructural evaluation, all stages of parasite development (trophozoites, schizonts, gamonts, and oocysts) were seen and they structurally resembled Cryptosporidium muris, which normally is found in stomachs of rodents. Cryptosporidia were primarily present in the upper one third of fundic glands that were often concurrently colonized by a Helicobacter heilmannii-like organism; however, no clear correlation was found between bacterial burden and the number of protozoa. The primarily mononuclear cellular infiltrate appeared to coincide with the presence of protozoa only in a few animals. Changes in mucous epithelial cells mainly occurred in animals that were part of a 39-week study. Mucous epithelial cells in affected glands contained an increased amount of mucus composed of predominantly acid mucosubstances compared to the normally present neutral mucosubstances. C. muris-like protozoa are newly recognized etiologies for opportunistic infections in the stomach of immunocompromized nonhuman primates. This is the first report of C. muris-like parasite in stomachs of monkeys.

Données nouvelles sur la structure et la minéralisation des écailles d'Anguilla anguilla (Osteichthyes, Anguillidae)

The structure of the scales in Anguilla anguilla was studied by light and electron microscopy and the mineral phase was analyzed by histophysical techniques. Although the scales of the eel are small in size and have a peculiar superficial ornamentation, which consists of a web of mineralized plates, they are composed of the three characteristic layers of the typical elasmoid scale. The discontinuous, superficial outer limiting layer is highly mineralized; in this layer, acid mucosubstances are abundant but collagen fibres are absent. Mineralization in the external layer is not oriented by the network of the thin collagen fibrils. In the basal plate, mineralization is oriented by the thick collagen fibres packed in bundles. The bundles are oriented from the basal part to the surface of the scale but they are not organized in the laminated structure characteristic of most other teleost scales. The mineral phase of the eel is typical of a teleost fish. The peculiar features of the scale in the eel are interpreted here as a discrete example of the phyletical reduction of the dermal skeleton among Actinopterygii.

The histology of salivary glands in the colubrid snake Sibynomorphus mikanii (Schlegel, 1837)

A study of the morphology of the salivary glands of the colubrid snake Sibynomorphus mikanii showed the following: (i) the acini of supralabial, infralabial, and premaxillary glands are formed by mucous cells, the tubules of lateral and median posterior sublingual glands are formed by mucoserous cells, and the Duvemoy's gland by seromucous cells; and (ii) mucous cells produce neutral and acid mucosubstances, mucoserous cells secrete neutral and acid mucosubstances and protein, and seromucous cells have neutral mucosubstance and protein secretions. The nuclear volume of acinar and tubule cells were evaluated morphometrically.

A HISTOCHEMICAL EVALUATION OF THE PYROANTIMONATE-OSMIUM REACTION

The chemical nature of the pyroantimonate-osmium (PAO) reaction in normal human bone marrow cells has been evaluated by the application of a number of digestion and blocking procedures as well as the electron microprobe. Five foci of reactivity are localized in cells fixed directly in the PAO reagent, viz., nucleoli, heterochromatin, cytoplasmic granules, particulate glycogen and the outer plasmalemmal surface. Heterochromatin and nucleolar staining are attributable to calcium bound to nucleic acids as well as to reactive amino groups on histones. Granule staining is dissociable into acid-dialyzable, ribonuclease (RNase)-stable and RNase-labile components but sulfate groups of acid mucosubstances are probably not involved. Glycogen staining by the PAO reagent has been verified and shown to result from the formation of organometallic complexes between the pyroantimonate ion and the C2-C3-free hydroxy groups of the glucose residues. PAO reactivity has been definitely localized along the outer plasmalemmal surface, but this component of PAO staining is resistant to all control measures employed. These studies have illustrated the complexity and polyvalency of the PAO reaction and have shown that PAO staining is not exclusively associated with metallic cation localization.

ULTRASTRUCTURAL LOCALIZATION OF DIALYZED IRON-REACTIVE MUCOSUBSTANCE IN RABBIT HETEROPHILS, BASOPHILS, AND EOSINOPHILS

For ultrastructural localization of acid mucosubstances in rabbit granulocytes, bone marrow and buffy coat specimens were fixed with formalin, glutaraldehyde, or osmium tetroxide, sectioned at 40 µ, and stained with the Rinehart and Abul-Haj solution of dialyzed iron (DI). Heterophils revealed DI staining on the outer surface of the plasma membrane, in the Golgi complex involved in primary granulogenesis, and in primary granules. The intragranular distribution of DI-stained material varied at different stages in the maturation of primary granules. Immature granules of heterophils fixed by any of the three methods contained a peripheral concentric band of DI-positive material; however, fully mature primary granules possessed a core of DI-reactive material in heterophils fixed with osmium tetroxide, but they contained little or no staining in heterophils fixed with formalin or glutaraldehyde. Secondary granules of rabbit heterophils failed to stain with DI. Tertiary granules, observed only in late heterophils, contained distinct DI-positive particles. Basophil granules exhibited intensely DI-stained material distributed in an orderly pattern throughout the granule. In eosinophils, DI staining was localized in the Golgi complex and in the rims of a few immature cytoplasmic granules.