Immunohistolocalization and gene expression of the carbonic anhydrase isoenzymes (CA-II and CA-VI) in glands associated with the canine lacrimal apparatus.

Cytosolic and secretory carbonic anhydrase isoenzymes (CA-II and CA-VI, respectively) were detected by immunohistolocalization using specific canine CA-II and CA-VI antisera. CA-II and CA-VI were identified in glands associated with the canine lacrimal apparatus, such as lacrimal gland, superficial gland of the third eyelid (third eyelid gland) and tarsal gland. CA-II and CA-VI mRNA signals were also detected by reverse-transcriptase polymerase chain reaction in the same tissues. Some serous acinar cells and duct segments in the lacrimal gland and serous acinar cells in the third eyelid gland were immunopositive for anti-CA-II and CA-VI antisera. In particular, some immunopositive acini to CA-II and CA-VI on the edge of the third eyelid gland are histologically similar to sebaceous gland cells. Sebaceous gland cells in the tarsal and ciliary glands also showed immunopositivity to both CA antisera. CA-II and CA-VI gene transcripts were detected in the same regions. These results suggest that secreted CA-VI may form together with cytosolic CA-II, a high-activity isozyme mostly considered as a bicarbonate producer, in a mutually complementary system for the maintenance of bicarbonate levels to regulate pH in tear fluid and protect the corneal epithelia against injuries. In sebaceous gland cells in the lacrimal apparatus, CA-VI may be related to lipogenesis in an unknown function.

Histological structure and distribution of carbonic anhydrase isozymes (CA-I, II, III and VI) in major salivary glands in koalas.

While the mandibular glands usually consist of only mucous acinar cells or a combination of mucous and serous cells in other species of mammals, those of koalas were serous glands. Rabbit mono-specific polyclonal anti-canine CA-I, II, III or VI antiserum showed cross-reactivity against corresponding koala carbonic anhydrase (CA) isozymes. Although immunohistochemical reactions to CA-I, II and VI in ductal cells were moderate to strong in the tested salivary glands, no reaction or only slight reactions were observed against CA-III. In the sublingual glands, moderate immunohistochemical reactions to CA-I, II and VI were also evident in serous acinar cells and serous demilunes. However, no reactions to the tested isozymes were observed in mucous acinar cells in these glands. With the exception of the histological structure of the mandibular glands, histological features and the distributional profile of CA isozymes of the salivary glands in koalas are relatively close to results obtained from horses.

Immunohistochemical localization of carbonic anhydrase isoenzymes in salivary gland and intestine in adult and suckling pigs.

Localizations of carbonic anhydrase isoenzymes (CA I, CA II and CA III) were investigated immunohistochemically in the salivary glands and intestine of mature and suckling pigs. Carbonic anhydrase isoenzymes were not detected in the salivary glands of sucklings, but were present in the adult. Bicarbonate ion in saliva might be important for the digestion of solid foods in mature pigs, but unnecessary for the digestion of milk in sucklings. Expressions of CA I and CA II were detected strongly in the large intestine of the adult and sucklings, and faintly only at duodenum in the small intestine. CA I and CA II isoenzymes in the large intestine may be involved, at least in part, in ion absorption and water metabolism during digestion and absorption of milk in suckling pigs. In addition, CA I and CA II expression in the duodenal villus enterocyte may support the process of bicarbonate absorption in the duodenum.

Comparative immunohistolocalization of carbonic anhydrase isozymes I, II and III in the equine and bovine digestive tract.

Immunohistochemical localizations of carbonic anhydrase isozymes (CA-I, CA-II and CA-III) in equine and bovine digestive tracts were studied. In the horse, epithelial cells in both the oesophagus and non-glandular part of the stomach lacked all three isozymes. In contrast, surface epithelial and parietal cells in the glandular region of the stomach showed reactivity for CA-II. In the small intestine, absorptive columnar cells covering the villi in the duodenum were positive for CA-II. The epithelium of the jejunum and ileum lacked all three isozymes. In the large intestine, CA-II was detected in the columnar cells in the upper part of the crypt. In cattle, epithelial cells of the oesophagus showed reactions for CA-I and CA-III but not for CA-II. Although the absorptive epithelial cells of the small intestine lacked CA-I, CA-II and CA-III, those of the upper part of large intestine crypts were heavily stained for all three isozymes.

Distribution of carbonic anhydrase isozyme III (CA-III)-positive cells in duct segments of the bovine submandibular gland.

The distribution of carbonic anhydrase III isozyme (CA-III)-positive cells in bovine submandibular glands was studied by immunohistochemistry. CA-III showed strong immunoreactivity in basal cells and some lining cells of the intercalated ducts as well as in striated and interlobular ducts cells. No significant immunoreactivity could be found in other portions of the glands. Electron microscopically, the immunoreactive basal cells contained scattered tonofibrils in their cytoplasm. The distribution of CA-III suggests that the CA-III-positive basal cells may play a special physiological role, and that they do not only represent undifferentiated lining cells.

Immunocytochemical localisation of the carbonic anhydrase III in the rat parotid gland.

Immunohistochemical localisation of the carbonic anhydrase III isozyme in rat parotid glands was studied. In parotid glands, CA-III was found to be present in the striated and excretory duct cells with heterogenous staining. No significant activity could be found in other regions of the glands. Ultrastructurally, the reaction of anti-CA-III isozyme was noted to occur diffusely in the cytoplasm of the cells.

Developmental changes in the ferret ileum during the postnatal period.

The development of the ferret ileum was studied in order to determine the pattern of morphological maturation during the postnatal period. In the newborn, intestinal villi were short, and lined by simple columnar enterocytes with striated borders and small vacuoles. At one week old, the equivalent cell had large vacuoles that were shown on TEM to be related to a tubulovesicular system in the apical region of the cytoplasm. At two and three weeks old, the epithelial cells at the same site showed a more extensive tubulovesicular system, and vacuoles occupied major areas of both the supra- and subnuclear cytoplasm. At six weeks old (weaning), although the enterocytes contained a few small intracellular vesicles, they appeared histologically more mature than in previous stages. At nine weeks and in the adult, the villi were longer and the enterocytes no longer contained vacuoles. In TEM, the epithelial cells had long microvilli, and the apical tubulovesicular system and vacuoles had completely disappeared from the cytoplasm.