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PubMed1978

Studies on the retina and the pigment epithelium in hereditary canine ceroid lipofuscinosis, I. The distribution of enzymes in the whole retina and pigment epithelium.

The massive accumulation of autofluorescent lipopigments, representative of autoxidation, is a key morphological feature in canine ceroid lipofuscinosis (CCL). In the eye peroxidase, catalase, and four acid hydrolases were compared with regard to aged and clinical condition in a series of English setters affected with CCL. In unaffected English setters "soluble" peroxidase increased in the RPE to adult levels at 2 yr of age. Affected dogs had higher RPE peroxidase activity earlier in life, which then decline with age. The soluble retinal peroxidase of both unaffected and CCL dogs increased steadily with age, but the latter group of dogs were much lower in activity. By 2 yr of age, RPE and retinal peroxidase values were only 25% and 47% of unaffected dog levels. Although the soluble enzyme of unaffected dogs exhibited a maturational profile, membrane-bound RPE peroxidase showed a hyperbolic curve reaching a maximum at 10 mo of age. By 2 yr of age, the "bound" enzyme in affected dogs was below unaffected levels in the RPE and retina. Three acid hydrolases were slightly increased in the RPE and retina of affected dogs. Acid lipase activity, however, was similar in both unaffected and CCL dogs. Catalase was not found in the RPE of either group of dogs. The catalase activity in the retina of both affected and unaffected dogs was at similar levels. Since catalase is not present in the RPE, the major defense against peroxidase accumulation and peroxide toxicity probably depends upon peroxidase. The present study indicates that a decrease in this key regulating enzyme may be related to the formation of lipopigments in the retina and RPE of dogs with CCL.

Age Factors↗
PubMed1981

Colon epithelium. I. Light microscopic, histochemical, and ultrastructural features of normal colon epithelium of male Fischer 344 rats.

Although the colon of the inbred F344 rat is not distinctly demarcated into ascending, transverse, and descending segments as in the human colon, it can roughly be divided into ascending and descending portions that show distinct light microscopic, histochemical, and ultrastructural features. The ascending colon is characterized by a "herringbone" pattern of mucosal folds and test-tube-shaped uniform crypts that contain mucous cells (MC) with abundant mucin (acidic mucopolysaccharide--mostly sialomucin) in the lower one-third of the crypt, whereas the upper one-third contains two putative cell populations: 1) MC containing large globules of neutral mucopolysaccharide or sulfomucin and 2) columnar cells (CC), the full capabilities of which are unknown. The descending colon has longitudinal folds and contains sparse MC with small mucous granules at the lower one-third of the crypt, whereas the upper one-third contains numerous goblet cells. Neutral mucopolysaccharide is sparse and the acidic mucin is exclusively sulfated. Histochemically, the descending segment of the rat colon resembles the human descending colon in that the predominant type of mucus is sulfomucin. Ultrastructurally, the cell types observed in both the ascending colon and the descending colon are: a) MC, b) CC, c) endocrine cells, and d) undifferentiated cells.

Animals↗