EXPERIMENTAL DIABETES IN THE CATFISH: NORMAL AND ALLOXAN-DIABETIC BLOOD GLUCOSE AND PANCREATIC HISTOLOGY1

Abstract

Alloxan diabetes has been demonstrated in the common lake catfish by correlated histo-logical and blood sugar studies. Anatomical considerations make this animal particularly suitable for this work. The conus arteriousus is conveniently situated for intravascular injection and serial blood sampling. The concentration of endocrine pancreas in a principal islet and accessory islets, all with limited exocrine tissue, facilitates histological preparations. In 237 determinations, using a Folin-Malmros micro method modified for fish blood, the normal blood sugar value was found to be 59 mg. %, with a standard deviation of 19 mg. %. Alloxan was administered through the conus of 50 fish, at 400 mg./kg. In alloxanized fish, blood sugar levels of 120-200 mg. % were typical. This hyperglycemia persisted through the 96 hour period studied and, in a few fish not sacrificed earlier for histological study, for 14 days, the longest period studied. In the intact animal, the principal islet is composed of many, heavily-granulated beta cells, with a similar number of other islet cells and a cortex of exocrine tissue. Within 3 hours of alloxan injection, degranulation of beta cells was apparent. In subsequent sampling periods, up to 96 hours, degranulation increased, accompanied by progressive hydropic degeneration and nuclear disintegration. These changes were found only in beta cells.