The crop as an organ of glyceride absorption in the American cockroach, Periplaneta americana L.

Abstract

The potential of the crop to absorb the products of triglyceride hydrolysis was investigated in the American cockroach P. americana. Isolated sacs of crop and midgut tissue were filled with test loads containing [1-14C]palmitic acid or glyceryl tri[1-14C]palmitic acid and the efflux of label monitored. Label from both preparations was recovered primarily from the free fatty acid fraction. Inclusion of midgut lipase enhanced the rate of 14C efflux from test loads containing labeled triglycerides. Comparison of the relative rates of 14C efflux from crop and midgut sacs shows that the greatest efflux occurs from midgut, although the crop possesses the potential to effect absorption of significant amounts of hydrolyzed triglyceride. The capacity of crop to absorb fatty acids was confirmed by monitoring the evolution of 14CO2 from insects in which the crop was ligated anterior to the proventriculus before they were fed a test meal containing [1-14C]palmitic acid. Ligated insects evolved 41.5% of the 14CO2 produced by non-ligated insects.