Comparative study of atrial granule concentration at the nuclear pole of atrial cells of the insect - eating bat P@istrellus Pipistrellus and the Wistar rat.

Abstract

Atrail myocardial cells of the rat and the rat have been compared in regard to number and cementation of atrial granules at the nuclear pole. Morphologically the granules appear' the same, being dense spherical and membrane bound. By morphometric measure, natriuretic material is higer in concentration in the rat than in the bat, the percentage volumes being 6.5 in the rat and 3.5 in the bat. This difference is statistically significant at P<0.003. Actual counts of granules at the nuclear pole showed that, on the average, cellls of the two species have equal numbers of granules. The finding of lower volume concentration of granule material in the bat which weighs much less (6gm) than the rat (I70gm) shows that there.is Not always an inverse relationship between granule concentration and animal size or weight as had been thought aggregation of nuclear material was observed at the nuclear pole in a number of atrial cells of the bat the significance of this unusual finding is not clear