Corpuscles containing crystalline formations in the exocrine pancreas of the dog

Abstract

IN studies pursued of the ultrastructure of experimental pancreatitis [3, 41, we were able to observe a significant increase in the number of intracytoplasmic crystalline formations in the acinar cells of the dog pancreas after intravenous injection of heterological serum. This observation bears on small pieces of 14 dog pancreas taken under general anaesthesia with Penthiobarbital of sodium, fixed in 2 per cent osmium tetroxide (phosphate buffer) embedded in Epon. The stain used was lead-hydroxide. Complex bodies were observed, measuring from 1 to 2 p in diameter, each separated from the surrounding cytoplasm by its own membrane having two or three layers. The formations themselves are of a heterogenous nature. They are composed of three types of elements (Fig. I): tridimensional crystals; highly osmiophilic, homogeneous and rounded droplets, probably of lipid nature; a heterogenous granular matrix. The crystals are made up of a uniform alignment of granules 110 A in average diameter separated from each other by a distance of approximately 160 A. The same cross section frequently shows crystals of different orientations (Fig. 2). What is the significance of these crystals? Their presence in the normal dog pancreas (7 animals) was observed in very rare cases. In contrast in 3 dogs, their number increased markedly in most cells after intravenous injection of 20 cc of rabbit serum containing anti-dog pancreas antibodies. Their multiplication has no relation, however, to a specific phenomenon of immunization, since the same results were obtained after intravenous injection, with the same dosage of previously non-immunized rabbit serum (1 animal), or after intravenous injection of previously non-immunized horse serum (1 animal). On the other hand, their appearance seems also to have no relation to a simple phenomenon of shock, since the injection of Histamine in sublethal doses (1 animal), as well as the intravenous injection of 20 cc of a solution of crystallized Ovalbumine diluted to 50/1000 (1 animal), does not increase their frequency. More over, Ichikawa [7] did not observe such crystals in the canine pancrease after hormonal stimulation. By morphological analogy with Tropomyosine crystals and those described as occurring at the time of ovogenesis of the Planorbis, these formations seem to us to be crystals of protein nature [2].