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  • Department of Pathology University of Texas Medical Branch, Galveston, Texas 77550

To the Editor:

Since submission and publication of the recent article by B. A. Nagy, S. K. File, and J. H. Smith, “Changes in enteric vasculature of mice infected with Schistosoma mansoni” (Am. J. Trop. Med. Hyg., 30: 999–1009), two additional studies bearing on our results have come to my attention. The first article appeared after submission of our paper and deals in vivo with much younger infections than those we studied; however, Dr. Bloch presents evidence of sacculations of intestinal venules adjacent to eggs from which he infers that the eggs elaborate a vasoactive substance. This effect is apparently quite localized since sacculation rather than dilatation of the vessel was observed. However, it is difficult to postulate that such a substance would produce venular muscular relaxation (sacculation) at the same time it produces hepatic portal vein sphincter contraction which could explain some of our findings. Nonetheless, these sacculations may be what we observed as micro-aneurysms in our preparations.