Anatomy of the intestine of Ascaris suum: a three dimensional study with silicone rubber casts

Abstract

To facilitate studies of the physiology of Ascaris suum the relations between the intestine and the other organs were investigated. The anterior intestine, which starts, with a thin-walled expansion chamber, is held by connective tissue and by the bellies of muscle cells. A coarctation of the intestine marks the junction of the anterior and midintestine and in the female this narrowing occurs near the genital pore. The midintestine lies free amongst the reproductive organs and terminates near the most posterior excursions of the ovaries and uteri in the female, and of the testis in the male. The posterior intestine is attached continuously, but not initially circumferentially, to the body wall. Relative lengths for the different parts of the female worm are given and microfil casts made in situ with both sexes yielded information about the relative volumes of the midintestine and posterior intestine. The coarctation is the narrowest pan of the intestine and the largest cross-sectional area is reached at the start of the posterior intestine. The attachments to the body wall indicate that the anterior and posterior intestine change length like an accordion when the muscles contract but the cross-sectional area of the lumen is decreased by dorsoventral compression.