Malpighian tubules

In centipedes the Malpighian tubules are a pair of long, forwardly running, blind tubules which originate at the junction of the mid- and hind-gut (Figs. 110, 111).

Lithobiomorpha

The Malpighian tubules of Lithobius forficatus have been described by Plateau (1878), Palm (1953) and Rilling (1968). The tubules open into the gut by way of a distinct urinary bladder or ampulla, the inner portion of which is a narrow tube piercing the intestinal wall (Fig. 151a). Palm failed to identify distinct sphincter muscles but thought it probable that the muscular coat of the intestine which surrounds the inner portion of the ampulla functions as a sphincter. Rilling (1968) stated that the ampullae show a typical mid-gut musculature but annexe the circular muscles of the hind-gut. In some specimens the tubules terminate in a small thin-walled transparent vesicle, Palm was unable to determine whether this was caused by physiological conditions or whether it was a morphological variation.

The epithelium of the ampulla has a strong basement membrane along which run very thin longitudinal muscle fibres; a few circular and oblique fibrils are also present. In many places connective tissue cells occur around the ampullae, either situated directly on the basement membrane or connected with it by fine cytoplasmic processes. The ampulla cells are tall and narrow with basal nuclei. The apical parts of the cells contain indistinct granules and more or less prominent vacuoles. There is no cell cuticle or brush border.