The structure and development of the Malpighian tubules of an aquatic bug: Sphaerodema rusticum Linnaeus (Hemiptera).

Abstract

In adult Sphaerodema rusticum Linnaeus there are four Malpighian tubules which join distally to form a cross. Each tubule shows four regions, namely capillary tube, proximal, middle and distal regions. The capillary tube is apart of the Malpighian tubule though it is conducting in function. Internally it is smooth and has no striated border. The rest of the regions are lined by a honeycomb-striated border. The embryonie development has established beyond doubt that the number of the tubules is four and not two as reported earlier for aquatic bugs. The entire developmental sequence has been described and the period divided into two phases: (i) cell production and rearrangement and (ii) cell rearrangement and enlargement. This type of sequence is unique and does not fit in with any described so far. The Malpighian tubules have been considered to be of endodermal origin.