STRUCTURE AND FUNCTION OF EXCRETORY SYSTEM OF ASCARIS LUMBRICOIDES L

The excretory system of Ascaris lumbriocoides L. is formed by one single cell. This cell is H-shaped, with the two long tubules running in each lateral chord on both sides of the animal. The diameter of tubular lumen declines rapidly along tubular length. The cellular wall is formed by layers of cytoplasma plates which seem to originate in a densely packed vesicle layer (Fig. 2). The outer cellmembrane has deep basal infoldings. Between cell and body cavity spongelike cells are located. The body cavity is lined with a basal membrane. The constancy of final urine osmolality during immersion in hypo- or hypertonic solutions demonstrated no important role of the excretory system in osmoregulation, whereas the Na+-and K+-excretion varied remarkably with the electrolyte composition of the bathing solution (Fig. 9), indicating the importance of the excretory system in ion regulation of body fluid. Inulin-C14 injected into body cavity was not excreted in the final urine, a result consistent with the finding that no filtration elements were detected by morphological examination. Therefore in this animal urine is formed by secretion. © 1969 Springer-Verlag.