[Electron-microscopic study of the excretory system of hungry females of the tick Hyalomma asiaticum P. Sch. et E. Schl. 2].

In H. asiaticum the cells of the Malpighian tubules and these of the rectal cas have the uniform structure: the apical surface is covered with microvilli, the basal plasmatic membrane forms relatively small invaginations. As to ultrastructural characters, there is no distinct division of the Malpighian tubule into departments. The distal ends of the tubules are not only somewhat enlarged and form the so-called ampulla cells of which are noticeably flattened. The microvilli and basal folds of the plasmatic membrane in this area of the tubule are indistinct. The cells of the ampulla and the neighbouring area of the tubule are characterized by the presence of inclusions with mucopolysaccharide secretion confined by the membrane. The microvilli are most developed on cells of the proximal ends of the Malpighian tubules. Well developed microvilli of the rectal sac form a striated border each containing a microtube inside. The basal invaginations are developed here better than in the cells of the Malpighian tubules.