Ultrastructure and histochemistry of the scolex of two Neotropical proteocephalidean species (Cestoda: Onchoproteocephalidea).

The internal ultrastructure of the scolex and the histochemical composition of the apical glands of two South American proteocephalideans cestodes, Monticellia magna and Proteocephalus pimelodi, were described for the first time. The study included the use of scanning and transmission electron microscopy to observe the tegumental ultrastructure, and histochemical techniques to detect types of gland secretion. Two types of glands were found in the scolex of M. magna and P. pimelodi. The pattern of microtriches described for M. magna was confirmed and that of P. pimelodi was described for the first time. Also, the internal ultrastructure of the microtriches in both species was described. Indications of the presence of sensory receptors were also found in M. magna. Finally, the systematic value of the characters studied is discussed, such as the internal structure of the gladiate spinitriches and the apocrine gland of M. magna.