CELLULAR RESPONSES OF PERIPLANETA-AMERICANA TO ACANTHOCEPHALAN LARVAE

The cellular responses of the cockroach, Periplaneta americana, to the larvae of the acanthocephalans Moniliformis dubius and Macracanthorhynchus hirudinaceus have been studied. M. dubius acanthors penetrate the gut and reach the hemocoel 1 to 14 days after infection. Acanthors undergoing normal development are surrounded by several layers of hemocytes for 4-6 days then hemocyte numbers decline. M. hirudinaceus acanthors induce extensive but temporary changes in histologic structure of gut around the site of penetration, including some destruction of epithelial cells, aggregation of hemocytes, and hyperplasia of adjacent tissues. The acanthors are soon melanized. Following injection into the hemocoel, acanthors of M. dubius develop normally but acanthors of M. hirudinaceus and eggs of both species are rapidly encapsulated and melanized. Envelope removal from later larval stages of M. dubius before injection leads to encapsulation and melanization. © 1969.