Biology of Schistosoma japonicum. From cercaria penetrating into host skin to producing egg.

The biology of the Chinese mainland strain of Schistosoma japonicum in mammalian phase of the life cycle has been studied in the past three decades. The mode of cercarial penetration is found to involve enzyme secretion and movement. The entry of schistosomulum into the blood vessel in the hypodermal connective tissue is evidenced after skin penetration. The growth and development of this fluke in mice and rabbits are investigated by physiological, histochemical and ultrastructural methods. The development of the fluke may be divided into eight stages. In the definitive host-range, at least 45 species and subspecies of 34 genera in 18 families of 7 mammalian orders have been demonstrated, and the susceptibility to infection in domestic animals is compared. The process of egg formation and embryonic development of this fluke are studied histologically and histochemically. It is suggested that the chemical nature of the egg shell should be a quinontanned protein system. The characteristics and dynamic changes of cytochemical substances in embryonation of eggs are described.