ATTACHMENT ORGANS OF TREMATODE FАSCIOLA HEPATICA LINNAEUS, 1758 P. 1. ORAL SUCKER

Abstract

The structure of oral sucker of trematode Fаsciolа hepatica, an organ of fixation to the walls of hepatic ducts in human and vertebrate animals, has been studied. Light and stereoscanelectronmicroscopicobservations on the oral sucker of trematode F. hepatica allow to determine that it consists of various complex circular and longitudinal muscle layers that differ from each other in the stageof development of musclefibers. Transverse muscle fibers connect circular muscles. The oral sucker performs nutrition and attachment functions. The oral sucker is very mobile and its diameter changes due to muscle contraction and relaxation. At contraction of musclefibers the cavity of oral sucker becomes smaller because of the vacuum generated in its cavity. F. hepatica is firmly attached to the walls of hepatic ducts. On the bottom of oral sucker is a mouth opening. When F. hepatica feels hungry its circular muscles contract, cover the mouth opening, and the oral sucker takes the shape of a funnel.