Electron Microscope Studies of Some Cephalic Structures of Xiphinema Americanum

Abstract

Transverse and longitudinal sections of Xiphinema americanum, from the lips to the posterior end of the spear extension, were studied by electron microscopy. The odontostyl is shown to be a cylinder with an eccentric lumen open to the oesophagus along its length by a longitudinal slit. The spear extension is a closed tube connected to the odontostyl by a sheath that enlarges posteriorly to form the three-flanged knob at its terminus. Between the flanges were observed paired bands of striated muscle, distinct from the protractor muscles. It is suggested that the striated muscles transmit to the spear the movements of the oesophageal wall brought about by the protractor and retractor muscles.