THE STRUCTURE AND FORMATION OF THE SYNGAMUS-TRACHEA EGGSHELL (NEMATODA, SYNGAMIDAE)

The structure and formation of the egg-shell in Syngamus trachea has b een examined for the first time in an electron microscopic investigati on. The egg-shell of Syngamus trachea is composed of four layers: the uterine, the vitelline, the middle chitinous, and the inner lipid laye r. The latter layer is up to 0.2 mum thick. It contains electron-trans parent vesicles, dispersed in a light matrix. The middle chitinous lay er is approximately 1 mum thick. The vitelline layer originates in the oolemma of the fertilized oocyte, its thickness varying between 0.05 and 0.1 mum. The surface of Syngamus trachea eggs is covered by a uter ine fibrous layer.