The tylenchid (Nematoda) egg shell: formation of the egg shell in Meloidogyne javanica

Abstract

SummaryOogonia of Meloidogyne javanica are radially arranged around a central rachis to which they are attached by cytoplasmic bridges. As the oocytes mature the rachis disappears and the oocytes pass through the oviduct in tandem. The oviduct-spermatotheca valve is constructed of two rows of tightly packed cells of which there are four per row. The nuclei of these cells are large and contain balloon-shaped cytoplasmic invaginations. The spermatotheca is characterized by microtubules which extend to its lumen and by invaginations of plasmalemma. Cells of the distal uterine region contain large intracytoplasmic spaces bordered by endoplasmic reticulum whereas proximal uterine cells have dense cytoplasm and large areas of compact endoplasmic reticulum. Egg-shell formation begins in the spermatotheca with the modification of the oolemma to form the vitelline layer. The chitinous layer begins in the distal portion of the uterus and appears to originate from the egg. Proline-containing protein is incorporated into the chitinous and lipid layers as the egg passes through the mid-region of the uterus and formation of the lipid layer in this region completes egg development.