Ultrastructural differentiations in the developing follicle cortex ofLocusta migratoria, with special reference to vitelline membrane formation

摘要

Electron microscopic studies on developing follicles ofLocusta migratoriashow the vitelline membrane to be composed of two ultrastructurally distinguishable components: The vitelline membrane bodies (VMBs) and, in addition, fine granular material, cementing the VMBs together. VMBs form first in the oocyte-near zone within the oocyte-follicle cell space. Subsequently, the second vitelline membrane substance is secreted between the VMBs through apical protrusions of the follicle cells. The possible origin of the VMBs is discussed.