Immuno‐Fluorescent analysis of follicular growth and development in whole ovaries of the Indianmeal moth

The differentiation and growth of ovaries was analyzed using immuno‐fluorescence microscopy and then correlated with the changes in the external morphology of female pupae during metamorphosis of the Indianmeal moth, Plodia interpunctella (Hübner). Fourteen developmental points coincident with a daily change in the light:dark cycle were chosen for observation to describe the progress of cuticular, ovarian, and follicular development during metamorphosis. Follicular structure was examined in whole mounts of ovaries using an immuno‐fluorescent labelling technique. The growth of oocytes and nurse cell cap in terminal follicles was measured throughout ovarian development. A rapid increase in the relative size of the nurse cells began during the fourth scotophase and continued until the beginning of the sixth scotophase. Following the sixth scotophase, the relative size of the nurse cells decreased until they disintegrated prior to choriogenesis. Oocytes began to grow rapidly during the fifth scotophase, coincident with the initiation of vitellogenesis, and continued to grow until choriogenesis was initiated just after adult eclosion. The rate of follicular growth was related to the position of the follicle in the ovariole; the closer to the terminal position, the greater the rate of growth. Thus, at adult eclosion, each ovariole contained a linear array of follicles in progressive stages of development with the terminal follicles ready to begin choriogenesis.