Structure-activity relationships in corpora allata of the cockroach Diploptera punctata: roles of mating and the ovary.

Abstract

Morphometric studies were made on corpora allata of the cockroach Diploptera punctata from animals in which increasing gland size is not coupled to hormone synthesis (ovariectomized mated females; last-instar larvae) and in which gland size is coupled to hormone synthesis (normal mated and virgin females; penultimate-instar larvae). Cell number, gland volume, and juvenile hormone synthesis were measured. From electron micrographs, nuclear, cytoplasmic, and extracellular volumes; and cell membrane area were calculated; and fine structure described. Low-activity glands of ovariectomized mated females resembled high-activity glands from mated females in high cell number, large overall and cytoplasmic volume, and low nuclear-cytoplasmic ratio; they differed in having organelles typical of low-activity glands, mitochondria with dense matrices and large whorls of smooth endoplasmic reticulum. Inactive last-instar larval glands resembled mated ovariectomized female glands in increased cell number and organelles characteristic of inactive glands; however, their nuclear-cytoplasmic volume ratio was much higher. Penultimate larval glands with high activity per cell resembled active glands of normal mated females. Ovariectomy did not change morphometric parameters of virgin female glands; thus mating results in increase in size of adult female glands whereas the growing ovary is needed for changes in mitochondria and endoplasmic reticulum associated with high juvenile hormone synthesis.