Morphological and histological aspects of the spermatheca as they relate to sperm organization in the grasshopper species Schistocerca americana and Dissosteira carolina (Orthoptera: Acrididae)

Abstract

The spermatheca of the acridid Orthoptera Schistocerca americana and Dissosteira carolina both consist of a ductus seminalis and a receptaculum seminis that ends in two blind sacs called the apical and preapical diverticula. The diverticula of acridid grasshoppers show high morphological variation that might imply functional differences. A microscopic examination of the structure of the spermatheca surface of both species found the presence of numerous gland ductules, but a lack of acanthae typical of many acridids. A histological study of macromolecules in the spermatheca of mated females found large carbohydrate and protein secretions present in all chambers. The secretion was not present in virgin S. americana but was present in virgin D. carolina. These secretions are likely glycoproteins either secreted by female gland ductules or contributed from males. Lipids were limited to small droplets contained within epithelial cells lining the walls of the spermatheca of both mated and virgin females. Histological sections of the spermatheca were utilized to track the course of sperm bundles in the chambers at various intervals following copulation initiation. In S. americana sperm bundles are found primarily in the diverticula and appear to be degraded in the apical diverticulum. In D. carolina sperm bundles are seen in all chambers of the spermatheca except the ductus seminalis and maintain a constant distribution an hour into copulation. Implications of this study are discussed in relation to the function of acridid spermatheca and sperm organization.