THE PROTHORACIC. GLANDS OF LEUCOPHAEA MADERAE (ORTHOPTERA)

Abstract

The prothoracic glands of Leucophaea are paired band-like structures close to and innervated by the prothoracic ganglion. The longitudinal axis contains striated musculature, a nerve and a trachea. The glands are well developed in nymphal stages, where they consist of layers of dense nuclei surrounded by scanty cytoplasm. The nymphal prothoracic glands exhibit a cyclic mitotic activity. In freshly emerged adults involution of the prothoracic glands occurs during the first week of the adult stage. It manifests itself by a breakdown of nuclei, and results in a reduction of the tissue bands to practically nothing but the muscular core. The glands are considered homologous with the prothoracic glands of Lepidoptera and Hymenoptera, with the "ventral glands" of lower Pterygota, with the "intersegmental organs" of Odonata, and possibly with the "parenchymatous tracheal organs" of Hemiptera. They have certain features in common with the thymus of the vertebrates.