MESADENES MATURATION AND ITS HORMONAL-CONTROL IN THE MILKWEED BUG, ONCOPELTUS-FASCIATUS

Adult maturation of the mesadenia was examined by electron microscopy. The glandular epithelium exhibits only one cell type with a polarity along the haemocoel-lumen axis. In newly emerged males, the glands sho w little signs of secretory activity although the narrow lumen contain s some material. Dramatic changes commence at day 2. The rER increases drastically, and at day 3 cisternae of the rER are considerably diste nded and include a fine granulated product. The lumen of the gland wid ens greatly and stores material of the same appearance as in the rER i nclusions. The mode of the secretory process is not clear since membra ne bound vesicles are not formed. SDS-PAGE of the secretion stored in the mesadenia reveals a predominant protein fraction of about 25 kDa b esides several less prominent protein fractions. The main protein has no correspondent in the haemolymph. Chemical allatectomy with precocen e II and counteraction of juvenile hormone III show that the secretory activity and intraglandular storage of the secretion are modulated by the corpus allatum. Allatectomy retards mesadenes maturation but does not prevent it. A role of ecdysteroids in glandular maturation is not discernible.