Extracellular Microtubules in the Aphid Gut

As part of an investigation of a plant virus which multiplies within the cells of its aphid vector (O'Loughlin and Chambers, 1967), the fine structure of the aphid gut was studied. The alimentary canal of aphids commences with the food canal which is formed by the apposition of grooves in the two interlocking feeding stylets . The stylet food canal leads to the sucking or pharyngeal pump within the aphid head, and this carries food into the foregut . The foregut is a narrow tube which opens via the esophageal valve into the first part of the midgut, usually referred to as the "stomach." The second part of the midgut, the "intestine," follows a devious course and is the longest part of the alimentary canal . It finally widens to become the hindgut which is thin walled and highly distensible . Specimens of Hyperomyzus lactucae (L .), reared on sowthistle (Sonchus oleraceus L .), were cut in half transversely in cold 3 % glutaraldehyde and fixed for up to 14 hr, followed by postfixation in cold 1 0/o osmium tetroxide in sodium cacodylate buffer pH 7 .4. They were dehydrated in acetone and embedded in Araldite. Thin sections were stained with uranyl acetate followed by lead citrate . The striated border of the intestine of the aphid Myzus persicae (Sulzer) has been reported to consist of typical microvilli (Forbes, 1964), but our observations, initially on H. lactucae, show that one can resolve the area surrounding each microvillus as made up of numerous extracellular microtubules that lie close to and parallel with the BRIEF NOTES