Bacteroids in the ovaries of a tsetse fly

Abstract

SYMBIONTS of Glossina previously described by Wigglesworth¹ as Gram-negative intracellular bacteroids are located in a group of specialised cells, the mycetome, in the midgut. Their intracellular nature is well known from studies with the light^1–3 and electron⁴ microscopes (see Fig. 4). Roubaud³ demonstrated bacteroids in the mycetome of the larval midgut of G. palpalis. He was unable to determine the mode of transmission, but suspected the involvement of the milk gland, as have other authors^5,6. Recent work on the ultra-structure of the milk gland has demonstrated that bacteroids occur extracellularly in the lumen of the gland⁷, thus adding support to the notion that transmission from one generation to the next may occur through the secretions of the milk gland. Bacteroids have not, however, been located in the cells of the milk gland, and it remains uncertain whether this route of transmission is used.