Microtubule and microfilament distribution during the secretory activity of an insect gland

The distribution of microfilaments and microtubules was studied in the secretory cells of the accessory glands of the medfly (Ceratitis capitata) female reproductive system. Actin, demonstrated by rhodamine-phalloidin and heavy meromyosin decoration, is present around the extracellular cavity at the level of microvilli and the subapical cytoplasm of the cell. The size of such a cavity varies in relation to the secretory cycle of the cells and also the disctribution of microfilaments. In the early stage of activity microtubules detected using an antibody against alpha-tubulin are distributed at the periphery of the cell and around the extracellular cavity. During secretion they occupy the whole of the cytoplasm and disappear at the end of the secretory cycle. The mechanism of the discharge of the secretion from the extracellular cavity is discussed.