The coxal glands of geophilomorpha (chilopoda): organs of osmoregulation.

The organs terminating at the coxal pores of the tug-legs of Geophilomorpha are not repugnatorial glands, but possess typical transport epithelia with deep apical and basal infolding of the cell membranes, between which numerous large mitochondria are located. Many transport vesicles are found in the basal region but fewer in the apical cytoplasm. The apex is characterized by bundles of longitudinally oriented microtubules, sparse endoplasmic reticulum and free ribosomes. Single neurosecretory axons with synaptoid areas are scattered among the cells. It is suggested that the coxal organs have a diuretic function in moist habitats and an antidiuretic effect in arid environments. The "switch-over" is evidently controlled by a neuroendocrine mechanism.