The fused synganglionic mass in the unfed Ornithodoros (Pavlovskyella) erraticus female is enclosed within a sinus of the circulatory system and consists of a neural lamelia surrounding an outer cortex and an inner neuropile containing the oesophageal canal. The neural lamelia consists of alternating layers of finely granular material containing collagenous-like fibers and may function to provide support to underlying tissues, resist positive hydrostatic pressure and allow permeability to nutrients and ionie exchange. Immediately below the neural lamelia is a perineural layer of glial cells. The remainder of the cortex comprises two types of neurosecretory cel! bodies, globuli cells and glial cells, and one type of non-neurosecretory cell. The glial cells are structurally related to the transfer of trophic material. The neuropile consists of nerve fibers (axons and dendrite) surrounded by glial cells