GLaz transcript is expressed in a subset of glial cells in the embryonic CNS from embryonic stages 12-16. Expression is confined mainly to the neuropil, and is localized to a symmetrical chain of cells aligned to the longitudinal connectives. At stages 13-16, GLaz transcript is expressed in 8 cells/hemineuromere; morphology and location indicate these are interface glial cells. There is no PNS expression. Outside of the CNS, GLaz transcript is expressed at a low level in blastoderm stage embryos. At embryonic stage 9-10, GLaz is expressed in the visceral mesoderm, and weakly in the amnioserosa. At stages 11-13, expression is observed in the developing hindgut, and at stages 13-14 in epithelial cells at the boundaries between the midgut and hindgut, and midgut and foregut. Late in stage 14, GLaz is expressed at the sites of the future midgut constrictions, then later in the midgut constrictions. Expression is also observed in the primordia of the salivary glands, anal pads and posterior spiracles, and a subset of cells in the clypeo-labral primordium.