The cell coat of the developing olfactory epithelium in the chick.

During development of the olfactory epithelium in the chick embryo, the cell coat is revealed by treatment with Ruthenium red. On day 4 of incubation the developing sensory epithelium displays a thicker apical and basal cell coat than the neighbouring head ectoderm. The lateral cell coat is of equal thickness in both epithelia. The apical cell coat of the olfactory epithelium increases in thickness from day 4 to day 19 of embryonic life, finally attaining a thickness of about 55 nm.