Fig. 9. Ciliary reversal in response to the photolysis (circled) of caged calcium at various portions of the cilia. (A) Weak reversal in response to application of UV to the tip of the cilia (cf. Fig. 6B). (B) Strong reversal in response to application of UV above the basal bodies (cf. Figs 5A, 6A). (C) Restriction of initial response to UV-treated cilia when UV was applied to both basal bodies and upper ciliary region. Following trichocyst exocytosis (t), ciliary reversal took place on the entire cell surface (cf. Fig. 7). (D) No cilium reversed their direction in response to UV application at the inner portion of the cell, although trichocyst exocytosis (t) took place, indicating [Ca²⁺]_i at the neighboring basal bodies. After trichocyst exocytosis (t), ciliary reversal occurred on the entire cell surface (cf. Fig. 8).