Distal tip and regional ablations. (A, D, G, J, M, P) Drawings and images of optic vesicles (OV) at time 0 (outlined with a back dashed line) indicate the location and extent of each ablation (white dashed line; A'-P'). The control non-ablated retina are shown on the left (B, E, H, K, N) and the ablated retina are shown on the right (C, F, I, L, O) after processing for in situ hybridization with a visinin probe. (A-C) A small distal tip ablation (n = 4) did not prevent the development of the visinin-free spot (circled) at E7. (D-F) Ablation of the anterior edge (n = 4) did not affect the development of the visinin free spot (circled). (G-I) Posterior OV edge ablations (n = 5) did not affect central patterning with the visinin-free spot (circled) observed in the control and ablated tissue. (J-L) A larger ablation (>20%) of the distal tip (n = 4) resulted in the loss of the visinin-free spot in the operated eye; compare circled regions in the control and ablated eyes. (M-O) Anterior dorsal ablations (n = 3) of less than 20% of the distal tip resulted in the loss of the visinin-free spot in the operated eye. (P-R) Removal of between 20-50% of the OV (n = 6) resulted in either small eyes (Q, right eye) compared to the non-operated eye (left eye) as shown, or pigmented blobs (R). Anterior (A), Posterior (P), Proximal (PR), and Distal (D) are indicated for the OVs. Dorsal (D), Ventral (V), Nasal (N) and Temporal (T) are indicated for the retinal flatmounts. Scale bar = 1 mm.