Fig. 4. Cell-proliferation is affected in the eye-antennal disc of ptc mutant individuals. (A-D) BrdU incorporation in wild-type and ptc mutant eye-antennal discs from late 3rd instar stages, stained with anti-BrdU. (A) Wild type. (B) A pair of eye-antennal discs from the same ptc^hdl/ptc^H84 individual; the disc on the right shows reduced BrdU incorporation (the bilateral difference in the incorporation is consistent with the unilateral head capsule defect). (C) Another pair of ptc^hdl/ptc^H84 eye-antennal discs; the disc on the right has very few BrdU-positive cells. (D) Domains of cells in a 3rd instar larval eye-antennal disc where Ptc expression is very strong. Note that there is a low level of Ptc expression in most of the cells in the eye-antennal disc. The loss of BrdU incorporation corresponds generally to the Ptc-expression domains. (E-G) Anti-Phosphohistone-3 (PH3) staining (red; green is Phalloidin staining) of the eye-antennal discs 1 hour after puparium formation. (E) Wild type, note that many cells are dividing. (F,G) ptc^hdl/ptc^H84 discs, a few cells are undergoing mitosis.