Fig. 3. Perception of CLV3 in stem cell neighbours is required for meristem regulation. (A,B) CLV1 expression as detected by RNA in situ hybridization in non-transgenic clv1-4 mutant (A) and CLV3::CLV1; clv1-4 (B) plants. Note expression in the epidermis in B which is not present in A (arrow). Hybridization with a sense probe did not produce any specific staining (not shown). (C-F) Scanning electron micrographs of secondary inflorescence meristems of wild type (C) and CLV1::CLV1-expressing (D), CLV3::CLV1-expressing (E) and non-transgenic (F) clv1-4 mutant plants, respectively. The meristem size of the CLV3::CLV1-expressing clv1-4 mutant is intermediate between the wild type and CLV1::CLV1-expressing clv1-4 mutant plants, on the one hand and the enlarged clv1-4 mutant meristem on the other. IM, inflorescence meristem. Scale bars: 50 µm (in A for A and B and C for C-F).