HISTOLOGICAL EXAMINATION OF TISSUE-CULTURE INITIATION FROM IMMATURE EMBRYOS OF MAIZE

The tissue origin, growth patterns and organization of in vitro tissue cultures initiated from immature maize (Zea mays L.) embryos were cytologically examined. Examination of thick sections from initiating cultures indicated that the scutellum is the tissue of origin. During culture initiation the scutellum, especially in the region of the epithelium, becomes highly meristematic and proliferates rapidly. These cultures were characterized by a cambial zone which provided for extended in vitro proliferation and by apical meristems developing on the culture surface. These meristems developed to the two leaf primordia stage under the cultural conditions of this study. Differentiation of root primordia associated with the apical meristems was not observed. The apical meristems appeared to arise de novo at the tissue surface and were probably multicellular in origin. The observations are discussed in relation to their significance concerning mutation and selection. © 1979 Springer-Verlag.