Desenvolvimento de protocormos de Catasetum pileatum Rchb. f. in vitro: aspectos estruturais e conceituais

Development of protocorms of Catasetum pileatum Rchb. f. in vitro: structural and conceptual aspects). Histological aspects of the development of protocorms of Catasetum pileatum obtained from germinating seeds in vitro are shown and the controversial definition and significance of these structures are discussed. The protocorms are constituted of a mass of parenchyma cells, delimited by a uni-stratified epidermis; the parenchyma cells of the upper part of the protocorms are smaller than the cells of the basal part. The upper part of the protocorm is responsible for the formation of the vegetative stem apex; the first adventitious root are formed endogenously, after the differentiation of several leaves. Remains of the parenchyma cells, and a new plant with well developed shoot and root were visualized around 120-days of culture.