Light and Electron Microscopic Study of in vitro Cultured Female Gametophyte of Araucaria araucana (Mol.) Koch LILIANA CARDEMIL1) and MIGUEL JORDAN2) 1) Departamento de Biologfa, Facultad de Ciencias Basicas y Farmaceuticas, Universidad de Chile, Santiago, Chile 2) Laboratorio de Botanica, Instituto de Ciencias Biol6gicas, Universidad Cat61ica de Chile, Santiago, Chile Received April 13, 1982 . AcceptedJune 16, 1982 Summary The female gametophyte of Araucaria araucana (Mol.) Koch consists of large haploid cells, about 180 p.m in diameter, that include many starch grains and several nuclei. Segments of megagametophyte, with and without embryonic tissue, were cultured at 25°C in Murashige and Skoog media, supplemented with 10 mg .1- 1 of NAA and 1 mg .1- 1 of kinetin. Megagame- tophyte segments including embryonic tissue only form callus when embryonic tissue also do so. After 15 days of culture, cells became about 500 p.m in diameter and their starch diminished considerably. After 20 to 25 days of culture, cell wall formation subdivides the cytoplasm of the cells into smaller territories with 3 or 4 nuclei each. Then, division of nuclei is initiated. This leads to the formation of meristematic cells whose descendants remain haploid and proliferate forming callus. Elongated cysternae that are lined up across the cytoplasm and paramural bodies of both types, plasmalemmasomes and lomasomes, appear at the time when cells increase in size and new cell walls are laid down. During this period dictyosomes are not observed and therefore, they do not seem to be involved in cell wall formation. Key words: Araucaria araucana, cysternae, dictyosomes, megagametophyte, multivesicular body, paramural body. Introduction There are several reasons why the seed of the conifer Araucaria araucana is conve- nient for developmental studies: The seed which do not exhibit dormancy other that imposed by environmetal con- ditions, are shed at the end of the fall and are covered by snow during winter. In spring, the metabolic activation of the seed begins. Seeds are produced abundantly and their viability is of about 99 %. Furthermore, removal of teguments produces partial synchronization of their embryonic development. Seeds, that are 1.5 cm in diameter and 3 cm in length, are larger than those of other conifers and their components are easely dissected. Finally, like the other conifers Araucaria seeds are unique in that they consist of two parts of different origin: the Z. Pjlanzenphysiol. Bd. 107. S. 329-338. 1982.