title: [Studies on sexual organs and embryological development morphology of Pterocypsela formosana].
abstract: In this study, the embryological characters of Pterocypsela formosana (Asteraceae) were investigated with the traditional paraffin section methods. The anther has 4 sporangiates, the anther wall development follows the dicotyledonous type and comprises of an epidermis, endothelium, a middle layer and a single-layered tapetum, the tapetum belongs to glandular type. Meiosis of the microspore mother cells is of the simultaneous type, for the formation of mostly tetrahedral tetrad, the mature pollen grains are 2 celled. The ovary is bicarpellate, unilocular, one ovule and basal placenta, the ovule is unitegmic, tenuinucellate, inverted campylotropous and with developed endothelium, archesporial cell of megaspore differentiates immediately below the nucellar epidermis and functions as megasporocyte after development and belongs to tenuinucellate ovule type. The megasporocyte undergoes meitotic to form a liner tetrad, only one chalazal megaspore becomes the functional megaspore which forms female gametophyte including 7-celled and 8-nucleated after three successive mitosis, the female gametophyte is of the Polygonum type. Two polar nuclei melt into a secondary nuclei before fertilization, the chalazal antipodal cells are ephemeral and degenerate shortly after forming. Fertilization is porogamous and belongs to premitotic type of syngamy. The division of the primary endosperm nucleus is earlier than the zygote, the endosperm is of the nuclear type with the presence of haustoria, and the embryogeny belongs to asterad type chicory variant. The developed suspensor on early stage has important significance to the embryo development.
authors.forename: Long
authors.initials: L
authors.lastname: Hua
authors.forename: Xue-ni
authors.initials: XN
authors.lastname: Ma
authors.forename: Heng-yu
authors.initials: HY
authors.lastname: Huang
mesh_terms: D019659:Asteraceae / Q000196:embryology*; D008540:Meiosis; D012098:Reproduction