英文摘要 |
The metamorphosis of spermatozoid and the formation of operculum in microgametophyte of Selaginella tamariscina (Beauv.) Spring are studied under EM. The distinct events during the metamorphosis are: (1) the elongation of the apical mitochondrion, (2) the separation of basal bodies and emergence of flagella, (3) the elongation of nucleus and (4) discard of excess cytoplasm. The formation and opening process of operculum described are the significant finding of microgametophyte in heterosporous lycopods. Operculum is derived from several jacket cells. After the operculum takes off, the spermatozoids spring out in a clump. Occasionally the jacket cells give rise to the spermatids, too. A mature spermatozoid bas a twisted long nucleus, an apical mitochondrion with or without a posterior mitochondrion, a posterior plastid containing several large starch grains and two flagella. The anterior flagellum exserts from the apex of the apical mitochondrion, while the posterior one exserts from the juncture of the apical mitohcondrion and the nucleus. |