宁夏枸杞的胚胎发生和胚乳发育

宁夏枸杞的胚胎发生属茄型,由顶细胞参与胚体的形成,基细胞仅形成六细胞胚柄。胚乳发育为细胞型,但也观察到少数核型胚乳的现象。初步探讨了核型胚乳与细胞型胚乳的关系。     

ON THE EMBRYOGENY OF SCHIZAEA DICHOTOMA

The zygote of Schizaea dichotoma divides transversely and the outer cell thus produced divides longitudinally. The three cells probably establish the organs: root, stem, and foot. The first leaf is not embryonic in origin but forms on the relatively old sporeling. Some general comments on gametophyte and embryo phylogeny are presented.     

STUDIES ON THE ONTOGENY OF THE DWARF MISTLETOES,ARCEUTHOBIUM. I. EMBRYOGENY AND HISTOGENESIS

Cohen , L. I. (Washington State U., Pullman.) Studies on the ontogeny of the dwarf mistletoes, Arceuthobium. I, Embryogeny and histogenesis. Amer. Jour. Bot. 50(4): 400–407. Illus. 1963.—A complete developmental study on the origin and organization of the main tissue systems in the embryo of Arceuthobium reveals a greater degree of internal differentiation in the mature embryo than hitherto reported. The mature embryo consists of rudimentary cotyledons, a well-defined hypocotyl and a highly organized radicle. The latter develops from the remaining undifferentiated portion of the globular embryo soon after the embryonic cortex and procambium are differentiated. The radicular promeristem is organized into 4 initiating zones: (1) a uniseriate layer of apical surface initials; (2) a subapical zone of central initials; (3) a peripheral zone; and (4) a zone of procambium initials. Comparison between the dwarf mistletoe embryo and those of several nonparasitic angiosperms indicates that their ontogenies, in many respects, are essentially similar.     

EMBRYOGENY AND HISTOGENESIS IN NERIUM OLEANDER II. ORIGIN AND DEVELOPMENT OF THE NON-ARTICULATED LATICIFER

Mahlberg , P. G. (U. Pittsburgh, Pittsburgh, Pa.) Embryogeny and histogenesis in Nerium oleander. II. Origin and development of the non-articulated Iaticifer. Amer. Jour. Bot. 48(1): 90–99. Illus. 1961.—Laticifer initials, collectively considered as a laticifer system, are differentiated in the globular embryo from meristematic cells which occupy a position within the potential procambial tissue. A total of usually 28 initials, in Nerium oleander, arise as an irregular ring of cells directly below the embryonic shoot apex, during initiation of the cotyledonary primordia. No anastomoses occur between laticifer initials. During subsequent development of the embryo, the laticifer initials grow in a bi-directional manner and penetrate into the root, cotyledons and toward the shoot apex. Upon enlargement the initials bifurcate repeatedly, many branches penetrate into the cotyledons, others grow into the cortex of the hypocotyl or penetrate between cells of the procambium. Repeated nuclear divisions within each initial result in the formation of a multinucleated protoplast in this cell type. The tips of laticifers occupy intercellular spaces during their growth; they do not penetrate into or through adjacent cells. A plexus of laticifer branches is formed within the cotyledonary node of the mature embryo. No new initials are formed during subsequent growth of the plant, rather certain branches from the cotyledonary nodal plexus penetrate into the enlarging shoot system. The nature of their growth habit and branching suggests that the tips of laticifer initials exhibit an intrusive form of growth.     

黑节草双受精过程及胚胎发育的研究

黑节草从传粉到受精约需１３０ｄ,精子在花粉管中形成,胚囊发育属蓼型胚囊,因反足细胞较早退化,故受精前胚囊多只由卵器和中央细胞组成。精卵核融合时,精核染色质进入卵核后凝集成颗粒状,并在原位与卵核的染色质融合,雌、雄性核仁一直维持至合子的第一次分裂期前。双受精作用正常,属于有丝分裂前配子融合类型,初生胚乳核发生２－３次分裂后逐渐退化消失,胚的发育局限于球形胚阶段。