Ultrastructure of the maturing egg apparatus in Arundo formosana hack. (Poaceae)

• Published in: International journal of plant sciences Vol. 158; no. 6; pp. 713 - 726
• Main Author: Jane, W.N
• Format: Journal Article
• Language: English
• Published: Chicago The University of Chicago Press 01.11.1997; University of Chicago, acting through its Press
• Subjects: ALMIDON; AMIDON; ARUNDO; Botany; CELL DIFFERENTIATION; Cell nucleus; CELL STRUCTURE; CELL WALLS; Cellular biology; CYTOPLASMIC ORGANELLES; DESARROLLO EMBRIONARIO; Development; DEVELOPPEMENT EMBRYONNAIRE; DICTIOSOMA; DICTYOSOME; DICTYOSOMES; DIFERENCIACION CELULAR; DIFFERENCIATION CELLULAIRE; Eggs; EMBRIONES VEGETALES; EMBRYO SAC; Embryogenesis; EMBRYON VEGETAL; EMBRYONIC DEVELOPMENT; ENDOPLASMIC RETICULUM; ESTRUCTURA CELULAR; MITOCHONDRIA; MITOCHONDRIE; MITOCONDRIA; NOYAU CELLULAIRE; NUCLEI; NUCLEO; NUCLEUS; ORGANITE CELLULAIRE; ORGANULOS CITOPLASMICOS; OVA; OVULE; OVULO; PARED CELULAR; PAROI CELLULAIRE; Plant cells; PLANT EMBRYOS; Plant reproduction; PLASMODESMATA; PLASTE; PLASTIDIOS; PLASTIDS; POLINIZACION; POLLINATION; POLLINISATION; RETICULO ENDOPLASMATICO; RETICULUM ENDOPLASMIQUE; STARCH; STRUCTURE CELLULAIRE; TISSUE ULTRASTRUCTURE; ULTRAESTRUCTURA; ULTRASTRUCTURE; VACUOLA; VACUOLE; VACUOLES
• ISSN: 1058-5893; 1537-5315
• DOI: 10.1086/297483

After cell compartmentation, the young embryo sac of Arundo formosana consists of seven cells: the egg, two synergids, the central cell with two polar nuclei, and three antipodal cells. All three cells of the newly formed egg apparatus surrounded by incomplete cell walls initially have similar cellular contents. However, as the egg apparatus develops, the egg and the synergids gradually differentiate in cellular contents prior to the initiation of the filiform apparatus. The egg develops many starch-containing plastids. The synergids become rich in rough endoplasmic reticulum (ER) and dictyosomes. These differences are retained throughout maturation. The micropylar common wall of the two synergids produces many cell-wall ingrowths, which consitute the filiform apparatus. Endoplasmic reticulum and dictyosomes are involved in filiform-apparatus formation. During maturation, the egg shows some changes: the nucleus migrates toward the cell center; the degree of vacuolation and the number of starch grains and oil bodies increase; the amount of ER and dictyosomes decrease. During synergid maturation, the organelles gradually show a polarized distribution: the plastids are present only at the chalazal pole, and most of mitochondria and dictyosomes are distributed at the micropylar pole. After pollination, vacuolation usually occurs at the chalazal pole of the persistent synergid, and the degenerated synergid becomes filled with electron-dense materials. During egg-apparatus expansion, cell-wall materials are deposited and condense at the chalazal pole, forming electron-dense particles at maturity. Plasmodesmata are always present in the micropylar gametophytic cell walls of the egg apparatus.