Claim · model-written summary
Megasporocyte expansion at the onset of megasporogenesis is accompanied by a decrease in cytoplasmic density.
- Taxon
- Arundo formosana
Arundo formosanae0 - Organ / stage
- megasporocytee1
- Outcome
- cytoplasmic densitye1
- Direction
- decreasee1
Verbatim
e0“The ovule of Arundo formosana Hack. is tenuinucellate”
e1“the expansion of the megasporocyte, which is accompanied by a decrease in cytoplasmic density”
Title
Ultrastructure of Megasporogenesis and Early Megagametogenesis in Arundo formosana Hack. (Poaceae)
Wann-Neng Jane; Su-Hwa Tsai Chiang International Journal of Plant Sciences 1996. doi:10.1086/297358
Other claims from this paper (18)
- Observation The Arundo formosana ovule is tenuinucellate.
- Observation The megasporocyte originates from a hypodermal cell of the ovule primordium.
- Observation Embryo sac development in Arundo formosana is of the Polygonum type.
- Observation At inception the megasporocyte is identical to surrounding nucellar cells except for its larger size and dominant nucleus.
- Observation Callose deposition in the expanded megasporocyte originates from the micropylar end and extends laterally.
- Observation During megasporocyte expansion the nucleus retains the micropylar location.
- Observation Meiosis forms a linear, T-shaped or intermediate tetrad.
- Observation The chalazal megaspore is functional and all other megaspores of the tetrad degenerate.
- Observation The functional megaspore appears least dense among the cells of the tetrad.
- Observation The functional megaspore seldom contains vacuoles.
- Observation As the megaspore enlarges, the organelles and the cytoplasmic density increase.
- Observation The callose wall of the enlarging megaspore is gradually digested.
- Observation An electron-dense wall appears around the enlarging megaspore.
- Observation Vacuoles in the megaspore are randomly distributed and then gradually migrate to both poles.
- Observation In a well-developed megaspore most plastids and dictyosomes are distributed in the micropylar region.
- Observation Polarized dictyosome and plastid distributions persist through the two- and four-nucleate embryo sac stages, respectively.
- Observation The two- and four-nucleate embryo sac has large central and chalazal vacuoles.
- Observation Plasmodesmata persist in the chalazal wall through megasporogenesis and megagametogenesis to the four-nucleate stage.