in my book it is written that centrioles are absent in almost all angiosperms .. so the question is how on earth do they divide?
where do the spindle fibres come from?
where do the spindle fibres come from?
-
In plants, cytokinesis involves formation of a cell plate, which separates two daughter cells.
Mitotic spindles are microtubule-based structures that separate chromosomes during mitosis. In fungal and animals cells, spindle microtubules nucleate from centrosomes. Plant cells lack centrosomes and their microtubules nucleate from near the nuclear envelope.
Mitotic spindles are microtubule-based structures that separate chromosomes during mitosis. In fungal and animals cells, spindle microtubules nucleate from centrosomes. Plant cells lack centrosomes and their microtubules nucleate from near the nuclear envelope.
-
"Stamens
Each stamen consists of:
a lobed anther, containing the microsporangia and supported by a thin filament
Meiosis of the diploid microspore mother cells in the anther produces four haploid microspores. Each of these develops into a pollen grain consisting of:
a larger vegetative cell (also called the tube cell) inside of which is a
a smaller germ cell (also called the generative cell).
At some point, depending on the species, the germ cell divides by mitosis to produce 2 sperm cells."
Each stamen consists of:
a lobed anther, containing the microsporangia and supported by a thin filament
Meiosis of the diploid microspore mother cells in the anther produces four haploid microspores. Each of these develops into a pollen grain consisting of:
a larger vegetative cell (also called the tube cell) inside of which is a
a smaller germ cell (also called the generative cell).
At some point, depending on the species, the germ cell divides by mitosis to produce 2 sperm cells."