57
Figure 32.
Prophase, prometaphase, metaphase, anaphase, and telophase are the
five stages of animal cell
mitosis that are depicted here using light microscopy and fluorescence. Typically, cytokinesis
occurs
concurrently with mitosis; shown here by a transmission
electron microscope
22
.
During
prophase
, the “first phase,” To grant access to the chromosomes in the nucleus, a number of
things need to happen. In addition to the Golgi apparatus and endoplasmic reticulum fragmenting and spreading
to the cell's periphery, the nuclear envelope begins to split into small vesicles. The nucleolus disappears. The
centrosomes begin to move to opposite poles of the cell. The centrosomes are pushed apart by the microtubules
that make up the mitotic spindle's foundation as the microtubule fibers lengthen. Under a light microscope, the
sister chromatids start to coil more tightly and become apparent.
During
prometaphase
, many processes that were begun in prophase continue to advance and
culminate in the formation of a connection between the chromosomes and cytoskeleton. The nuclear envelope's
remains vanish. As more microtubules assemble and extend across the length of the former nuclear region, the
mitotic spindle continues to grow. Chromosomes get smaller and appear more distinct.Each sister chromatid
attaches to spindle microtubules at the centromere via a
protein complex called the
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