spindle fibres

Unstriated muscles These are smooth, involuntary muscles. Each muscle fibre is a long, narrow, spindle shaped tapering cell. The cell is uninucleate. Delicate threads called myofibrils run longitudinally through the cell. These muscles are found in the walls of the alimentar..

The four chromatids (in two pairs) are attached to spindle fibres by two centromeres and face opposite pol..

It is of a short duration compared to prophase-I. No significant changes take place in the chromosomes. Nuclear membrane and nucleolus disappear. Asters and spindle fibres are forme..

After the centrioles reach their positions corresponding to the two opposite poles, the chromosomes arrange themselves upon the equator of a spindle, which is formed in the cell by delicate cytoplasmic threads radiating from the centrioles. Each sister chromatid is attached at its centro..

The chromosomes at each pole uncoil and elongate to form the chromatin. A nucleolus reappears at each pole. Spindle fibres and asters disappear and centrioles split. A nuclear membrane is formed at each pole resulting in the formation of two daughter nucle..

It is a rapid stage. Each centromere splits into two Spindle fibres pull the daughter centromeres to the opposite poles The separated chromatids, now called chromosomes, are pulled along with centromeres to the opposite pole..

Beginning at the centromere, the sister chromatids undergo mutual repulsion and are seen to split longitudinally into two halves. Each sister chromatid is now called a daughter chromosome The daughter chromosomes separate and begin to move towards opposite poles. The spindle fib..

In this phase, chromosomes move to the equator of the cell. Pairs of chromatids become attached to the spindle fibres at their centromeres fig. 17.3 - Stages of Mito..

: Separation of the chromosomes is now complete with paternal and maternal chromosomes having exchanged portions of chromatids. The chromosomes condense again. The chiasmata disappear by sliding towards the tips of the chromatids. This process is called terminalisation. By the time these change..

They are spindle-shaped cells that are neurosensory. They have hairs on their free ends and on the other end, they have nerve fibres. They number 5-15 in each taste bu..