Spindle fibres are made up of

During which phase of mitosis do the nuclear envelope and nucleolus completely disappear?

Choose the correct combination of options to select the correct statement for prophase:
$I.$ Chromosomal material condenses to form compact mitotic chromosomes.
$II.$ The assembly of mitotic spindle is initiated by the microtubules.
$III.$ Cells do not show organelles when viewed under the prophase.
$IV.$ The nucleolus or nucleoli degenerate completely.

The first phase of mitosis which follows interphase is

$A$ student observed a slide of mitosis under the microscope and noted that the chromosomes were positioned at the opposite poles. Which stage was the student observing?

Spindle apparatus is formed during which stage of mitosis?