The process of formation of microspores from a pollen mother cell is called

$A$ typical angiosperm anther is

In which stage of the pollen grain are the male gametes formed?

In which family is a monothecous anther found?

When mature anthers of $Datura$ $innoxia$ are cultured in a culture medium supplemented with phytohormones named kinetin,coconut milk,and plum juice,several embryos can be obtained floating inside the microsporangia. These embryos can develop into plants that are:

$P -$ This cell is big,has abundant food reserve and a large irregularly shaped nucleus.
$Q -$ This cell is small and floats in the cytoplasm of the vegetative cell. It is a spindle-shaped cell with dense cytoplasm and a nucleus.
$\quad\quad \quad P \quad \quad Q$