Centre of each microsporangium is occupied by :

sporogenous tissue

The sporogenous tissue refers to a group of compactly arranged homogenous cells located at the center of each microsporangium. These cells are responsible for the formation of microspores through the process of meiosis. Microspores are the precursor cells that eventually develop into pollen grains.

Each cell of the sporogenous tissue within the microsporangium has the potential to give rise to a microspore tetrad, which consists of four cells. These cells are referred to as pollen or microspore mother cells (PMCs). The process by which microspores are formed from a PMC through meiosis is known as microsporogenesis.

During microsporogenesis, the PMCs undergo meiotic division, resulting in the formation of microspores. These microspores are initially arranged in clusters of four cells, known as microspore tetrads. As the anthers mature and dehydrate, the microspores separate from each other and develop into individual pollen grains.

Inside each microsporangium, thousands of microspores or pollen grains are formed. These pollen grains are released when the anther undergoes dehiscence, which is the process of opening to release the pollen.