The pollen sacs represent microsporangia. Thus each anther
has four microsporangia, two in each anther lobe. These are covered by the
common epidermis of the anther. They contain pollen grains or microspores
1. Very young anther consists of group of actively
dividing parenchymatous cells surrounded by a layer of epidermis.
2. It becomes two lobed; each anther lobe develops
into two microsporangia in its two corners.
3. In each lobe in the two corners one cell becomes
conspicuous from the rest- archesporial cell.
4. Archesporial cell divides to form an outer
parietal cell and an inner sporogeneous cell
5. Parietal cell divides to form concentric layers
of pollen sac wall
6. The pollen wall externally is made up of a
single layered epidermis. Inner to the epidermis is a single layer of radially
elongated cells with fibrous thickenings which help in dehiscence. The cells in
the shallow groove between two microsporangia remains thin walled and form
stomium. Inner to the endothecium lie three to four layers of thin walled cells
occur in between which disintegrates in mature anthers. The innermost layer of
cells with dense cytoplasm which nourishes developing pollen grains is called
The primary sporogeneous cell divides to produce
a mass of sporogeneous cell or microscopore mother cell.
Microspore mother cell undergoes meiosis to give
rise to four haploid microspores. The microspores are arranged in a cluster of
four cells to form tetrad. As the anthers mature and dehydrate, microspore
dissociates from each other and form pollen grains. In some microspores do not
separate but together form compound pollen grains.