If a mature anther of an angiosperm is grown in tissue culture, which part of the anther could form haploid plants?

Pollens (n) are product of meiosis in microspore mother cell and hold the potential to produce male gametes. Therefore, young pollen grains are used to produce androgenic haploids in anther cultures. Other structures of anther such as epidermis, endothecium, middle layers and tapetum are diploids and do not undergo meiosis to form haploid cell. Hence these do not give rise haploid plants.