During spermatogenesis and oogenesis, various structures are formed that are either haploid or diploid in nature. Based on ploidy, the structures can be classified as:
Diploid (2n): Spermatogonia, primary spermatocyte, oogonia, and primary oocyte.
Haploid (n): Secondary spermatocyte, spermatids, spermatozoa, polar bodies, secondary oocyte, and ovum.