Read the following:        

(A) Primary oocyte

(B) Secondary spermatocyte

(C) Spermatids

(D) Second polar body

(E) Secondary oocyte

Which of the above haploid cells of human develop into mature gametes?

Spermatids and secondary oocyte are haploid cells of human which develop into mature gametes.

• Spermatids are haploid cells that develop into mature sperm (spermatozoa) in humans. During spermiogenesis, spermatids undergo a series of structural changes, including the development of a flagellum (tail), which transforms them into mature sperm.
• Secondary oocytes are haploid cells, but they do not directly develop into mature gametes (ova). Instead, during the process of fertilisation, if a secondary oocyte is fertilised by a sperm cell, it undergoes a second meiotic division to become a mature ovum (egg), which is the female gamete. This second meiotic division is completed only if fertilisation occurs. If fertilisation does not happen, the secondary oocyte does not progress further and eventually degenerates.

Primary oocyte is diploid.

Polar body is haploid but undergoes degeneration (it does not develop further).