Arrange the following stages of oogenesis in correct sequence of thei…

The correct answer is Option (4) → (B), (D), (A), (C)

(B) Oogonia — first. Oogonia are the egg mother cells, formed in each ovary while the girl is still a foetus.

(D) Primary oocyte — second. The oogonia enter prophase I of meiosis and stop there; they are now primary oocytes.

(A) Secondary oocyte — third. Inside the tertiary follicle, the primary oocyte completes the first meiotic division, giving a large haploid secondary oocyte and a tiny first polar body.

(C) Ovum — last. The secondary oocyte completes the second meiotic division only when a sperm enters it, giving the ovum and a second polar body.

Note: A similar question was also asked in CUET (UG) 2026 on 18-05-2026 (Slot 1), in CUET (UG) 2025 on 13-05-2025 (Slot 2), and in CUET (UG) 2024 on 15-05-2024 (Slot 1).

NCERT Extract:
Gametogenesis – “… Oogenesis is initiated during the embryonic development stage when a couple of million gamete mother cells (oogonia) are formed within each fetal ovary; no more oogonia are formed and added after birth. These cells start division and enter into prophase-I of the meiotic division and get temporarily arrested at that stage, called primary oocytes.”
Gametogenesis – “… The theca layer is organised into an inner theca interna and an outer theca externa. It is important to draw your attention that it is at this stage that the primary oocyte within the tertiary follicle grows in size and completes its first meiotic division. It is an unequal division resulting in the formation of a large haploid secondary oocyte and a tiny first polar body (Figure 2.8b).”
Fertilisation and Implantation – “… During fertilisation, a sperm comes in contact with the zona pellucida layer of the ovum (Figure 2.10) and induces changes in the membrane that block the entry of additional sperms. Thus, it ensures that only one sperm can fertilise an ovum. The secretions of the acrosome help the sperm enter into the cytoplasm of the ovum through the zona pellucida and the plasma membrane. This induces the completion of the meiotic division of the secondary oocyte. The second meiotic division is also unequal and results in the formation of a second polar body and a haploid ovum (ootid).”