Question

Oocyte is liberated from ovary under the influence of LH, after completing

• A. Meiosis and before liberating polar bodies
• B. Meiosis I and before liberating second polar bodies
• C. Meiosis
• D. Meiosis II after release of first polar body

Answer 1

Answer: (B)

Meiosis I and before liberating second polar bodies

Each primary oocyte then gets surrounded by a layer of granulosa cells and then called as the primary follicle. The primary follicles get surrounded by more layers of granulosa cells and a new theca and called as secondary follicles. The secondary follicle soon transforms into a tertiary follicle, which is characterised by a fluid-filled cavity called as antrum. The theca layer is organised into an inner theca interna and an outer theca externa.

At this stage, 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. The secondary oocyte retains the bulk of the nutrient rich cytoplasm of the primary oocyte. The tertiary follicle further changes into the mature follicle or Graafian follicle. The secondary oocyte forms a new membrane, called as zona pellucida surrounding it. The Graafian follicle now ruptures to release the secondary oocyte (ovum) from the ovary by the process, called as ovulation.

So, the correct answer is option B.