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Human Reproduction — BIOLOGY STD 12 Science — Question

Bihar BoardEnglish MediumSTD 12 ScienceBIOLOGYHuman Reproduction5 Marks
Question
Answer the following questions:
Explain the changes the primary oocyte undergoes while in different follicular stages before ovulation.
✓

Answer

Changes in the primary oocyte:
  • Each primary oocyte gets surrounded by a single layer of granulosa cells and is known as primary follicle.
  • Primary follicle get surrounded by more layers of granulosa cells and a new theca and form secondary follicle.
  • A secondary follicle transforms into tertiary follicle characterised by a fluid-filled space, the antrum.
  • Primary oocyte undergoes first meiotic division and produces two unequal haploid cells-a large haploid secondary oocyte and a tiny first polar body.
  • The tertiary follicle further changes into the mature Graafian follicle.
  • The secondary oocyte forms a new membrane called zona pellucida around it.

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