Primary oocyte is formed after
High-Yield Explanation
In the female, the primordial germ cells (oogonia) continue to proliferate by mitosis, reaching a peak of 5-7 million by 20 weeks of gestation. However, only some enter meiosis and become primary oocytes, arresting in diplotene of the first meiotic prophase, and become surrounded by a single layer of flattened pregranulosa cells, forming primordial follicles.Ref: Clinical endocrinology and infeility; 8th edition; Chapter 3; The Ovary--Embryology and Development