Primordial follicles are the earliest stage of follicle development in the [ovary](https://). These are the microscopic, spherical structures that consist of an immature [oocyte](https://) surrounded by a single layer of flattened [granulosa cells](https://). They are crucial in the reproductive system as they represent the initial pool of follicles from which mature [oocytes](https://) will eventually develop.
