Granulosa cells are specialized cells found in the ovaries, specifically within the ovarian follicles. They play a crucial role in the development of oocytes (egg cells) by providing essential nutrients and hormones. These cells surround the oocyte and are involved in the production of estrogen, which is vital for regulating the menstrual cycle and supporting reproductive health. As the follicle matures, granulosa cells undergo changes and can also produce other hormones, such as progesterone. They are essential for the overall function of the female reproductive system and contribute to the process of ovulation, where a mature egg is released for potential fertilization.