Dit is waarom:

* Granulosa cells are the main cell type in the follicle. They surround the oocyte (the developing egg) and produce hormones, primarily estrogen.

* Theca cells are another cell type found in the follicle, specifically in the outer layer called the theca layer. They primarily produce androgens, which are converted to estrogen by the granulosa cells.

So, while both granulosa and theca cells contribute to hormone production within the follicle, it's the granulosa cells that are considered the secretory cells due to their direct role in producing and releasing estrogen.