The granulosa cell layer develops gradually with the growing oocyte. Early previtellogenic oocytes are accompanied by flat epithelial granulosa cells [red arrowhead], granulosa cells with larger oocytes [blue arrowheads] have a higher appearance.

The theca cell layer is composed of stroma cells [green arrowheads] and contains capillaries [c]. The theca layer is continuous [black arrowheads] over neighbouring oocytes.