Oocytes - are the immature ova. There are approx. 400,000 during the time of development. Are in an arrested state of development. Only about 400 will ever continue on to develop further.
Produce estrogens .
A clear cell free area. Follicle walls thicken. Fluid secreted into the vesicles amongst the follicular cells. Increase in size and becomes fluid filled. Antrum enlarges - inc.