Differentiate between secondary follicle and tertiary follicle in human ovary.

1. Secondary follicles are formed during puberty when a large number of primary oocytes degenerates and the remaining ones get surrounded by layers of granulosa cells and theca while tertiary follicles are the one that are formed from secondary follicles.

2. Secondary follicle lacks a fluid-filled cavity called antrum while tertiary follicles have antrum.