A primordial follicle consists of an epithelial layer of follicular granulosa cells enclosing an oocyte. Most malignant thyroid cancers are papillary, followed by follicular, medullary, and thyroid lymphoma. Additionally, tretinoin stimulates mitotic activity and increased turnover of follicular epithelial cells. The follicular antrum is the portion of an ovarian follicle filled with follicular fluid. Ovarian function may be measured by gynecologic ultrasonography of follicular volume. Blood spread is also possible in thyroid cancers, especially in follicular and anaplastic carcinoma. This trend is seen in cancers such as colorectal carcinoma and follicular lymphoma. The core of a follicle is surrounded by a single layer of follicular cells. A degenerative process called follicular atresia reabsorbs vitellogenic oocytes not spawned. The TSH receptor is found mainly on thyroid follicular cells. It also fails to explain the detrimental effects of losing ovarian follicular activity. Food intake increases by approximately 10% during the luteal phase compared to the follicular phase. The grafts are obtained from either follicular unit transplantation (FUT) or follicular unit extraction (FUE). An inadequate biopsy might be read as actinic keratosis with follicular involvement. The lack of iodide transport inside follicular cells tends to cause goitres.