Follicle and a corpus luteum; ultrasound
Key words: wave, bovine, CL, corpus luteum, follicle, cow, ultrasound
Image size: 640 x 480px
A large follicle (the non-echogenic structure) adjacent to a corpus luteum (CL) in the ovary of a cow; as seen during transrectal ultrasonography. Follicles grow and regress in waves during the bovine estrous cycle. There are commonly two or three waves of follicle growth during the diestrous period. When there are three waves, the estrous cycle is longer (21 to 22 days) then when they are two follicle waves (19 to 20 days). Less commonly, cows may even have four follicle waves. Therefore the discovery of a large follicle during diestrus (as in this case) does not necessarily mean that a cow is approaching estrus.
