Ex Vivo Study of Macroscopic Feature and Sonogram Imaging of Bovine Ovarian Corpus Luteum

In the clinical procedure, corpus luteum identification in the ovary is important to determine the reproductive status of cows. There are two methods to determine corpus luteum in live cows, rectal palpation and ultrasound examination.
However, real imaging cannot be obtained by these methods. Thus, the current study aimed to describe the macroscopic
feature and sonogram imaging of the corpus luteum in the bovine ovary as an ex vivo study. Twenty-eight pairs of
bovine ovaries from a slaughterhouse were used in this study. Ovaries were classified based on the diameter of the
corpus luteum crown into five categories (≤0.5, 0.5-1, 1-1.5, >1.5cm, and none). We observed and measured the corpus
luteum crown and corpus luteum tissue using a vernier calliper and ultrasound. Descriptive and statistical analyses were carried out using the SAS program. The corpus luteum crown was identified as a circular folding tissue on the ovary surface, during corpus luteum tissue as a yellowish lobed structure by macroscopic observation and hypoechoic structure by ultrasonography. Ovaries with corpus luteum crown diameter 0.5-1.0cm were dominant (41%). However, we found no correlation between the area of the corpus luteum crown with the area of corpus luteum tissue by macroscopic (P=0.121) and ultrasound observation (P=0.151). The Corpus luteum crown and corpus luteum tissue described in this study can be used as a reference by practitioners. Further correlation analysis is needed between corpus luteum crown and corpus luteum tissue in live cows.