1. Normal follicle veterinary ultrasound image (see Figure 1) Image analysis: This image is an image of an ovary in water with one large follicle on the ovary but no other small follicles or corpus luteum.

As can be seen from Figure 1, the follicle has a clear outline, and the follicular fluid, follicular wall and surrounding tissues have a good contrast in density. It is round and the follicle diameter is 0.50 cm. Because the follicle is filled with follicular fluid, it is an echo-free dark area, and the follicle wall is a strong echo bright area.

2. Normal corpus luteum veterinary ultrasound image (see Figure 2)

Image analysis: Figure 2 is an ultrasound image of an ovary in water with only a corpus luteum on the ovary. The diameter of the corpus luteum is 0.95 cm, and the corpus luteum almost fills the entire ovarian parenchyma (after the ovary is cut open with a surgical blade, it is also confirmed that the corpus luteum tissue almost fills the entire ovarian parenchyma and is a cavity-free corpus luteum) and the surrounding medium-water, forming a clear contrast. There are scattered, evenly distributed dots and lines of bright spots on the corpus luteum tissue, which may be caused by the trabeculae and blood vessels in the corpus luteum tissue, which is also one of the main differences from the follicles in the image. Another difference from the follicle image is that the corpus luteum tissue is weakly echoed and lighter in color than the follicle.

3. Veterinary ultrasound image of corpus luteum and follicle on the same ovary (see Figure 3)

Image analysis: Figure 3 is an ultrasound image of an ovary in water with both follicles and corpus luteum. Since the corpus luteum and follicle exist on the same ovary, the images are in one image, which can more clearly compare the difference between the follicle and the corpus luteum in the ultrasound image. As shown in Figure 3A, there is a follicle with a diameter of 0.39 cm above the ovary and a corpus luteum with a diameter of 0.82 cm below. As shown in Figure 3B, there is a follicle with a diameter of 0.25 cm on the upper right of the ovary and a corpus luteum with a diameter of 0.71 cm on the lower left.

4. Veterinary B-ultrasound images of multiple follicles on the ovary (see Figures 4 and 5)

Image analysis: Figure 4 is a veterinary B-ultrasound image of an ovary with two follicles in water. The two follicles are clearly visible, with diameters of 0.26 cm and 0.22 cm respectively. Figure 5 is a B-ultrasound image of multiple follicles. Five follicles can be found in the ovary by naked eye observation. From the size of the follicles, it is inferred that they should be antral follicles; but from the image, only two follicles are clearly visible, one follicle is blurred, and the remaining three do not appear in the image. The reason is that the two follicles overlap on a cross section.

Veterinary B-ultrasound image characteristics of follicles: From the shape point of view, most of them are round, and a small part is oval or pear-shaped; from the color of the image, since the follicles are filled with follicular fluid, the ultrasound scan is echoless, and the image is a dark area, which forms a clear contrast with the strong echo (bright) area of the follicle wall and surrounding tissues. Ultrasound imaging characteristics of the corpus luteum: From the shape point of view, most of the corpus luteum tissue is round or oval. Since the corpus luteum tissue has weak echoes in ultrasound scanning, the image color is not as dark as the follicle. In addition, the biggest difference between the ovary and the corpus luteum in imaging is that there are trabeculae and blood vessels in the corpus luteum tissue, so there are scattered dots and lines of bright areas in the image, but there are no follicles.