Sonographic imaging of the bovine fetus.

Transrectal sonography documenting the anatomical features of 71 bovine fetuses was performed between Day 30 and 10 mo of gestation. Sector scanners, which have a wider field of view into the depth of the uterus, were used, and it was found that most macroscopic organs were visible with B-scan ultrasound. The first organ detected around the end of the first month of pregnancy was the heart. The orbit, the stomach and the braincase were identified at Day 40. Most bones of the skeleton and the scrotum appeared around Month 3. Characteristic sonographic images of the head, neck, vertebral column, thorax, stomach, liver, kidneys, urinary bladder, limbs, scrotum-respectively teats, as well as the umbilical cord, amnion and allantois are described in this study.