The ultrasound shows two ova after ovulation. Ovulation is the release of the mature ova from the follicles. After ovulation and after floating around in the body cavity for a short while the ova enter the oviduct. Prior to entering the oviduct the ova are round. After they enter the oviduct they take on the oblong shape of the shelled/oviposited eggs (the tube of the oviduct squishes them to an oblong shape).
The image shows this process. One ovum is still large and round (free floating in the body cavity) and the other ovum has just entered the oviduct and has taken on the oblong shape of the shelled egg.
Cool, huh? And nobody guessed it!!!
Mark
