Ultrasonic examination of the placentome development in sheep

The aim of this study was to determine the in vivo development of the placentome diameter during the pregnancy in sheep. 32 ewes of four different breeds were involved. After the first detection of the placentomes (28 day p. c.) the ewes were scanned by transrectal ultrasound (Aloka SSD 500, 5 MHz linear probe) in a standing position every second or third day until day 50 p.c. and after the every week until parturition. The maximum diameters of 10 placentomes were measured. The placentome diameter increased rapidly until the middle of the third pregnancy month followed by a slight decrease. Between the 110th day p.c. and the parturition the diameter was nearly constant, but 40% of the animals showed a second increase at this time. The placentome diameter could be a good mark to describe the function of the placenta in sheep but it is only stipulate fit for the diagnosis of the state of the pregnancy.