Ultrasonographic Assessment Of Embryonic And Fetal Development, And Adult Femle Genital System Changes In The Yak

The present study was carried out by using ultrasonography to observe the change of genital organs and ovary during superovulation period of the Tianzhu white yak, and to scan the embryonic and fetal development in vitro uterus of Plateau Type Yak. Moreover, the anatomic index of reproductive system was also measured. These results showed as follow:(1)Two situation were observed after superovulation treatment: ovulation and anovulation. In the group of anovulation, theⅡ-follicle was relatively dominant and all of them were atresia when they grew to certain size. In the group of ovulation,one or two follicles which belonged to theⅣ-follicle ovulated. More atresia follicles were found in ovaries on which no obvious corepus luteums were found.(2)The conceptus can firstly be seen in 26～80th day of gestation;Fetal eyes were explicit in 36～40th day of gestation;The demarcation between Fetal head and fetal truck was apparent in 41～45th day of gestation;The cavity of skull, cardiac region,bone of trunk and abdominal region were obviously seen in 46～50th day of gestation; The echo of trunk reinforce in 52～56th day of gestation; Edge sharpness of fetal head was clear in 56~60th day of gestation;The bone of trunk,four limbs,skull possess dense echo and the echo of hoof was gray in 61～65th day of gestation,meanwhile genital armature was marked;After the 66th day of gestation, fetal organs were distinct and cervical ribs was widening. Especially, the length of fetus was obviously growing and echo of bone was gradually strengthening after the 45th day of gestation.(3) The changes of the in vitro genital system organ of Plateau Type Yak during 24～80th day of gestation were as follow :the uterus,cotyledonarian,the blood vessel on the surface of uterus and ovarian artery was thickening;The fluctuation of uterus was stringing;The distribution of fetus was mainly at the basic or middle region.(4)The change of pH value in different length of fetus was that the pH value in vagina,cervix,horn of uterus were decreasing with fetus growing. During 24～80th day of gestation,it was alkality in vagina and cervix,which was different from anestrus that were at pH 6.8;but it was acidity in the horn of uterus, which was the same as the anestrus at pH 6.9.The pH in allantoic bladder and amniotic fluid was at 6.8～6.9. (5)The length and width of ovary at side of gestation obviously had no change, and the weight were increasing. The length and width of luteum corpus also have no change, and the weight can increase to 50% of whole ovary;The weight of ovary in monozygotic twins was heavier than that of singnal birth at the same time;The weight of ovary in dizygotic twins was the same as that of singnal birth,but the weight of luteum corpus in the yak having twins was heavier than that of single birth;There were about 23% luteum corpus that were outpocketing on the ovary.