DETERMINATION OF FETAL SEX BY ULTRASONOGRAPHY AND PCR USING FETAL FLUID ASPIRATED BY AMNIOCENTESIS IN COWS

通过超声检查判断胎儿性别，用聚合酶链式反应扩增胎儿Y染色体特异性DNA，经阴道-输卵管超声引导羊水抽吸。从第35天到第93天，对68头奶牛进行了117次试验的超声检查。男性43/46(95.3%)，女性40/44(90.9%)。有27头牛没有被诊断出性别。总共使用了30头母牛、15头荷斯坦奶牛和15头日本黑人在怀孕59天到250天期间的35份吸液。每隔10天对5头奶牛进行两次吸气。在硬膜外尾部麻醉下，将5.0 MHz凸阵换能器与扫描仪相连，插入阴道。传感器在探头载体内配备了一根65厘米长、21英寸的针头。本研究使用了牛的雄性特异引物和牛的中性引物。除两头母牛外，其余母牛均在妊娠早期采集胎液。五只动物在抽吸后一周内流产。共收集33份标本，其中羊水标本29份，尿囊液标本4份。胎儿性别鉴定31/33例(女性18例，男性13例)。性别也通过产后或流产后对后代外生殖器的肉眼检查来确定。通过对16名女性和13名男性抽出的胎液进行聚合酶链式反应分析，正确地确定了胎儿性别。经阴道超声引导羊膜腔穿刺术和抽吸细胞DNA的聚合酶链式反应分析可用于准确确定怀孕70至100天的奶牛的胎儿性别。这一过程需要相当多的技巧，而且对胎儿存活率也不是没有风险。

Sex of the bovine fetus was predicted by ultrasonography and Y-chromosome specific DNA amplified by PCR in fetal fluid, which was aspirated by transvaginal-transuterine ultrasound-guided amniocentesis. Ultrasound examination were done in 68 cows through 117 trials between Day 35 to 93. Sex was correctly diagnosed as male in 43/46 (95.3%) and as female in 40/44 (90.9%) . Sex was not diagnosed in 27 cows. A total of 35 aspirates from 30 cows, 15 Holsteins and 15 Japanese Blacks at from 59 to 250 days of pregnancy were used. Five cows were aspirated twice at a 10 day interval. A 5.0 MHz convex array transducer connected to a scanner was inserted into the vagina under caudal epidural anesthesia. The transducer was equipped with a 65cm long, 21 gauge needle within the probe carrier. A bovine male-specific primer and a bovine gender-neutral primer were used. Fetal fluid was obtained from all except two cows in early pregnancy. Five animals aborted within one week following aspiration. A total of 33 samples, 29 of amniotic fluid and 4 of allantoic fluid, were subjected to PCR analysis. Fetal gender was identified in 31/33 samples (18 females and 13 males) . Gender was also determined by gross examination of external genitalia of offspring after calving or abortion. Fetal gender was correctly identified by PCR analysis of aspirated fetal fluid in 16/16 females and in 13/15 males. Transvaginal ultrasound-guided amniocentesis followed by PCR analysis of aspirated cell DNA can be used to accurately determine fetal sex in cows at from 70 to 100 days of pregnancy. The procedure requires considerable skill and is not without some risk to fetal viability.