Curran S, Pierson R A, Ginther O J
J Am Vet Med Assoc. 1986 Nov 15;189(10):1295-302.
The ultrasonographic appearance of the conceptus on days 20 to 60 was determined by daily examinations in 15 heifers. The mean length of the embryo proper increased from the day of first detection (day 20.3 +/- 0.3; 3.8 +/- 0.3 mm) to day 60 (66.1 +/- 1.7 mm). The growth curve was quadratic, with an increasing growth rate after approximately day 50. The embryo initially had the appearance of a short, straight line and developed a C shape on day 25.4 +/- 0.8 and an L shape on day 32.7 +/- 1.1. The average day of first detection of various structures was as follows: allantois, 23.2 +/- 0.3; spinal cord, 29.1 +/- 0.5; forelimbs, 29.1 +/- 0.3; amnion, 29.5 +/- 0.5; optic area, 30.2 +/- 0.4; hindlimbs, 31.2 +/- 0.3; placentomes, 35.2 +/- 1.0; optic lens, 40.0 +/- 0.6; split hooves, 44.6 +/- 0.7; fetal movements, 44.8 +/- 0.8; and ribs, 52.8 +/- 0.5. Embryonic death, as indicated by cessation of heartbeats, occurred in one heifer on day 26. The embryonic mass increased in echogenicity and was maintained with a gradually decreasing fluid volume until the occurrence of estrus 17 days after death.
通过对15头小母牛进行每日检查，确定了妊娠20至60天期间孕体的超声图像特征。从首次检测到的那天（第20.3±0.3天；3.8±0.3毫米）到第60天（66.1±1.7毫米），胚胎本身的平均长度不断增加。生长曲线呈二次函数型，大约在第50天后生长速率加快。胚胎最初呈短直线状，在第25.4±0.8天发育成C形，在第32.7±1.1天发育成L形。首次检测到各种结构的平均天数如下：尿囊，23.2±0.3天；脊髓，29.1±0.5天；前肢，29.1±0.3天；羊膜，29.5±0.5天；视区，30.2±0.4天；后肢，31.2±0.3天；胎盘小叶，35.2±1.0天；晶状体，40.0±0.6天；蹄裂，44.6±0.7天；胎动，44.8±0.8天；肋骨，52.8±0.5天。在第26天，有一头小母牛出现胚胎死亡，表现为心跳停止。胚胎团块的回声增强，并且在死亡后17天发情之前，随着液体量逐渐减少而保持这种状态。
