Descent of mesonephric duct to the final position of the vas deferens in human embryo and fetus.
Descent of mesonephric duct to the final position of the vas deferens in human embryo and fetus.
复制标题
在人类胚胎和胎儿中，中肾管的下降到VAS延迟的最终位置。
DOI：
10.5115/acb.2016.49.4.231
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发表时间：
2016-12
影响因子：
1.1
通讯作者：
Rodríguez-Vázquez JF
中科院分区：
文献类型：
--
作者：
Jin ZW;Abe H;Hinata N;Li XW;Murakami G;Rodríguez-Vázquez JF
由于输尿管起源于肾中膜或沃尔夫管（WD），因此WD开口应沿泌尿生殖窦或未来尿道向下移动。然而，这一下降过程在以往的研究中尚未得到形态计量学的评价，我们对下降的中间形态知之甚少。本研究对15例胎龄6-12周标本的连续矢状切片和20例胎龄6-10周标本的连续水平切片进行了分析。水平切片监测显示，直到9周，膀胱和尿道中仍有一个心形、菱形或椭圆形的初始泌尿生殖窦。因此，未来的膀胱和尿道不能通过横切面或平面来区分。6-10周时泌尿生殖窦或膀胱的最大宽度为0.8 mm， 10周时其上下端长度达到5 mm。然而，在早期阶段，WD的内侧移位相当明显。根据膀胱平滑肌向上生长的程度，输精管的下降在10-12周时变得明显。尿道横纹肌的发育可能导致泌尿生殖窦分化为尿道和膀胱，然后形成具有3层平滑肌的膀胱颈。前列腺的发育遵循这些形态学变化，随后加速了WD开口的进一步下降。由于其密切的地形关系，10-12周脐带的轻微异常或意外可能对正常解剖产生重大影响。
Because the ureter arises from the mesonephric or Wolffian duct (WD), the WD opening should migrate inferiorly along the urogenital sinus or future urethra. However, this process of descent has not been evaluated morphometrically in previous studies and we know little about intermediate morphologies for the descent. In the present work, serial sagittal sections of 15 specimens at gestational age 6–12 weeks and serial horizontal sections of 20 specimens at 6–10 weeks were analyzed. Monitoring of horizontal sections showed that, until 9 weeks, a heart-, lozenge- or oval-shape of the initial urogenital sinus remained in the bladder and urethra. Thus, the future bladder and urethra could not be distinguished by the transverse section or plane. The maximum width of the urogenital sinus or bladder at 6–10 weeks was 0.8 mm, although its supero-inferior length reached 5 mm at 10 weeks. During earlier stages, however, the medial shift of the WD was rather evident. Depending on the extent of upward growth of the bladder smooth muscle, the descent of the vas deferens became evident at 10–12 weeks. Development of the urethral rhabdosphincter likely resulted in the differentiation of urogenital sinus into the urethra and bladder before formation of the bladder neck with 3-layered smooth muscles. Development of the prostate followed these morphological changes, later accelerating the further descent of the WD opening. Because of their close topographical relationships, slight anomalies or accidents of the umbilical cord at 10–12 weeks may have a significant effect on normal anatomy.