METHODS: Using sagittal histological sections from five embryos (crown-rump length or CRL, 14-21 mm), nine early fetuses (CRL 24-35 mm) and 12 midterm and near-term fetuses (CRL 82-272 mm), we revisited the development and growth of the human ear aqueduct.
RESULTS: The atrium took on a thick tube-like appearance as an antero-inferior continuation of the aqueduct, but soon divided into multiple gulfs. Most of the gulfs corresponded to the ampullae of semicircular ducts, while one gulf at the antero-medio-inferior corner corresponded to the future saccule. Notably, in eight of the 14 embryos and early fetuses, the aqueduct ended at the utricle near the primitive ampulla of the anterior (superior) or posterior semicircular duct. Conversely, an embryo of CRL 21 mm was the smallest specimen in which the aqueduct joined the gulf-like saccule. At midterm and near-term, the growing perilymph space separated the aqueduct from the utricle and appeared to push the aqueduct toward the saccule. A topographical change occurred between the embryonic superiorly located utricle and the inferiorly-located saccule to create the antero-posterior arrangement in adults.
CONCLUSIONS: Consequently, the vestibular end of the aqueduct was most likely to migrate anteriorly from the utricle to the saccule at 6-8 weeks possibly due to differential growth of the endothelium. Previous reconstructions of the embryonic aqueduct might be biased by the adult morphology.
方法:使用来自五个胚胎的矢状组织学切片(冠-臀部长度或CRL,14-21mm),9个早期胎儿(CRL24-35mm)和12个中期和近期胎儿(CRL82-272mm),我们重温了人耳渡槽的发展和成长。
结果:作为渡槽的前下延续,中庭呈现出厚厚的管状外观,但很快就分成了多个鸿沟。大多数的海湾对应于半圆形管道的壶腹,而前中下角的一个鸿沟对应于未来的囊。值得注意的是,在14个胚胎和早期胎儿中有8个,渡槽在前(上)或后半规管的原始壶腹附近的囊处终止。相反,CRL21mm的胚胎是最小的标本,其中渡槽与海湾状囊相连。在中期和近期,不断增长的外淋巴空间将渡槽与导管分开,并似乎将渡槽推向囊。胚胎位于上方的囊和位于下方的囊之间发生了地形变化,从而在成人中形成了前后排列。
结论:因此,导水管的前庭端最有可能在6-8周时从囊向球囊向前迁移,这可能是由于内皮的差异生长。先前对胚胎渡槽的重建可能受到成人形态的影响。