Department of Otolaryngology-Head and Neck Surgery, Tohoku University Graduate School of Medicine, Sendai, Japan.
Department of Otolaryngology-Head and Neck Surgery, Tohoku University Graduate School of Medicine, Sendai, Japan.
Ann Anat. 2023 Oct;250:152113. doi: 10.1016/j.aanat.2023.152113. Epub 2023 Jun 8.
The aqeductus vestibuli (aqueduct) is believed to connect to the saccule in embryos and adults. However, in embryos, the saccule and utricle are known to communicate widely to provide a common endolymph space "atrium".
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.
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.
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.
导水管（aqueduct）被认为在胚胎和成人中与球囊相连。然而，在胚胎中，已知球囊和椭圆囊广泛相通，提供一个共同的内淋巴空间“心房”。
使用来自五个胚胎（头臀长或 CRL，14-21 毫米）、九个早期胎儿（CRL 24-35 毫米）和 12 个中期和近中期胎儿（CRL 82-272 毫米）的矢状面组织学切片，我们重新研究了人耳导水管的发育和生长。
心房呈厚管状外观，作为导水管的前下延续，但很快分为多个海湾。大多数海湾与半规管的壶腹相对应，而前中下部的一个海湾与未来的球囊相对应。值得注意的是，在 14 个胚胎和早期胎儿中的 8 个中，导水管在靠近原始前（上）或后半规管壶腹的前庭处终止于椭圆囊。相反，CRL 为 21 毫米的胚胎是导水管连接到类似囊状球囊的最小标本。在中期和近中期，生长的外淋巴间隙将导水管与前庭分开，并似乎将导水管推向球囊。胚胎时位于上方的前庭和下方的球囊之间发生了地形变化，从而在成人中形成了前后排列。
因此，导水管的前庭端可能由于内皮的差异生长而最有可能从前庭向球囊迁移，时间在 6-8 周左右。之前对胚胎导水管的重建可能受到成人形态的影响。
