切开骨或前颌骨的切开管是狭窄的骨管,鼻腭神经及其伴随血管通过。然而,它的胎儿发育仍然模糊。为了评估它的发展,26个人类胎儿头部的连续前部,胎龄9-20周(冠-臀部长度,46-183毫米),进行了检查。神经最初穿过一个宽阔的松散组织空间,但是在12-15周时切开骨的上部骨化后,运河变得狭窄,充满了紧密的纤维组织。七个胎儿的运河扩张并单侧或双侧开放。在这七个胎儿中的两个,鼻腭导管穿过管道,并将鼻腔连接到切开窝的旁正中上皮珍珠的中央管腔(而不是口腔)。即使运河关闭了,管道可能会保持在封闭部分的上方和下方。所有大于110毫米(15周)的标本中都存在Paramedian珍珠,有或没有中线珍珠的关联。这些辅助钻石珍珠通常向扩张或开放的运河突出和/或延伸,暗示这些珍珠,没有任何原始的口鼻交流途径,有助于保持运河的开放。扩张的运河,位于第二和第三牙齿芽的超内侧,似乎通常被进一步的骨化所封闭。即使在胎儿中,鼻腭导管似乎是正常腭融合后暂时发生的变异或不寻常的发育阶段。AnatRec,300:1093-1103,2017.©2016威利期刊,Inc.
The incisive canal of the incisive bone or premaxilla is a narrow bony canal through which pass the nasopalatine nerve and its concomitant vessels. However, its fetal development remains obscure. To assess its development, serial frontal sections of the heads of 26 human fetuses, of gestational age 9-20 weeks (crown-rump length, 46-183 mm), were examined. The nerve initially passed through a wide loose tissue space, but after ossification of the upper part of the incisive bone at 12-15 weeks, the canal became narrow and filled with tight fibrous tissue. Canals in seven fetuses were dilated and open unilaterally or bilaterally. In two of these seven fetuses, a nasopalatine duct passed through the canal and connected the nasal cavity to a central lumen of the paramedian epithelial pearl in the incisive fossa (not to an oral cavity). Even if the canal was closed, the duct was likely to remain above and below the closed part. Paramedian pearls were present in all specimens larger than 110 mm (15 weeks), with or without association of midline pearls. These paramedian pearls usually protruded toward and/or extended into the dilated or open canal, suggesting that these pearls, not any primitive oronasal communication pathway, contributed to keeping the canal open. The dilated canal, located on the superomedial side of the second and third teeth buds, seemed to be usually closed by further ossification. Even in fetuses, the nasopalatine duct seemed to be a variant or unusual phase of development temporally occurring after normal palate fusion. Anat Rec, 300:1093-1103, 2017. © 2016 Wiley Periodicals, Inc.