Gillis J Andrew, Criswell Katharine E, Palmer Michael A, Baker Clare V H
Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, Marine Biological Laboratory, Woods Hole, MA 02543, USA.
Department of Biology, Saint Francis University, Loretto, PA 15940, USA.
Development. 2025 Sep 15;152(18). doi: 10.1242/dev.204767. Epub 2025 Sep 29.
The spiracular organ is an epithelial pouch or tube lined with mechanosensory hair cells that is found embedded in the wall of the spiracle in many non-teleost jawed fishes. It is innervated via a branch of the anterior lateral line nerve and usually considered a specialised lateral line organ, despite its presumed function as a proprioceptor for jaw movement. It is homologous to the paratympanic organ: a hair cell-lined epithelial pouch embedded in the wall of the middle ear of birds, alligators and Sphenodon. A previous study showed that the chicken paratympanic organ and its afferent neurons originate from a molecularly distinct placode immediately dorsal to the geniculate placode. Here, fate mapping in a cartilaginous fish (little skate, Leucoraja erinacea) shows that the spiracular organ derives from a previously unrecognised neurogenic placode immediately dorsal to the geniculate placode that is spatially and molecularly distinct from lateral line placodes. Retrograde labelling of the spiracular organ identified afferent neurons located within the geniculate ganglion, as reported previously for paratympanic organ afferents. These findings support the independence of this unique jawed-vertebrate mechanosensory organ from the lateral line system.
喷水孔器官是一种上皮囊或管道，内衬机械感觉毛细胞，存在于许多非硬骨颌鱼类的喷水孔壁中。它通过前侧线神经的一个分支接受神经支配，尽管其被认为具有颌运动本体感受器的功能，但通常被视为一种特化的侧线器官。它与副鼓室器官同源：副鼓室器官是一种内衬毛细胞的上皮囊，存在于鸟类、短吻鳄和楔齿蜥的中耳壁中。先前的一项研究表明，鸡的副鼓室器官及其传入神经元起源于膝状神经节板背侧一个分子特征不同的基板。在这里，对一种软骨鱼（小鳐，Leucoraja erinacea）的命运图谱研究表明，喷水孔器官源自膝状神经节板背侧一个先前未被识别的神经源性基板，该基板在空间和分子层面上与侧线基板不同。如先前对副鼓室器官传入神经的报道，对喷水孔器官的逆行标记确定了位于膝状神经节内的传入神经元。这些发现支持了这种独特的颌类脊椎动物机械感觉器官独立于侧线系统。
