Benzekri Noëlle A, Reiss John O
Department of Biological Sciences, Humboldt State University, Arcata, California 95521, USA.
J Morphol. 2012 Jan;273(1):68-87. doi: 10.1002/jmor.11008. Epub 2011 Sep 20.
The structure of the olfactory organ in larvae and adults of the basal anuran Ascaphus truei was examined using light micrography, electron micrography, and resin casts of the nasal cavity. The larval olfactory organ consists of nonsensory anterior and posterior nasal tubes connected to a large, main olfactory cavity containing olfactory epithelium; the vomeronasal organ is a ventrolateral diverticulum of this cavity. A small patch of olfactory epithelium (the "epithelial band") also is present in the preoral buccal cavity, anterolateral to the choana. The main olfactory epithelium and epithelial band have both microvillar and ciliated receptor cells, and both microvillar and ciliated supporting cells. The epithelial band also contains secretory ciliated supporting cells. The vomeronasal epithelium contains only microvillar receptor cells. After metamorphosis, the adult olfactory organ is divided into the three typical anuran olfactory chambers: the principal, middle, and inferior cavities. The anterior part of the principal cavity contains a "larval type" epithelium that has both microvillar and ciliated receptor cells and both microvillar and ciliated supporting cells, whereas the posterior part is lined with an "adult-type" epithelium that has only ciliated receptor cells and microvillar supporting cells. The middle cavity is nonsensory. The vomeronasal epithelium of the inferior cavity resembles that of larvae but is distinguished by a novel type of microvillar cell. The presence of two distinct types of olfactory epithelium in the principal cavity of adult A. truei is unique among previously described anuran olfactory organs. A comparative review suggests that the anterior olfactory epithelium is homologous with the "recessus olfactorius" of other anurans and with the accessory nasal cavity of pipids and functions to detect water-borne odorants.
利用光学显微镜、电子显微镜以及鼻腔树脂铸型，对无尾目原始蛙类——尾蟾（Ascaphus truei）幼体和成体的嗅觉器官结构进行了研究。幼体嗅觉器官由与一个包含嗅觉上皮的大的主嗅腔相连的无感觉的前鼻管和后鼻管组成；犁鼻器是该腔的腹外侧憩室。在口前颊腔中，位于鼻后孔前外侧也存在一小片嗅觉上皮（“上皮带”）。主嗅觉上皮和上皮带都有微绒毛受体细胞和纤毛受体细胞，以及微绒毛支持细胞和纤毛支持细胞。上皮带还含有分泌性纤毛支持细胞。犁鼻上皮仅含有微绒毛受体细胞。变态后，成体嗅觉器官分为三个典型的无尾目嗅觉腔室：主腔、中腔和下腔。主腔的前部含有一种“幼体型”上皮，具有微绒毛受体细胞和纤毛受体细胞，以及微绒毛支持细胞和纤毛支持细胞，而后部衬有“成体型”上皮，仅具有纤毛受体细胞和微绒毛支持细胞。中腔无感觉。下腔的犁鼻上皮与幼体的相似，但以一种新型微绒毛细胞为特征。在成年尾蟾主腔中存在两种不同类型的嗅觉上皮，这在先前描述的无尾目嗅觉器官中是独一无二的。一项比较综述表明，前嗅觉上皮与其他无尾目动物的“嗅隐窝”以及负子蟾科动物的副鼻腔同源，其功能是检测水中的气味物质。
