The olfactory anatomy and histology of Lethenteron reissneri were researched using a stereo microscope, a light microscope, and a scanning electron microscope. As in other lampreys, it shows same characters as follows: i) a single olfactory organ, ii) a single tubular nostril, iii) a single olfactory chamber with gourd-like form, iv) a nasal valve, v) a nasopharyngeal pouch, vi) a sensory epithelium (SE) of continuous distribution, vii) a supporting cells with numerous long cilia, viii) an accessory olfactory organ. However, the description of a pseudostratified columnar layer in the SE and Non SE is a first record, not reported in sea lamprey Petromyzon marinus. In particular, both 19 to 20 lamellae in number and olfactory receptor neuron’s quarter ciliary length of the knob diameter differ from those of P. marinus. From these results, it might be considered that the olfactory organ of L. reissneri shows well adaptive structure of a primitive fish to slow flowing water with gravel, pebbles, and sand and a hiding habit into sand bottom at daytime. The lamellar number and neuron’s ciliary length may be a meaningful taxonomic character for the class Petromyzonida.

中文翻译：

---

远东溪七鳃鳗 Lethenteron reissneri (Pisces, Petromyzontidae) 嗅觉器官的显微研究

使用立体显微镜、光学显微镜和扫描电子显微镜研究了 Lethenteron reissneri 的嗅觉解剖和组织学。与其他七鳃鳗一样，它具有以下相同的特征：i) 单个嗅觉器官，ii) 单个管状鼻孔，iii) 单个葫芦状嗅腔，iv) 鼻瓣，v) 鼻咽袋， vi) 连续分布的感觉上皮 (SE)，vii) 具有许多长纤毛的支持细胞，viii) 附属嗅觉器官。然而，SE 和非 SE 中伪分层柱状层的描述是第一次记录，在海七鳃鳗 Petromyzon marinus 中没有报道。特别是，19 到 20 个薄片的数量和嗅觉受体神经元的节直径的四分之一纤毛长度与 P. marinus 的不同。从这些结果来看，可以认为，L. reissneri 的嗅觉器官表现出原始鱼类对带有砾石、鹅卵石和沙子的缓慢流动的水的良好适应性结构，以及白天躲在沙底的习性。层数和神经元的纤毛长度可能是石油粘菌纲的一个有意义的分类特征。