Nakamuta Shoko, Yamamoto Yoshio, Nakamuta Nobuaki
Laboratory of Veterinary Anatomy, Faculty of Agriculture, Iwate University, Iwate, Japan.
J Vet Med Sci. 2022 Jul 1;84(7):885-889. doi: 10.1292/jvms.22-0173. Epub 2022 May 5.
In the olfactory organ of lungfish, recesses at the bases of lamellae comprise sensory and nonsensory epithelia. The sensory epithelium of the recesses, the recess epithelium, is distinguished from the olfactory epithelium covering the lamella by the absence of ciliated olfactory receptor cells. Therefore, it has been suggested that the recess epithelium is a primordium of the vomeronasal organ of tetrapods. However, developmental changes in the number and distribution of recesses in the olfactory organ of lungfish were unknown. We examined four Protopterus aethiopicus specimens of body lengths 215-800 mm to determine the localization of recesses in their olfactory organs. Histological examination showed recesses at the bases of lamellae in all individuals examined. The recesses were localized mainly in the medial and caudal parts of the olfactory organs, especially in juveniles. Compared to smaller fish, larger fish had a larger number of recesses, distributed more broadly in their olfactory organs. Significance of the recess localization and its relationship to the function of lungfish olfactory organ warrants further investigation.
在肺鱼的嗅觉器官中，鳃小片基部的凹陷包含感觉上皮和非感觉上皮。凹陷处的感觉上皮，即凹陷上皮，与覆盖鳃小片的嗅觉上皮不同，其缺乏纤毛嗅觉受体细胞。因此，有人提出凹陷上皮是四足动物犁鼻器的原基。然而，肺鱼嗅觉器官中凹陷数量和分布的发育变化尚不清楚。我们检查了4个体长为215 - 800毫米的非洲肺鱼标本，以确定其嗅觉器官中凹陷的位置。组织学检查显示，在所有检查的个体中，鳃小片基部都有凹陷。这些凹陷主要位于嗅觉器官的内侧和尾部，尤其是在幼鱼中。与较小的鱼相比，较大的鱼有更多的凹陷，且在其嗅觉器官中的分布更广泛。凹陷定位的意义及其与肺鱼嗅觉器官功能的关系值得进一步研究。
