Zoology Department, Faculty of Science, Zagazig University, Zagazig, Egypt.
Open Vet J. 2024 Jan;14(1):512-524. doi: 10.5455/OVJ.2024.v14.i1.46. Epub 2024 Jan 31.
Catadromous fishes have well-developed elongated olfactory organs with numerous lamellae and different types of receptor neurons related to their breeding migration.
The current study showed how the olfactory system adapted to the catadromous life. Our work declared the need of the migratory fishes for the sense of smell that is exhibited by a higher number of the olfactory lamellae and the receptor neuron verification in the olfactory epithelium.
Ten specimens of fully grown, but pre-matured, silver eels of were captured at the outlet of Edco Lake, overlooking the Mediterranean Sea, east of Alexandria. Olfactory rosettes were dissected and fixed for scanning electron microscope (SEM) and transmission electron microscope (TEM).
Our study gave a morphological description of the olfactory system of . At the ultrastructural level using SEM and TEM, one olfactory rosette was provided with 90-100 flat radial olfactory lamellae. The nasal configuration allowed water to enter and exit, transferring odorant molecules to olfactory receptor cells which comprise long cylindrical ciliated and microvillous receptors as well as rod-tipped cells. These cells are bipolar neurons with upward dendritic knobs. The olfactory epithelia also include crypt receptor cells. Interestingly, the olfactory neurons are delimited by nonsensory supporting cells, including long motile kinocilia and sustentacular supporting cells beside mucus secretory goblet cells and ionocytes or labyrinth cells that contribute to the olfaction process.
Olfaction is crucial in all vertebrates, including fishes as it involves reproduction, parental, feeding, defensive, schooling, and migration behaviors. Here, is an excellent model for catadromous fishes. It has a well-developed olfactory organ to cope with the dramatic climate change, habitat loss, water pollution, and altered ocean currents effect during their catadromous life for reproduction.
溯河洄游鱼类的嗅觉器官非常发达，具有许多薄片和不同类型的受体神经元，这与它们的繁殖洄游有关。
本研究展示了嗅觉系统如何适应溯河洄游生活。我们的工作表明，洄游鱼类需要嗅觉，这表现为嗅上皮中嗅觉薄片和受体神经元数量的增加。
在俯瞰地中海的亚历山大以东的 Edco 湖出口处，捕获了 10 只完全成熟但尚未成熟的银鳗标本。嗅球被解剖并固定用于扫描电子显微镜 (SEM) 和透射电子显微镜 (TEM)。
我们的研究对 的嗅觉系统进行了形态描述。在使用 SEM 和 TEM 的超微结构水平上，一个嗅球具有 90-100 个扁平的放射状嗅觉薄片。鼻状结构允许水进出，将气味分子转移到嗅觉受体细胞，这些细胞包括长圆柱形纤毛和微绒毛受体以及棒状细胞。这些细胞是具有向上树突棘的双极神经元。嗅上皮还包括隐窝受体细胞。有趣的是，嗅觉神经元被非感觉支持细胞所限制，包括长的能动纤毛和支持细胞，旁边是粘液分泌杯状细胞和离子细胞或迷路细胞，它们有助于嗅觉过程。
嗅觉在包括鱼类在内的所有脊椎动物中都至关重要，因为它涉及繁殖、亲代、摄食、防御、洄游和迁移行为。在这里， 是溯河洄游鱼类的绝佳模型。它具有发达的嗅觉器官，以应对其溯河洄游生活中的剧烈气候变化、栖息地丧失、水污染和改变的海流影响，以进行繁殖。
