Al-Zahaby Sheren A, S Al-Zahaby Al-Ahmady, Mohamed Radwa A, Sawitri Dyah Haryuningtyas, Elsheikh Eman H
Department of Zoology, Faculty of Science, Zagazig University, Zagazig, Egypt.
Open Vet J. 2025 Feb;15(2):939-953. doi: 10.5455/OVJ.2025.v15.i2.43. Epub 2025 Feb 28.
Olfaction regulates animal behavior; hence, its organs are present early in fish development. Due to their aquatic lifestyle, fish use olfaction to communicate chemical signals during gustation.
In this study, we investigated the morphogenesis and ontogeny of the European seabass's (, Linnaeus, 1758) olfactory organ.
Scanning electron microscopy was used to study the development of these organs in fries, fingerlings,juveniles, and adults.
Both placodes were thickened and invaginated, generating simple olfactory pits with undifferentiated cells. The non-sensory and sensory olfactory cells (OC) emerged after the first day of hatching. In addition to occasional mucous goblet cells, ciliated receptor cells are more common than microvillous receptor cells. Long, thin, disordered kinocilium and small microvilli of ciliated and microvillous supporting cells cover some of the pit floor. The SEC- lined pit bottom deepens 45 days after hatching. Fries develop tube-shaped anterior incurrents and broader posterior excurrent nostrils by the 75th day post-hatching, along with a broad epidermal nasal bridge. In this stage and after fingerling formation at 90 days post-hatching, the bottom olfactory epithelium lining each chamber forms a multilamellar rosette of lamellae that radiates equally from the median raphe. Fully mature European seabass have 38-40 lamellae. The pseudostratified epithelia surrounding each lamella are sensory and nonsensory. The first one, scattered in islets between the second, has receptor (ciliated, microvillous, and rod-tipped) and supporting (ciliated and microvillar) cells, whereas the nonsensory epithelium has ciliated and microvillar supporting cells and masses of superficial epidermal cells. Goblet mucous cells and basal stem cells on the epithelium's basal lamina are abundant in nonsensory areas but rare in sensory parts.
These findings underscore the functional specialization of OCs, reflecting the organ's pivotal role in chemical communication and environmental adaptation throughout the European seabass' development.
嗅觉调节动物行为；因此，其嗅觉器官在鱼类发育早期就已出现。由于其水生生活方式，鱼类在味觉过程中利用嗅觉来传递化学信号。
在本研究中，我们调查了欧洲鲈（Dicentrarchus labrax，林奈，1758）嗅觉器官的形态发生和个体发育。
使用扫描电子显微镜研究这些器官在鱼苗、鱼种、幼鱼和成鱼中的发育情况。
两个基板均增厚并内陷，形成带有未分化细胞的简单嗅窝。孵化第一天后出现非感觉性和感觉性嗅觉细胞（OC）。除了偶尔出现的黏液杯状细胞外，纤毛受体细胞比微绒毛受体细胞更常见。纤毛和微绒毛支持细胞的长而细、无序的动纤毛和小微绒毛覆盖了部分嗅窝底部。孵化后45天，由分泌细胞衬里的嗅窝底部加深。孵化后第75天鱼苗发育出管状的前流入孔和更宽的后流出鼻孔，以及宽阔的表皮鼻桥。在此阶段以及孵化后90天形成鱼种后，每个腔室的底部嗅觉上皮形成多层板状玫瑰花结，从正中缝均匀放射状排列。完全成熟的欧洲鲈有38 - 40个板层。围绕每个板层的假复层上皮既有感觉性的也有非感觉性的。第一个，散布在第二个之间的胰岛中，有受体（纤毛、微绒毛和杆状顶端）和支持（纤毛和微绒毛）细胞，而非感觉性上皮有纤毛和微绒毛支持细胞以及大量浅表表皮细胞。杯状黏液细胞和上皮基底层上的基底干细胞在非感觉区域丰富，但在感觉部分很少见。
这些发现强调了嗅觉细胞的功能特化，反映了该器官在欧洲鲈整个发育过程中在化学通讯和环境适应方面的关键作用。
