中华乌塘鳢嗅觉器官的形态结构研究

Study on Morphology and Structure of the Olfactory Organ in Bostrchthys Sinensis

形态解剖、光镜观察表明:中华乌塘鳢(Bostrichthys sinensisLacepede)具一对纺缍形嗅囊,由前、后鼻孔与外界相通,嗅上皮向嗅囊腔内突起形成10-16个初级嗅板,初级嗅板上有次级嗅板,可增大嗅上皮的表面积。嗅板由嗅上皮和中央髓两部分构成,中央髓主要由疏松结缔组织和毛细血管构成;嗅上皮排列于中央髓的两侧,由多层细胞组成。扫描和透射电镜观察表明:嗅上皮分为非感觉区和感觉区两部份,非感觉区位于嗅板边缘,较薄、较平滑,外缘高倍放大呈指纹状或块状结构;感觉区位于中央部位,呈连续分布,细胞种类多样,表层为纤毛非感觉细胞,中上层为纤毛感受细胞和柱状细胞,中下层为支持细胞,底层为基细胞。纤毛感受细胞为一种双极神经元,树突在上皮表面形成嗅结;轴突则穿过基膜,在固有层内集合成束,形成嗅神经纤维,终止于嗅叶。

Morphology and structure of olfactory organ were systematically investigated by means of histology and electron microscopy in the Chinese black sleeper Bostrichthys sinensis.The results were as follows:the Chinese black sleeper has a pair of fusiform olfactory sacs in front of the eyes;each sac has an in current and an excurrent nostril.There are 10-16 primary olfactory lamellae radiating from the wall of olfactory chamber in the fish,longitudinally arranging and paralleling to each other.The primary olfactory lamellae are different in height,the one situating at the ventral part of the olfactory chamber is highest,reaching the other part of the chamber.The primary lamellae contain secondly lamellae in order to enlarge the olfactory epithelium area.The lamellae are composed of two layers of olfactory epithelium and a central core.The central core is located at the central part of olfactory lamellae.The central core is composed of collagenous fiber,reticular fiber and blood capillary.The olfactory epithelium is consisted of many layers of cells,with a layer of cilia in the free surface orienting in the same direction.Under scanning electron microscopy,the olfactory epithelium is consisted of sensory and non-sensory areas.Non-sensory region at the margin of the lamella is thinner and smoother. Under high amplification,non-sensory area is composed of fingerprint-like-pattern microridges and granule microridges.Some microholes with the vesicle secretion among these two microridges are observed. Sensory area is continuous in the center,composed of many kinds of cells,ciliated receptor cell,ciliated non- sensory cell,rod cell and supporting cell.No microvillans receptor cells are observed.Ciliated non-sensory cells widely distribute in non-sensory area and sensory area;each can protrude 8-16 thin and long cilia, which are about 4.7-8.9um long and 0.19-0.27um wide.Ciliated receptor cells distribute in sensory area,each has an olfactory knob,from which 1-11 cilia protrude,and the cilia are about 0.2-4.6um long and its diameter is about 0.25-0.31um,which are shorter and wider than the cilia of ciliated non-sensory cell.Mature Bostrichthys sinensis has two types of olfactory knob:full and flat,while immature one just has the full type olfactory knob,it is suggested that the ciliated receptor cells with flat knob are sex pheromones’ receptors while those with full knob are amine acids’ receptors.Rod cells distribute in sensory area and are often mixed with other types cell,it has a rod-shaped protrusion,which is about 3.5-7.2um long and 0. 8-1.7um wide.Supporting cells generally distribute in the sensory area,with micro-protrusions.Under transmission electron microscopy,the olfactory epithelium is mainly composed of ciliated receptor cells,ciliated non-sensory cells,supporting cells,rod ceils and basal cells.According to the location of cell nucleus,ciliated non-sensory cells are on the free surface,and ciliated receptor ceils and rod cells are next to ciliated non- sensory cells,followed by supporting cells and the basal cells at the bottom.The cilia of ciliated receptor cell and ciliated non-sensory cell both have 9+2 microtubule structure.The olfactory receptor cell is a bipolar neuron,protruding a single dendrite to the surface and a thin axon to the opposite direction.The axons pass through the basal lamina of epithelium,aggregating to form larger bundles,which connect to the olfactory lobe.The terminal of dendrite swells to form the olfactory knob,which slightly protrudes from the epithelial surface.There are bundles of microtubules in rod cell’s protrusion and many mitochondria in rod cell;the microtubules also have 9+2 structure.The support cells lie tightly beside the ciliated receptor cell.The support cell stretches a little foot from its bottom and the near two little feet would form the interdigitation. The basal cell’s nucleus is large and it occupies the most of the whole cell and some of them have sub-cells.