中华乌塘鳢嗅觉系统孕酮受体的免疫细胞化学研究

Progesterone receptor immunoreactivities in Bostrichthys sinensis(Lacépède) olfactory system

为了进一步探讨中华乌塘鳢[Bostrichthys sinensis(Lacépède)]感受性信息素(17α-P和17α,20β-P)的作用机制,以免疫细胞化学(SABC)法进行中华乌塘鳢嗅觉系统孕酮受体的免疫定位和数量分析。结果显示,孕酮受体免疫阳性细胞在性成熟中华乌塘鳢的嗅上皮、嗅神经和嗅球上均有分布,免疫阳性细胞数量由高到低依次为:嗅上皮、嗅球、嗅神经。半定量分析结果表明,中华乌塘鳢嗅觉系统的孕酮受体免疫阳性细胞的数量与其性腺发育程度有关。性成熟雄鱼和雌鱼嗅上皮的免疫阳性细胞数量分别显著或极显著(P<0.05或P<0.01)高于性未成熟雄鱼和雌鱼;性未成熟鱼嗅神经上未发现孕酮受体免疫阳性细胞;性成熟雌鱼嗅球上的免疫阳性细胞数量显著高于性未成熟雌鱼(P<0.05)。本研究证实了硬骨鱼类嗅觉系统中存在孕酮受体免疫阳性细胞。

We evaluated the morphology and structure of the olfactory system in the Chinese black sleeper,Bostrichthys sinensis（Lacepede） using histology.The olfactory system consisted of the olfactory sac,olfactory nerve,and olfactory bulb.The olfactory sac（the rosette） was fusiform in shape and located inside the olfactory chamber,which had two openings that allow water to flow through the rosette as the fish moves.There were 10–16 primary olfactory lamellae radiating from the wall of the olfactory chamber.These lamellae were longitu-dinally arranged and parallel to each other.The primary olfactory lamellae differed in their height and some pos-sessed secondary olfactory lamellae.Olfactory lamellae were composed of the olfactory epithelium and central core.The olfactory epithelium consisted primarily of ciliated receptor cells,ciliated non-receptor cells,supporting cells,and basal cells.The axons of the primary olfactory receptor neurons in each rosette converged to form a pair olfactory nerves that exceeded 1 cm in length in a 17 cm fish.The paired olfactory nerves extended from the pos-terior ventral base of each rosette to the ipsilateral olfactory bulb.The two olfactory bulbs,in close contact with the telencephalon,were slightly oval and sessile.Each olfactory bulb consisted of three,roughly distinguishable layers,in order from the surface：（1） the olfactory nerve layer,containing the axons of the olfactory receptor neu-rons,（2） the glomerular and mitral cell layer,where the axons of the olfactory receptor neurons arborized into glomeruli and the secondary neurons（mitral cells） were scattered around glomeruli,and（3） the granule cell layer,consisting of densely-packed small size cells.Afferent fibers of nerve bundles reached the anterior bulb,spread along the periphery of the bulb and terminated on the dendrites of mitral cells in the glomerular and mitral cell layer.The olfactory nerve layer extended more caudally in the ventral lateral field than in the dorsal medial field.The glomerular and mitral cell layer was thinner in the medial field than in the lateral field of the olfactory bulbs.Using immunocytochemistry SABC,we determined the distribution and numbers of progesterone receptor im-munoreactive cells in the B.sinensis olfactory system.Progesterone receptors were present in the olfactory system of the fish,with the largest number of PR immunoreactive cells occurring in the olfactory epithelium,followed by the olfactory bulb and the olfactory nerve.PR immunoreactivity was confined to the cell nucleus in the olfactory epithelium.We only observed a few neurons that were immunostained with antibodies against PR in the olfactory nerve in mature fish.In addition,we noted the presence of some PR immunoreactive cells on the vascular wall during the spawning season.We observed a higher density of PR immunoreactive cells in the olfactory bulb.The immunoreactive intensity in the bulb was higher in the lateral field and ventral fields than in the mid and dorsal fields,respectively.In the sections that were immunostained with antibodies against PR,we observed immunore-active mitral cells in the glomerular and mitral cell layers.The numbers of immunoreactive cells were linked to the reproductive status of the fish.In the olfactory epithelium,the numbers of immunoreactive cells in mature males and females was significantly（P〈0.05 or P〈0.01） higher than in immature males and females.Similarly,immu-noreactive cells were not detected in the olfactory nerve in immature fish.The numbers of immunoreactive cells in the olfactory bulb was significantly（P〈0.05） higher in mature females than in immature females.To our knowl-edge,this is the first report documenting the distribution of immunoreactive progesterone receptor cells in the ol-factory system of a teleost.