Whitehead Darryl L, Gauthier Arnault R G, Mu Erica W H, Bennett Mike B, Tibbetts Ian R
School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, 4072, Australia.
J Morphol. 2015 May;276(5):481-93. doi: 10.1002/jmor.20355. Epub 2014 Dec 17.
Ampullae of Lorenzini were examined from juvenile Carcharhinus leucas (831-1,045 mm total length) captured from freshwater regions of the Brisbane River. The ampullary organ structure differs from all other previously described ampullae in the canal wall structure, the general shape of the ampullary canal, and the apically nucleated supportive cells. Ampullary pores of 140-205 µm in diameter are distributed over the surface of the head region with 2,681 and 2,913 pores present in two sharks that were studied in detail. The primary variation of the ampullary organs appears in the canal epithelial cells which occur as either flattened squamous epithelial cells or a second form of pseudostratified contour-ridged epithelial cells; both cell types appear to release material into the ampullary lumen. Secondarily, this ampullary canal varies due to involuted walls that form a clover-like canal wall structure. At the proximal end of the canal, contour-ridged cells abut a narrow region of cuboidal epithelial cells that verge on the constant, six alveolar sacs of the ampulla. The alveolar sacs contain numerous receptor and supportive cells bound by tight junctions and desmosomes. Pear-shaped receptor cells that possess a single apical kinocilium are connected basally by unmyelinated neural boutons. Opposed to previously described ampullae of Lorenzini, the supportive cells have an apical nucleus, possess a low number of microvilli, and form a unique, jagged alveolar wall. A centrally positioned centrum cap of cuboidal epithelial cells overlies a primary afferent lateral line nerve.
对从布里斯班河淡水区域捕获的未成年公牛真鲨（全长831 - 1045毫米）的罗伦氏壶腹进行了检查。壶腹器官结构在管壁结构、壶腹管的总体形状以及顶端有核的支持细胞方面与之前描述的所有其他壶腹不同。直径为140 - 205微米的壶腹孔分布在头部区域表面，在详细研究的两条鲨鱼中分别有2681个和2913个壶腹孔。壶腹器官的主要变异出现在管上皮细胞，这些细胞表现为扁平鳞状上皮细胞或第二种假复层轮廓嵴状上皮细胞形式；两种细胞类型似乎都向壶腹管腔释放物质。其次，这种壶腹管因内卷的壁而有所不同，形成了三叶草状的管壁结构。在管的近端，轮廓嵴状细胞邻接立方上皮细胞的一个狭窄区域，该区域靠近壶腹恒定不变的六个肺泡囊。肺泡囊包含许多由紧密连接和桥粒结合的感受器和支持细胞。具有单个顶端动纤毛的梨形感受器细胞在基部通过无髓神经终扣相连。与之前描述的罗伦氏壶腹不同之处在于，支持细胞有一个顶端核，微绒毛数量少，并形成独特的锯齿状肺泡壁。立方上皮细胞位于中央的中心帽覆盖着一条初级传入侧线神经。
