Herwig H J
Cell Tissue Res. 1980;209(2):187-200. doi: 10.1007/BF00237625.
A comparative ultrastructural study was made of the pineal organ of two related species of the Syngnathidae, the pipefish, Syngnathus acus, and the seahorse, Hippocampus hudsonius. Both species have a relatively small pineal organ, which ultrastructurally shows several similarities with the pineal of other teleosts. In the pineal organ of Syngnathus acus, the photoreceptor cells have well-developed outer segments consisting of about 15 to 60 saccules. The pineal supporting cells are characterized by the presence of numerous myeloid bodies. In Hippocampus hudsonius the pineal outer segments are scarce and poorly developed; generally, they show not more than 20 saccules. The apical parts of the supporting cells contain dense-core vesicles with a diameter varying from 100 to 180 nm. Corresponding vesicles were not observed in the pineal organ of Syngnathus acus. Arguments are presented for the suggestion that the pineal organ of the Syngnathidae, in spite of its relatively small size, still has a functional significance. In Syngnathus acus, light reaching the pineal organ directly might have a regulating effect on pineal activity. In Hippocampus hudsonius, however, light acting directly on the pineal organ appears to have minor effect on pineal function.
对海龙科两种近缘物种——尖吻海龙（Syngnathus acus）和胡氏海马（Hippocampus hudsonius）的松果体进行了超微结构比较研究。这两个物种都有一个相对较小的松果体，在超微结构上显示出与其他硬骨鱼松果体的一些相似之处。在尖吻海龙的松果体中，光感受器细胞具有发育良好的外段，由大约15至60个囊泡组成。松果体支持细胞的特征是存在大量髓样小体。在胡氏海马中，松果体外段稀少且发育不良；一般来说，它们显示不超过20个囊泡。支持细胞的顶端部分含有直径从100到180纳米不等的致密核心囊泡。在尖吻海龙的松果体中未观察到相应的囊泡。有观点认为，尽管海龙科的松果体相对较小，但仍然具有功能意义。在尖吻海龙中，直接到达松果体的光可能对松果体活动有调节作用。然而，在胡氏海马中，直接作用于松果体的光似乎对松果体功能影响较小。
