Denizot Jean-Pierre, Bensouilah Mourad, Roesler Ritva, Schugardt Christian, Kirschbaum Frank
C.N.R.S., Unité de Neurosciences Intégratives et Computationnelles, 91198 Gif-sur-Yvette, France.
J Comp Neurol. 2007 Apr 10;501(5):810-23. doi: 10.1002/cne.21278.
Promormyromasts were found in the epidermis of the head of the larvae of five species of mormyrids bred in captivity. The promormyromast is a larval electroreceptor belonging to the specific lateral line system. In 12-day-old larvae this electroreceptor is characterized by a single sensory cell and two types of accessory cells. One type of accessory cell has dark cytoplasm, few microtubules, and contacts the sensory cell directly, whereas a second type has pale cytoplasm, many microtubules, and forms an outer layer not directly in contact with the sensory cell. This second type is referred to as a long pyriform accessory cell. This assembly of cells is situated below an intraepidermal cavity filled with acid polysaccharides. The bordering epidermal cells extend microvilli into the intraepidermal cavity. The apexes of the sensory cell, and of the two types of accessory cells, also open into the intraepidermal cavity but bear no microvilli. The promormyromast is innervated by an unmyelinated sensory nerve fiber passing through the basal membrane, which then splits into several branches between the accessory cells. These branches contact the periphery of the sensory cell with terminal boutons. At the site of each contact a ribbon-like structure surrounded by vesicles is present in the cytoplasm of the sensory cell. In older larvae of Campylomormyrus cassaicus, membrane foldings develop at the periphery of the pyriform accessory cells and accessory cell staining properties change just before transformation to become a mormyromast. The functional role of the promormyromast of the larval mormyrids is discussed.
在人工饲养的5种裸臀鱼幼体头部的表皮中发现了前裸臀电感受器。前裸臀电感受器是一种属于特定侧线系统的幼体电感受器。在12日龄的幼体中，这种电感受器的特征是有一个感觉细胞和两种类型的辅助细胞。一种辅助细胞的细胞质暗，微管少，直接与感觉细胞接触，而另一种辅助细胞的细胞质淡，微管多，形成不直接与感觉细胞接触的外层。第二种类型被称为长梨形辅助细胞。这种细胞组合位于充满酸性多糖的表皮内腔下方。相邻的表皮细胞将微绒毛延伸到表皮内腔中。感觉细胞以及两种辅助细胞的顶端也通向表皮内腔，但没有微绒毛。前裸臀电感受器由一条无髓感觉神经纤维支配，该神经纤维穿过基膜，然后在辅助细胞之间分成几个分支。这些分支通过终末扣与感觉细胞的周边接触。在每个接触部位，感觉细胞的细胞质中都有一个被囊泡包围的带状结构。在卡氏曲臀鱼的老龄幼体中，梨形辅助细胞的周边会形成膜褶皱，并且在转变为裸臀电感受器之前辅助细胞的染色特性会发生变化。文中还讨论了幼体裸臀鱼前裸臀电感受器的功能作用。
