02385nas a2200157   4500008004100000022001400041245011300055210006900168260001600237520163800253100002601891700002101917700002001938700002201958856024701980       2020                        eng d  a0021-996700aOntogeny of the electric organ discharge and of the papillae of the electrocytes in the weakly electric fish0 aOntogeny of the electric organ discharge and of the papillae of   cDec-08-20203 a<p>The electric organ of the mormyrid weakly electric fish, Campylomormyrus rhynchophorus (Boulenger, 1898), undergoes changes in both the electric organ discharge (EOD) and the light and electron microscopic morphology as the fish mature from the juvenile to the adult form. Of particular interest was the appearance of papillae, surface specializations of the uninnervated anterior face of the electrocyte, which have been hypothesized to increase the duration of the EOD. In a 24.5&thinsp;mm long juvenile the adult electric organ (EO) was not yet functional, and the electrocytes lacked papillae. A 40&thinsp;mm long juvenile, which produced a short biphasic EOD of 1.3&thinsp;ms duration, shows small papillae (average area 136&thinsp;&mu;m2). In contrast, the EOD of a 79&thinsp;mm long juvenile was triphasic. The large increase in duration of the EOD to 23.2&thinsp;ms was accompanied by a small change in size of the papillae (average area 159&thinsp;&mu;m2). Similarly, a 150&thinsp;mm long adult produced a triphasic EOD of comparable duration to the younger stage (24.7&thinsp;ms) but featured a prominent increase in size of the papillae (average area 402&thinsp;&mu;m2). Thus, there was no linear correlation between EOD duration and papillary size. The most prominent ultrastructural change was at the level of the myofilaments, which regularly extended into the papillae, only in the oldest specimen &ndash; probably serving a supporting function. Physiological mechanisms, like gene expression levels, as demonstrated in some Campylomormyrus species, might be more important concerning the duration of the EOD.</p>
1 aKorniienko, Yevheniia1 aTiedemann, Ralph1 aVater, Marianne1 aKirschbaum, Frank  uhttps://onlinelibrary.wiley.com/doi/abs/10.1002/cne.25003https://onlinelibrary.wiley.com/doi/pdf/10.1002/cne.25003https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fcne.25003https://onlinelibrary.wiley.com/doi/pdf/10.1002/cne.25003