Comparative histology of the adult electric organ among four species of the genus Campylomormyrus (Teleostei: Mormyridae)

• Published in: Journal of Comparative Physiology Vol. 201; no. 4; pp. 357 - 374
• Main Authors: Paul, Christiane, Mamonekene, Victor, Vater, Marianne, Feulner, Philine G. D, Engelmann, Jacob, Tiedemann, Ralph, Kirschbaum, Frank
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.04.2015; Springer Berlin Heidelberg; Springer Nature B.V
• Subjects: adults; Animal Physiology; Animals; Biomedical and Life Sciences; Campylomormyrus; Electric Fish - anatomy & histology; Electric Fish - growth & development; Electric Fish - physiology; Electric Organ - anatomy & histology; Electric Organ - growth & development; Electric Organ - physiology; Electrodes; Female; histology; innervation; Life Sciences; Male; Mormyridae; Neurosciences; Numenius; Original Paper; Photomicrography; Species Specificity; Teleostei; Zoology; Electric organ ontogeny; Electric organ discharge; Electrocyte geometry; Mormyridae
• ISSN: 0340-7594; 1432-1351
• DOI: 10.1007/s00359-015-0995-6

The electric organ (EO) of weakly electric mormyrids consists of flat, disk-shaped electrocytes with distinct anterior and posterior faces. There are multiple species-characteristic patterns in the geometry of the electrocytes and their innervation. To further correlate electric organ discharge (EOD) with EO anatomy, we examined four species of the mormyrid genus Campylomormyrus possessing clearly distinct EODs. In C. compressirostris, C. numenius, and C. tshokwe, all of which display biphasic EODs, the posterior face of the electrocytes forms evaginations merging to a stalk system receiving the innervation. In C. tamandua that emits a triphasic EOD, the small stalks of the electrocyte penetrate the electrocyte anteriorly before merging on the anterior side to receive the innervation. Additional differences in electrocyte anatomy among the former three species with the same EO geometry could be associated with further characteristics of their EODs. Furthermore, in C. numenius, ontogenetic changes in EO anatomy correlate with profound changes in the EOD. In the juvenile the anterior face of the electrocyte is smooth, whereas in the adult it exhibits pronounced surface foldings. This anatomical difference, together with disparities in the degree of stalk furcation, probably contributes to the about 12 times longer EOD in the adult.