Morphological, cytochemical, and cytofluorimetric features of supramedullary neurons of the fish Solea ocellata.
Various teleost species belonging to different orders possess a particular neuronal system formed by giant supramedullary neurons (SNs). In some species, SNs are scattered along the spinal cord; in others they are organized in a compacted and well-defined cluster located at the boundary between the medulla oblongata and spinal cord. In addition to the many morphological, physiological, and histochemical studies performed both in vivo and in vitro by several authors since the end of the 19th century, quantitative microfluorometric evaluation of the DNA content of SNs has showed that clustered SNs but not aligned SNs have a DNA content much greater than the normal value of 2C. Such a high DNA content is exceptional for vertebrate neurons. In the present study, we extend this analysis of SNs to the fish Solea ocellata. Our results show that the organization of the SNs of S. ocellata is neither strictly aligned nor clustered, but somewhere in between, and that this is also true of both their morphological characteristics and DNA content values. Interspecific differences in the distribution and morphology of SNs may reflect functional differences, possibly related to environmental or behavioral differences among species. In addition, the possible functional significance of endoreplication in SNs is discussed.
Cuoghi
Barbara
B
Department of Paleobiology Museum and Botanical Garden, Anatomical Museums, University of Modena and Reggio Emilia, 41100 Modena, Italy.
Mola
Lucrezia
L
D000818:Animals; D003592:Cytophotometry; D004261:DNA Replication; D005412:Flatfishes / Q000033:anatomy & histology* / Q000235:genetics; D006651:Histocytochemistry; D009474:Neurons / Q000166:cytology* / Q000502:physiology / Q000648:ultrastructure; D013045:Species Specificity; D013116:Spinal Cord / Q000166:cytology