The colour change of the minnow, Phoxinus phoxinus with particular reference to the effect of spinal lesions

Abstract

With 2 plates and 3 figures in the text)An account is given of the anatomy of the spinal cord of the minnow, Phoxinusphoxinus L., and comparisons are made with the spinal cords of other teleosts. The effects on the rapid, neurally controlled colour responses of complete transection of the spinal cord at different levels indicated that, in the particular fish used for this work, the sympathetic pigmento-motor fibres had a localized outflow from the spinal cord around vertebra 13. Partial lesions of the spinal cord at vertebrae 3, 4, 10 and 11 and their effects on the colour responses indicated that, at these spinal levels, the pigmento-motor fibres were dorsomedially located within the dorsal horns. Complete and partial transection of the spinal cord at any single level between vertebrae 12 and 14 and partial transection of the dorsomedial spinal tissues at vertebrae 3,4, 10 and 11 resulted in differential paling of the entire dorsolateral skin of the fish in response to a change of background from black to white. It would appear that in both cases this differential response of the melanophores was the result of transecting a proportion of the spinal pigmento-motor fibres.

Flatfish (Pleuronectiformes) chromatic biology

“…However, Grove (1994) concludes that it is difficult to understand how such a single sympathetic neurone could control body patterns on variegated backgrounds. Overall, histological and experimental observations on the cyprinid fish, Phoxinus phoxinus (Whitear 1952;Gray 1955Gray , 1956Burton 1964Burton , 1966Burton , 1969 indicate functional relationships between specific spinal pigmentomotor neurons within the substantia gelatinosa Rolandi and corpus commune posterius and the nerve plexus and melanophores in localised areas of the skin, rather than with a diffuse dermal nerve net. Such a relationship would make it theoretically possible, but not essential, for local areas within flatfish patterns to be controlled through separate neuronal pathways from distinct cerebral centres.…”

Sensory Biology of Aquatic Animals

“…A locus in the medulla contains cells whose descending axons exit the spinal cord (at a species-specific vertebra) (see Healey 1951Healey , 1954Scott 1965;Burton 1969;Wilhelm 1969;Iwata and Fukuda 1973), enter the autonomic chain ganglia, and exit via peripheral nerves to innervate melanophores (von Frisch 1911). (This entire pathway has not been confirmed.…”

A physiological interpretation of pattern changes in a flatfish

“…Theoretical relationships between retinal stimulation, central processing and possible neural pathways to localized areas of the skin have been discussed (Ramachandran et al, 1996;Anderson et al, 2003). Observations on a cyprinid fish, the European minnow Phoxinus phoxinus (L.) indicate that spinal cord dorsomedial pigmentomotor neural pathways within the substantia gelatinosa Rolandi and corpus commune posterius (Burton, 1964(Burton, , 1966(Burton, , 1969 (Whitear, 1952;Gray, 1955Gray, , 1956Burton, 1964Burton, , 1966Burton, , 1969. Partial damage to the spinal pigmentomotor tract affects melanophore responses in discrete localized areas of the skin (Burton, 1964(Burton, , 1966.…”