Sclerotization of the perisarc of the calyptoblastic hydroid, Laomedea Flexuosa 1. The identification and localization of dopamine in the hydroid.

With histochemical methods, the perisarc and a certain cell type in Laomedea flexuosa have been shown to contain a catecholamine. The only catecholamine detected in methanolic extracts of the hydroid is dopamine. It is thought to be transferred from spherical inclusions in these cells to the perisarc and to be involved in sclerotization. The dopamine-containing cells appear to differentiate in specific regions of the colony and migrate out to all other regions by active amoeboid movement between ectodermal epithelial cells. The rivets (or desmocytes) contain an unidentified phenolic substance and may also be sclerotized structures.