Effect of hydrostatic pressure on morphogenesis in nerve‐free hydra

Abstract

Abstract Tissue stretching was controlled in hydra which lack nerves by preventing the accumulation of osmotic fluid within the gastrocoelic cavity. Hydra lacking nerves (epithelial hydra) became highly distended and swollen during the course of regular daily culturing conditions. Animals that were kept deflated for several days lost some of the abnormal morphology characteristic of epithelial hydra. The hypostome became conical and the upper portion of the body column became constricted. These new, more normal characters persisted for two days after deflation was discontinued. After long term deflation, the mesolamella was thick and regions of peristaltic annulations were altered. Furthermore, animals failed to bud at normal rates or elongate when pressure, in the gastric cavity was continually low. Thus, hydrostatic pressure, arising from gastrocoelic fluid, affects the long term histological and morphogenetic organization of hydra tissue.