STRUCTURE AND REACTIONS TO STIMULI OF ARTERIES (AND CONUS) IN THE ELASMOBRANCH GENUSRAJA

Abstract

Elastic and muscular types of arteries in R. diaphanes and stabuliforis, their structure and innervation, and their reaction to distension, temperature and sympatho- and parasympathomimetic drugs are described. The elastic type responds quickly to changes in distension. With rising temperature the circular muscle layer contracts to a maximal extent between 12 and 14 °C., but the longitudinal contracts only above 20 °C. The arteries of these elasmobranchs resemble the arteries of mammals in being contracted by adrenaline and barium chloride, but differ from them by being not relaxed, but contracted by acetylcholine. Atropine relaxes an artery contracted by acetylcholine. The rhythm of the spontaneous contractions of the conus arteriosus is greatly affected by distension and rise of the surrounding temperature, being increased in both instances.