Ultrastructural changes in neurohaemal tissue of the stick insect,Carausius morosus,induced by the ionophores Br-X-537 A and A-23187

Summary The antibiotic ionophores Br-X-537A and A-23187 alter the ultrastructure of neurohaemal tissue on the transverse nerve of the stick insect, Carausius morosus. Br-X-537A induces dramatic changes in the ultrastructural appearance of all three types of neurosecretory fibres present in the neurohaemal tissue. The neurosecretory granules become more electron-lucent and the mitochondria become more electron-opaque. The bounding membrane of the granules is frequently ruptured. A-23187, on the other hand, has no effect on two of the three types of fibres, but does produce an increase in the number of exocytotic profiles in the third.The two ionophores therefore have different effects on the same tissue. The results are discussed in the light of previous work with the use of these ionophores.We wish to thank Mrs. J. Birch for assistance with the electron micrographs, and Roche Products Ltd. and Lilly Research Centre Ltd. for gifts of the ionophores Br-X-537A and A-23187. The work was supported by the Science Research Council