INDUCED CHANGES IN THE CELLS OF THE OVOTESTIS OF THE SLUG, DEROCERAS RETICULATUM (MÜLLER), WITH SPECIAL REFERENCE TO THE NUCLEOLUS

Abstract

The germinal epithelium lining the ovotestis of the slug, Deroceras reticulatum, gives rise to spermatozoa, eggs, and nurse cells. The behavior of the nucleolus has been followed in these cells, particularly in the development of the oocytes. Changes in size, number, and staining reactions of the nucleolar components occur during the rapid growth of the egg. Exposure of animals to low temperature (0 °C.) causes two changes in the germinal epithelial cells. The normal flattened cells with elliptical nuclei now become greatly elongated towards the lumen of the gonad and their nuclei become rounded and conspicuous. The ovotestis shows other changes as a result of exposure to cold, such as loss of organization and, in extreme cases, complete disappearance of the cytoplasm of the eggs, leaving only the nuclei. These changes are accompanied by changes in the behavior of the nucleolus. Similar effects of disorganization and loss of cytoplasm follow the injection of an anterior pituitary hormone "Synapoidin") into slugs, but there was no effect on the germinal epithelium. The number of eggs per follicle increased with the number of injections of the hormone. The general effects of these two agents resemble an induced premature maturation followed by senescence. It is suggested that this may be due to interference with the enzyme or hormonal systems of the normal cells.