In vitro bio-assay for the study of the mitosis-stimulating factor in the optic gland ofSepia officinalis

A fast, reliable and quantifiable bioassay has been developed to study the factor in the optic gland ofSepia officinalis L. that stimulates mitosis in both gonial and follicle cells. Male germ cells, follicle cells, nidamental and oviducal gland cells of maturing cuttlefish (sampled in 1988 and 1989 in the Bay of Seine) were mechanically and enzymatically dispersed. Incorporation rates of³H thymidine by the dispersed cells and measurements of their aspartate-transcarbamylase activity were used as indicators of mitotic activity. Both assays were stimulated after incubation with optic-gland extracts of haemolymph from maturing individuals. The optimal conditions for the bioassay were determined. The factor stimulating mitosis does not appear to be sex-specific but does display seasonal variations.