A Simple Device for Making Successive Photomicrographic Records of Large Groups of Developing Organisms

摘要

In our analysis of the effect of ionizing radiationupon the cleavage of sea urchin zygoteswe found it necessary to take successive photomicrographsof a large number of eggs, indifferent samples, which had been exposed tograded doses of ionizing radiation (Hsiao andDaniel, 1960). In order to estimate the rateof cleavage of the irradiated samples of fertilizedeggs it is highly desirable to follow thecleavage of each egg in every sample and makephotomicrographic records for later analysis.In other words, we need to take time-lapsepictures of the developing eggs subjected todifferent amounts of radiation so as to calculatethe rate of cleavage and correlate it withdosage. After some preliminary trials we haveput together, using commonly available materials,a simple device capable of taking photomicrographsrepeatedly from the same fieldin a series of samples of irradiated eggs atspecified time intervals. By lining up, accordingto time, prints made from each field, eachegg can be identified and its cleavage followedfrom the first to the last frame in the series,and its rate of cleavage can be calculated. Itoccurs to us that investigators who have occasionto record developmental and other recurrentphenomena may find this simple deviceuseful. A brief description of its method of constructionand manipulation is reported in thispaper.