On the hypothetical grain analysis in EM autoradiography

Abstract

Analyzing EM autoradiographs remains a troublesome problem because of their considerably poor resolution. In the present study, the authors examined an availability of the hypothetical grain analysis proposed by Blackett and Parry (1977) and Salpeter et al (1978).
Materials used are palatal shelves of day 13.5 mouse fetuses incubated for one hour in Eagle's MEM containing ³H-proline in a CO₂ incubator. To prepare autoradiographs, thin sections were coated with Ilford L4 emulsion by means of the dipping method reported by Kopriwa (1973). They were exposed for 12 weeks and developed by phenidone developer. The values of source density for source compartments estimated by hypothetical grain analysis and the grain density, which is equivalent to the grain density per unit area for each compartments, were compared to each other.
Although the relationship of estimated values of source density for source compartments was quite similar to that of grain density, the range of values of the former was wider than that of the latter. And the standard errors of values of source density were relatively small.
Thus, the hypothetical grain analysis to estimate the sourse dentity is considered to be an effective method to obtain more precise information for the analysis of EM autoradiographs than by using grain density.