Winter and spring changes in the microsporogenous cells of the Scotch pine as revealed by Feulgen photometry and Auramin fluorometry

Abstract

Sporogenous cells of Scotch pine microsporangia were separated from the other tissues of the strobilus. This made it possible to spread them on slides as a one-cell layer for cytophotometric studies. Feulgen photometry using Schiff s reagent showed that during the overwintering period the DNA level of these cells remained more or less constant. The nuclei in a microsporangium were not fully homogeneous in size and stainability. DNA synthesis occurred in the spring, preceding and overlapping the cell divisions that led to the formation of pollen mother cells. Auramin fluorometry showed that in spite of the steadiness of the DNA quantity, the sporogenous cells were not in a state of complete rest during the winter. Their stainability fluctuated so that it increased during the middle of the winter, reached a peak in February, and then dropped. Higher dye attachment was seen again in the May material. The factor(s) causing the wintertime fluctuation is unknown at the present.