Interaction of nucleus and cytoplasm during oogenesis in Pteridium aquilinum (L.) Kuhn

Abstract

By means of auto-radiography, the synthesis of deoxyribonucleic acid has been followed throughout oogenesis in Pteridium aquilinum, the deoxyribonucleic acid having first been made radioactive by feeding the gametophyte with tritiated thymidine. It has been found that in the mature egg the deoxyribonucleic acid is dispersed throughout the whole cell. The failure of the nucleus of the mature egg to stain with the Feulgen reagent at this stage is believed to be a consequence of this dispersal of the deoxyribonucleic acid. Quantitative comparisons have been made of the amounts of radioactivity in the egg and in various nuclei of the archegonium which were expected on developmental grounds to con­tain the same amount of labelled deoxyribonucleic acid. Evidence is presented that the egg contains twice as much deoxyribonucleic acid as the non-gametic nuclei, and it is suggested that its chromosomes have entered the prophase condition.