Abstract
Cell populations in exothecium and endothecium of Allium cepa L. pollen sacs were studied throughout the time covering the development of meiosis in the accompanying pollen mother cells (PMCs). In both layers of the anther most of the cell population is already differentiated in G0, with a 2C DNA content, at early meiotic prophase.
However, there is a subpopulation of cells, around 3.5% of the whole population which is still slowly replicating in exothecium during the whole PMCs meiosis, without reaching the 4C DNA content.
In endothecium, there is also a minor subpopulation cycling throughout the whole development of the meiotic stages. The frequency of cells replicating reaches its maximum (3.8%) at pachytene. Such peak is followed by a maxium in mitotic index (3.6%) at diplotene-diakinesis-metaphase I, suggesting the existence of certain synchrony in such endothecial cycling population.
