Behavior of membrane system in the cell during cell divisions of microsporogenesis in Tradescantia paludosa. 3. Postmeiotic mitosis.

Abstract

Behavior of membrane system in meiotic mitosis was observed in the pollen mother cells of Tradescantia paludosa with electron microscopes. Unlike the cases of somatic mitosis such as premeiotic mitoses (Maruyama 1963) and postmeiotic mitoses in T. paludosa (Maruyama 1966), and somatic mitoses in root meristematic cells (Porter and Machado 1960), the cisternal form of membranes in the cell vesiculate extensively at diakinesis. That is, the nuclear envelope and the cisternae in the cytoplasm as well break down into small vesicles, some of which fuse and swell to form vacuoles. At anaphases and telophases of both the 1st and the 2nd divisions, these elements, including the vacuoles, take parts in the formations of the new nuclear envelopes and the plasma membranes. After completion of the meiosis, a huge vacuole is formed in the microspore by fusion and swelling of the smaller vacuoles. The Golgi body seem to originate from these vesicles in the cytoplasm of the microspore which are formed from the disintegrating nuclear envelope and the cisternae in the cytoplasm at diakinesis. The intracytoplasmic cisternae are formed later in the microspore by branching of the nuclear envelope. From these results of observation, the relationship of various membranes in the cell was discussed.