Studies On The Procession Of Nuclear Extrusion And The Phenomenon Of Apoptosis In Root Tip Cell Of Allium Sativum

Observation combined light microscopes with TEM on the process of nuclear extrusion and apoptosis in root tip cell of Allium sativum used the method of semithin section and ultrathin section. Through semithin section the phenomenon of nuclear extrusion and apoptosis was normality in growth and development of plants. Root tip cell of Allium sativum is made up of root crown, vegetative point, elongation region and root hair region. Nuclear extrusion appeared in elongation region firstly and 3 cell layers of superficies externa which had protect ion role arranged tightly. When migration of many nucleus started, apoptosis of cytoplasm and cell organs began, cell walls dissolved, cell space shaped and formed tube.The procession of nuclear extrusion: First, chromatin dispersed uniformly in cell nucleus, only a cytoplasm layer around it which had large volume and lied in the middle; Second, chromatin collected gradually, and went to cell walls from the middle; At last, the road of cell conjugation appeared in the cell walls, through which chromatin in cell nucleus transferred to flanking cell from one or more roads. The two methods of nuclear extrusion: Mostly a cell went to a cell, then to another; One cell went to two or three cells or to the same cell from two or three cells.The procession of apoptosis: After cell nuclear extrusion, nuclear happened changed. Karyolemma appeared reductus, condensed and broken to form apoptotic body.So nuclear extrusion belonged to a phenomenon of apoptosis in the procession of growth and development of the plants.