The Change Of Ovule Tapetum In The Development Process Of Female Gametophyte In Pinus Tabulaeformis Carr

There is a great significance for revealing the plant gametophytic development regulation mechanism to carry out the research on the tapetum, which is recognized as the "nursing organization" of sporophyte generation turning to the gametophyte generation. Ovule tapetum is a carrier of the development of plant female gametophyte:It is an important guarantee for the normal development of the embryo and seed;The abnormal growth of the ovule tapetum will lead to the ovule abortion; In order to observe this change of the characteristics of the female gametophyte in a period switching from the free nuclear breaking donnacy to the archegonium forming and the change characteristics of the cells and tissues around the female gametophyte. the ovule of pinus labulaeformis was selected as the research material on the basis of previous studies.The cell changes of the tapetum, integument, nucellus tissue of the female gametophyte development process in pinus labulaeformis are analysised from the view of anatomy, cytology and histochemical; Morever, which demonstrates the role and enrich the relevant data of the ovule tapetum in the female gametophyte development ofpinus tahulaeformis. The results as follows:1. The morphological observation of the female gametophyte development pinus labulaeformis shows:The tapetum cells continue the centripetal mitosis after the free nuclear breaking dormancy,its development undergo the changes in a series of stages of early, middle, active division and cellularization. In active division stage of the free nuclear.there are some features which have shorter duration and faster division,Mainly concentrated in March.2. The pinus tahulaeformis is of single integument and thick nucellus tissue that will not degradate.There are different origins of the ovule tapetum of pinus labulaeformis and the integument tapetum of angiosperm. the former develops from several inside layers of cells of nucellus.The cellular structure and nutrient changes are closely related to gametophyte development. Early free nuclear fission stage, the tapetal cell expaned volume and stained shallow, and tightly surround the female gametophyte:As the free nuclear division, volume of female gametophyte increases, the tapetal cells become Thiner, they begin to digest themselves to supply nutrient for gametophyte development.At vigorous division stage of free nuclear, the tapetum only consists of a thin layer of cells; Early cellularization stage, the tapetal cells degradate to discontinuous residue or merging into the nucellus. The tapetal cells disappear entirely after cellulari/ation stage, According to each development period of tapetum^integument and nucellus tissue in the female gametophyte of pinus tabulaeformis, the conclusion is:In the period from the free nuclear breaking donnacy to the archegonium formed of pinus tabulaeformis.The main source for the supply of nutrients to female gametophyte development should be:ovule tapetum,integument, nucellus tissue; Tapetum plays a key role in female gametophyte development. The action of ovule tapetum is consistent to the integument tapetum of angiosperm. Also, they play a dual "barrier’role that against the dissolving enzyme invasion and preventing inclusions outflow.These results supplied reference for further studies on abortive mechanism of the sterile lines female gametophyte28of pinus tabulaeformis.At the same time, it adds the research content of the ovule tapetum of pinus tahulaeformis.included gymnosperms.