The Programmed Cell Death (PCD) In The Process Of Ovule Anatomy Development Of Ginkgo Biloba Van Epiphylla Mak.

(1) The development ovule of secretory cavities in Ginkgo biloba var. epiphylla Mak.The ovule in Ginkgo biloba var. epiphylla has developed secretory structures, they were shown the characteristics of PCD (programmed cell death) were in the development ovule of Ginkgo biloba var. epiphylla and Ginkgo biloba, these phenomena of PCD existed in the development of plant. Their characteristics were as follows:with the formation of intercellular space, first, the cell wall had been disintegrated, followed by the disintegration of the central secretory cells, then, the degradation of its neighboring cells, secretory vesicles were adjacent phagocytic cells, but their had no inflammatory response, its showed that the function of autophagy, finally secretory cavities were formed. The formation pattern of the secretory cavities were schizo-lysigeneous between Ginkgo biloba var. epiphylla and Ginkgo biloba.(2) The differentiation of micropyle, nucellus and pollen chamber in Ginkgo biloba var. epiphylla Mak.Normal ovule organizations had already differentiated completely before pollination, and the integument grew rapidly, then drew together in apex of the nucellus gradually in normal ovule. Meanwhile, there were no differentiation in collar and nucellus, but with some ridge gibbosities in epiphyllous ovule which obtained the nutrition from the vascular bundle in gibbosities. Then the palisade tissue and spongy tissue differentiated along with the development of gibbosities. In pollination period, there was pollination drop secreted by the nucellus and then the pollen chamber formed by the programmed cell death of the nucellus in normal ovule. While there was no pollination drop in epiphyllous ovule, besides the collar and nucellus had already differentiated with the rostrate micropyle, the extended micropylar canal. But no pollen chamber was formed because there was no cell degradation in the bottom of micropylar canal in epiphyllous ovule. Then epiphyllous ovule and ovule were into free nuclei stage of female gametophyte after pollination period.(3) The development of integument in Ginkgo biloba var. epiphylla Mak.During the development of meso-integument and inner integument of epiphyllous ovule in Ginkgo biloba var. epiphylla, nuclei condensation and margination and nucleus degeneration occurred, it showed a character of programmed cell death (PCD); but it was exclusive of outer integument. After fertilization60days, the inner integument of epiphyllous ovule in Ginkgo biloba var. epiphylla remains during the whole process of seed develpoment and a layer of impermeable endothelium is formed. It encloses the female gametophyte tightly。(4) In this study, epiphyllous ovule was not observed the megasporocyte and archegonium.