THE ULTRASTRUCTURE OF THE MATURE EMBRYO SAC IN THE NATURAL TETRAPLOID OF RED CLOVER (TRIFOLIUM PRATENSEL.). THAT HAS A VERY LOW RATE OF SEED FORMATION

摘要

In this study, ultrastructural organization of cells in the mature embryo sac of natural tetraploid Trufolium pratense L. Was in- vestigated. The mature embryo sac of this plant contains an egg cell with two synergids at the micropylar end, and a central cell with two polar nuclei. The ultrastructure of these cells agrees with what is known for most angiosperms studied with the electron microscope. The egg cell is a large and highly vacuolate cell, partially surrounded by a wall. Much of the cytoplasm is located around the nucleus at the chalazal end and there are few numbers of channel-shaped endoplasmic reticulum, mi- tochondria, plastids and numerous ribosomes distributed throughout the cytoplasm.