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In this study ultrastructural differences between endothelial cells of different location in Penstemon gentianoides have been examined with electron microscope at mature embryo sac phase. Embryo sac is of the Polygonum type and surrounded by endothelium except the micropylar region. The cuticle is located primarily around the chalazal three-fourths of the embryo sac. Endothelium cells around the chalaza and toward the micropylar region are rich in cytoplasmic organelles. The cytoplasm of endothelial cells near the central cell has large vacuoles and few organelles. There are also plasmodesmas on the anticlinal walls of endothelial cells. The endothelium and the micropylar integumentary cells play a role in transport of metabolites into the embryo sac.

In this study, development of anther wall of Helianthus annuus L. male fertile HA 89 "B" line and cytoplasmic male sterile HA 89 "A" line were compared by light and electron microscopy. It was observed that there was no difference between male fertile HA 89 "B" line and male sterile HA 89 "A" line development of anther wall until tetrads were formed. After tetrad stage it was observed in male fertile HA 89 "B" line that the middle layer was lost, tapetum was parted from anther wall and it surrounded the microspores. In cytoplasmic male sterile HA 89 "A" line, middle layer was vacuolated and widened, tapetum also enlarged and it filled anther sac. It was determined that middle layer and tapetum were permanent with epidermis and endothecial cell during the further development of anther wall, and also there was no secondary thickening in endothecial cells. In conclusion it was found that the plasmodial tapetum which developed in fertile HA 89 "B" line transferred nutrients to microspores and helped them develop normally, but in cytoplasmic male sterile HA 89 "A" line the plasmodial structure did not develop. The inner tangential wall of the tapetum which was related with tetrads was not degenerated, sufficient nutrient were not transferred to microspores and thus they degenerated into the callose wall.

Embryo sac cells are highly differentiated in plants. The central cell is one of the most important cells of the embryo sac. It forms endosperm by fusion with a sperm cell. Ultrastructure of the central cell in the mature embryo sac of Castilleja wightii was investigated in this study. Nucleolus which had a lot of vacuole in a large secondary nucleus and numerous dictyosomes, vesicles, mitochondria, amyloplasts in cytoplasm were seen in this cell. Also free ribosomes in the form of polysomes and large lipid bodies were detected in the cytoplasm. Numerous vacuoles of different size were observed and some of them had autophagic function. Both smooth and rough endoplasmic reticulums were seen. Although invaginations were seen in the plasmalemma of the central cell to the inside of the embryo sac, a thick cuticular layer was observed outer side on the cell wall. The aim of this study was to contribute studies about the ultrastructure of embryo sacs.