بررسى فراساختارى مراحل تكوين سلول هاى پاپى در كلاله گل تاتوره(Datura stramonium L)

Ultrastructural study of the stigmatic papillae in Datura stramonium

Stigma of Datura stramonium L. is bilobed, papillate and at maturity covered with a sticky exudates (wet papillate type).There is a little information on the stigmatic excretion of the mature stigma of Datura stramonium. In the present study, the ontogenetic and ultrastructural aspects of papillae were investigated in four stages of stigma development, using transmission electron microscopy. After gathering 5-75mm buds and in order to perform histological studies, different stages of fixation, blockage, and section were done by ultra-microtome. Fine sections stained with uranil acetate and citrate lead. In the course of development, papillae as well as underlying stigmatic cells showed secretory activity. Remarkable expansion of the endoplasmic reticulum and great modification of vacuolar contents during the ontogenesis of papillae suggested their effective role in the secretion process. Secretion began very early in 20-25 mm long buds. In this stage, electron dense droplets appeared in the cytoplasm and vacuoles. Furthermore, dense black aggregates were observed at the surface of the endoplasmic reticulum. These structures represented stigmatic secretion material. High electron density of secretory components gets recognizable following the post fixation with 0s04 by means of transmission electron microscopy. In the mature stigma, droplets increased in number, coalesced and formed large lipid bodies under the cuticle and on the stigma surface. This procedure caused the cuticle to ruptures and become distanced from the cell wall.