Developmental Aspects of Ultrastructure and Histochemistry of the Stylar Transmitting Tissue of Nicotiana sylvestris

The structure and histochemistry of the solid style of Nicotiana sylvestris Speg. and Comes have been studied by light and electron microscopy. The transmitting tissue develops large intercellular spaces filled with secretions rich in proteins and carbohydrates during maturation. The cells possess large nuclei, numerous plastids with starch grains, mitochondria, ribosomes and well developed endoplasmic reticulum and golgi apparatus. The plastids in the stylar region immediately below the stigma produce electron-dense osmiophilic substances which are probably transferred into the cytoplasm by a process resembling budding-off of vesicles. The Golgi apparatus may use the starch grains as a source of sugars for the synthesis and secretion of extracellular polysaccharides. The structural and cytochemical differences between the glandular cells of the stigma and the stylar transmitting tissue are discussed.