The transmitting tissue in the pistil produces a secretion that provides nutrition and guidance for the pollen tubes. In Lilium this tissue consists of an epithelium lining the stylar canal and forming a narrow band in each of the three ovarian locules. The ultrastructure of the canal cells has been studied in several laboratories. The purpose of the work presented here was to supplement those results with corresponding data from the ovarian transmitting tissue.
In Lilium regale the uppermost part (which lacks ovules) of the ovarian locules have their secretory cells differentiated as typical transfer cells already at anthesis. The wall inbuddings constitute an extensive 'labyrinth'. At this stage the corresponding epithelial cells on the placenta are still immature but within 4 days they develop into transfer cells with a moderately thick wall labyrinth zone.
The secretory cells in the ovary are rich in mitochondria, dictyosomes and secretory vesicles and may further contain a few cytoplasmic and nuclear protein crystals. The RER is extensively proliferated. Below the cell wall extensions there is a distinct space with a granular secretion of high electron opacity.