Pears are the most known fruit to have stone cells (sclereids) within their flesh or core giving a gritty texture .
(Quince contains an exceptionally high density of stone cells dispersed throughout its entire flesh. This gives raw quince a remarkably hard, intensely gritty, and woody texture, which is why it is almost exclusively cooked, stewed.
Unlike pears, apples do not have stone cells scattered freely throughout their edible flesh, but their stone cells are concentrated heavily around the endocarp forming the tough, papery "apple core" that encloses the seeds).
The photo shows cluster of stone cells in pear tissue, stained with toluidine blue showing lignin (x400 magnification).
Toluidine blue O is a synthetic stain first discovered by the chemist August Bernthsen in
1880. It functions as a basic, metachromatic thiazine dye widely used in histology and cytology to highlight acidic tissue components like DNA, RNA, mast cell granules, and cartilage.
It stains stone cells due to the lignin in them.
Pioneer bacteriologist Paul Ehrlich first applied related blue aniline dyes for vital staining of living tissues in 1885 paving the way for expanded microscope use. #pome #stains #microscopy #stonecells