Brachysclereids are isodiametric

Show ramiform pits

A most common form of sclereids exists as brachysclereids (also termed stone cells) which are isodiametric, possess very thick lignified cell walls, and clearly reveal numerous pits, many of which may be branched (thus are said to be ramiform in organization). Such ramiform pits develop by fusion of simple pits during the increase in thickness of the secondary wall.

Fresh brachysclereids are naturally yellow in pear (Pyrus communis), but in this micrograph are stained with phloroglucinol that gives them a reddish appearance due to the presence of lignin. The sclereids are embedded in the fruit ground tissue (pulp) stained greenish. They give support to the soft tissues of the fruit. Due to concentric cell divisions, clusters of sclereids typically develop as shown here. If pears are left to ripen on the tree, most or all of the fruit flesh is converted to brachysclereids.

1 = primary wall, 2 = secondary wall, 3 = ramified pit, 4 = cell lumen, 5 = cross-sectioned pit

Right-hand illustration modified from: Weier, Stocking & Barbour, 1974, Botany: An Introduction to Plant Biology, 5th Ed. This material is used by permission of a subsidiary of John Wiley & Sons, Inc.