title: The cell wall-plasmalemma interface in sieve tubes of barley.
abstract: Both thick- and thin-walled sieve tubes in leaf-blade veins of Hordeum vulgare L. exhibit a distinct, electron-opaque inner wall layer after fixation in glutaraldehyde-osmium tetroxide and staining with uranyl acetate and lead citrate. This inner wall layer is thickest at the sieve plates and lateral sieve areas where it is permeated by a labyrinth of tubules formed by the plasmalemma. Along the lateral walls between sieve areas the inner wall layer apparently is penetrated by numerous microvilli-like evaginations of the plasmalemma, giving the cell wall-plasmalemma interface the appearance of a brush border. It is suggested that a similar brush-border-like structure may occur at the cell wall-plasmalemma interface of sieve elements in a wide variety of vascular plants.
authors.affiliation: Department of Botany, University of Wisconsin, 53706, Madison, WI, USA.
authors.forename: R F
authors.initials: RF
authors.lastname: Evert
authors.forename: R J
authors.initials: RJ
authors.lastname: Mierzwa