THE FINE STRUCTURE OF WALL MODIFICATIONS AND ASSOCIATED STRUCTURES IN CALLUS TISSUE OF ANDROGRAPHIS PANICULATA NEES.

In established callus cultures of Andrographis paniculata grown on a solidified nutrient medium, numerous spherical multivesiculate bodies, c. 0.6–3 μ in diameter, are visible. These usually contain membrane-bounded vesicles and tubules of up to 0.2 μ diameter enclosed within one to several membranous lamellae, but myelin-like forms also oeeur. The origin of sueh multivesiculate bodies is uncertain but the Golgi apparatus or endoplasmie reticulum may be implicated. The multivesiculate bodies apparently f'use to the cell wall to form lomasomes and these organelles deposit their membranous contents into the wall and give rise to membranous wall bodies. These bodies eontain a plethora of membrane-bounded vesicles, or membrane segments which may be isolated or associated in myelin-like configurations. The vesicles probably contain precursor materials utilized in the synthesis of the fibrillar material in which the membranous inclusions in the wall are embedded. Associated with the membranous wall bodies, numerous wall invaginations develop in seneseing tissue and divide the cells into progressively smaller compartments. The latter eventually become almost completely occluded, apparently due to the secretion of fibrillar material into their lumens by multivesiculate bodies and membranous wall bodies.