Macrosporogenesis and Development of the Macrogametophyte of Solanum tuberosum

Abstract

1. A single archesporial cell, hypodermal in origin, may function as a macrospore mother cell. Frequently, however, a multiple archesporium is differentiated from hypodermal and subhypodermal cells of the nucellus. In such case each archesporial cell may function as a macrospore mother cell, but usually only one of them so functions. 2. A linear row of four macrospores is formed. The chalazal macrospore develops into an embryo sac; the other three spores disintegrate. 3. The micropylar cells of the nucellus break down and the developing embryo sac comes into contact with the inner epidermis of theintegument, which functions as a nutritive layer. 4. In the 4-nucleate embryo sac the spindle persists between each pair of sister nuclei, but no cell plate has been observed at this stage. 5. A typical 8-nucleate embryo sac is formed, at each end of which the four nuclei are connected with one another by fibers from thespindle of the third division as well as by persistent spindle fibers from the second division...