Fine structure of the plasmodesm

The cytopla,smic continuity b~tween raer{st,eraatic cells was a raatter of controversy till S'trugger (1957) and Buvat (1957) studied the cytoplasmic bridges which traverse the walls with the electronmicroscope. Later Whatey et al. (t960) .sugaested ~he continuity of the tubules .of the endopla,sraic reticulura acros.s the cell wall, and Porter and Machado (1960) po,inted out that the configuration .of the plasmodesm is related to the formation of the cell plate a~t the telophase. A't this moraent the cell plate is cr.o,ssed by tracts ,of the endoplasmic reticulum which determine the location o[ the pla.smo, desms. Recently, Frey- Wyss 1 in get al. (1964), studying the cell plate formation, macle the same observa~tions as Porter and Machado. Nevertheless, .a,s Buvat (1953) writes, "the cont, inuous passage of the filaments of the endopla.smic reticnlum from a cell to its neiahbours is still debatable," and only a few details of the ultrastructure .of the plasmodesms are known. In thi,s comraunicati.on we present some new evidence on tMs question, and sugg,e,st a model of the plasraodesra as well.