Intranuclear and Cytoplasmic Annulate Lamellae in Plant Cells

Annulate lamellae (AL) have hitherto been described for ammal cells (m particular, for germ cells), for embryomc systems, and for rapidly growing cells hke tumor and cancer ceils (for review, see references I0, 16) Such cisternae, which are either single or arranged m stacks of parallel lamellae, are characterized by the presence of pore complexes, i.e., pores of a relatively unitbrm srze distribution which are associated with distinct granulo-fibrillar structures and are arranged m a symmetrical subarchitecture identical to that of nuclear pore complexes (e g., 10, 14). No micrograph has so far been published which documents the presence of such structures in plant ceils. Kessel (10), though, in an addendum to his review, mentioned nonpublished observations of Skvarla who claimed the existence of "extensive profiles of annulate lamellae in pollen of Canna during pollen wall formation " We have been able to confirm this remark and, additionally, have found that stacks of AL occur also m earher stages of microsporogenesls (e g , pollen mother ceils) of Cannaceae and Zzngzberaceae 1 Sen (15) has demonstrated membranous stacks of Lilzurn microsporocyte metotto prophase and discussed a relationship to annulate lamellar formations, but these lamelIae do not show any pore complexes and thus are to be regarded as stacked endoplasmic ret iculum (ER) e rather than AL The question is whether AL in plant cells are confined to pollen development of a few species or are of more general occurrence Since in animal cells AL have been described mostly from cell types with a high R N A synthesis including, e g. diverse