Ultrastructure of the Developing Wheat Endosperm

Abstract

The application of modern electron-microscope techniques to the developing endosperm of the variety Gaho wheat (Triticum vulgare) demonstrates that before cell walls form between the close-packed free nuclei some undifferentiated spherical bodies are present although none can be classified as plastids, mitochondria, or Goigi complexes. Apparently the initial development of cell walls does not take place by an alignment of vesicles along a plane as occurs in normal meristematically dividing plant tissues. Soon after cell wall formation organelles become recognizable, although their origin is still obscure. Extensive sac-like proliferations of the outer nuclear membrane are seen and a connection with the endoplasmic reticulum membrane system is postulated. A blebbing of the inner nuclear membrane also occurs; nuclear material appears in the proliferations of the outer nuclear membrane and, it is supposed, this material becomes continuous with the ground cytoplasm.