Introduction to the Fine Structure of Plant Cells

It is appro pi ate to the contents of this book to recall a few highlights in the history of plant cytology from its inception over three centuries ago. Robert Hooke in 1663 presented his observations of what he called « cells" in cork and other plant parts and beautifully illustrated and described these in his classic « Micrographia" published two years later. More detailed exploration of the cell and its contents awaited almost two centuries for Robert Brown's discovery of the nucleus in 1831. Discoveries of other cell organelles followed, particularly in the latter part of the 19th and early part of this century. As is frequently noted each of these achievements was preceeded by advances in the resolution of the microscope. Now history repeats and recent developments in electron microscopy have given the biologist the opportunity to study cell morphology in far greater detail than at any time previously. Indeed, the resolution of the electron microscope is several hundredfold better than that available in the finest light microscopes. These advances in instrumentation plus improvements in the techniques of specimen preparation have made possible the ex­ amination of plant cells of almost any type. It is the resulting wealth of new information now accessible to the botanical cytologist that has prompted this publication. In this book we have brought together electron micrographs represent­ ing a number of cell types from higher plants.

1. General Cell Structure.- 1.1 Typical Plant Cell.- 1.2 Meristematic Plant Cell, Permanganate Fixed.- 2. Fine Structure Interphase Cell and Cell Organelles.- 2.1 Organelles of the Meristematic Cell.- 2.2 Dictyosomes.- 2.2a Dictyosome in Face View.- 2.3 Membranes of Cell and Cell Organelles.- 2.4 Microtubules in the Cell Cortex.- 2.4.1 Molecular Structure of Microtubules.- 2.5 Freeze-Etch Image of a Cell.- 2.6 Diagram Including Fine Structure of Typical Plant Cell.- 3. Dividing Cells.- 3.1 Cytokinesis and Cell Plate Formation.- 3.1a Phragmoplast and Microtubules.- 3.2 Diagram of Changes in Fine Structure during Mitosis.- 4. Cell Wall and Plasmodesmata.- 4.1 Plasmodesmata between Cells.- 5. Vascular Tissues.- 5.1 Secondary Xylem.- 5.2 Bordered Pit.- 5.3 Primary Phloem.- 5.3a Sieve Plate.- 5.3.1 Sieve Element and Companion Cell.- 5.4 Vascular Cylinder from Root.- 5.5 Vascular Cambium.- 5.6 Primary Xylem.- 6. Schlerenchyma and Collenchyma.- 6.1 Fibers.- 6.2 Stone Cells.- 6.3 Collenchyma.- 7. Epidermal Cells and Variants.- 7.1 Epidermal Cell.- 7.2 Epidermal Cuticle of Petiole.- 7.3 Gland Cells.- 7.4 Secretory Cells of a Nectary.- 7.5 Leaf Stoma.- 7.5a Leaf Epidermis, Face View.- 8. Photosynthetic Apparatus.- 8.1 Mesophyll Cell.- 8.2 Chloroplast.- 9. Cells with Special Inclusions.- 9.1 Chromoplasts.- 9.2 Raphid Cell.- 9.3 Laticifer.- 9.4 Tannin Cell.- 10. Germinative Tissues.- 10.1 Sporogenous Cells of Anther.- 10.2 Pollen Mother Cell.- 10.3 Tetrad of Microspores.- 10.4 Tapetum and Sporopollenin Formation.- 10.4a Microsporangial Wall.- 10.5 Pollen Grain: Microgametophyte.- 10.6 Archesporium or Megasporangium.