cytoplasm

CYTOPLASM

           Within the cell wall the inner content of the cell is the protoplast, which is differentiated in to the cytoplasm and the nucleus. Cytoplasm remains surrounding the nucleus, and thereby it is known as the extranuclear part of protoplast. Optically it appears to be clear and hyaline in nature, consisting of somewhat viscous fluid. It embeds many granular bodies known as organelles. The viscous fluid of the cytoplasm is also termed as hyaloplasm, due to its hyaline appearence. The external surface layer of the cytoplasm lying against the cell wall is called the ectoplasm,while the internal layer around the vacuoles  are called tonoplasm. The granular cytoplasmic substances inbetween these two layers are called the endoplasm.

                                                                                  
         



                  Recent studies with the help of electron microscope reveales that the outermost part of the cytoplasm  i.e, the ectoplasm from a membrane or a bounding wall, also called as plasmamembrane. It remain close to the cell wall and  thus sarves as a boundary layer inbetween  the outer non living wall and internal cytoplamic ground substance or cytoplasmic matrix. Chemically plasmamembrane is  composed of protein and phospholipid, in such a way  that a layer of phospholipid is enclosed  on either  sides by two layears of protein. This lipo-protein  composition of the membrane offers it a semipermeable nature i.e, it allows only few selective compounds to pass through it. Therefore, it is otherwise known as semipermeable membrane or selectively permeable membrane. Some authors refers it also as unit membrane, and regard that lipo-protein composition is a characteristic of all the cell membranes.
             
                The various components of the  cytoplasm distributed over  the hyaloplasm are mainly vacuoles,organelles, and other living and non-living substances.

Vacuoles

               Vacuoles are the greatly expanded cavities inside the cytoplasm, filled with watery fluid or the sap. In matured cells two or three vacuoles may be present, and their size increase with the increase of the size and age of the cell. In meristematic cells the vacuoles are minute or even absent. Each vacuole is bounded by a plasmamembrane, known as  tonoplasm or tonoplast.
                                                                                           

 Organelles or Subcellular particles

                Organelles are the living bodies of different structures having some definite functions, and found suspended inside the cytoplasm. The chief organelles present inside the plant celles are plastids, mitochondria, endoplasmic reticulum, ribosomes, golgi bodies, lysosomes, spherosomes and centrosomes.
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