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Although single large vacuoles are most common, the size and number of vacuoles may vary in different tissues and stages of development. For example, developing cells in the meristems contain small provacuoles and cells of the vascular cambium have many small vacuoles in the winter and one large one in the summer.
The spongiome serves several functions in water transport into the contractile vacuole and in localization and docking of the contractile vacuole within the cell. Paramecium and Amoeba possess large contractile vacuoles (average diameter of 13 and 45 μm, respectively), which are relatively comfortable to isolate, manipulate and assay.
These vacuoles are what account for the size that scientists had previously thought impossible, and account for roughly 98% of the cell volume. [32] Because of the vast size of the liquid central vacuole, the cytoplasm separating the vacuole and the cell membrane is a very thin layer reported to be around 0.5-2 micrometers thick.
Pigments that color the cell are sometime located in the cell sap. Vacuoles can also increase the size of the cell, which elongates as water is added, and they control the turgor pressure (the osmotic pressure that keeps the cell wall from caving in). Like lysosomes of animal cells, vacuoles have an acidic pH and contain hydrolytic enzymes.
The entire cell contains several cytoplasmic domains, with each domain having a nucleus and a few chloroplasts. [5] Cytoplasmic domains are interconnected by cytoplasmic "bridges" that are supported by microtubules. [5] The peripheral cytoplasm (whose membrane is overlaid by the cell wall) is only about 40 nm thick. [5]
Diagram of an animal cell with only the vacuole labelled: Date: 15 April 2009: Source: File:Biological_cell.svg: Author: MesserWoland and Szczepan1990 modified by smartse: Permission (Reusing this file) Own work, copyleft: Multi-license with GFDL and Creative Commons CC-BY-SA-2.5 and older versions (2.0 and 1.0) Other versions: File:Biological ...
The cytoplasm of the centric diatom is located along the inner surface of the shell and provides a hollow lining around the large vacuole located in the center of the cell. This large, central vacuole is filled by a fluid known as "cell sap" which is similar to seawater but varies with specific ion content.
T. magnifica ' s cell includes a similar vacuole [3] that occupies most of the cell (65–80% by volume) and pushes the cytoplasm to the periphery of the cell (the thickness of cytoplasm varies from 1.8 to 4.8 microns).