The endoplasmic reticulum is a net-like labyrinth of minuscule tubes and flattened sacs that extend from the cytoplasm in individual cells, according to Molecular Biology of the Cell, 4th edition. The ER membrane forms a continuous sheet that encloses a single space within a cell, and this part of a cell usually occupies more than 10 percent of a total cell's volume.Continue Reading
Encyclopaedia Britannica explains the ER creates a series of flattened, tube-like sacs within the cytoplasm. Cytoplasm is a semi-fluid inside the outer cellular membrane that surrounds the nucleus and contains all of a cell's organelles. Scientists believe the ER transports, synthesizes and processes proteins and lipids within cells. The transport system also communicates with the nucleus of a cell regarding protein synthesis.
Biology4Kids.com indicates the size and composition of an individual cell determines the size and shape of the ER. Cells that require a lot of protein, such as liver cells, require larger ER structures. Red blood cells have no such tubular structures whatsoever.
ER structures come in smooth and rough varieties, according to Biolody4Kids.com. The tiny sacs formed by rough ER contain protein molecules transported throughout a cell. Smooth ER structures store lipids and steroids. Cells in the body that contain and release oils have larger smooth ER organelles than cells that do not have oil processing capabilities. Smooth ER structures help detoxify cells and remove dangerous substances, according to Encyclopaedia Britannica.Learn more about Molecular Biology & DNA