THE GOLGI APPARATUS
The Golgi apparatus, as seen under digital compound microscopes, consists of a system of membrane-bound vesicles arranged ap¬proximately parallel to each other. The smooth membranes of the Golgi apparatus often have connections (probably transient) with the membranes of the endoplasmic reticulum and therefore constitute another portion of the complex cellular mem¬brane system.

The cell membrane, as seen under digital compound microscopes, is more than an envelope that gives mechanical strength and shape and some protection to the cell. It is also an active component of the living cell, preventing some substances from enter¬ing it and others from leaking out. It regulates the traffic in materials between the […]

Long, hollow, cylindrical structures, the microtubules, as seen under digital compound microscopes, seem to play a role in intracellular movement and support, like the microfil¬aments. Though not recognized as tubules at the time, they were probably first seen in the spindle of dividing cells. (The spindle, a basketlike arrangement of tubules formed during the process […]

Animal cell coats
In plants, fungi, and bacteria, the cell wall is en¬tirely separate from the plasma membrane, as seen under digital compound microscopes. If the cell shrinks in a hypertonic medium, the membrane separates from the much more rigid wall. By contrast, the cell coat of an animal cell is not an independent entity. The […]

Despite the widespread, almost routine, acceptance of the idea that cells are bounded by a plasma membrane, direct proof of its existence using digital compound microscopes has been obtained only in the last three decades. Most of the earlier conceptions of the membrane had to be deduced from other charac¬teristics of the cells themselves, for […]

MICROBODIES
A variety of organelles similar to lysosomes in structure and appear¬ance, as seen under digital compound microscopes, but containing enzymes of other kinds, have been reported in recent years in one or another group of organisms. Some plant cells, for example, especially in seeds with large fat reserves, possess organ¬elles called glyoxysomes that contain enzymes […]

Biologists have long known that plant cells and the cells of fungi and most bacteria have strong, thick walls containing much carbohydrate. But only in recent years have they come to realize that most animal cells, too, have a carbohydrate coat on the outer surface of their plasma membranes, and that this coat plays an […]