Page 48 - Anatomy and Physiology of Farm Animals, 8th Edition

Anatomy and Physiology of the Cell / 33

Chromosomes and DNA
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Centrioles

Secretory
granule Golgi
apparatus
Microtubules

Nuclear
envelope Cell
membrane
Nucleolus
Glycogen

Ribosomes
Lysosome

Mitochondrion Granular Smooth Micro laments
endoplasmic (agranular)
reticulum endoplasmic
reticulum
Figure 2-7. The general organization of a cell. Source: adapted from Guyton and Hall, 2006. Reproduced
with permission from Elsevier.

metals concentrate inhibit the passage of nucleolus and chromatin material,
electrons, giving an electron‐dense appear­ which forms into chromosomes during
ance that shows up as a dark area in the cell division. A membrane called the
final photographic print. After fixation, the nuclear envelope surrounds the nucleus.
tissue is dehydrated and infiltrated with The cytoplasm contains a number of
plastic and embedded in plastic for section­ structures, or organelles, including the
ing. The sections are cut extremely thin endoplasmic reticulum, Golgi apparatus,
(less than 30 nm), placed on a grid, and mitochondria, and inclusions.
examined with the electron microscope.
The picture of the typical cell (Fig. 2‐7)
viewed with the electron microscope (see The Cell Membrane
Fig. 1‐2) still shows most of the structures
described by light microscopy but in Structure of the Membrane
much greater detail. The typical cell
seen in light microscopy consists of a The outer cell membrane, also known
nucleus and cytoplasm surrounded by the as plasma membrane, and other mem­
cell membrane. The nucleus contains a branes within the cell primarily consist of