Chapter 1: Introduction to Histology
Remember in school biology, you were taught that the basic component of all living things is cells? Groups of cells make-up a tissue. Groups of tissue make-up an organ and groups of organs make-up a system. Histology means study of tissue. There is a more complicated definition as well. Read on.
Tissue consists typically of groups of cells surrounded by their matrix.
I. The Cell
In all chapters, when we describe a cell, we usually focus on certain characteristics of the cell in the light-microscope and in the electron microscope. Through the light micrscope, we focus on the cell’s structure, the nucleus structure and the acidity or basicity stain of the cytoplasm (we have to stain the cell using dye, otherwise it’s colourless).
And through the electron microscope, we discuss the various organelles and granules present which sometimes substantiates the cytoplasm’s stain. More details on stain a bit later.
And finally, we discuss the cell’s function in consideration to the organelles within the cell. In addition, tissues contain different types of cells and not just one type of cell.
II. The Extracellular Matrix
Roughly matrix means complex network of stuff which is composed of liquid and solid molecules mostly made by the cell. The fancy name we give this matrix is extracellular matrix to indicate that the complex network is outside. Furthermore, in the case of connective tissue, the solid protein molecules are generally referred to as fibers and the rest as ground substance.
Extracellular matrix mainly function to provide mechanical support and metabolic transportation medium. Also, the matrix contains the extra-cellular signals (proteoglycans and glycoproteins) which greatly effect the functioning of the cell.
Therefore histology actually is- 1. The study of the structure and contents of different types of cells and their extracellular matrix that make up a tissue, 2. How they function together and 3. What the tissue looks like as whole.
The textbook definition for Histology, and this is what you should memorize (the above will be clearer later on), is the science which studies the microstructures that compose tissues and the relationship between their structure and function in human beings.