Histology
Dr. C.N. Edeh
Introduction to Histology
• Histology is that branch of anatomy that
studies tissues of animals and plants.
• However, we are just going to discuss Human
Histology because we are studying Medicine
which deals specifically with human beings so
we are going to study Human tissues.
• This anatomical study is done with the aid of a
microscope.
Introduction to Histology
• In its broader aspect, the word histology is used
as if it were a synonym for microscopic anatomy,
because its subject matter encompasses not only
the microscopic structure of tissues but also that
of the cell, organs, and organ systems.
• The body is composed of cells, intercellular
matrix, and a fluid substance, extracellular fluid
(tissue fluid), which bathes these components.
Introduction to Histology
• It intertwines the disciplines of cell biology,
biochemistry, physiology, embryology, gross
anatomy, and, as appropriate, pathology.
Introduction to Histology
• The subject of histology no longer merely
deals with the structure of the body; it also
concerns itself with the body's function. In
fact, histology has a direct relationship to
other disciplines and is essential for their
understanding.
Introduction to Histology
• Students will recognize the importance of this
subject as they will notice that later in their
careers. An excellent example of this relationship
will be evident when the reader learns about the
histology of the kidney and realizes it is the
intricate and almost sublime structure of that
organ (down to the molecular level) that is
responsible for the kidney's ability to perform its
function. Alterations of the kidney's structure are
responsible for a great number of life-threatening
conditions.
METHODS OF STUDY IN HISTOLOGY
DR. C.N. EDEH
MICROSCOPY
PREPARATION OF TISSUES
• THE COMMON PROCEDURE IN THE STUDY OF
TISSUE IS THE PREPARATION OF
HISTOLOGICAL SECTIONS OR TISSUE SLIDE
THAT CAN BE STUDIED UNDER THE
MICROSCOPE (LIGHT).
STEPS IN TISSUE PREPARATION
• FIXATION – tissues must be fixed in order to avoid tissue digestion
by cell enzymes(autolysis) and also preserve the structure of the
tissue, it is done immediately after removal from the animal’s body.
It is done by chemicals or less frequently physical methods.
A fixative is a chemical solution that stabilizes or forms cross
linkages. E.g. Formalin (Formaldehyde) , glutaraldehyde in electron
microscope glutaraldehyde plus osmium tetroxide is used to
preserve lipids and proteins.
• EMBEDDING AND SECTIONING- tissues are usually infiltrated with
some solid medium to make it have a rigid consistency facilitating
easy cutting of sections or facilitate sectioning. Embedding
materials include paraffin wax and plastic resins.
• Steps in paraffin embedding include dehydration and clearing.
• STAINING
