A positive control is included in each kit for
the purpose of checking the effectiveness of the
FUNGUS (PL. FUNGI)
Fungi are heterotrophic, chlorophyll-free,
thallophyllic organisms. They reproduce by
spores, which germinate into long filaments called
hyphae. As the hyphae continue to grow and
branch, they develop into a mat of growth
called the mycelium (pl. mycelia). From the
mycelium, spores are produced in characteristic
arrangements. These spores, when dispersed to
new substances, germinate and form new growths.
Reproduction is often asexual, usually by
budding, as in yeast, but certain fungi have
Common superficial infections of the skin
caused by fungi are athletes foot and ringworm
of the scalp.
POTASSIUM HYDROXIDE (KOH)
IDENTIFICATION OF FUNGI
Fungi are seen in clustered round buds with
thick walls accompanied by fragments of mycelia.
Scrapings from the affected area of the skin are
mounted in 10 percent KOH for positive labora-
Demonstration of the fungi in infected tissue
can be accomplished by the following method:
1. Place skin, hair, or nail scrapings from the
affected area on a slide and add a drop of
10 percent KOH. Dissolve 10 g of KOH in 100 ml
of distilled water.
2. Place a coverslip on the preparation.
3. Warm the preparation gently over a flame,
being careful not to boil it, and allow it to
stand until clear. Do not allow the preparation
to dry out.
4. Read preparation, using a high-power
objective with subdued light.
a. Fungi in the skin and nails appear
as refractive fragments of hyphae.
b. In the hair, fungi appear as dense
clouds around the hair stub or as linear
rows inside the hair shaft.
Blood transfusion, the term used for the
process of transferring blood from one person to
another, is often a lifesaving remedy, especially
in cases of severe hemorrhage, anemia, and
In 1900 Landsteiner discovered the first blood
group system that initially comprised groups A,
B, and O. Later the AB system was added.
The work showing that blood can be classified
into these four groups was done by random cross
matching of the bloods of a large number of
people. Two specific antigens (also called
agglutinogens) were found on the red cells.
These were called A and B. One group of red cells
contained no A or B antigen and was called O.
A fourth group contained both A and B antigens
and was called AB. Antibodies (agglutinins) were
found in the serum of blood. These were called
anti-A and anti-B antibodies. A person of group
A blood (A antigen) has anti-B antibodies
(agglutinins) in the serum. A group B individual
has anti-A antibodies; a group O individual
has both anti-A and anti-B antibodies; and
group AB individuals have neither antibody in
the serum. With the exception of certain patients
with autoimmune diseases, individuals do
not have antibodies against their own blood
Landsteiners rule states that when an antigen
is on a red blood cell, the corresponding antibody
is never present simultaneously. Instead, the
reciprocal red cell antigen is present in the plasma
or serum. For example, if an individual has blood
cells of group A, anti-B antibodies are always
present in the serum but never anti-A.
Blood grouping is accomplished by comparing
the effects of agglutination by the antibodies
on the corresponding antigens within the red
To determine the group to which blood
belongs, it is necessary to mix separately a
suspension of its red cells with serum of a known
group A and a group B that contains agglutinin
B and agglutinin A, respectively. The resulting
agglutination or absence of agglutination
determines the group to which it belongs and is
a necessary procedure with the blood of both the
donor and the recipient. Only compatible blood
is selected for transfusion. One of the four