Page 70 - Headlines Histology2024_Neat

• Heparin is anticoagulant. Histamine causes dilatation of small blood
vessels and increase capillary permeability leading to exudation of fluid.
SRS-A Cause contraction to the smooth muscle cells.

Agranulocytes

Lymphocytes

• They are the second most common leukocytes in circulating blood. They
account for 20-45% of the total leukocytic counts A round, densely stained
nucleus and a relatively small amount of pale basophilic non-granular
cytoplasm characterize them. According to their size, there are three types:
small (6-8 ?m), medium (8-10 ?m) and large (10-14?m).

• With EM, the nucleus is small spherical and often slightly indented. The
little cytoplasm contains a few mitochondria, a rudimentary Golgi
apparatus, little or no rER and large number of free ribosomes accounting
for the LM basophilia. Azurophilic granules (lysosomes) are also present.

• On the basis of their functional properties, small lymphocytes are classified
into two main groups: T and B-lymphocytes. Their functions will be
considered with the immune system.

Monocytes

• They are the largest members of the white blood cell series that account for 2-
10% of the total leucocytic count. They are highly motile cells and migrate into
connective tissue where they are called histiocytes or tissue fixed
macrophages. The

• Large eccentricity located nucleus is bean or kidney-shaped with less densely
stained chromatin than that of other leukocytes.

• With LM, The cytoplasm is extensive and is filled with azurophilic granules
(lysosomes). It has a frosted-glass appearance.

• With EM, lysosomes are abundant, the Golgi is well developed, rER is diffuse
and mitochondria are abundant than other leukocytes. It is also rich in

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