Page 69 - Headlines Histology2024_Neat

Eosinophils

• They account for 1-6 % of the total leucocytic counts. The cell size range
from 12-15 ?m. Eosinophil has a bilobed, less deeply stained nucleus. The
cytoplasm is packed with coarse, large, refractile, eosinophilic granules.

• With EM, the cytoplasm is filled with large, ovoid, specific granules
containing dense crystalloid in the long axis of the granules (dog, cat and
goat). They are membrane-bound and their matrix contains a variety of
hydrolytic enzymes including histaminase. Other cytoplasmic organelles
such as mitochondria, rER and Golgi are relatively sparse.

Functions

• The number of eosinophils in circulating blood increases during
parasitic infestations and allergic conditions.

• Phagocytosis of the antigen-antibody complex.
• Deactivate histamine produced during inflammatory or allergic

response.
Basophils

• They are about 10-12 ?m in diameter. They are the least common cell types
that constitute less than 1% of the total leucocytic count. The nucleus is
bilobed and completely obscured by numerous large deeply basophilic
granules.

• With EM, the bilobed nucleus is clearly visible and the cytoplasm is filled
with membrane-bound electron dense granules.

Functions

• The specific granules of the basophils contain heparin, histamine, other
inactive amines, and slow reacting substance of anaphylacsis (SRS-A). The
contents of the specific granules are released by exocytosis in response to
interaction of antigen with antibodies attached to the basophil cell
membrane.

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