Page 71 - Headlines Histology2024_Neat

microtubules and microfilaments. Pseudopodia are prominent reflecting their
capacity for ameoboid movement and phagocytosis.
Function
• The principal function of the macrophage is phagocytosis and destruction of
the cellular debris.
• Antigen presentation and antigen processing thus participating in both
humoral and cell-mediated immune response.
III) Blood platelets (thrombocytes)
• They are small, non-nucleated cells formed in the bone marrow by budding

from the cytoplasm of huge cells called megakaryocytes In birds, platelets
are nucleated hence they are called thrombocytes.
• With LM, they are round or oval biconvex discs about 2-3 ?m in diameter.
• The cytoplasm has a purple-stained granular appearance due to its high
contents of organelles. The organelles are concentrated towards the center
of the cell (granulomere). The peripheral cytoplasm (hyalomere) contains
microfilaments and microtubutels arranged underneath the plasmalemma.
It has few organelles and is very poorly stain.
• With EM, the cytoplasm is rich in membrane bound granules of two types:
1) very dense granules are sparse and contain serotonin, ADP, ATP and
calcium. 2) Alpha granules which are more common and contain hydrolytic
enzymes.
Functions
• Blood clot formation.
• Release serotonin that reduces the blood flow by constricting the
damaged vessels.

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