Page 42 - Headlines Histology2024_Neat

cell granules that promote the immediate hypersensitivity reaction or
anaphylaxis.
• The granules of the mast cells contain hstamine, heparin, ECF-A
(eosinophil chemotactic factor for anaphylaxis) and serotonin in rat and
mouse. The histamine causes dilatation of small vessels and increases
capillary permeability. The serotonin is a vasoconstrictor. The heparin is
a potent blood anticoagulant.

3) Plasma cells

• Plasma cells are spherical, oval or pear-shaped cells with spherical,
eccentric nucleus.

• The nuclear chromatin is condensed peripherally giving the nucleus a
characteristic “cartwheel” appearance.

• The cytoplasm is strongly basophilic with a prominent negative Golgi
image.

• With EM, the cytoplasm contains a prominent Golgi apparatus, abundant
rER with dilated cisternae contain electron-dense spherical inclusion
known as Russel bodies, free ribosomes and mitochondria.

• They are located in the loose connective tissue specially that of the
digestive, respiratory and female reproductive system. Plasma cells
develop from B-lymphocytes.

Functions

• Production of antibodies.

4) Melanocytes

Melanocytes are derived from neural crest. They are large pigmented cells
with numerous long branching processes.
They occur in epidermis, uterine caruncles of sheep, meninges, choroid and
iris.

42