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Original Article

Morphological and behavioural variation in CNS

innate defence cell microglia is development and

age sensitive

Payel Ghosh, Anirban Ghosh
Department of Zoology and Immunobiology Laboratory, Panihati Mahavidyalaya, West Bengal State University, Sodepur, Kolkata
700110, West Bengal, India.
Payal Ghosh is a Junior Research Fellow holding Dr. Anirban Ghosh is working on neuroimmunology
the prestigious UGC-NET fellowship from for last 15 years. Also, he is interested on microglia and
MHRD, Government of India and working with its morpho-functional features, colonization pattern
Dr. Anirban Ghosh for over three 3 years. She is etc. in brain development and maturity, as well as the
involved to find out the colonization and morpho- contribution of microglia in glioma restriction and/
functional pattern of microglia with its cellular or progression. His research is supported by different
adaptability throughout the developmental Government of India funds like UGC, SERB, ICMR &
continuum in rodent model. CSIR and he has considerable publications throughout
the period in the field.

A B S T R AC T
Aim: Microglia, the innate defence cells in central nervous system (CNS), alters their shapes and function with age. We observed
and identified these morphological changes and functional association throughout the developmental gradient until adulthood in rat
brain. Methods: Early and late embryonic stages, neonates and adult brains of albino rats were sectioned for routine Haematoxylin
Eosin (HE) staining and specialized silver-gold staining to show distribution and morphological variation in situ. Isolated microglia
from different age groups was subjected to scanning electron microscopy (SEM) for observing ultrastructural shapes of microglial
cells. The Viability of isolated cells was measured by trypan blue staining and their cellular identity by immuno-staining for CD11b.
Finally, phagocytic limitations of the cells in normally developing brain were assessed by carbon particle ingestion and oxidative
burst through nitroblue tetrazolium assay to investigate microglial age-sensitivity behavioural response. Results: HE staining
spotted overall cellular distribution in the brain and cells with monocytic appearance among the other CNS cells. On contrary,
silver-gold staining showed variable morphologies of microglia in various age groups and also showed the appearance of ramified
microglia in adult. Nearly 90% of isolated cells were viable and positive for CD11b. SEM showed variable shapes of amoeboid
and ramified forms. Immunofluoresence confirms microglial identity. Functionally, microglia showed an age dependent baseline
phagocytic capacity in normal condition which changes with developmental phase and age with most active phagocytic behaviour
around perinatal phase. Conclusion: In normally developing brains, microglia shows variability in morphology and baseline
phagocytic activity that changes with age. These results may represent the normal physiology of CNS development and function.

Key words: Microglia; central nervous system; development; phagocytosis; nitroblue tetrazolium assay

INTRODUCTION are myeloid/monocytic lineage cells and acting as the
sentinel of this delicate organ on behalf of the innate
Among the ectodermal allies in brain there are some immunity of the body. Although there is a consensus
mesodermal aliens spread throughout the tissue. They about the myeloid origin of microglia, much controversy
remains regarding the precise nature of microglial
Corresponding Author: Dr. Anirban Ghosh, Department
of Zoology and Immunobiology Laboratory, Panihati progenitors. Many authors claim that microglial cells
Mahavidyalaya, West Bengal State University, Barasat arise early during development from progenitors in
Road, Sodepur, Kolkata 700110, West Bengal, India. Email:
aghosh06@gmail.com.
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Cite this article as: Ghosh P, Ghosh A. Morphological and behavioural
DOI: variation in CNS innate defence cell microglia is development and age
10.20517/2347-8659.2015.32 sensitive. Neuroimmunol Neuroinflammation 2016;3:38-47.
Received: 25-07-2015; Accepted: 04-11-2015

38 © 2016 Neuroimmunology and Neuroinflammation | Published by OAE Publishing Inc.