Chromaffin Cells in the Adrenal Medulla of the Mouse: A Morphological Study of their Innervation

Faraj Bustami, Salim Khraisha


Objective: To study the synaptic nerve endings on the adrenaline(A), noradrenaline(NA) and small
granular Chromaffin (SGC) cells of the mouse before and after puberty and the possible functional
relationship between these cells.
Methods: Male albino mice bred at the animal house-Jordan University, which aged 5, 10 & 12 days
and 5 weeks were used. After sacrifice, the adrenal glands were removed from the animals and
processed for examination with a Philips 300 electron microscope.
The percentage of SGC cells and the number of synaptic endings on A and NA cells were calculated.
Results: All the nerve endings observed are typical in appearance with the cholinergic-type synaptic
endings. No evidence of an adrenergic innervation of Chromaffin tissue of the adrenal medulla has been
obtained during the present work, though the elongated processes of small granular Chromaffin cell
could readily be misinterpreted as adrenergic nerve fibres.
The processes of these cells come close to other Chromaffin cells, both A, NA cell and form synapses.
Frequent exocytotic figures related to these cells were observed.
Conclusion: The present findings suggest that the SGS cells form an intrinsic system that regulates the
activity of other chromaffin cells, particularly in the early postnatal period when the extrinsic
innervation of the chromaffin cells is not yet fully developed.


Chromaffin cells, synaptic nerve endings, exocytosis.

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