Two populations or granular vesicles in constricted post-ganglionic sympathetic nerves

Area of Science:

• Neuroscience
• Cell Biology
• Histology

Background:

• Granular vesicles in nerve axons are crucial for neurotransmission.
• Previous studies have focused on large granular vesicles, with less known about smaller populations.

Purpose of the Study:

• To compare the effects of various fixatives on the ultrastructural appearance of granular vesicles in constricted cat hypogastric nerves.
• To investigate the nature and origin of different granular vesicle populations.

Main Methods:

• Comparative ultrastructural analysis of cat hypogastric nerves.
• Application of different fixatives: osmium tetroxide, glutaraldehyde with post-osmication, and acrolein with sodium dichromate.
• Examination of nerves from both normal and reserpinized cats.

Main Results:

• Osmium tetroxide and glutaraldehyde fixation revealed large granular vesicles (65-90 nm).
• Acrolein and sodium dichromate fixation identified an additional population of small granular vesicles (30-50 nm).
• Reserpine treatment depleted both small and large granular vesicles, with large vesicles significantly reduced.

Conclusions:

• The presence of small granular vesicles may depend on catecholamine content, suggesting a link to noradrenergic axons.
• Alternatively, nerve constriction might induce the formation of these small vesicles.
• Further investigation is needed to elucidate the precise origin and function of small granular vesicles in nerve axons.