Splanchnic preganglionic neurons in man. I. Morphometry of preganglionic cytons

Area of Science:

• Neuroscience
• Anatomy
• Physiology

Background:

• The thoracic sympathetic preganglionic outflow is crucial for maintaining normal blood pressure while standing.
• There is a lack of normative data regarding the neuron cell bodies within the intermediolateral column (ILC).

Purpose of the Study:

• To establish normative data for the counts and size distribution of intermediolateral column (ILC) neuron cell bodies in the human thoracic spinal cord.
• To investigate the relationship between ILC neuron cell body counts and age.

Main Methods:

• Human spinal cord segments (T6, T7, T8) from 12 individuals were analyzed within 4-6 hours of death.
• A specialized methodology was used to accurately count neuron cell bodies (cytons) and correct for errors, preventing shrinkage artifacts.
• Cyton counts and size distributions were analyzed across different spinal cord segments and correlated with age and sex.

Main Results:

• Mean ILC cyton counts were approximately 5002 (T6), 5004 (T7), and 4654 (T8).
• No significant differences in cyton counts were observed between sexes.
• A progressive reduction in ILC cytons with age was found, with an estimated loss of 370 cytons (8%) per decade in adults.
• Most cytons ranged from 8-23 micrometers, with peaks at 12-13 and 16 micrometers.

Conclusions:

• The study provides the first normative data on human thoracic ILC neuron cell body counts.
• The age-related decline in ILC cytons suggests a potential morphological basis for the reduced ability to maintain blood pressure in the elderly (postural hypotension).