Chronomorphology of the duodenum in man

Area of Science:

• Gastroenterology
• Chronobiology
• Human Physiology

Background:

• The gastrointestinal tract exhibits complex physiological processes.
• Understanding diurnal variations in the small intestine is crucial for human health.
• Previous research suggests varying degrees of circadian influence across species.

Purpose of the Study:

• To investigate circadian rhythmicity in human duodenal morphological structures.
• To identify specific duodenal components that display significant 24-hour variations.
• To compare the distinctness of human duodenal circadian rhythms with those observed in animal models.

Main Methods:

• Morphological analysis of human duodenal tissue samples collected over a 24-hour period.
• Measurement of intestinal villi height, microvilli dimensions, and glycocalyx thickness.
• Assessment of mitotic activity and Paneth cell granularity at different time points.
• Statistical analysis to determine the significance of observed diurnal changes (p<0.05).

Main Results:

• Intestinal villi height significantly varied, being greater during the day than at night.
• The proportion of small and medium-sized villi changed significantly between day and night (p<0.05).
• Mitotic activity peaked at 02:00 and 06:00, with the lowest activity at 10:00 and 14:00 (p<0.01).
• Glycocalyx thickness was slightly higher during the day compared to the night.
• No significant circadian changes were observed in microvilli dimensions or Paneth cell granularity.

Conclusions:

• Circadian rhythmicity in human duodenal morphology is less pronounced than in animals.
• Significant diurnal variations exist in specific duodenal parameters, including villi height and mitotic activity.
• These findings highlight a subtle but measurable influence of the circadian clock on the human small intestine.