Meconium containing intestinal structures: a histological study using human fetuses

Area of Science:

• Gastroenterology
• Developmental Biology
• Histology

Background:

• Meconium, the first fetal stool, is primarily composed of intestinal epithelial cells, bile, and mucus.
• The precise architectural origins and formation mechanisms of meconium components remain incompletely understood.

Purpose of the Study:

• To investigate the histological architecture of meconium in human fetuses.
• To identify the cellular and tissue origins of meconium structures, including meconium corpuscles and detached mucosal elements.

Main Methods:

• Histological and immunohistochemical analysis of abdominal tissue sections from 40 fetuses (20-31 weeks gestation).
• Microscopic examination of meconium samples to characterize corpuscle and tissue composition.

Main Results:

• Identified distinct "meconium corpuscles" in solid meconium (colon/rectum) composed of atrophied cells and fibrous sheaths.
• Observed loose meconium (stomach, duodenum, colon) containing mucosal folds, villi, and fragmented epithelia.
• Detected chromogranin-positive and cytokeratin-positive cells within meconium, indicating mucosal origin.
• Ring-like structures suggested detachment of entire mucosal layers, potentially via mechanisms beyond simple apoptosis-driven defoliation.

Conclusions:

• Meconium formation involves not only defoliated villi but also the incorporation of intact or detached mucosal elements.
• The presence of large detached mucosal structures points towards specific intrauterine events, such as intussusception, playing a role in meconium composition.