Abstract
Introduction Efficient intestinal peristalsis is a function of intact enteric nervous system,
muscle, and connective muscularis propria tissue. Malfunction of any component results
in impaired peristalsis. Hirschsprung disease (HD) as prototypic enteric neural migration
disorder is increasingly well characterized. More recently, intestinal myopathies
and particularly defects of myenteric collagenization have entered the focus of attention.
However, detailed development of muscularis propria connective tissue is not well
known. The aim of this study was to morphologically characterize intestinal connective
tissue in fetal and postnatal development and intestinal pseudo-obstruction.
Materials and Methods In this study, 130 archival specimens of fetal autopsies, intestinal resections,
and biopsies were analyzed. Patients' age was 10th gestational week (gw) to 70 years.
Muscularis mucosae, muscle layers, collagen tissue, and enteric plexus were analyzed.
Picrosirius red stains, enzyme histochemistry, and immunohistochemistry for collagens
I, III, and IV were performed.
Results Total 89 normal intestinal specimens were from fetal autopsies or intestinal resections;
41 patients showed a primary structural colon wall defect (HD, desmosis). Our results
showed a constant increase in tunica muscularis propria thickness with age. Separation
into circular and longitudinal muscle layer first occurred in the 11th gw. A tendinous
collagen plexus layer first arose in the 10th gw and showed a steady caliber increase.
Muscularis mucosae first appeared in the 10th gw and grew independent of any primary
gastrointestinal disease. In the 11th gw, enteric ganglia were fully developed. In
desmosis, a collagen plexus layer was absent. In contrast, in HD, muscularis mucosae
showed hypertrophy, but the collagen plexus layer was intact in the aganglionic segment.
In intestinal neuronal dysplasia and hypoganglionosis, nerve cell development was
disturbed; connective tissue and muscle layers were well developed.
Conclusion Our comprehensive study of intestinal connective tissue development in comparison
to neural intestinal wall components in normal and pathological conditions showed
that tendinous tissue develops parallel to muscularis propria and arises early in
embryogenesis. In enteric nervous system disorders, ganglionic lesions develop independently
of impaired collagen network, whereas mucosal biopsies serve for diagnosis of HD,
seromuscular biopsies are required to prove desmosis in gastrointestinal dysmotility
disorders.
Keywords
intestinal pseudo-obstruction - Hirschsprung disease - desmosis - connective tissue
- enteric nervous system
