Histogenesis of Muscularis Mucosa and Muscularis Externa of Stomach: A Human Foetal Study.

Introduction: The histological and developmental knowledge of musculature of stomach wall is vital for the assessment and management of various associated congenital abnormalities like hypertrophy of pyloric musculature and pathologies of nerve terminals and ganglia.

Aim: To study the development of muscularis mucosa and muscularis externa in human foetal stomach.

Materials And Methods: The study was conducted on 22 aborted human foetuses of varying gestational ages ranging from 10-26 weeks. The foetuses were procured after obtaining Institutional Ethical Clearance and informed consent of parents of the aborted foetuses. Stomach was dissected and immersed fixed in 10% formalin and then sectioned and stained with Haematoxylin and Eosin and Masson's Trichrome.

Results: The muscularis mucosa appeared as a thin layer of smooth muscle strands at 14 weeks of gestation and later developed as a continuous and well developed layer by 22 weeks. Muscularis externa was composed of only two layers in early gestational ages from 10-15 weeks with predominant circular and discrete outer longitudinal muscle coat. The innermost layer of oblique muscle developed later at 16 weeks of gestation.

Conclusion: The gastric muscularis mucosa and muscularis externa developed and differentiated sequentially in the human foetuses. The musculature in pyloric region of stomach was more developed and thick than the body and fundus of stomach in all foetuses at all gestational ages.