[Morphologic studies in swine with anal atresia]

Area of Science:

• Veterinary Pathology
• Developmental Biology
• Anatomy

Context:

• Anorectal malformations (ARM) are congenital defects affecting the terminal portion of the gastrointestinal tract.
• Investigating the histological features of ARM in piglets provides a model for understanding human congenital anomalies.
• Previous research has focused on the incidence and types of ARM, with less emphasis on the detailed muscular anatomy of the malformed structures.

Purpose:

• To histologically examine the anal sphincter muscles in piglets with various types of anorectal malformations.
• To determine the presence, location, and characteristics of the internal and external anal sphincter muscles in relation to anorectal fistulas.
• To compare the histological features of the sphincter muscles in malformed openings with those of a normal anal opening.

Summary:

• A histological investigation was conducted on 33 piglets diagnosed with anorectal malformations (24 males, 9 females).
• High deformities (18 piglets) presented with recto-urethral or recto-vaginal fistulas, while 15 piglets had low deformities.
• Both sphincter internus and sphincter externus muscles were identified in all piglets. The sphincter internus was consistently found surrounding the fistula, which exhibited features of a normal anal opening.

Impact:

• This study elucidates the muscular anatomy associated with anorectal malformations in a porcine model.
• Findings suggest that despite malformations, the anal sphincter complex may retain functional characteristics, offering potential insights for surgical repair.
• Provides a basis for further research into the embryological development and potential therapeutic strategies for anorectal malformations in veterinary and human medicine.