Microvascular circulation of the small intestine in horses.

The research reveals the characteristics of the small intestine’s microvascular anatomy in horses, achieved by analyzing results of different microscopy methods and vascular replicas in 14 horses. This study informs understanding of horses’ intestinal blood supply and circulation, contributing to better medical practices in equine health.

Methods and Procedure

• Heparin was used to ensure the blood did not clot in the horses during the process. Once this was complete, the horses were euthanatized.
• A section of the jejunum (part of the small intestine) was severed and flushed of blood using an isotonic sodium chloride (NaCl) solution.
• The team used two different approaches based on the type of results they wished to gather:
  • For six horses, they perfused a radio-opaque medium into the circulatory system to map out the blood vessels radiographically. Histologic methods were used for examining these sections further.
  • The remainder of the horses had their sections infused with two types of plastics to allow for gross or scanning electron microscopy.

Findings

• The research discovered that the marginal arterial arcade feeds into vessels that penetrate the jejunum, either directly or supplying only one side of the mesenteric angle.
• The arteries in the submucosa branched extensively, feeding into various parts of the intestine including the muscular and serous coats, as well as the mucosa.
• Arterial vessels that supply the mucosa penetrated the muscular layer of the mucosa and branched to feed two capillary networks.
• The base of the villus (small, finger-like projection in the small intestine) contained an off-center arteriole that spiraled to the tip, forming a mesh-like capillary network that drained 1 to 3 – but most commonly 2 – venules. These venules gathered from nearby villi and drained through the submucosal veins.

Implications of the Research

This research, although seemingly obscure, is important because understanding the precise anatomical structure and blood vessel organization of the horse’s small intestine can have direct implications for surgical and medical interventions, equine health, and treatment for intestinal diseases or disorders. The study examined different features at both the micro and macro scale, giving a comprehensive view of the intestinal circulatory system. The findings also provide a basis for future research in this area.