Final answer:
The mucosa layer's lamina propria, part of the alimentary canal, contains lymphocytes that protect against disease by defending against pathogens in the digestive tract.
Step-by-step explanation:
The layer of the alimentary canal tissue capable of helping to protect the body against disease is the mucosa, specifically the component known as the lamina propria. Among its many functions, the lamina propria contains numerous clusters of lymphocytes, which are part of the mucosa-associated lymphoid tissue (MALT). These lymphocytes serve as a critical component of the immune system, actively defending the body against pathogens introduced through the alimentary canal. The lamina propria's lymphocytes are especially concentrated in areas known as Peyer's patches, found substantially in the distal ileum. The presence of these immune cells in the lamina propria highlights the immune system's adaptation to threats encountered along the alimentary tract, allowing for the defense against foodborne bacteria and other foreign matter.