
Overview: epithelium
The small intestine is lined by a simple columnar epithelium, primarily composed of absorptive cells, enterocytes, with microvilli. Scatter goblet cells with their expanded apical portions containing mucinogen are also seen. Also present are lymphocytes, macrophages and microfold or M cells which provide immune surveillance. M cells occur among the enterocytes, but lack microvilli, having instead microfolds of their apical surface that endocytose antigens, transporting them to surveilling lymphoid tissue in the lamina propria beneath them. M cells are antigen delivery cells for initiating mucosal immune responses.

Epithelium
The small intestine is lined by a simple columnar epithelium, primarily composed of enterocytes, which are absorptive cells with microvilli. Scattered goblet cells, with expanded apical portions containing mucinogen, are also present. Wandering lymphocytes and macrophages provide immune surveillance. 1000x

- Enterocytes
The small intestine is lined by a simple columnar epithelium, primarily composed of enterocytes, which are absorptive cells with microvilli. Scattered goblet cells, with expanded apical portions containing mucinogen, are also present. Wandering lymphocytes and macrophages provide immune surveillance. 1000x

- Microvilli
The small intestine is lined by a simple columnar epithelium, primarily composed of enterocytes, which are absorptive cells with microvilli. Scattered goblet cells, with expanded apical portions containing mucinogen, are also present. Wandering lymphocytes and macrophages provide immune surveillance. 1000x

- Goblet cells
The small intestine is lined by a simple columnar epithelium, primarily composed of enterocytes, which are absorptive cells with microvilli. Scattered goblet cells, with expanded apical portions containing mucinogen, are also present. Wandering lymphocytes and macrophages provide immune surveillance. 1000x

Lymphocytes and macrophages
The small intestine is lined by a simple columnar epithelium, primarily composed of enterocytes, which are absorptive cells with microvilli. Scattered goblet cells, with expanded apical portions containing mucinogen, are also present. Wandering lymphocytes and macrophages provide immune surveillance. 1000x

Lamina propria
The small intestine is lined by a simple columnar epithelium, primarily composed of enterocytes, which are absorptive cells with microvilli. Scattered goblet cells, with expanded apical portions containing mucinogen, are also present. Wandering lymphocytes and macrophages provide immune surveillance. 1000x