Under The Light Microscopic View

Identifying structures on a histology slide of the ileum involves examining various layers and components of the tissue. The ileum is the final part of the small intestine, and its histology reflects its role in nutrient absorption. Here is a detailed description of key structures you might observe on an ileum histology slide:

Mucosa:
- Villi: Look for finger-like projections extending into the lumen. Villi increase the surface area for nutrient absorption.
- Microvilli: These are tiny projections on the surface of epithelial cells, forming the brush border. They further increase the absorptive surface.
Epithelium:
- Simple Columnar Epithelium: The lining of the mucosa consists of a single layer of columnar cells. These cells are absorptive and play a crucial role in nutrient absorption.
Lamina Propria:
- Blood Vessels: Observe the presence of capillaries in the lamina propria. These vessels are involved in the absorption of nutrients.
- Goblet Cells: Look for mucus-secreting goblet cells scattered among the absorptive cells.
Submucosa:
- Meissner's Plexus: This is a submucosal nerve plexus that regulates glandular secretion and the smooth muscle of the mucosa.
Muscularis Externa:
- Circular and Longitudinal Muscle Layers: Identify the two layers of smooth muscle responsible for peristalsis.
- Myenteric Plexus (Auerbach's Plexus): Located between the muscle layers, this plexus controls the contractions of the muscularis externa.
Serosa:
- Connective Tissue: Observe the outermost layer, which is composed of connective tissue and is continuous with the mesentery.
Blood Supply:
- Blood vessels: Note the presence of arteries and veins throughout the tissue. These vessels are essential for nutrient transport and waste removal.
Peyer's Patches:
- Lymphoid Aggregates: Look for clusters of lymphoid tissue in the submucosa. These are Peyer's patches, which are part of the gut-associated lymphoid tissue (GALT) and play a role in immune defense.
Crypts of Lieberkühn:
- Invaginations: Observe the tubular structures extending from the mucosal surface into the lamina propria. These are the crypts and house stem cells for epithelial cell renewal.
Paneth Cells:
- Located at the base of the crypts: These cells secrete antimicrobial peptides and play a role in the immune defense of the small intestine.

When analyzing an ileum histology slide, pay attention to the organization and interaction of these structures, as they collectively contribute to the digestive and absorptive functions of the small intestine.

Histology slide image of the ileum, showcasing labeled areas for unique structures like Peyer’s patches, shorter villi, goblet cells, and the distinct tissue layers.

Ileum (Small Intestine) Overview

Anatomy:
The ileum is the final section of the small intestine, connecting to the large intestine at the ileocecal valve. Histologically, it has layers similar to the rest of the small intestine: mucosa, submucosa, muscularis externa, and serosa. The ileum is characterized by shorter villi and abundant Peyer's patches (lymphoid nodules) in the submucosa, which help in immune response.

Physiology:
The primary role of the ileum is to absorb vitamin B12, bile salts, and any remaining nutrients that were not absorbed in earlier parts of the intestine. The presence of villi and microvilli aids in nutrient absorption, while Peyer’s patches provide immune protection against pathogens.

Histopathology:
On histological slides, the ileum shows relatively shorter villi, many goblet cells, and Peyer’s patches in the submucosa. Inflammatory or degenerative changes, such as villous atrophy, increased immune cells, or disruption of Peyer’s patches, can indicate diseases like Crohn’s disease, infections, or autoimmune conditions affecting the small intestine.

Clinical Significance:
The ileum is essential for absorbing nutrients and vitamins critical for health, and its disruption can lead to malabsorption syndromes, weight loss, anemia, and diarrhea. Pathological changes in the ileum are often associated with Crohn's disease, celiac disease, and infections. Histological examination of the ileum helps diagnose these and other disorders, assisting in appropriate treatment and management.