General Plan of Histological Structure
When studying histological slides, it is important to understand the general structural plan. Usually (though not always), the mucous membrane consists of three consecutive layers commonly referred to as lamina:
- Epithelium. This is the most superficial cellular layer. It always rests on the basement membrane and directly borders the lumen of the organ.
- Lamina propria (lamina propria). Located immediately beneath the epithelium, serving as its support.
- Muscularis mucosae (lamina muscularis). A specialized layer consisting of smooth myocytes. The main function of this structure is to serve as a boundary separating the mucosa itself from the underlying submucosa.
Features of the lingual mucosa
The histological picture of the lingual mucosa perfectly demonstrates how tissues adapt to different conditions. The differences are especially clear when comparing its surfaces.
- Inferior surface of the tongue. The relief in this zone is completely smooth, with papillae entirely absent. The surface is covered by stratified non-keratinized squamous epithelium. An important histological feature: the lamina propria (lamina propria) transitions smoothly into the submucosa without sharp boundaries. The submucosa itself is very well developed here, contains large blood vessels, and provides slight mobility of the mucosa relative to the muscles. Notably, unlike other regions, salivary glands are absent in the submucosa of the inferior surface of the tongue—they are hidden deeper within the thickness of the tongue muscles.
- Lateral surface of the tongue. Here, the relief becomes more complex due to the appearance of foliate papillae (papillae foliatae), which are separated by narrow clefts. The epithelium remains stratified non-keratinized squamous, but acquires a new function: numerous taste buds are present within its thickness on the lateral surfaces of the papillae.
Ureter wall in cross-section
When analyzing a histological slide of the ureter in cross-section, the logic of the answer must always proceed strictly from the lumen to the periphery.
The first thing to note is the lumen of the organ. It has a characteristic stellate (or tortuous) appearance. This shape is due to the presence of deep longitudinal folds of the mucosa.
The layers of the ureter wall from center to outside are arranged in the following order:
- Mucous membrane (mucosa). Lined with transitional epithelium (urothelium) facing the lumen. Directly beneath the epithelium lies the lamina propria (lamina propria).
- Submucosa (tela submucosa). Located beneath the lamina propria of the mucosa.
- Muscular layer (tunica muscularis).
- Adventitia. This is the outermost layer of the wall, although it may not fall into the field of view on a specific educational slide.
Epithelium of villi and crypts
In some organs, the mucous membrane forms a specific relief to perform its functions. For example, the epithelium may not just line a flat surface, but cover protruding structures—villi—while simultaneously lining depressions—crypts.
The type of covering tissue in such areas is strictly defined: it is simple columnar brush-border epithelium. This structure multiply increases the area of contact with the lumen of the organ.
For quick memorization of the classical layers of the mucosa, use the "E-L-M" rule: Epithelium (at the luminal border), Lamina propria (support), Muscularis mucosae (boundary with the submucosa).
Class and exam questions
Does the mucous membrane always consist of three lamina?
No, the presence of three lamina is a common, but not the only, variant. For instance, on the inferior surface of the tongue, the lamina propria transitions into the submucosa without sharp boundaries.
Where are the glands located on the inferior surface of the tongue?
Unlike other regions, glands are absent in the submucosa of the inferior surface of the tongue. They are located deeper—directly within the thickness of the tongue muscles.
Why does the lumen of the ureter look stellate in cross-section?
The stellate or tortuous appearance of the lumen is due to the presence of deep longitudinal folds of the mucous membrane.
Where exactly are taste buds localized on the lateral surface of the tongue?
Taste buds are present within the thickness of the stratified non-keratinized squamous epithelium on the lateral surfaces of foliate papillae.
What else to study on this topic
- Histological structure of foliate papillae (papillae foliatae)
- Structural features of transitional epithelium (urothelium)
- Morphology of villi and crypts of the mucous membrane
- The role of the submucosa (tela submucosa) in the wall of organs
- Blood vessels of the submucosa of the inferior surface of the tongue
Master the entire topic in the "Histology" course
This is a summary. The course covers everything tested in classes and exams.
- Complete study guide on "Structure of the Mucous Membrane" and 3,485 more pages of the subject
- Assignments and quizzes after every topic — just like in a colloquium
- AI tutor answers questions on the topic anytime
- 137 video lessons on the subject
Other topics in the section "Digestive system: oral cavity, pharynx, and esophagus"
Free video lessons: histologyShort lessons with study notes — no registration required.
Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.