00:00 / 00:00
Organ system histology
Arteriole, venule and capillary histology
Artery and vein histology
Cardiac muscle histology
Adrenal gland histology
Pituitary gland histology
Thyroid and parathyroid gland histology
Eye and ear histology
Nasal cavity and larynx histology
Small intestine histology
Lymph node histology
Skeletal muscle histology
Central nervous system histology
Peripheral nervous system histology
Ureter, bladder and urethra histology
Cervix and vagina histology
Fallopian tube and uterus histology
Mammary gland histology
Prostate gland histology
Testis, ductus deferens, and seminal vesicle histology
Bronchioles and alveoli histology
Trachea and bronchi histology
0 / 1 complete
The gastrointestinal or GI tract extends as a single tube from the esophagus all the way to the distal portion of the anal canal.
Although different parts of the tract may appear to have very different structures and functions, the wall still maintains 4 main layers all throughout the GI tract: the mucosa, submucosa, muscularis propria, and either an outer serosa or adventitia.
Even in this low power cross-section of the esophagus, we can see the inner mucosa, submucosa, and muscularis propria, although the outer adventitia isn’t present in this image.
All 4 layers have variations to their structure and function in different regions of the GI tract, but the mucosa is the layer that typically has the most significant changes.
The mucosa of the esophagus consists of 3 main layers.
At 20x magnification, we can see each of the layers more clearly.
The epithelium, lamina propria, and muscularis mucosa.
The thick epithelial layer lines the lumen of the esophagus and consists of stratified squamous non-keratinized cells, which has their typical appearance of flat, overlapping cells that are more flat as they move away from the base or basal cell layer.
The lamina propria is a much thinner layer of dense irregular connective tissue.
It provides a supporting function to the epithelium, such as the blood vessels within the connective tissue that supply blood to the epithelium.
The muscularis mucosa is the outermost layer of the mucosa and is comprised of smooth muscle.
The muscle fibers in this image have a circular or dot-like appearance because the fibers run longitudinally or in the same direction as the esophagus.
The lower esophageal sphincter or LES for short is actually not an anatomical sphincter, which means histologically, there is no well-defined thickening or muscle that controls the LES.
Instead, the LES is considered a physiological or functional sphincter.
But when this sphincter isn’t functioning properly, it can lead to gastric acid reflux into the lower esophagus, which can cause heartburn.
Also, over time, prolonged exposure to gastric acid can cause damage to the epithelium of the esophagus.
The esophagus is a muscular tube that carries food and liquids from the pharynx to the stomach. It has four layers of tissue, which are the mucosa, the submucosa, the muscularis propria, and either the serosa or adventitia.
The mucosa is a thin layer of cells that line the inside of the esophagus, and has glands that secrete mucus that protect the lining of the esophagus and keeps it moist. Beneath lies the submucosa that consists of connective tissue that supports the mucosa, and contains blood vessels, lymphatic vessels, and nerve endings. Next, lies the muscularis propria consisting of smooth muscle tissue that contracts to move food and liquids through the esophagus. Finally, comes the adventitia, which is the outer layer of the esophagus, which takes the name of serosa in the abdominal cavity after it's covered by the visceral peritoneum.
Latest on COVID-19
Nurse Practitioner (NP)
Physician Assistant (PA)
Create custom content
Raise the Line Podcast
Copyright © 2024 Elsevier, its licensors, and contributors. All rights are reserved, including those for text and data mining, AI training, and similar technologies.
Cookies are used by this site.
Terms and Conditions
USMLE® is a joint program of the Federation of State Medical Boards (FSMB) and the National Board of Medical Examiners (NBME). COMLEX-USA® is a registered trademark of The National Board of Osteopathic Medical Examiners, Inc. NCLEX-RN® is a registered trademark of the National Council of State Boards of Nursing, Inc. Test names and other trademarks are the property of the respective trademark holders. None of the trademark holders are endorsed by nor affiliated with Osmosis or this website.