Lecture 5 & 6
NORMAL HISTOLOGICAL FEATURES OF THE DIFFERENT ORGANS OF THE
RESPIRATORY SYSTEM
General Histological features of the Nasal Cavity
It is divided into an inferior portion (the vestibule), middle portion (the respiratory
region) and the upper portion (the olfactory region). The vestibule is lined by stratified squamous
epithelium, the respiratory portion by pseudo-stratified ciliated columnar epithelium and the
olfactory by special type of epithelial cells which carry the sensation of smell.
Paranasal Sinuses
The epithelium ciliated pseudostatified columnar is containing a few goblet cells. The glands and
blood vessels are present in the propria submucosa .
General Histological features of the Naso-pharynx
In the naso-pharynx lined with pseudo-stratified ciliated columnar epithelium are found. Sub-
epithelial layer of elastic type C.T. may be seen. Sub-mucosa of C.T. may also be distinguished.
Mixed type of glands may be seen in the sub-mucosa. Outside the sub-mucosa are the skeletal
muscles of the pharynx.
General Histological features of the Larynx
The wall of larynx consists of mucosa, sub-mucosa, a series of irregular shaped cartilages
connected by fibro-elastic membranes and a group of intrinsic skeletal muscles. Two types of
epithelia line the walls of the larynx, pseudo-stratified ciliated columnar and stratified squamous.
Outside the epithelium is the lamina propria rich in elastic fibers and lymphocytes. The sub-
mucosa has few C.T. fibers and mixed glands. Most of the cartilages which make the frame-work
of the larynx are of hyaline variety.
General Histological features of the Trachea
The trachea and major bronchi are similar in structure. They consist of a system of “C”- shaped
hyaline cartilages united by fibro-elastic membrane and smooth muscles. They are lined by
mucous membrane.
Mucosa:
It is lined by pseudo-stratified columnar ciliated epithelium resting on a basement membrane.
Goblet cells are also present. The lamina propria consists of elastic fibers, blood vessels, nerves,
lymphatics and lymphocytes.
Sub-Mucosa:
It consists of loose C.T. It contains numerous tubule-alveolar glands of mixed variety and
tracheal glands.
Cartilages:
“C”-shaped hyaline cartilages form the frame work of trachea and bronchi. They are open
posteriorly, the ends joined together by a dense irregular fibrous tissues. This layer is fused with
the perichondrium and contains smooth muscle fibers called trachealis.
Adventitia:
It consists of loose C.T., blood vessels, nerves and few tracheal glands.
ANAT-104 Systematic Veterinary Histology & Embryology Dr. Nisar Ahmed
NORMAL HISTOLOGICAL FEATURES OF THE DIFFERENT ORGANS OF THE
RESPIRATORY SYSTEM
General Histological features of the Nasal Cavity
It is divided into an inferior portion (the vestibule), middle portion (the respiratory
region) and the upper portion (the olfactory region). The vestibule is lined by stratified squamous
epithelium, the respiratory portion by pseudo-stratified ciliated columnar epithelium and the
olfactory by special type of epithelial cells which carry the sensation of smell.
Paranasal Sinuses
The epithelium ciliated pseudostatified columnar is containing a few goblet cells. The glands and
blood vessels are present in the propria submucosa .
General Histological features of the Naso-pharynx
In the naso-pharynx lined with pseudo-stratified ciliated columnar epithelium are found. Sub-
epithelial layer of elastic type C.T. may be seen. Sub-mucosa of C.T. may also be distinguished.
Mixed type of glands may be seen in the sub-mucosa. Outside the sub-mucosa are the skeletal
muscles of the pharynx.
General Histological features of the Larynx
The wall of larynx consists of mucosa, sub-mucosa, a series of irregular shaped cartilages
connected by fibro-elastic membranes and a group of intrinsic skeletal muscles. Two types of
epithelia line the walls of the larynx, pseudo-stratified ciliated columnar and stratified squamous.
Outside the epithelium is the lamina propria rich in elastic fibers and lymphocytes. The sub-
mucosa has few C.T. fibers and mixed glands. Most of the cartilages which make the frame-work
of the larynx are of hyaline variety.
General Histological features of the Trachea
The trachea and major bronchi are similar in structure. They consist of a system of “C”- shaped
hyaline cartilages united by fibro-elastic membrane and smooth muscles. They are lined by
mucous membrane.
Mucosa:
It is lined by pseudo-stratified columnar ciliated epithelium resting on a basement membrane.
Goblet cells are also present. The lamina propria consists of elastic fibers, blood vessels, nerves,
lymphatics and lymphocytes.
Sub-Mucosa:
It consists of loose C.T. It contains numerous tubule-alveolar glands of mixed variety and
tracheal glands.
Cartilages:
“C”-shaped hyaline cartilages form the frame work of trachea and bronchi. They are open
posteriorly, the ends joined together by a dense irregular fibrous tissues. This layer is fused with
the perichondrium and contains smooth muscle fibers called trachealis.
Adventitia:
It consists of loose C.T., blood vessels, nerves and few tracheal glands.
ANAT-104 Systematic Veterinary Histology & Embryology Dr. Nisar Ahmed
