Comparative Histological Study of Different Age – Related Changes in the Respiratory System in Sprague-Dawley Rats

The purpose of this study was to compare the gross histological characteristics of the trachea and lung between rats thirty postnatal and adults, as well as to define the developmental organization of these organs. Thirty healthy rats were divided into two sets of rats, each consisting of fifteen adults and fifteen 15 day old rats. Gross research; describe how the trachea and lungs develop; measure the trachea's length and diameter at various rat ages. Specimens from various tracheal and lung regions were used for histological investigations. They were fixed in 10% formaldehyde, embedded in paraffin wax, sectioned, and stained with Masson's Trichrome, routine stain, and AB. At 15 days of age, the trachea measured (1.820 ±0.013 a) cm in length and (0.11 ±0.008 a) cm in diameter while the adults rat was (3.9±0.08 a) and diameter (0.610±0.006 a), the number of ring of trachea in the 15 day postnatal was (18±0.30a) while the adult was (24± 0.34a)

The results of the statistical study also showed that the trachea's weight and length varied considerably (P>0.05) in the 15-day postnatal period. The findings showed that a 15-day-old postnatal's trachea was lined with pseudostratified columnar non-ciliated epithelium that included developing mucous glands, lamina propria, and loose connective tissue in the submucosa.

An adult rat's lamina propria is composed of robust connective tissue and is surrounded by ciliated pseudostratified columnar epithelium that contains seromucous glands. The adventitia inside the lacunae is composed of loose connective tissue with many elastic fibers, whereas the hyaline cartilage is composed of chondrocytes. Masson's Trichrome makes this observation.