Morphometric Evaluation of Tracheal Epithelium Following Elongation within the Physiological Range

• Published in: Transactions of the American Microscopical Society 1994-04, Vol.113 (2), p.190-199
• Main Author: Gatto, Louis A.
• Format: Article
• Language: English
• Subjects: Air breathing; Biological and medical sciences; Cell nucleus; Cell physiology; Epithelial cells; Epithelium; Fundamental and applied biological sciences. Psychology; Intestines; Mucus; Nematodes; Respiratory system: anatomy, metabolism, gas exchange, ventilatory mechanics, respiratory hemodynamics; Secretory cells; Specimens; Trachea; Vertebrates: respiratory system
• ISSN: 0003-0023; 2325-5145
• DOI: 10.2307/3226647

The trachea is a highly elastic organ subject to substantial changes in length under physiological conditions, and its surface epithelium is capable of swift longitudinal accommodations known to alter cell shape throughout the airway. Because the trachea undergoes substantial longitudinal collapse upon excision, morphometric studies of excised tracheas do not reflect conditions in situ. This study quantified for the first time the effects of airway elongation on cell counts made over fixed lengths of epithelium. To this end, counts were made on 60-µm lengths of collapsed tracheas and on 60-µm lengths of tracheas stretched by 50%. A third set of counts was made on 30 µm of collapsed tracheas to determine if changes associated with elongation could be equated to changes caused by a decrease in the number of cells per epithelial length. Comparisons between the stretched and the collapsed showed significant differences in cell concentration, which were greater than shifts in cell populations known to occur with drug stimulation. Also, cell grouping patterns present in the collapsed 60-µm specimens were not discernible in the stretched specimens. I concluded that morphometric evaluations of collapsed airways overestimate cell populations and spatial relationships of essence to mucociliary function. However, stretching of the trachea within the physiological range amounts to a significant reduction in sample size that affects the reliability of cell counts. An optimal morphometric protocol would involve airways maintained at in vivo dimensions and observations based on epithelial lengths averaging at least 15 cells.