Gross and histologic changes in the developing rabbit subglottis in response to a controlled depth of injury.

Objective: Our goal was to determine the effects of both perichondrial and intracartilaginous injury in the developing rabbit subglottis versus normal development.

Design: We conducted a descriptive, pilot study of changes in the shape and histology of the subglottis after a controlled depth of injury in 27 New Zealand White rabbits, ages 4 weeks, 8 weeks, and 1(1/2) years.

Intervention: Within each age group, 3 animals underwent no surgery, 3 underwent perichondrial injury, and 3 underwent intracartilaginous injury.

Results: Perichondrially injured animals in the 4-week age group developed a marked abnormality in the shape of the cricoid cartilage in the injured region. Cartilage of the perichondriallly injured animals in the 8-week and 1(1/2)-year groups became histologically consistent with fibrous tissue. The cartilage of all animals that underwent intracartilaginous injury was replaced with fibrous tissue.

Conclusion: In this observational study, we identified 3 relevant findings. First, the responses of the cartilage to a perichondrial injury suggest that the luminal soft tissues may exert some morphologic control in developmentally young animals. Second, only the 4-week-old group's cartilage was tolerant of a perichondrial injury with continued growth of the ring. Third, no animal's cartilage could withstand an intracartilaginous injury regardless of age.