An Ultrastructural Study of Pulmonary Bronchiolar and Alveolar Epithelium in Sheep

Abstract

Summary The cellular population lining the bronchiolar and alveolar epithelium of the lower respiratory tract of three clinically healthy, purebred Suffolk lambs of both sexes and 3–4 months old was studied using a transmission‐electron microscope. The epithelium of primary and secondary bronchioles consisted of four cell types: basal cells, intermediate cells, ciliated cells, and non‐ciliated (Clara) cells, whereas the epithelium of terminal and respiratory bronchioles consisted of only two kind of cells: ciliated and Clara cells. The alveolar wall, including alveolar ducts and saccules, was covered by type I and type II pneumocytes. In addition, the presence of pulmonary intravascular macrophages was a constant in most of the alveolar capillaries. The morphologic characteristics of all these cells are described in detail and discussed.

Morphometric analysis of the immunohistochemical expression of Clara cell 10-kDa protein and surfactant apoproteins A and B in the developing bronchi and bronchioles of human fetuses and neonates

“…In addition, CC10-positive cells were mainly located in the terminal bronchioles and it might therefore be assumed that the bronchiolar Clara cells may possibly be stem cells of the peripheral conducting airway. The previous in vivo and in vitro studies showed that Clara cells possess not only self-renewal activity but also a capability of differentiation to ciliated cells [8,9,17]. Together with these findings, the increase in the number of CC10-positive cells in bronchi and bronchioles thus supports the correlation of functional maturation with the structural development in the peripheral lung tissue.…”

A novel segmental challenge model for bleomycin-induced pulmonary fibrosis in sheep

“…One important difference is that alveoli size and matrix components of alveoli walls are considerably larger in sheep and humans compared to mice [26,[34][35][36][37]. It is thought that the lungs of larger species require additional interstitial matrix to provide structural support for a larger lung mass [35,38,39].…”

Enhanced Surfactant Protein and Defensin mRNA Levels and Reduced Viral Replication during Parainfluenza Virus Type 3 Pneumonia in Neonatal Lambs

“…Ovine PI-3 virus is a member of the family Paramyxoviridae and is similar to human PI-3 virus in antigenic epitopes, epidemiology, and disease pathogenesis (15,16,36). PI-3 virus infection results in consistent lesions, and the pathogenesis and lesions (bronchiolar epithelial cell necrosis, inflammatory cell infiltrate, and epithelial cell proliferation) in sheep are similar to PI-3 virus infection in humans (7,15,23). Furthermore, human neonates have elevated risk for severe PI-3 virus infection (23), and similarly, neonatal sheep infected with PI-3 virus exhibit more severe lesions than older sheep (15, 36; B. Grubor and M. R. Ackermann, unpublished data).…”