Distribution of tracheal and laryngeal mucous glands in some rodents and the rabbit

Abstract

We used scanning electron microscopy to count the number of mucous gland openings in the tracheae and lower portion of the larynges of the rat, guinea pig, hamster, mouse and rabbit. Cells of the airway surface epithelium were removed by protease digestion better to visualise the gland openings. The distribution of glands was further studied by conventional histology and by PAS\Alcian blue staining of whole mounts. In all rodent species, gland openings in the larynx occurred with a frequency of 1-2 per mm#. Mice had no gland openings in their tracheae, and hamsters, only a handful. Rat tracheae contained 126p42 gland openings (p..; n l 6) at a frequency of " 0n6 per mm# at the top of the trachea and " 0n15 per mm# at the bottom. Guinea pig tracheae contained 153p90 gland openings (p..; n l 5), with 54 % being in the top 40 % of the trachea. In both rat and guinea pig, tracheal glands were found in the ventral aspect between the cartilaginous rings, and were absent from the dorsal membranous portion. Gland openings in most species were simple circles of " 50 µm diameter. However, glands in the rat trachea generally opened obliquely into shallow (" 20 µm deep) oval troughs (" 150i75 µm), which had their long axes oriented from head to tail. In the rabbit, there was no evidence of tracheal or laryngeal glands histologically. However, the tracheal and laryngeal surfaces contained numerous pits (" 30 µm diameter) distributed evenly over and between cartilages at a frequency of " 4 per mm#. These may correspond to the ' nests ' of goblet cells described by others.

Microscopic Anatomy of the Lower Respiratory System of the African Giant Pouched Rat (Cricetomys gambianus, Waterhouse 1840)

“…Although the cellular composition of the respiratory epithelium in mammalian airway is basically similar, pronounced differences exist in the distribution pattern of epithelial cell types at the various levels of the airway (Reznik, 1990). These differences have been reported in the regional distribution of tracheal mucous gland in different rodents and other mammals (Goco et al, 1963;Korhonen et al, 1969;Choi et al;Widdicombe et al). In some species, tracheal mucous glands are concentrated between the cartilaginous rings, whereas in others, the glands are evenly distributed over and between the rings (Choi et al).…”

“…Histology of the lower respiratory system in other rodents such as the laboratory rat (Spicer et al, 1982;Choi et al, 2000;Widdicombe et al, 2001), hamster (Kennedy et al, 1978), squirrel (Nakakuki, 1979) and guinea pig (Kliment et al, 1972) have been described in detail. However, such description in the African Giant pouched rat is lacking.…”

Aquaporin-5 Dependent Fluid Secretion in Airway Submucosal Glands

“…There is little information available on the number and distribution of submucosal glands in mice, except for the finding that very few glands are present in trachea below the larynx (22,23). A series of stained plastic sections were analyzed from different regions of the nasopharynx (as defined in Fig.…”

Parasympathetic control of airway submucosal glands: Central reflexes and the airway intrinsic nervous system

“…The distribution of airway glands within airways and across species has been well studied by Widdicombe and his colleagues (Choi, Finkbeiner et al 2000;Widdicombe, Chen et al 2001;Widdicombe and Pecson 2002). A key point to emerge from these studies is that the density of glands per unit area of airway surface is highest in large airways and then declines linearly with airway diameter, essentially disappearing at airway diameters of ≤ 2 mm.…”