Mast cells in the pars flaccida of the tympanic membrane. A quantitative morphological and biochemical study in the rat

Abstract

Experientia 39 (1983), Birkh~iuser Verlag, CH-4010 Basel/Switzerland 287 mainly in the terminal position occur in morphologically identical cell types. In the case of intracellular staining of galactose residues we do not know whether the latter represent terminal saccharides or incompletely glycosylated glycoconjugates. The distribution of binding sites for DBA (specific for N-acetyl-galactosamine 2~ and BSA I (specific for D-galactopyranosy121) in gastrointestinal cells showed a lack of correlation between PAS reactivity and lectin binding. While surface epithelium and Brunner's gland cells were mainly positive for DBA, PAS positive neck ceils usually failed to stain with DBA-HRP ( fig.), Antra1 gland cells also gave an irregular staining pattern; nonreacting and reacting cells were seen in the same histological preparation. PAS negative parietal cells were positive with DBA; chief cells were almost negative. In the case of BSA I binding, a similar pattern was found. Goblet cells and columnar striated cells exhibited an irregular staining pattern with the 4 lectins used (see table). Generally, the lectins did not bind only to cells with secretory activity but also to glycosylated nonmucus cell products. The heterogeneous lectin binding in histological preparations of normal mucosa suggests qualitative and quantitative differences in the composition of glycoconjugates. This might be due to different functional states and maturation stages; studies including diseased mucosae are needed.1 This study was supported by the Deutsche Forschungsgemeinschaft (Ku 257/5-2 and Ku 257/6-3) Bonn (FRG).Summary. The present study has shown that the pars flaccida of the tympanic membrane of the rat is extremely rich in mast cells. The findings were compared with those from earlier investigations in the rat; the pars flaccida is one of the tissues in this animal in wich mast cells are most abundant.

Ketotifen induced inhibition of histamine release in a non‐IgE model of middle ear effusion

“…In these diversified experimental approaches, the effusion contained significant levels of histamine, hypothetically derived from mast cells that reside in the pars flaccida. Indeed, the pars flaccida of the rat houses numerous mast cells (13) and their activation might call forth degranulation and subsequent release of histamine and other potent mediators of inflammation into the external milieu. This in turn causes vasodilatation, increased permeability of blood vessels and leakage of various substances from the vascular bed into the connective tissue, as well as infiltration of the latter with inflammatory cells.…”

Acute otitis media develops in the rat after intranasal challenge of Streptococcus pneumoniae

“…In earlier studies, we have proposed that the pars flaccida (PF) of the TM is the earliest reacting tissue of the middle ear in a developing case of AOM 8 . One unique feature of the PF is the large amount of mast cells 9,10 . These cells have multiple functions, including defense against bacterial infection 11 .…”

Degranulation of Mast Cells Provokes a Massive Inflammatory Reaction in the Tympanic Membrane

“…The pars flaccida (PF) of the tympanic membrane (TM) contains numerous mast cells (MCs), 1,2 whereas the pars tensa (PT) has only a few MCs located alongside the manubrial vessels and in its most posterior and superior portion. Mast cells are also present in the tympanic cavity, in areas of the mucosa covered by tracts of ciliated and secretory cells on the medial wall of the cavity, and in the floor of the tympanic bulla.…”