An overlooked site of tissue mast cells--the human tympanic membrane. Implications for middle ear affections

Area of Science:

• Otolaryngology
• Immunology
• Histology

Background:

• The tympanic membrane is a crucial component of the auditory system.
• The cellular composition of the tympanic membrane, particularly regarding immune cells, is not fully understood.
• Mast cells play significant roles in inflammatory and allergic responses.

Purpose of the Study:

• To investigate the presence and distribution of mast cells in the human tympanic membrane.
• To quantify mast cells in different regions of the tympanic membrane.
• To discuss the potential implications of mast cells in middle ear physiology and pathology.

Main Methods:

• Histological examination of tympanic membranes from 14 deceased individuals without a history of ear disease.
• Microscopic analysis to identify and count mast cells.
• Calculation of mast cell volume density and number per square millimeter in the Shrapnell membrane (pars flaccida).

Main Results:

• A high concentration of mast cells was observed in the Shrapnell membrane (pars flaccida).
• Very few mast cells were found in the pars tensa, primarily near blood vessels along the malleus handle.
• The volume density of pars flaccida mast cells was 3.9%, with 299 ± 35 mast cells/mm².

Conclusions:

• The Shrapnell membrane is a site rich in mast cells within the tympanic membrane.
• The localized presence of mast cells suggests a potential role in middle ear immune surveillance.
• Further research is warranted to elucidate the specific functions of these mast cells in health and disease.