HM Hohner 4 draw reed. SEM operating conditions: AV 25 kV; Spot Size 100 nm.  From the tip edge there are several scattered dark dots (a few are coloured yellow to facilitate their view) corresponding to flat pulmunary macrophages. They are mostly concentrated in an approximately 1 mm square area close to the reed tip. The reed surface discloses a complex substructure: 1) a major pattern composed of thin longitudinal ridges running parallel to the long reed axis (black arrows); 2) a secondary pattern of obliquely oriented ridges (arrowheads). Gross longitudinal ridges derived from the fusion of the thin ones are also recognized (white arrows)