Figure 2
Comparison of contrast and resolution of biological membranes after different sample preparation protocols and with different acceleration voltage conditions. Mitochondria clusters (m) from zebrafish retina samples. (a) Sample coated with platinum/carbon (Pt/C; 10 nm) after MC treatment permits detection of membranes but, fine details as mitochondrial cristae are less well resolved as with the use of’ MC only. (a’) High magnification of insert in a. (b) Sections treated with MC and uranyl acetate (UA/MC; 3 mg/ml of 2% MC in water). Membranes are visible but, many small and large holes (arrows) appear in the tissue. (b’) High magnification of insert in b. (c) Section incubated with MC only (MC). Mitochondria cristae and membrane of the outer segment (os) are clearly visible. No signs of tissue damage are observed. (c’) High magnification of insert in c. (d) PVA is also a good tissue protectant for the SEM and similar results as with MC are obtained (PVA). (d’) High magnification of insert in d. (e) Zebrafish retina imaged at 1.5 keV. Outer segments (asterisks) and mitochondria (m) appear as dark elements. (f) Same sample imaged at 0.7 keV. Outer segments (asterisks and mitochondria (m) clusters appear as white elements at the beginning of the imaging. Melanin granules are labelled with an arrow. (f’) After scanning at low speed mitochondria membranes can be observed in high detail. Scale bars in a–d: 200 nm. Scale bars in inserts: 200 nm. Scale bars in e and f: 500 nm.
