Open AccessCounting unstained, confluent cells by modified bright-field microscopy
Author(s) -
L. Louis Drey,
Michael Graber,
Jan Bieschke
Publication year - 2013
Publication title -
biotechniques/biotechniques
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.617
H-Index - 131
eISSN - 1940-9818
pISSN - 0736-6205
DOI - 10.2144/000114056
Subject(s) - bright field microscopy , microscopy , optics , condenser (optics) , pinhole (optics) , fluorescence microscope , microscope , staining , cell counting , materials science , differential interference contrast microscopy , optical microscope , fluorescence , cell , chemistry , physics , pathology , scanning electron microscope , light source , biochemistry , cell cycle , medicine
We present a very simple procedure yielding high-contrast images of adherent, confluent cells such as human neuroblastoma (SH-EP) cells by ordinary bright-field microscopy. Cells are illuminated through a color filter and a pinhole aperture placed between the condenser and the cell culture surface. Refraction by each cell body generates a sharp, bright spot when the image is defocused. The technique allows robust, automatic cell counting from a single bright-field image in a wide range of focal positions using free, readily available image-analysis tools. Contrast may be enhanced by swelling cell bodies with a brief incubation in PBS. The procedure was benchmarked against manual and automated counting of fluorescently labeled cell nuclei. Counts from day-old and freshly seeded plates were compared in a range of densities, from sparse to densely overgrown. On average, bright-field images produced the same counts as fluorescence images, with less than 5% error. This method will allow routine cell counting using a plain bright-field microscope without cell-line modification or cell staining.