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Sf21 cells (IPLB-Sf21-AE) are ovarian cells isolated from Spodoptera frugiperda (Fall Armyworm).  They are spherical in shape with unequal sizes, and have a somewhat granular appearance.  Sf21 cells can be thawed and used directly in suspension culture for rapid expansion of cell stocks, propagation of baculovirus stocks, and production of recombinant proteins.  Because Sf21 cells attach firmly to surfaces, they can be used as a monolayer for transfection or plaque assay applications.

Healthy Sf21 Cell Morphology

The images below show the morphology of healthy Sf21 insect cells in suspension culture (Figure 3.3) and in adherent culture at confluency (Figure 3.4).  Note that insect cells should be subcultured when they reach confluency (see When to Subculture).



Figure 3.3: 
Phase contrast images of healthy Sf21 insect cells grown in suspension. The culture was started in a shake flask at a seeding density of 3 × 105 viable cells/mL in Sf-900 II SFM medium and it was maintained in a 28°C, non-humidified, ambient air-regulated incubator. The images were obtained using 10X and 20X objectives (panels A and B, respectively) 3 days after seeding.



Figure 3.4: 
Phase contrast images of Sf21 insect cells grown as an adherent monolayer in 293 SFM II medium.  The cells were plated at a seeding density of 5 × 104 viable cells/cm2 in a T-25 flask and grown as monolayers in a 28°C, non-humidified, ambient air-regulated incubator. The images were obtained using 10X and 20X objectives (panels A and B, respectively) 7 days after seeding, when the culture had reached confluency.