  Many cell types spontaneously order like nematic liquid crystals, and, as
such, they form topological defects. While defects with topological charge
$\pm$1/2 are common in cell monolayers, the defects with charge $\pm$1,
relevant in the formation of protrusions and for cell migration in living
systems, are more elusive. We use topographical patterns to impose topological
charge of $\pm$1 in controlled locations in cell monolayers. We compare the
behavior of 3T6 fibroblasts and EpH-4 epithelial cells on such patterns,
characterizing the degree of alignment, the cell density near the defects, and
their behavior at the defect core. The patterned substrates provide the right
conditions to observe isotropic packing of 3T6 cells in the +1 defects. We also
observe density variation in the 3T6 monolayers near both types of defects over
the same length-scale. These results indicate a defect core size of
150$\mu$m-200$\mu$m, with isotropic packing possible in the +1 defects and, in
other cases, a defect core with rich internal structure.
