Neutrophils are the cells that first reach to the infection side and kills the bacteria.Neutrophils comprises most part of WBCs approximately 50-70% of total WBCs. Neutrophils kills the foreign bacteria by engulfing them and this process is called phagocytosis.
The engulfed bacteria is called phagosome and phagosome then fuse with lysosome making phagolysosome. Now fused lysosome secrete lytic enzymes like proteases, lipases and glycosidases which kills the engulfed bacteria by digesting them.
So neutrophils will be the first cells migrates to prevent bacterial infection in the hand of 20 year old boy who shoots his hand with nail gun.
Anaphase is the answer. In metaphase the chromatids line up next to each other and the spindle attaches to the centroid. In anaphase, the chromatids are pulled apart into opposing sides of the cell by the spindle fiber