Pathology assistants typically are hired to do grossing of tissues in
a pathology lab. Who pays their salary -- the hospital or the
pathologist/pathologist group?

The hospital actually "hires" a pathology company to provide a testing
facility. The lab staff are paid by the pathology company they work
for. In a private pathology situation, the company is the sole
payroll, but in the public system there can be a cross-over with the
hospital.

Baz :)