A trichinella larva enters a cell and develops there, probably as a way of concealing itself from the immune system.
The parasite has evolved a way of stimulating blood vessel development around the cell, in order to receive the nutrients it needs.
In mycology, a nurse cell is any hyphae that supplies food material to spores that have detached from the basidia; used especially in reference to taxa from the family Sclerodermataceae.
In fruit flies (Drosophila), nurse cells surround the developing oocyte and synthesize proteins and RNAs that are to be deposited in it.
This damaging effect would otherwise befall the DNA of the egg cells if they were responsible for their own synthesis.