Final answer:
The term used to describe the heat treatment on each filament end to seal and round it is flaming loop.
Step-by-step explanation:
The term used to describe the heat treatment on each filament end to seal and round it is flaming loop in the context of microbiological media and laboratory equipment. The process involves heating the filament to high temperatures using a microincinerator or similar device. This heat treatment ensures the proper sealing and rounding of the filament ends, making it suitable for high-temperature applications such as furnace tubes, lighting tubes, melting crucibles, and more.