There is no known biological term or concept called "hetrocytes". It's possible that the term is misspelled or a made-up word.

If you could provide more context or a source where you encountered this term, I might be able to help you understand what it refers to.

For example, perhaps you meant:

* Heterocytes: These are specialized cells found in some cyanobacteria that are responsible for nitrogen fixation.

* Erythrocytes: These are red blood cells, crucial for oxygen transport in the body.

* Leukocytes: These are white blood cells, playing a vital role in the immune system.

Please clarify the term or provide more information, and I'll do my best to assist you.