Final answer:
Reactive lymphocytes are a type of immune response lymphocyte with larger nuclei and irregular shapes, containing visible nucleoli involved in protein synthesis.
Step-by-step explanation:
Reactive lymphocytes are a type of lymphocyte that play a role in the immune response. In terms of nuclear characteristics, reactive lymphocytes typically have larger nuclei compared to normal lymphocytes. Their nuclei may also have irregular shapes and contain visible nucleoli, which are small structures involved in protein synthesis.
One example of reactive lymphocytes is seen in an immune response to a viral infection. When a virus enters the body, it triggers the production of reactive lymphocytes, which are larger and more active than normal lymphocytes. These reactive lymphocytes help to identify and destroy the virus.