system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
Which of the following cells become tissue macrophages
assistant
The correct answer is  Monocytes enter the blood from the bone marrow and circulate for about 72 hours. They then enter the tissues and become tissue macrophages.
Ganong 23 rd ed, pg 65