This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General physiology, Subject name: Physiology
[{'content': 'A single cell within a culture of freshly isolated cardiac muscle cells is injected with a fluorescent dye that cannot cross cell membranes. Within minutes, several adjacent cells became fluorescent. The most likely explanation for this observation is the presence of \nSelect and explain. \nA. Gap junctions, B. IP3 receptors, C. Transverse tubules, D. Desmosomes', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Gap junctions are pores composed of paired connexons that allow the passage of ions, nucleotides, and other small molecules between cells.Ref: Guyton; 13th edition', 'role': 'assistant'}]