prophase is the first stage of karyokinesis in mitosis and is marked by the initiation of condensation of chromosomal material . As the cell progresses through this stage, specific structures including the endoplasmic reticulum (ER), nucleolus, and Golgi complex begin to disappear . The sources explicitly state that by the end of prophase, these structures, along with the nuclear envelope, are no longer visible when viewed under a microscope . Understanding these precise chronological events in the cell cycle is a high-priority strategy for medical aspirants, as NCERT textbooks provide the definitive foundation for approximately 95% of NEET Biology questions .