The main sign of advanced prophase is nuclear envelope destruction with complete condensation of chromatin, which turns into typical mitotic chromosomes #1, #2. Some parts of the cell still contain some fragments of the nuclear envelope, whereas the largest portion of this structure is present as some blurry contours only. In the nuclear envelope, first the nuclear lamina is destroyed (this layer is adjacent to the nuclear surface of the inner nuclear membrane). Thus, the nuclear envelope is broken down forming some groups of short cisterns and vesicles looking like endoplasmic reticulum or Golgi apparatus. Processes of chromatin condensation involve condensins whose protein complexes provide for chromosome compaction by loop and superhelix generation, etc. In mitosis, mitochondria do not degrade but divide on their own. Interestingly enough, there are many free ribosomes in the cytoplasm for the production of cytosol proteins, mainly tubulins, to form further a mitotic spindle.