What does entering of sex chromosomes to gametes mean during meiosis I?
I seem to now understand the sentence. I read the clause in other words:


  During meiosis I, the sex chromosomes of the gametogonia separate in
  anaphase I and II and become eventually different sperm or egg cells
  after cell differentiation and maturation: male spermiogenesis and
  female maturation into ovum.


Female thing does not seem to have a special name for the maturation thing.
Female does not seem to have differentiation part at the last part similarly as male, since only one ovum is formed after the sequence of events. 
Sex chromosomes refer to your parents genotypes. [jg89]

Problem seems to be solved now.

I would not personally use the word "enter" in a such sequence. It is a shortcut. Better would be "enter eventually" or "enter after a sequence of events". I prefer explicity instead of implicity.