Which chromosome is involved in the production of 'masked' mRNAs for early development?

Lampbrush chromosomes are giant chromosomes found in the growing oocytes (immature eggs) of many animals, exceptionally during the diplotene stage of meiotic prophase I. They are highly active in transcribing large amounts of RNA, including 'masked' maternal mRNAs. These masked mRNAs are stored in the egg cytoplasm and remain translationally inactive until fertilization, providing the genetic instructions necessary for early embryonic development.