Practice question

Lampbrush chromosomes represent exceptionally extended diplotene bivalents observed during prolonged prophase I arrest in vertebrate oocytes, particularly Xenopus, axolotl and birds. They consist of large chromomeres from which pairs of lateral loops containing actively transcribed DNA expand, coated with nascent ribonucleoprotein matrix visible by light microscopy as brush-like structure. High transcription from loops produces maternal RNAs stored for early embryogenesis while homologous chromosomes remain paired and recombined. Giant size due to active decondensation makes them excellent models for transcription visualization, not found in mitotic somatic cells.