Question

Lampbrush chromosomes are

• A. salivary gland cells of Drosophila
• B. oocytes of amphibians
• C. spermatocytes of amphibians
• D. gonads of man.

Answer 1

Answer: (B)

oocytes of amphibians

Answer 2

Lampbrush chromosomes were first observed by Flemming (1882), but were first described by Ruckert (1892). These chromosomes occur in the diplotene stage of meiotic prophase-I during oogenesis in amphibian oocytes. The chromosomes are highly elongated special kind of synapsed midprophase or diplotene chromosome bivalents (i.e. two pairs of sister chromatids held together by" chiasmata). These chromosomes are larger than even polytene chromosomes. In lampbrush chromosome, the strands of chromosome ( consisting of two double strands of DNA) are dotted with about 5000 chromomeres (dark staining irregular structures).Twin loops emerge from chromomeres. These loops are identical on both pairs of sister chromatids.