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Updated: Aug 10, 2026

07:34
FISH for Pre-implantation Genetic Diagnosis
Published on: February 23, 2011
Chromosomes of the chocolate gourami: a cytogenetic anomaly
Abstract:
The chocolate gourami, Sphaerichthys osphromonoides, has the lowest chromosome number reported for fishes, with 2n = 16 and n = 8. Other members of the family Belontiidae have somatic numbers of 42 to 48. Chromosome instability is demonstrated by the presence of somatic abnormalities and meiotic multivalents.
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In 1882, Flemming observed lampbrush chromosomes (LBC) in salamander eggs. Later in 1892, Rückert observed LBCs in shark egg cells and coined the term "lampbrush chromosomes" because they looked like brushes used to clean kerosene lamps.
LBCs are made up of two pairs of conjugating homologous chromatids. Each chromatid consists of alternatively positioned regions of condensed-inactive chromatin and loosely placed-active side loops, which can be contracted and extended. The loops resemble the...
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Polytene chromosomes are giant interphase chromosomes with several DNA strands placed side by side. They were discovered in the year 1881 by Balbiani in salivary glands, intestine, muscles, malpighian tubules, and hypoderm of larvae Chironomus plumosus. Hence, these are also called "Salivary gland chromosomes." These are found in insects of the order Diptera and Collembola; in certain organs of mammals; and synergids, antipodes of flowering plants. Polytene chromosomes are also regularly...

