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Lampbrush chromosome. Lampbrush chromosome are a special form of chromosome found in the growing oocytes (immature eggs) of most animals, except mammals. They were first described by Walther Flemming and Ruckert in 1882. [1] Lampbrush chromosomes of tailed and tailless amphibians, birds and insects are described best of all.
Lampbrush chromosome from the cell nucleus of an ovarial egg from Triton sp., a salamander. Harold Garnet Callan FRS FRSE (15 March 1917, in Maidenhead – 3 November 1993), [1] known as Mick Callan, was an English zoologist and cytologist. [2] He is especially remembered for his work on Lampbrush chromosomes.
Joseph Grafton Gall (April 14, 1928 – September 12, 2024) was an American cell biologist whose studies revealed many details of chromosome structure and function. Gall's studies were greatly facilitated by his knowledge of many different organisms because he could select the most favorable organism to study when approaching a specific question about nuclear structure.
These regions of chromatin that have not been transcribed are located at the ends of the loops that were formed by the sister chromatids of a lampbrush chromosome. [2] Each chromomere can have up to several pairs of loops from lampbrush chromosomes originating from it, as well as micro-loops that cannot be detected with a light microscope. [6]
These intensive RNA biosynthese are mirrored in the structure of the chromosomes, which decondense and form lateral loops giving them a lampbrush appearance (see Lampbrush chromosome). Oocyte maturation is the following phase of oocyte development. It occurs at sexual maturity when hormones stimulate the oocyte to complete meiotic division I.
Clarence Erwin McClung (April 5, 1870 – January 17, 1946) was an eminent American zoologist and prairie pioneer cytologist who discovered the role of chromosomes in sex-determination. [ 1 ] [ 2 ] Graduating pharmacy at the University of Kansas in 1892, after a year of teaching he entered the college as a graduate student (A.B.,1896, A.M.,1898 ...
In 1907, he described, for the first time, the additional or supernumerary chromosomes, now called B-chromosomes. The same year he became a foreign member of the Royal Netherlands Academy of Arts and Sciences. [9] Wilson published many papers on embryology, and served as president of the American Association for the Advancement of Science in 1913.
Synapsis and recombination during meiotic prophase I in these unisexual females is thought to ordinarily occur between identical sister chromosomes and occasionally between homologous chromosomes. Thus little, if any, genetic variation is produced. Recombination between homeologous chromosomes occurs rarely, if at all. [46]