Cytogenetic studies of four Species of Anura, (Amphibia).
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Date
1985
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Publisher
Obafemi Awolowo University
Abstract
The chromosomes of four species of Anura were studied. The four species consists of two species of Bufonidae, (Bufo regularis and Bufo latifrons) and two species of Ranidae, (Ptychadema oxyrhincus and Rana galamensis). The chromosomes were prepared from bone marrow treated with hypotonic potassium chloride solution, fixed in 3:1 methanol acetic acid mixture and stained in 1% acetic-orcein stain.
Chromosomes of well spread cells were counted, measured, and their arm ratios, relative lengths and centromeric indices were determined. From these measurements, the chromosomes were classified and their idiograms were constructed. Photomicrographs of well spread mitotic metaphase chromosomes were taken and from these the haryotypes were arranged.
A chromosome complement of 2n = 20, 2n = 20, 2n =24 and 2n = 26 were recorded for :ado regularis, Bufo latifrons, Ptychaaema hincus and Rana galanensis respectively. The chromosomes show clear demarcation into large and small elements. There were no satelites and no microchromosomes. No sex chromosomes were observed.
The small number of chromosomes where are relatively large in size and which were bi-armed marks the amphibians as a conservative and primitive group of vertebrates in comparison with the reptiles and birds which have large number of microchromosomes. The probable evolution of the 20 and 22 chromosome complements of Bufo regularis and Bufo latifrons is considered.
Description
48P
Keywords
Amphibians, Bone marrow, Photomicrographs, Metaphase
Citation
Fakayode, S.F (1985) Cytogenetic studies of four species of Anura, (Amphibia).