The duration of meiosis and spermiogenesis was studied in the dog by following the kinetics of [3H]thymidine-labeled canine spermatocytes autoradiographically. Leptotene appears to last for at least 4.20 days, zygotene for less than a day, and pachytene for about 15.50 days. The transition from diplotene to metaphase II is extremely rapid and requires approximately a day. The duration of spermiogenesis is at least 19.60 days. Both meiosis and spermiogenesis are completed by 42.15 days.

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Study on meiotic chromosomes of grasshopper, Gesonula punctifrons and interphase polytene chromosomes from Dipteran larvae as of Chironomus striatipennis and Drosophila melanogaster following staining by periodic acid-Schiff technique revealed that chromosomes contained polysaccharides as an integral part of their organization. PAS ?ve nature of the chromosomes both at highly condensed state as available during meiotic cell division and at extended state as in polytene chromosomes supports the idea that chromosomes contain polysaccharides as one of the constituent biological macromolecules. PAS ?ve chromosomes appeared to be fluorescent under fluorescence microscope and fluorescence was found to be more or less uniform along the whole length of the meiotic chromosomes, while in case of polytene chromosomes intense fluorescence could be noticed along the band regions of the chromosomes.

Background Nine species of Chironomus evolved throughout the world were measured for their divergence with regard to their DNA sequences concerning 18S rRNA since it is conserved for a specific species. With the advancement of the field of molecular evolution, cytogenetics requires further correlation between molecular architecture and morphological features of a species to compare amongst others to decipher their role in speciation. Therefore, divergence of DNA sequences of the Chironomus were compared with differences in the polytene chromosome features of most of the species under this investigation to evaluate underlying correlation among them, if any, to finally establish a novel method of molecular classification broadly applicable in cytogenetics studies. Results When Chironomus javanus Kieffer was considered as a reference organism, an in silico pair-wise alignment of sequences for the 18S rRNA gene regions of the other eight different species of the same genus exhibited nucleotide sequence homology ranging from 67 to 98%. This divergence of the species under consideration might be due to environmental impact causing alteration of nitrogenous bases probably due to mismatch pairing in DNA replication. This may be suggested as a cause of evolution of species in nature. A concomitant study on the polytene chromosome band patterns of majority of these species belonging to this series also indicated a divergence ranging from 10% to 30%. Conclusions Sequence analysis based on 18S rRNA of nine species of Chironomus under this investigation shows a similarity in the polytene chromosome organization in most of the Chironomid species of the series. Hence, molecular divergence in the species is consistent with cytological difference among Chironomid species. Therefore, molecular data based on 18S rRNA and cytological characters based on the polytene chromosome features of the Chironomid species may be useful for their taxonomical recognition. Moreover, variations concerning two aspects of this study may be correlated to their environmental distinctions.