Venema, Gerhardus

English

Proceedings - University of Groningen

   University of GroningenAn experimental study in the origin of abnormal mitoses in tumoursVenema, GerhardusIMPORTANT NOTE: You are advised to consult the publisher's version (publisher's PDF) if you wish to cite fromit. Please check the document version below.Document VersionPublisher's PDF, also known as Version of recordPublication date:1962Link to publication in University of Groningen/UMCG research databaseCitation for published version (APA):Venema, G. (1962). An experimental study in the origin of abnormal mitoses in tumours. s.n.CopyrightOther than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of theauthor(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons).The publication may also be distributed here under the terms of Article 25fa of the Dutch Copyright Act, indicated by the “Taverne” license.More information can be found on the University of Groningen website: https://www.rug.nl/library/open-access/self-archiving-pure/taverne-amendment.Take-down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediatelyand investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons thenumber of authors shown on this cover page is limited to 10 maximum.Download date: 03-06-2022SUMMARY 1.  arl lier and current theories of carcinogenesis are briefly surveyed. 2. The present study considers whether the commonly observed abnormal mitoses in tumour cells are caused by the presence of increased amounts of substances which are able to  interfere with mitosis. The analysis was carried out by examining the effects of 8 tumour and normal tissue extracts on mitosis in root-tip meristems of Allium cepa. 3. From the effects analyzed, comprising stickyness of the chromo- somes, abnormalities due to abnormal spindle function and chro- mosomal breakage, it was concluded that quantitative differences between the abnormality inducing capacity of tumour and nor- mal tissue extracts exist. 4. Analysis of the effects on root-tip mitosis of 2 necrotic tissue extract.. obtained from tumours revealed considerable abnor- mality inducing capacity. This evidence suggested that some of the abnormalities induced by tumour extracts may be caused by the presence of necrotic tissue substances. In addition it  is likely that increased amounts of abnormality inducing sub- stances are present in tumour cells as compared with normal cells. 5. Autolytic products, arising from necrotic tissues are envisaged as a n  external factor contributing to the mitotic and chromo- soma1 instability of the tumour cells, whereas the increase of abnormality inducing substances in the tumour cells is regarded as due to changes in metabolism caused by an abnormal environ- ment. These two factors, to which the mitotic and chromosomal instability is attributed, together with the abnormal environment are considered as factors establishing the stemline and may - possibly account for some, tumour properties such as high glycolytic activity and decrease or loss of enzymes involved in the functions of the differentiated cell. 6. Mitotic and chromosomal instabilit~ of tumour cells may there- fore be considered as secondary phenomenona resulting from environmental changes during tumour growth. The results ob- tained and discussed on the basis of known studies do not sup- port the theory of carcinogenesis involving abnormal mitosis or chromosomal changes, but are not inconsistent with any of the other theories surveyed in this work. 

An experimental study in the origin of abnormal mitoses in tumours

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An experimental study in the origin of abnormal mitoses in tumours

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Proceedings - University of Groningen