Experimental Modification of the Sexual Cycle of the Greenfinch
| Autor: | P. H. Damsté |
|---|---|
| Rok vydání: | 1947 |
| Předmět: | |
| Zdroj: | Journal of Experimental Biology. 24:20-35 |
| ISSN: | 1477-9145 0022-0949 |
| DOI: | 10.1242/jeb.24.1-2.20 |
| Popis: | 1. ‘Mewing’ of song-birds is a traditional practice of Dutch bird-catchers who make use of it to produce singing decoys in the autumn. The birds are encaged early in May, the daylight is progressively reduced by means of curtains during May and the birds are kept in darkness throughout June, July and the first half of August. From the middle of August onwards the curtains are gradually opened and by the end of the month the birds are in daylight and in full song once more. 2. This procedure was carried out with the greenfinch (Chloris chloris) under laboratory conditions in order to study the behaviour, song and moulting of the birds and the histology of their gonads before, during and after mewing. 3. In the early stages of mewing the testes decrease in size till in total darkness they have the same diameter as the inactive testis. 4. When the birds are exposed to normal daylight again the testes enlarge rapidly until after some weeks of increasing spermatogenesis they are fully mature. By this time the birds are in full song and it is likely that song coincides with sexual maturity and is induced by the male sex hormone. 5. The diameter of the testis tubules varies in the same way as the diameter of the gonads. 6. In the middle of October, after some weeks of sperm production, regression of the testis sets in. During the ensuing stage of sexual inactivity some birds were exposed to increasing quantities of (electric) light from the beginning of December until the beginning of February. These birds showed increasing spermatogenesis and developed their full song. 7. Thus by means of mewing and ‘extra lighting’ it was possible to bring birds into breeding condition three times within one year. |
| Databáze: | OpenAIRE |
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