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Weibliche Spermaspeicherung

in Entwicklung 02.12.2012 15:29
von franzpeter | 17.422 Beiträge

Weibliche Spermaspeicherung

Weibchen können Sperma bis zu sechs Monaten speichern. Les Stokes berichtet in eibnem Artikel benannt "Länge der Fruchtbarkeit durch eine Befruchtung ", ("Fancy Guppy Association Journal," Februar 1968, England, und nachgedruckt in den Extrakten) über ein von ihm durchgeführtes Experiment. Er setzte 17 befruchtete Weibchen, die mindestens einmal geworfen hatten, an. Sie wurden von den Männchen isoliert. Ein Weibchen warf jeden Monat bis zum sechsten Monat. Drei andere Weibchen warfen bis zum vierten Monat nach der Befruchtung. Vier Weibchen warfen einmal und dann nicht wieder. Eier werden in speziellen Beuteln, Follikeln, produziert. Die Eier entwickeln sich kontinuierlich.

Englische Version
Females store sperm for about six months. Les Stokes, in an article called "Length of Fertilization from One Impregnation," ("Fancy Guppy Association Journal," February 1968, England and reprinted in the Extracts) reports on an experiment he performed. He set aside 17 pregnant females who had dropped at least one brood. They were isolated from the males. One female dropped every month up to six months. Three other females dropped up to four months after insemination. Four females dropped once and then never dropped again.

Eggs are produced in special sacs called follicles. Eggs develop continuously.

The Egg Production Line

Experiments have shown that is possible to culture these eggs in special solutions and bring them to birth maturity.

Although the guppy is a livebearer, it merely develops the eggs internally. There is no placenta or connective organ between the mother and the embryo, unlike some other Poeciliad fish. It appears that the guppy embryo draws its primary nutrition from its yolk sac, not from the mother. However there is some gas exchange between the female guppy and young, including oxygen, carbon dioxide and probably nitrogen.

Researchers have found that adding sugar to the special solutions in which guppy eggs were brought to maturity speeded their development. This suggests that that the female guppy provides some nutrition to her developing young. Further evidence is the large size of the fry at birth. They could not have reached the large size purely on nutrition supplied by the yolk sac. Feeding pregnant females a well-balanced diet is important.


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