United Staler Fish and Wildlife Service 



ARTIFICIAL INSEMINATION OF FISH AT A RAINBOW-TROUT HATCHERY 



By stroking a mature female fish, the fish-breeder forces ripe eggs into a pan of 

 water. Then he "strips" the seminal fluid into the water from a male fish 



hormone", which is absorbed into the blood and carried to all parts of the body. 

 As each egg ripens, it detaches itself from the ovary and floats in the fluid of 

 the body cavity. 



During copulation, the seminal fluid is discharged into the vagina, which 

 connects with the lower end of the womb, or uterus (see illustration, p. 383). 

 The sperm cells swim in the mucus secretion lining the womb, and into the 

 oviducts. An egg cell descending the Fallopian tube may be fertilized at any 

 point where the tgg and sperm meet. The fertilized egg starts segmentation 

 immediately after the fusion of the two nuclei. 



The developing embryo attaches itself to the lining of the uterus by means 

 of outgrowths, or "villi", through which food material is absorbed from 

 the lymph of the mother (see page 423). At a certain stage in its de- 



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