152 



COLLEGE ZOOLOGY 



Dorsal nerve 



ricie 



Body wall-| Epidermal syncytiu 

 Muscle cell 



Ovary 



Growth zone 



(^ Germinal zone 



Rod border of intestine 

 Intestinal epithelium 

 Lumen of intestine 

 Excretory tube 

 Lateral line 



Oviduct 

 Uterus 



Egg 



Pseudocoel 

 Muscle cell process 



Longitudinal muscle fibrils 



Ventral nerve 



Protoplasmic process 



Cytoplasm 



Nucleus 



Contractile muscle fibrils 



Figure 79. Cross section of a female AscaHs in the upper figure. Details of a muscle cell in 

 the lower figure. 



tine, where they begin to hatch within a 

 few hours. 



The newly hatched larvae burrow into the 

 wall of the small intestine and enter the 

 veins or lymphatic vessels. If the larvae 

 pass into the lymphatics, they are eventually 

 carried into the blood and to the right side 

 of the heart. They may also be carried in 

 the blood to the liver and then to the right 



side of the heart. From here they pass on 

 to the lungs, where they pass into the air 

 passages, after which they move through the 

 trachea, throat, esophagus, and stomach, to 

 the small intestine again. This journey 

 through the host requires about 10 days. 

 They become mature worms in the intestine 

 in about IVi months. 

 Ascaris worms found in man and pigs are 



