Morphological observation experiment on Schistosoma weissei (Schistosoma japonicum)

Summary

This experiment is from the official website of Parasitology, School of Medicine, Shandong University.

Operation method

Morphological observation experiment on Schistosoma weissei (Schistosoma japonicum)

Principle

Schistosoma welchii is one of the most important species of human schistosomes, and is the main schistosome that causes lung-type schistosomiasis (paragonimiasis, pulmonary schistosomiasis). Schistosoma welchii, also known as pulmonary schistosomiasis, adult parasites mainly in the lungs of humans, cats, dogs, etc. The eggs are excreted with feces, enter the water to develop and hatch out of the trichinae. Trichinella invade the first intermediate host Kawasaki snails, through the cystic larvae, female Lei larvae, child Lei larvae and caecal larvae, caecal larvae from the snail body to escape, and then invade the second intermediate host stone crabs or mayflies. They develop into cystic larvae in the body and infect people by eating raw food containing stone crabs or mayflies. The larvae need to migrate through the body to reach the lungs.

Move

I. Self-observation

1. Slide specimen of schistosoma eggs: the eggs of schistosoma are larger than those of Ascaris lumbricoides, with the size of 80-118×48-60 micrometers, and the morphology varies a lot, but they are basically oval, golden-yellow in color, and the widest part is near the end of the egg cover. The egg cover is large, often with a tilt, but there is also a lack of egg cover, the thickness of the egg is not uniform, the egg contains more than ten yolk cells, when discharged from the body, the egg cell has not yet divided, often located in the center. It has been described as resembling a small asymmetrical tile jar.

schistosoma eggs

2. Stained specimen of adult Schistosoma pneumoniae: body oval, length to width ratio 2:1, oral and abdominal suckers slightly the same size, abdominal sucker located before the midline of the body. The digestive system is degraded with a mouth and no anus. The ovaries and uterus of the reproductive system are juxtaposed behind the ventral sucker, and the two testes are also juxtaposed at the back of the body, which is characteristic of this worm.

adult schistosomiasis

3. Slide specimen of Schistosoma cysticerci: low magnification observation is round, there are two layers of internal and external cystic walls, inside the cysts can be seen to contain particles of excretory sacs, but also can be seen curved intestinal branches.

II. Demonstration

1. Adult Schistosoma weissei: adult body is plump, reddish-brown and translucent when alive, grayish-white after death, short or long oval, flattened on the ventral surface, elevated on the back, 7.5-12 mm long, 4-6 mm wide, 3.5-5 mm thick, shaped like half a grain of peanut rice.

2. Life history of Schistosoma welchii: Stages of development of Schistosoma pulmonarum, with attention to the site of parasitism of the adult, the first intermediate host is the river snail. The second intermediate host is the stone crab or crayfish, and the infective stage is the cysticercus.

3. A macroscopic specimen (bottled specimen) of Schistosoma pneumoniae parasitized in the lungs.

4. Slide specimen of adult Schistosoma smithiensis.

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