Morphological observation of fine-grained echinococcus tapeworm (Echinococcus granulosus)

Summary

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

Operation method

Morphological observation of fine-grained echinococcus tapeworm (Echinococcus granulosus)

Principle

Echinococcus granulosus is also known as the tapeworm or canine tapeworm. Adult tapeworms are parasitized in the small intestine of canines, and larvae (called echinococcidia or encapsulated tapeworms) can be parasitized in the tissues and organs of humans and a variety of herbivores, resulting in a serious zoonotic disease called echinococcosis, hydatid disease, and hydatidosis. Adult tapeworms parasitize the small intestine of carnivores such as dogs and wolves. Its echinococcus larvae are mainly parasitized in the guts of herbivores such as cattle and sheep, and their infection is associated with the contamination of grasslands with worm eggs. People get echinococcosis from contact with sick dogs that accidentally eat the occupied eggs and become occasional intermediate hosts. Echinococcus larvae parasitize the human liver, lungs and other internal organs and grow slowly. Note the organization of echinococcus larvae. What should be noted in the diagnosis of echinococcosis?

Move

I. Self-observation

1. Adult stained slide specimen: made by alum card red staining, observed under low magnification microscope, the body of the worm consists of 4-5 segments (head and neck segments, immature segments, mature segments and pregnant segments). The head was pear-shaped with four suckers, a terminal protuberance and two rings of small hooks. The last segment is the gestation segment, mostly occupied by the uterus, which forms a pouch-shaped branch bilaterally and contains the eggs.

Echinococcus granulosus (tapeworm)

2. Heads of echinococcus larvae (echinococcus sand): note the size of the head and the suckers and hooks on it.

II. Demonstration

1. Adult specimen: adult worms were obtained from the intestinal tract of infected dogs and fixed in formalin. The adult worms were observed with the naked eye to be milky white, with a small body of about 3 to 6 mm in length.

2. Pathological specimen: Echinococcus granulosus parasitized in human and animal liver.

3. Cestode larvae of canine tapeworm - Echinococcus granulosus: macroscopic specimen of camel's liver.

Echinococcus larvae are spherical in shape and vary greatly in size, their diameter can range from a few millimeters to tens of centimeters, and their basic structure is as follows:

The cyst wall is divided into two layers:

Outer layer: transparent, for the cuticle, no nucleus, this layer is like a thick powdery skin, with a protective effect.

The inner layer: with many nuclei, granular, for the hair layer, from which many head nodes and some young vesicles (also called cysts) are produced.

Cystic fluid: colorless and transparent or light yellow, the head or cysts can fall into the cystic fluid through the wall of the cyst, which is called echinococcus larva.

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