Demonstration Sheets for Nematodes (Lab 4)
Phylum Nematoda
Ascaris %
Cross-section of a pseudocoelomate worm. Know the following structures
(indicated on the diagram):Testes, Intestine, Pseudocoelom, Cuticle, Epidermis.
See Figure 22.11a, p. 375 (8th edition)
CBS 30-6906 (Z1025), Dissecting Scope
Phylum Nematoda
Ascaris &
Cross-section of a pseudocoelomate worm. Know the following structures
(indicated on the diagram): Ovaries, Horns of uterus, Intestine, Pseudocoelom,
Cuticle, Epidermis. See Figure 22.11b, p. 375 (8th edition)
CBS 30-6918, Dissecting Scope
Phylum Nematoda
Ascaris larvae in lung tissue
Ingested eggs hatch in the small intestine, burrow into the hepatic portal
system, migrate through the body and emerge in the alveolar sacs of the lung
(seen here). The larvae move up the bronchiole tubes and trachea, cross over
the epiglottis and are swallowed again. The worms mature when they return the
small intestine after their larval transit through the host’s body.
See Figure 26.5e (p. 434)
92W 5679, 10X
Phylum Nematoda
Ascaris lumbricoides adults
This species is the largest nematode that lives in the intestinal lumen of humans.
It is estimated that approximately ¼ of people world-wide are infected with these
worms. Transmission occurs through oral consumption of the eggs by fecal
contamination.
Specimens
No Scope
Phylum Nematoda, Order Trichurida, Family Trichuridae
Trichuris trichiura
Whipworm
Prevalence of this worm in children in some regions of the southeastern
US has been measured between 20-25%. See Figure. 23.1, p. 400 (8th edition)
Carolina 30-7050 & specimen in bottle
Dissecting Scope
Phylum Nematoda, Order Trichurida, Family Trichuridae
Trichuris trichiura
Ovum
Egg with characteristic blunt ends. See Figure. 23.2, p. 400 (8th edition).
Wards 92W 5793, 10X
Phylum Nematoda, Order Trichurida, Family Trichuridae
Trichinella spiralis
Skeletal muscle (diaphragm) of mouse infected with encysted J3 larvae.
The worms invade host muscle cells that then lose their myofilaments and
become nurse cells. The nurse cells secrete collagen around the worm and a
network of host blood vessels nourishes the cysts. See Figures 23.11 and 23.12,
p. 406 (8th edition)
Wards 92W 5764, 10X
Phylum Nematoda, Order Trichurida, Family Trichuridae
Trichinella spiralis
Larval worms are embedded inside vertebrate host striated muscle cells
(skeletal and cardiac). This is a worm that is an INTRACELLULAR parasite at
this stage of development. Humans are usually infected by eating infected,
uncooked pork, but uncooked meat from any predator (e.g. bear meat) is a
potential source of infection. See Figures 23.11 and 23.12, p. 406 (8th edition)
Triarch ZE 4-13, 4X
Phylum Nematoda, Order Trichurida, Family Trichuridae
Trichinella spiralis
Migratory larvae
These larvae are transported by lymph vessels to striated muscle where
they encapsulate within muscle cells.
PS 2445, 40X
Phylum Nematoda, Order Rhabditida
Strongyloides stercoralis
Common in puppies from kennels with poor sanitation. People with
suppressed immune systems are at risk of infection. Adults can be both freeliving and parasitic.
Wards 92W 5741, 10X
Phylum Nematoda, Order Strongylida, Family Ancyclostomidae
Necator americanus
Male and female hookworms. The COPULATORY BURSA is present on
males only. Necator possesses flat plate-like teeth to hold on to host villi while
Ancylostoma possesses fang-like pointed teeth. (Compare with adjacent
slide.)Females are larger than males. See Figure 25.7, p. 422 (8th edition)
7-40, 4X
Phylum Nematoda, Order Strongylida, Family Ancyclostomidae
Ancylostoma duodenale
The Ancylostoma mouth possesses characteristic prominent teeth rather
than plates as in Necator. See Figure 25.8, p. 423 (8th edition) and compare with
Necator slide on adjacent microscope.
17-38, 40X
Phylum Nematoda, Order Strongylida, Family Ancyclostomidae
Necator americanus
Infective FILARIFORM J3 larvae. The usual method of infection is by
burrowing into people’s feet. The esophagus does NOT have a bulb. See Figure
24.2i, p. 415 (8th edition) and compare with Figure 24.1.
2-42, 10X
Phylum Nematoda, Class Rhabditea
VISCERAL & CUTANEOUS LARVAL MIGRANS
These nematodes were taken from the skin and the connective tissues
surrounding the internal organs of a feral cat. Notice the transparent SHEATH
that protects the worms from the host’s immune system.
Specimens, Dissecting scope
Three displays of nematodes taken from the stomachs of deer, hammerhead
shark and alligator. (You will not be held responsible for knowing which of these
examples was taken from what host.)