Veterinary Parasitology CH3 - Introduction to Nematodes

Study material for Chapter 3 of Diagnostic Parasitology for Veterinary Technicians. For class BIO225 at MWCC.

The common name of Nematodes is...

Roundworms

Nematodes are...

Multicellular and unsegmented, long, round on both ends

Size range of Nematodes is...

2mm - 1m long, 35um - 1.2cm wide

Nematodes shapes are...

Spherical or Whiplike

Cuticle

Secreted from the hypodermis

Cervical alae

Flattened extensions around the anterior end

Caudal alae/Copulatory bursa/Bursa rays

• Lateral flattened extensions of posterior end of male nematodes — holds female during mating

• Contains "chitinous spicules" (penis)

The somatic muscular layer is essential for what?

Locomotion

The muscles of the body cavity (pseudoceolom) are essential for what?

Movements of feeding and reproduction

What are the two most important organs?

Reproductive and digestive

The 2-8 lips around the mouth or in some worms, papillae, are called what?

Leaf crown

True or false: Males have a rectum like the females

False; the male has a cloaca

Nematodes are dioecious, this means...

They have separate male and female sexes

Ascaroid egg

Single cell within egg shell, oviporous

Strongyle egg

Morula (multicellular), oviporous

Spiruroid egg

First stage larva within egg shell, ovoviviparous

Trichuroid/Trichinelloid egg

Single-cell stage within egg shell, oviparous

Oviparous

Eggs contain single cell or multi-cell (morula) stage inside shell

Ovoviviparous

Eggs contain first stage larva inside shell

Larviparous

Female retains eggs in uterus, gives birth to live larvae

Life cycle of nematodes

1. Female produces single cell egg

2. Cell divides (morulates) into tadpole​

3. Develops into first stage larva​

4. Hatches from egg and molts (sheds cuticle) into second stage larva — in environment or intermediate host​

5. Molts again into infective third stage larva — infects definitive host

6. Molts into fourth then fifth stage larva — immature adult​

7. Migrates to preferred organ and develops into sexually mature adult

Direct life cycle

Does not go through intermediate host

Indirect life cycle

Goes through intermediate host