Introduction to Nematodes

Question 1

Nematoda

Answer 1

All round worms (cylindrical) of animal/human parasitology importance

Question 2

Body Morphology

Answer 2

Cylindrical; pseudocoelum
Simple digestive system
Simple excretory system
Simple nervous system
Simple reproductive system

Question 3

Cuticle

Answer 3

covering of the body of the worm; should have close-set circular striations; very tough

Question 4

Internal leaf crowns

Answer 4

inside rim of mouth opening

Question 5

External leaf crowns

Answer 5

on the rim itself

Question 6

Cervical papillae

Answer 6

in esophageal region; paired

Question 7

Caudal papillae

Answer 7

near the tail; paired

Question 8

Prebursal papillae

Answer 8

just anterior to bursa

Question 9

cephalic vesicles

Answer 9

cuticle inflated around mouth opening

Question 10

Cervical Vesicles

Answer 10

cuticle inflated in the esophageal region

Question 11

Alae

Answer 11

flattened expansions of cuticle

Question 12

Bursa alae

Answer 12

caudal alae (flattened expansions of cuticle) have become elongated lobes in the male; function in reproduction. Caudal papillae elongated to support them are called bursal rays

Question 13

Digestive system of nematode

Answer 13

tubular; floats in fluid-filled body cavity

Question 14

Mouth opening of nematode

Answer 14

Called stoma
Can be surrounded by 1) 2-3 lips
2) leaf crowns
Blades, cutting plates, or teeth may be present

Question 15

Purpose of knowing esophagus shapes

Answer 15

Shapes help to identify nematodes, especially larvae

Not commonly done in a typical practice

Question 16

Filariform (esophagus shape)

Answer 16

simple, posterior diameter slightly greater than anterior diameter

Question 17

Rhabditiform (esophagus shape)

Answer 17

anterior and posterior swellings

Question 18

Bulb-shaped (esophagus shape)

Answer 18

large posterior swelling

Question 19

Double-bulb-shaped (esophagus shape)

Answer 19

bulb constricted behind its middle

Question 20

Trichuroid (esophagus shape)

Answer 20

fine lumen; appears to pass through a single column of cells

Question 21

Intestine description

Answer 21

simple tube leading from esophagus

Question 22

Anus description

Answer 22

usually near the posterior end, has cuticular lining

Question 23

Excretory system

Answer 23

Very primitive

Collecting tubules end at mid-ventral excretory pore, in esophageal region

Question 24

Female reproductive system

Answer 24

Organs single or double
Ovary, oviduct, uterus, vagina, vulva
Eggs or 1st stage larvae passed from vulva
Some have ovijectors just before vulva that hold and eject eggs
Vulva may be covered by cuticular vulvar flap

Question 25

Male Reproductive System

Answer 25

Organs
Testis, vas deferens, seminal vesicle, can have copulatory bursa and spicules (chitinous structures near tail – dilate vulva of female)
Organs
Testis, vas deferens, seminal vesicle, can have copulatory bursa and spicules (chitinous structures near tail – dilate vulva of female)

Question 26

Essential Nematode Life Cycle

Answer 26

Egg – In final host
L1
Molt 1
L2
Molt 2
L3
Molt 3
L4
Molt 4
L5 – young adult

Question 27

Bursa

Answer 27

a fluid-filled sac or saclike cavity, especially one countering friction at a joint.

Question 28

papillae

Answer 28

a small rounded protuberance on a part or organ of the body.