Lecture #2: Nemotoda/Ascarids

Question 1

What are the morphologic features for Phylum Nematoda?

Answer 1

1. Spindle shaped
   
   1. tapering at 1 or both ends
      
      1. anterior end of nematodes are crucial for identification
2. Body not segmented
3. Body cavity and digestive tract present
4. separate sexes (dioecoius)

Question 2

List what the arrows are pointing to in the attached image.

Answer 2

IN: Intestine

UT: uterus

OV: ovary

MU: somatic muscle tissue

Question 3

True/False

The intestine in female nematodes ends with the cloaca with vas deferens.

Answer 3

False

Female nematode: the intestine ends in the rectum, while the reproductive tract has a separate opening

male nematode: the intestine ends in cloaca along with vas deferens (CONVENIENCE!)

Question 4

What characteristic provides turgor and keeps body straight in a nematode?

What provides locomotion to the nematode?

Answer 4

1. pressure from the pseudocoelom:
   
   1. pseudocoelom contains fluid that is highly allergenic or toxic to host
2. somatic muscle cells

Question 5

1. What does the nematode body wall consit of?
2. What’s the thick, tough protective outer covering of nematode body wall?

Answer 5

1. Cuticle, hypodermis, and muscle cells
2. Cuticle

Question 6

Describe the path that sperm would go through during copulation.

Describe the path that an ovary would go though during parturition.

Answer 6

1. Coiled testis -> vas deferens -> enlarged seminal vesicle -> muscular ejaculatory duct -> cloaca
2. ovary -> oviduct -> uterus -> muscular ovejector -> vulva

Question 7

You and your buddies walk into a bar, you’re wanting the number of the female that lays eggs with an undeveloped embryo. What’s her name?

Your weird friend is into female nematodes that give birth to larvae, but isn’t into any females that lay eggs. What’s the female nematode’s name?

Your drunk friend doesn’t care the development. Your friend goes up to get a drink and sees a female nematode that prefers to lay an egg that contains a first-stage larve. Interest is struck instantly, but your friend’s drunkened self can’t remember the name.. Could you help your friend out?

Answer 7

You: Oviparous nematodes: female lay eggs with an undeveloped embryo

Weird friend: Viviparous: female gives birth to larvae instead of laying eggs

Drunk friend: Ovoviviparous: female lays an egg that contains a first stage larva

Question 8

Label the three arrows on the attached image.

Answer 8

Question 9

Which female would you consider this nematode would be classified as?

Answer 9

Oviparous

Question 10

Which female would you consider this nematode would be classified as?

Answer 10

oviparous

Question 11

Which female would you consider this nematode would be classified as?

Answer 11

ovoviviparous

Question 12

Which female would you consider this nematode would be classified as?

Answer 12

Viviparous

Question 13

At which larval stage does the new host become infected?

Answer 13

L3

Question 14

What’s the morphology of the anterior and poster ends of adult Ascarids?

Answer 14

anterior: 3 lips

long, narrow alae (wings

posterior: males do NOT have a bursa

Question 15

What’s the morphology of Ascarid eggs?

Answer 15

round or elliptical

shell is thick, rough, and pitted

internal contents: single cell (almost fills entire shell)

Question 16

In what ways can ascarids be infected?

Answer 16

Fecal - oral of infective eggs

Transplacental - major path

Transmammary - minor

via paratenic host (transfer host)

Question 17

Where would you find the infective larve (L3) for Ascarids?

Answer 17

develops inside the egg

Question 18

What are the ascarids that affect dogs and cats?

Answer 18

dogs: toxocara canis and toxascaris leonina
cats: toxocara cati

Question 19

What is the definitive host(s) for toxocara canis?

Answer 19

wild and domestic canids

Question 20

Your puppy ingests feces that’s contaminated with T. canis. What’s the likely pathway that the T. canis travels through to reek havoc on the poor pup? (Start from L3’s ingestion)

Answer 20

• Consumed by young animal
• 4 hours the L3 are now in duodenum
• Go to lymphatics to meenteric LN then through portal circulation to Liver (takes 24 hours)
• 12-72 hours: have gone through Vena Cava to heart to the lungs then they hang out in alveolar capillaries
• In alveoli: migrate up bronchioles to the trachea
• Get coughed inton pharynx and swallowede and goes through to SI (takes 10-15 days)
• Leads to eggs being produced in intestine (30-35 days)

Question 21

That puppy has grown up to be an adult dog, and admittedly he isn’t the sharpest tool in the shed. You’ve realized he’s eaten some feces that you believe is contaminated by T. canis. What’s the likely pathway for infected larvae (L3)? (start with ingestion of L3)

Answer 21

• Consumed by adult
• 4 hours the L3 are now in duodenum
• Go to lymphatics to meenteric LN then through portal circulation to Liver (takes 24 hours)
• 12-72 hours: have gone through Vena Cava to heart to the lungs then they hang out in alveolar capillaries
• At alveoli, reenter bloodstream and go to heart
• Gets pumped systemically into somatic tissue and become hypobiotic larvae
• Can invade tissue and hang out in tissue
• Granuloma will form around them (survive a year)

Question 22

You have a bitch that has T. canis hypobiotic larvae in somatic tissue. In late pregnancy, you grow worried about it getting to her puppies. What route would the larvae go through to infect her pups?

Answer 22

• Hypobiotic larvae are in somatic tissue
• Last trimester for female, the larvae are active again
• go into circulation of bitch and enter uterine circulation
• larvae crosses placenta and goes into fetal circulation
• it goes into fetal liver
• Then after birth, the larvae travels from liver to lung
• then to trachea to be ingested and on through to small intestine

Question 23

What pathway would a lactogenic transmission of T. canis L3 to the puppies occur?

Answer 23

• Hypobiotic larvae activated in late gestion and early lactation
• Migrate to mammary glands
• Pups ingest larvae in colostrum and milk
• some ingested larvae directly mature in small intestine

Question 24

If T. canis was planning on infecting a host by using paratenic hosts. What route would it take?

Answer 24

• larvae are in paratenic hosts (mouse)
• eaten an egg with L3 in it, gone through: SI to liver to heart to lungs to systemic circulation into somatic tissue (in a granuloma)
• dog eats the infected mouse
• L3 is activated
• young dog: larvae is ingested, L3 at SI goes through portal circulation to liver, then goes to lung via vena cava/heart, then goes up to trachea and down through GI tracts to intestine, where egg production occurs
• adult dog: larvae is ingested, L3 at SI goes through portal circulation to liver, then goes to lung via vena cava/heart, then larvae goes back into systemic circulation to somatic tissue to feast in granuloma for the rest of its days

Question 26

What are the morphologic features for Phylum Nematoda?

Answer 26

1. Spindle shaped 1. tapering at 1 or both ends 1. anterior end of nematodes are crucial for identification 2. Body not segmented 3. Body cavity and digestive tract present 4. separate sexes (dioecoius)