FINALS

posterior part assumes a globular shape

Simondsia sp.

after copulation, female swells and become almost spherical

Tetrameres sp.

2 types/ forms of larvae

• Rhabditiform: free-living worm

• Filariform: parasitic worm

Note: Rhabditiform will eventually transform to filariform

Nematodes in general are elongated, cylindrical, and tapering exept 2

1. Tetrameres spp.

• adults are normally elongated and cylindrical, but after copulation, gravid females become spherical and attach to the lumen of the GIT ⤷ typically either in the proventriculus or the crop!

2. Simondia spp.

• posterior ends of gravid females become globular after copulation

There is one (1) exception to these worms being dioecious (Nematode)

• Caenorhabditis elegans is considered to be androdioecious; consisting of hermaphrodites and rare males!

is considered to be androdioecious; consisting of hermaphrodites and rare males!

• Caenorhabditis elegans

Nematode Body Layers and Composition

Ectoderm: body covering

Mesoderm: muscle layer

Ectoderm: digestive tract

Pseduocoelom: space between the endoderm and muscle layer

the space between the endoderm and the next layer is known as the

e pseudocoelom, which contains the perienteric fluid

Perienteric fluid is produced by the cells which line the esophagus, known as

Pseudocoelomites or Stellate Cells

Perienteric Fluid

• this fluid is produced by the cells which line the esophagus, known as pseudocoelomites or stellate cells

• it is composed of substances such as ions

• it functions to maintain the worm’s internal pressure, which is ½ atmospheres higher compared to the external environment

lines the digestive tract, consisting of the oral cavity, the esophagus, and the intestines

Endoderm

• muscular layer consisting of only a longitudinal muscle layer

• no circular muscle layer is present!

Mesoderm

• body covering, or the cuticle

• together with the muscular layers, the cuticle prevents the explosion of the worm due to the high internal pressure

Ectoderm

The whole body of a nematode is referred to as the

Hydrostatic Skeleton

Nematodes excrete their waste in the form of

NH3 (Ammonia)

Nematodes excrete their waste in the form of NH3 (Ammonia) through

Paired Nephridia

Marine Nematodes excrete their waste through

Rennete Cells

Plaques and Cordons

Spicule

Amphid

phasmid

Cuticular Modification

1. Phasmid

2. Amphids or Deirids

3. Leaf crown or Lips

4. Cervical or Caudal Papillae

5. Cervical or Caudal Alae

6. Plaques and Cordins

7. Spicules

8. Gubernaculum

9. Telamon

• depression at the posterior extremity

• has sensory function (chemoreceptive)

• the presence or absence of this organ depends on the species of nematode

Phasmid

• counterpart of phasmids

• found at the anterior extremity

• on either side of the head

Amphid or Deirids

• row of papillae around the rim of the buccal capsule

★ These are predominant in horse roundworms!

Leaf crown or lips

These are predominant in horse roundworms!

Leaf crown or lips

spine-like or finger-like processes which are sensory or supportive in function

Cervical or Caudal papillae

flattened, wing-like expansions of the cuticle in the esophagus and tail regions

Cervical or Caudal Alae

plate-like and chord-like ornamentations present in the cuticle of many nematodes

Plaques and Chords

• structure utilized by male nematodes that functions for attachment during copulation and expands the vagina

• ⤷ done by parting the vulva of their mating partners!

• the number of spicules varies based on the species

• ⤷ e.g. Trichuris spp. have 1 spicule, while Trichinella spp. have 2 spicules!

• ★ Doc Vitz’s MNEMONIC:

• TrichurIs has 1 ‘i’ at the end, hence only one spicule, while TrichineLLa has 2 ‘l’s at the end, hence having two spicules!

Spicules

cuticular thickening in the dorsal wall of the cloaca of males which guides the spicules for copulation

Gubernaculum

cuticular thickening in the ventral wall of the cloaca of males which guides the spicules for copulation

Telamon

How do nematode move?

mainly through the less than ½ atmosphere pressure difference compared to the external environment

The musculature of nematodes is divided into 2 major planes:

1. Dorsal Field: Dorsal Epidermal Chord

2. Ventral Field: Ventral Epidermal Chord

• the demarcation line between these two layers is the lateral epidermal chord

Nematodes have 4 types of nerves:

1. Dorsal Nerve: motor function

2. Ventral Nerve: sensory function

3. Lateral Nerve (2): both for sensory and motor fnx

• somatic division is voluntary

• autonomic division is involuntary; further divided into sympathetic + parasympathetic sections

• motor function

Dorsal Nerve

• innervates cuticular modifications such as the phasmids, amphids, and cervical and caudal papillae

• Sensory fnx

Ventral Nerve

This part of nematode is equivalent to the “BRAIN”

Circum-oesophageal commisures

Nematodes detect objects in their path through the

• Amphid

• Cervical papillae

these structures will then send signals for the ventral nerve, which then propagates the signals to the “brain” to move its body via the command of the dorsal and lateral nerves

• Amphid &

• Cervical papillae

There are 2 main types of purgatives/dewormers, namely:

• Vermifugal- which result in intact worms being passed out in the feces

• Vermicidal-which result in damaged or macerated worms being passed out in the feces

TYPE OF ESOPHAGUS

1. Bulb shapes

2. Double-bulb shape

3. Rhabditiform

4. Filariform

5. Muscular gland

6. Trichuroid

• has a large posterior swelling, like in ascarids

• present in the ff. families:

• ○ Family Ascarididae

• ○ Family Hetarakidae

Bulb shape

What families under Esophagus Bulb-shaped

• Family Ascarididae

• Family Hetarakidae

• has double large posterior swellings, like in oxyurids

• present in the ff. families:

• ○ Family Oxyuridae ONLY

• pinworms

Double-bulb shape

What families under Esophagus Double- Bulb shaped

• Family Oxyuridae

• as a slight anterior and posterior swelling

• present in pre-parasitic larvae of many nematodes, and in any adult free-living nematodes

• present in the ff. families:

• ORDER: RHABDITIDA

• ○ Family Strongyloididae ONLY

Rhabditiform

What families under Esophagus Rhabditiform

• Family Strongyloididae

• Simple and slightly thickened posteriorly,

• as in bursate nematodes

• present in families under the

• Order Strongylida

• Superfamily Strongyloidea

• Family Strongyloididae

• Family Stronglidae

• Family Stephanuridae

• Family Syngamidae

• Family Ancylostematidae

• Family Trichostrongylidae

• Family Trichonematidae

Filariform

What families under Esophagus Filariform

• Strongyloididae

• Strongylidae

• Stephanuridae

• Syngamidae

• Ancyslostomatidae

• Trichostrongylidae

• Trichonematidae

• muscular anteriorly,

• glandular posteriorly,

• like in filariids and spirurids

• present in families under

• Order Spirurida

• Superfamily Spiruroidea

• -   Family Acuriidae

  • Family Acuriidae

  • Family Dracunculidae

  • Family Filariidae

  • Family Gnathostomatidae

  • Family Onchoceradae

• Family Physalopteriidae

• Family Steriidae

• Family Spiruridae

• Family Thelaziidae

• Family Tetrameridae

Muscular-glandular

Family under Esophagus Muscular Glandular

• Family Acuriidae

• Family Dracunculidae

• Family Filariidae

• Family Gnathostomatidae

• Family Onchoceradae

• Family Physalopteriidae

• Family Steriidae

• Family Spiruridae

• Family Thelaziidae

• Family Tetrameridae

• capillary form

• lined with stichosomes, which are stacked in columns and function for phagocytosis

• present in families under

• Order Enoplidae

• Superfamily Trichuroidea, Dioctophymatoidea

• Family Dioctophymidae

• Family Capillaiidae

• Family Trichiellidae

• Family Trichuridae

Trichuroid

Family under Esophagus Trichuroid

• Family Dioctophymidae

• Family Capillaiidae

• Family Trichiellidae

• Family Trichuridae

Presence of phasmids

Phasmidia or Secernentea

Absence of phasmids

Aphasmidia or Adenophorea

found in the members of Order Strongylida (SSSSATT)

Bursate (only with copulatory bursa)

Found in every other nematode family

Non-bursate

only one group of nematodes lack phasmids, which belong to what family

• Order Enoplida

• Family Dioctophymidae

• Family Capillaiidae

• Family Trichiellidae

• Family Trichuridae

females readily produce eggs which are passed out of the body

Oviparous

females produce eggs which are present within the body, and the larvae hatch WITHIN the body of the helminth before being released into the external environment

Ovoviviparous

females do NOT produce eggs, instead they produce larvae which are readily expelled from the body

Viviparous

Number of Ovaries

Monodelphic- 1 ovary

Dipelphic- 2 ovary

Multidelphic- more than 2 ovaries

Location of Ovaries

Prodelphic- ovaries anterior to vulva

Ophistodelphic- ovaries posterior to vulva

Amphidelphic- located both anteriorly and posteriorly to the vulva

Male nematodes possess spicule/s, which are the male reproductive organs, as well as guiding apparatuses known as the

gubernaculum and telamon

Order Ascaridida Consists of three (3) superfamilies

1. Ascaridoidea → bulb-type esophagus

a. Family Ascarididae

i. Ascaris

ii. Toxocara

iii. Parascaris

iv. Toxascaris

v. Anisakis

2. Oxyuroidea → double-bulb-type esophagus

a. Family Oxyuridae

i. Oxyuris

3. Subuluroidea → bulb-type esophagus

a. Family Hetarakidae

i. Hetarakis

ii. Ascaridia

Migration routes of family Ascarididae

• Species: Ascaris suum

• Transplacental

• Transmammary

• Tracheal

• Somatic

• Species: Ascaris suum

• Transplacental: X

• Transmammary: X

• Tracheal: CHECK

• Somatic: X

Migration routes of family Ascarididae

• Species: Parascaris equorum

• Transplacental

• Transmammary

• Tracheal

• Somatic

• Species: Parascaris equorum

• Transplacental: X

• Transmammary: X

• Tracheal: CHECK

• Somatic: X

Migration routes of family Ascarididae

• Species: Toxocara cati

• Transplacental

• Transmammary

• Tracheal

• Somatic

• Species: Toxocara cati

• Transplacental: X

• Transmammary: CHECK

• Tracheal: CHECK

• Somatic: CHECK

Migration routes of family Ascarididae

• Species: Toxocara canis

• Transplacental

• Transmammary

• Tracheal

• Somatic

• Species: Toxocara canis

• Transplacental: CHECK

• Transmammary: CHECK

• Tracheal: CHECK

• Somatic: CHECK

Migration routes of family Ascarididae

• Species: Toxascaris leonina

• Transplacental

• Transmammary

• Tracheal

• Somatic

• Species: Toxascaris leonina

• Transplacental: X

• Transmammary: X

• Tracheal: X

• Somatic: X

Migration routes of family Ascarididae

• Species: Toxocara vitulorum

• Transplacental:

• Transmammary:

• Tracheal:

• Somatic:

• Species: Toxocara vitulorum

• Transplacental: X

• Transmammary: CHECK

• Tracheal: X

• Somatic: CHECK

Common Name of Parascaris equorum

Cn: Equine Roundworm

Scientific Name of Equine Roundworm

Parascaris equorum

Scientific Name of Canine Roundworm

Toxocara canis

Common Name of Toxocara canis

canine roundworm

Most common roundworm affecting both domestic and wild canids

Toxocara canis

The cervical alae of these species given the appearance of arrow-headed worms

Toxocara canis

Toxocara cati

Toxascaris leonina

When these helminths migrate to visceral organs, this phenomenon is known as

Viscera larva migrans

species of nematodes that are capable of performing viscera larva migrans, which include the ff.

Toxocara canis- dog

Toxocara cati- cat

Toxocara borina- cattle, buffalo, zebu

Capillaria hepatica- rats

Lagochilascaris minor- dog, cat, and other mammal

Common name of Toxocara cati

Feline Roundworm

Scientific name of Feline roundworm

Toxocara catis

Nematode which parasitizes both dogs and cats

Toxascaris leonina

Paratenic host of Toxascaris leonina

Rodents

Comon name of Neoascaris/ Toxocara vitulorum

Bovine roundworm

Scientific name of Bovine Roundworm

Neoascaris/ Toxocara vitulorum

Scientific name of Pig Roundworm/ Large Roundworm of pig

Ascaris suum

Roundworms parasitizing the small intestines, lungs, and liver of swine

Ascaris suum

Common name of Ascaris suum

• Pig Roundworm

• Large Roundworm of pig

Roundworms parasitizing cattle

Neoascaris/ Toxocara vitulorum

These Ascaris suum have a pathognomonic Lx produced by L3 larvae upon necropsy

milk spot of the liver

Ascaris suum have unique ova in that these eggs have:

(a) mammilated layer → golden brown due to the host’s bile

(b) lipid layer → coating made up of ascarosides

Common name of Ascaris Lumbricoides

• Large Roundworm

• Giant roundworm

• Human intestinal roundworm

Scientific name of

• Large Roundworm

• Giant roundworm

• Human intestinal roundworm

Ascaris lumbricoides

Largest roundworm parasitizing the small intestines, lungs, and liver of humans

Ascaris lumbricoides

Roundworms parasitizing raccoons

Ascaris procyonis

Roundworms that parasitize fish and marine mammals

Anisakis spp.

Toxocara canis

Toxocara cati

Toxascaris leonina