NEMATODES INTRODUCTION Flashcards
Nematodes also known as
Roudworms
General Characteristics of NEMATODES
- Cylindrical in shape
- free-living or parasitic
- unisexual
- may have a direct or indirect life cycle
- unsegmented
- present alimentary canal
- with body cavity filled with fluid
NEMATODES General Morphology of the Integumentary System
- elongated, cylindrical, and tapering at the extremities
- body is covered by a smooth cuticle
All nematodes are elongated, cylindrical, and tapering at the extremeties except
Tetrameres & Simondsia
Tetrameres are found in this organ
Proven of chicken
It swells after copulation giving the spherical appearance
Tetrameres
Type of nematodes which globular posteriorly
Simondsia
the cuticle of nematodes may form special adhesive structures like
hooks
thickenings
cresent cephalic collar
the cuticle of nematodes may form special adhesive structures like hooks and are present in these nematodes/roundworms
Tetrameres & Rictularia
the cuticle of nematodes may form special adhesive structures like simple or more complicated thickenings and are present in these nematodes/roundworms
Gongylonema & Acuaria
the cuticle of nematodes may form special adhesive structures like cresent cephalic collar and are present in these nematodes/roundworms
Physaloptera
The cuticle of nematode is formed by an underlying syncytium of cells called the
hypodermis
It forms 4 longitudinal thickenings, two of which are part of the excretory system and the 2 others are nerve cords.
Hypodermis
The hypodermis of nematodes forms 4 longitudinal thickenings, two of which are part of the ________ and the 2 others are _______.
excretory system
nerve cords
The cuticle has a variety of modifications namely:
- leaf crowns
- Cervical or caudal papillae
- Cervical and caudal alae
- Copulatory bursa
- Plaques and Cordons
- Mouth
- Amphids
- Phasmids
rows of papillae around the rim of buccal capsule
leaf crowns
Leaf crowns are prominent in these nematodes
horse nematodes
The function is unknown but its is suggested that it is used to pin a patch of mucosa in position during feeding or they may prevent entry of foreign matter into the buccal capsule when the worm has detached from the mucosa
Leaf crowns
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 region
Cervical and caudal alae
structure that embraces the female during copulation; highly developed in strongylids; derived from the much expanded caudal alae
Copulatory bursa
This structure is not present in Ascaris and Trichuris
Copulatory bursa
highly developed in these namatodes
strongylids
plate-like and cord-like ornamentation present in the cuticle of many nematodes of the superfamily Spiruroidea
Plaques and Cordons
Plaques and Cordons are present in the cuticle of many nematodes of this superfamily
superfamily Spiruroidea
sometimes subdorsal or subventral; it is usually surrounded by 2 or 3 lips which bears papillae
Mouth anterior
depression on each side of the head
Amphids
depression on the posterior extremity, these structures act as chemororeceptors. It is used as a basis for classification (Phasmidea and Aphasmidea)
Phasmids
Phasmids act as
chemororeceptors
It is used as a basis for classification (Phasmidea and Aphasmidea)
Phasmids
the buccal capsule may contain tooth (Strongyloid). The esophagus is another basis for classifying nematodes. It has triradiate lumen lined with a cuticle. The wall contains 3 esophageal glands which secrete digestive enzyme. It is muscular enabling it to pump food into the intestine
Buccal capsule or esophagus
the buccal capsule may contain tooth, can be seen in this nematode
Strongyloid
is another basis for classifying nematodes
Buccal capsule or esophagus
The wall of the Buccal capsule or esophagus contains this gland which secretes the digestive enzyme.
3 esophageal glands
It is muscular enabling it to pump food into the intestine
Buccal capsule or Esophagus
simple tube with non-muscular wall. It is composed of a single layer of columnar cells
Intestine
lined with cuticle; into which the genital duct opens-in male (cloaca)
Rectum
Situated behind the anal or cloacal opening
Tail
Nematodes absorption of nutrients is via
microvilli in the gut
region between muscle and alimentary canal
perienteric space
The perienteric space contains ________ which is composed of proteins, fats, glucose, enzymes and oxyhemoglobin which serves the function of blood.
perienteric fluid is composed of
(FEGOP)
fats
enzymes
glucose
oxyhemoglobin
proteins
which serves the function of blood
oxyhemoglobin
This fluid produces high pressure which maintains the turgidity and shape of the nematode.
perienteric fluid
male genital system of nematodes
Spicule
Testis
Copulatory bursa
Ejeculatory duct
Vas deferens
Female genital system of nematodes
Ovary
uterus
Vagina
Vulva
structure of the copulatory bursa
Spicula
Anus
Dorsal lobe
Lateral lobe
Bursal rays
Copulatory bursa
The basic forms of esophagus found in nematodes
- Double-bub
- Muscular-glandular
- Trichuroid
- Rhabditiform
- Filariform
- Bulb
Double-bub form of esophagus is found in this nematode
Oxyurids
Causative agent of anal scooting
Oxyurids
Muscular-glandular form of esophagus is found in this nematode
Filaroids
Trichuroid form of esophagus is found in this nematode
Trichuroids
Rhabditiform form of esophagus is found in this nematode
Freeliving
Ancylostoma Larva of strongyloides
Filariform form of esophagus is found in this nematode
Parasitic Strongyloides
Bulb form of esophagus is found in this nematode
Ascarids
Toxocara
Integumentary System of Nematodes
✓ buccal capsule or esophagus
✓ intestine
✓ rectum
✓ anus
✓ tail
brain of the nematodes is called
circumesophageal ring
It consist of a number of ganglia “connected by fibers forming the nerve ring which surround the esophagus
circumesophageal ring
found around the mouth, which act as chemoreceptors
amphids
found around the anus which act as chemoreceptors
phasmids
Male nematodes are usually smaller than females
Male reproductive organs:
Single testes
vas deferens
seminal vesicle
muscular ejaculatory duct
cloaca
the structure that opens in the cloaca which serves during copulation for attachment and to expand the vagina and direct the flow of sperms
usually paired but some species have only one (Trichuris) or none (Trichinella
spicule
Spicule are usually paired but some species have only one (what sp.?) or none (what sp.?)
Trichuris
Trichinella
cuticular thickening in the dorsal wall of cloaca which guide the spicule; may or may not be present
gubernaculum
cuticular thickening in the ventral wall of cloaca
Melamon
Female reproductive organs
✓ two ovaries
✓ oviduct
✓ seminal receptacle
✓ uterus
✓ vagina
✓ vulva
where eggs are sorted and fertilized
seminal receptacle
Where egg shells are formed
uterus
a short muscular organ located at the junction of the uterus and vagina in some species which assists in egg-laying
Ovijector
found in some Trichostrongylids; it has the same function with ovijector
Vulva flap
Vulva flap is found in some of these nematodes
Trichostrongylids
Infective stage of a direct life cycle
L3
This nematode causes anal scooting
Oxyurids
Digestive system of Nematodes
• Mouth
• buccal capsule or esophagus (w/ esophageal glands)
• intestine with microvilli
• rectum
• anus
