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nematodes morphology
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- 2. Topics Size Shape Body wall (Outer body tube) Digestive system (inner body tube) Reproductive system Excretory system Nervous system Respiratory and Circulatory systems Definition 2 7/20/2017Walia CCSHAU
- 3. Size Human andAnimal parasites are big and visible to the naked eyes Ascaris lumbricoides …………………...30 cm Dracunculus medinensis……………….1m Placentonema gigantissimma ………...8 m (longest) Free-living nematodes microscopic Greeffiella minutum…………………….82 µm (smallest) Plant parasitic nematodes Microscopic, range……………………..0.3 – 2.0 mm Paralongidorus epimikis ……………1.2 cm (longest) 3 7/20/2017Walia CCSHAU
- 4. Relative Size &Shape 4 7/20/2017Walia CCSHAU
- 5. Shape Normal shape Vermiform Sexualdimorphism 5 7/20/2017Walia CCSHAU
- 6. Body regions, Colouration,Segmentation Head – Continuous or set off Tail - body portion beyond anus, shapes variable Appendageless Colourless Body wall transparent No metameric segmentation All natural openings on one side - ventral side 6 7/20/2017Walia CCSHAU
- 7. Body Organization andSymmetry Body tubular Outer tube – Body wall Inner tube – Alimentary canal Body Cavity – Pseudocoelome Bilateral symmetry 7 7/20/2017Walia CCSHAU
- 8. Body Wall 1. Cuticle2. Hypodermis 3. Muscle layer 8 7/20/2017Walia CCSHAU
- 9. Cuticle – Non-cellular – Toughbut elastic – Exoskeleton – Regulates permeability – Regulates body growth – Helps in locomotion – Plays role in respiration – Plays role in excretion – Moults four times – Consists of structural proteins (keratin, collagen, matricin) – Chitin absent in cuticle 9 7/20/2017Walia CCSHAU
- 10. Cuticular markings A.Transverse Smooth StriatedAnnulated Striated Annulated 10 7/20/2017Walia CCSHAU
- 11. Cuticular markings Caudal alae(Bursa) Leptoderan Peloderan B. Longitudinal Lateral alae 11 7/20/2017Walia CCSHAU
- 12. Hypodermis & Musculature Hypodermis:Cellular or syncytial, secretes new cuticle after every moult, forms 4 hypodermal chords Musculature : Somatic, Specialized 12 7/20/2017Walia CCSHAU
- 13. Musculature Somatic muscles Attachedto body wall Nvbnvbn • Specialized muscles Associated with special organs e.g., stylet, spicules A. Platymyarian B. Coelomyarian C. Circomyarian 13 7/20/2017Walia CCSHAU
- 14. Alimentary Canal –The Inner Body Tube Stomodaeum – The Fore gut Oral aperture (Mouth) Stoma ( Buccal cavity) Oesophagus (Pharynx) Cardia (Oesophago-intestinal valve) Mesenteron – The Mid gut Intestine Proctodaeum – The Hind gut Rectum Anus 14 7/20/2017Walia CCSHAU
- 15. Stomodaeum - Oralaperture En-face view 15 7/20/2017Walia CCSHAU
- 16. Microbivorous Predator Phytophagous Stomodaeum- Stoma 16 7/20/2017Walia CCSHAU
- 17. Cephalic Sclerotization &Stylet 17 7/20/2017Walia CCSHAU
- 18. Stomodaeum - TheStylet Stomatostylets in Tylenchids Conus Shaft Knobs(3) Lumen 18 7/20/2017Walia CCSHAU
- 19. Stomodaeum - TheOesophagus Corpus Postcorpus 19 7/20/2017Walia CCSHAU
- 20. Stomodaeum - PPNs NoGland overlap Gland overlap 20 7/20/2017Walia CCSHAU
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- 22. The Mesenteron andProctodaeum Mesenteron Intestine Wall made up of single layer of epithelial cells; inner margins lined with microvilli Proctodaeum Rectum In males, intestine joins vas deferens to form common tube – cloaca Anus Females have a separate opening; pore-like on ventral side 22 7/20/2017Walia CCSHAU
- 23. Reproductive System Nematodesare dioecious Both sexes look alike Reproductive system is tubular Males v/s Females • Males are slightly shorter • Tail end curved ventrally • Possess secondary sexual organs • Spicules • Gubernaculum • Bursa 23 7/20/2017Walia CCSHAU
- 24. Female Reproductive System Ovary Germinalzone: Production of oogonia Growth zone: Oogonia increase in size Oviduct A narrow passage for oogonia Spermatheca Store sperms; oogonia get fertilized when pass through Uterus Columellar glandular cells – deposit egg shell around fertilized egg Vagina Expulsion of egg Vulva Slit-like on ventral side; help in egg laying and copulation 24 7/20/2017Walia CCSHAU
- 25. Female Reproductive System Terminology No.of genital tracts • Monodelphic One • Didelphic Two Direction of genital tracts • Prodelphic Directed anteriorly • Opisthodelphic Directed posteriorly • Amphidelphic One directed anteriorly, second posteriorly 25 7/20/2017Walia CCSHAU
- 26. Male Reproductive System Testis Productionof spermatogonia Seminal vesicle Storage of sperms till mating Vas Deferens Passage for sperms, merges with intestine to form cloaca Cloaca Common tube for digestive and reproductive systems Cloacal aperture Common opening for both systems Spicules Sclerotized, a pair, movable, mating organ Gubernaculum Plate-like, not movable, guides the movement of spicules Bursa External cuticular extensions on lateral side, a pair, leptoderan or peloderan, hold female during mating 26 7/20/2017Walia CCSHAU
- 27. Excretory System Phylum Nematodadivided into two classes based on the type of excretory system Function speculatory, may be secretory, osmotic regulation etc. Canalicular or Tubular type Present in Class Secernentea Basically H–shaped, variable Two main longitudinal excretory ducts running in lateral hypodermal chords Joined in oesophageal region by a transverse duct A terminal duct arises and opens on ventral side - the excretory pore Glandular type Present in Class Adenophorea Single (Renette) cell leads to an excretory duct and opens outside through pore 27 7/20/2017Walia CCSHAU
- 28. Nervous System • Mainnerve centre (Brain) is a ring called Nerve Ring or Circum-oesophageal commissure encircling the isthmus region of oesophagus • Main nerves arise from nerve ring and run anteriorly and posteriorly in the hypodermal chords • These longitudinal nerves are interconnected at regular intervals throughout length 28 7/20/2017Walia CCSHAU
- 29. Sense organs • Chemoreceptors (toperceive the sense of chemicals in vicinity) Amphids A pair, opening on lateral sides in head region, help in locating plant roots (Host finding/Chemotaxis) Phasmids A pair, opening on lateral sides in tail region, enlarged phasmids are called Scutellae • Tactoreceptors (to perceive the sense of touch) Papillae/Setae Cephalic Cervical Caudal 29 7/20/2017Walia CCSHAU
- 30. Other Systems RespiratorySystem Well developed organs lacking Oxygen required for aerobic PPNs diffuses through cuticle Circulatory System Well developed organs lacking Pseudocoelomic fluid serves as the means of transport since it bathes different organs 30 7/20/2017Walia CCSHAU
- 31. Definition Nematodes are triploblastic, bilaterallysymmetrical, unsegmented, pseudoceolomate invertebrates, with four main hypodermal chords, a triradiate oesophagus, circum-oesophageal nerve ring, and lacking specialized organs for respiration and circulation; they have tubular gonads which open separately in females but join alimentary canal in males to open through a cloacal aperture. Gross Morphology 31 7/20/2017Walia CCSHAU