VET350 Sections 6.1-6.2.2 PowerPoint-1

Page 1: Structural Features and General Biology of Nematodes

• Sections 6.1-6.2.2

Page 2: Introduction

• Nematodes are one of the most numerous and diverse life forms on the planet.

• Most are free-living, but some are parasitic to plants or animals.

Page 3: Structural Features

• Key Structural Elements:

  • Lateral muscle

  • Dorsal nerve cord

  • Dorsal epidermis

  • Pseudocoelom

  • Gut cavity

  • Pharynx

  • Cuticle

  • Excretory system (excretory vesicle, gland, seminal duct)

  • Reproductive structures (testis, sperm)

  • Anus and cloaca

Page 4: Recognition Features

• Surface Structures:

  • Cuticle covering may have sensory papillae, alae, or swellings.

• Body Regions:

  • Cephalic: Head-end

  • Cervical: Behind the head

  • Caudal: Tail-end

• Accessory Sexual Structures (Males):

  • Spicules: Rod-like structures for sperm transfer.

  • Bursa: Clasping organ at the posterior end.

  • Nematodes: Bursate (with bursa) vs. Nonbursate (without bursa).

Page 5: Head, Mouth, and Associated Structures

• Features:

  • Leaf crown: Rows of leaf-shaped structures around the mouth.

  • Buccal cavity: Large space behind the mouth.

  • Teeth: Located around the mouth or at the base of the buccal cavity.

  • Cutting plates: Serve a function similar to teeth.

• Digestive Passage:

  • Mouth leads to the pharynx, with a Rhabditiform oesophagus having two thickenings separated by a constriction (common in free-living and plant parasitic nematodes).

Page 6: Histological Appearance

• Focused on the appearance of nematodes in histological sections.

Page 7: General Biology

• Feeding Mechanisms:

  • Most nematodes feed on host secretions or various cells.

  • Plug feeders can cause aggressive feeding and lead to bleeding ulcers.

• Life Cycle Stages:

  • Egg > L1 > L2 > L3 > L4 > Adult.