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Table 1 Morphometric and morphological features reported for the microscopic identification of the third-stage larvae of the gastrointestinal nematodes (GIN) of sheep

From: Practical guide for microscopic identification of infectious gastrointestinal nematode larvae in sheep from Sardinia, Italy, backed by molecular analysis

Species/genus Full body length (µm) Sheathed tail length (µm) Group (sheathed tail) Number of intestinal cells Shape and configuration of intestinal cells Shape of head Shape of tail base Shape of sheathed tail Presence of sheathed tail filament (proportion of sheathed tail)
Trichostrongylus spp. 693–714a 25–29a Short (A) 16 Triangular, 1 terminal cell Rounded 1–3 tubercles or smooth Conic No
622–796b 21–40b
710c 18–31c
Teladorsagia circumcincta 819–907a 32–46a Short (A) 16 Triangular/pentagonal, 1 terminal cell Flat/square, cranial inflexion Smooth Blunt No
797–910b 30–60b
830c 30–44c
Haemonchus contortus 657–733a 40–80a Medium (B) 16 2 terminal cells Bullet–shaped Smooth and pointed Slightly curved base Yes (small, 10–15%c)
650–751b 65–78b
730c 65–82c
Cooperia spp. 752–862a 74a Medium (B) 16 Triangular, 1 terminal cell Square/rounded, 2 refractile bodies Smooth Pointed Yes (20%c)
711–924b 35–82b
865c 39–82c
Oesophagostomum spp. 796–940a 130–170a Long (C) 24–32a Triangular/pentagonal Roundedb Smooth / Yes (long,
771–923b 125–160b 16–24b Squarec
850c 122–207c 18–22c  
Chabertia ovina 747–800a 105–120a Long (C) 24–32a Rectangular Roundedb Smooth / Yes (long, 25%c)
710–789b 110–150b 24–32b Squarec
750c 101–150*c 28–32c  
  1. Data acquired from the following sources: I.N.R.A. [27]a, Zajac and Conboy [20]b and van Wyk [19] and van Wyk and Mayhew [13]c . No specific reference was placed in the table if all sources agree