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Table 1 Modified Knott’s test recovery comparison of D. immitis microfilaria, MO and JYD isolates, using Year 1 cryopreservation procedure

From: Feasibility and comparative analysis of Dirofilaria immitis microfilaria freezing and fixation for student instruction and assessment of clinical parasitology skills

DayIsolateRecoveryMeasurementsSizeScore
0MO> 1000215.0–255.0 × 2.5–5237.0 × 32.4
7MO> 1000257.5–312.5 × 5288.0 × 52.1
21MO1189255.0–300.0 × 5276.8 × 52.2
70MO897222.5–270.0 × 2.5–5240.5 × 4.82.1
0JYD> 1000257.5–292.5 × 5274.0 × 53
7JYD> 1000257.5–302.5 × 5275.5 × 52
21JYD> 1000250.0–292.5 × 5271.8 × 52
70JYD> 1000237.5–270.0 × 5253.0 × 51.9
  1. Day 0, no cryopreservation added, Day 7, 21, and 70 cryopreservation added followed by freezing at − 20 °C
  2. MO and JYD isolates from experimentally infected dogs
  3. Modified Knott’s slide with 50-uL of sediment, number of microfilaria detected
  4. Range for the 10 microfilaria measured in μm
  5. Average length and width of the microfilaria measured in μm
  6. Average Head Score- 1-3 scale, 3 = clear and distinguished head; 2 = stained head but lighter than body; 1 = stained same color as body or indistinguishable