Specific features of embryonic development of Trichuris skrjabini (Baskakov, 1924) nematode eggs parasitizing in sheep

Specific features of embryonic development of eggs isolated from gonads of Trichuris skrjabini nematodes females, obtained during helminthological opening in sheep, were studied. It is proved that during the growth and development of this species of trichurises eggs there are significant changes in the metric indices of their length and width, as well as in the length and width of their lids. It is determined that at 27 °С in laboratory conditions T. skrjabini eggs become infectious during 51 days with survival rate of 80.0±0.82 % (20.0±0.81% of eggs stop in development and subsequently die). The embryogenesis process has six morphologically distinct stages: protoplast (from the 1st to the 12th day); blastomeres formation (from the 6th to the 24th day); bean-like embryo (from the 12th to the 33d day), tadpole-like embryo (from the 15th to the 36th day); larval formation (from the 27th to the 48th day); and mobile larva (from the 27th to the 51st day). The development of T. skrjabini eggs to the infectious stage in laboratory conditions is characterized by their lengthening to 75.7±0.36 μm (by 2.0%, р < 0.05), narrowing to 37.3±0.30 μm (by 2.4%, р < 0.05) and lengthening to 12.2±0.42 μm (by 16.4%, р < 0.01) and thinning to 12.1±0.10 μm (by 5.5 %, р < 0.01) of the egg lids. The changes of egg shell thickness were not statistically significant. Considering the data on the morphological structure and the period of nematodosis pathogens eggs development it is possible to plan the time of taking measures to prevent and control trichurosis in sheep.