Peculiarities of embryogenesis morphology and biometric parameters of Trichuris suis Schrank, 1788 eggs sampled from different organic substrates are described. The eggs of T. suis under laboratory conditions at a temperature of 27 °С reach the infectious stage in 40 days and pass through seven stages of embryogenesis. The study revealed significant differences in growth and development of eggs obtained from the nematode gonads and the faeces of infected animals (Sus scrofa domesticus Linnaeus, 1758), according to length and width of eggs and eggshell plugs. The excreted T. suis eggs were shown to be better adapted to environment (survivability 96.6 ± 0.33 %), than the eggs obtained from the gonads of female nematodes (survivability 89.3 ± 0.33 %).
Morphometric peculiarities of the development of Оesophagostomum dentatum Rudolphi, 1803 from egg to infective larva were studied under laboratory conditions at various temperatures. The determined optimum temperature for embryonic and post-embryonic development of О. dentatum larvae from domestic pig (Sus scrofa domesticus Linnaeus, 1758) is 22 °С. At this temperature, 81 % of larvae develop to the third stage (L3) on the 10th day. Temperatures of 24 °С and 20 °С are less favorable for the development of the nematode, at those temperatures only 67 and 63 % of larvae, respectively, reached infective stage by the 10th day of cultivation. Embryonic development of О. dentatum eggs is characterized by their lengthening (by 8.87-9.50 %, р < 0.01) and widening (by 6.77-9.35 %, р < 0.05-0.01), and post-embryonic larval development is associated with lengthening (by 4.59-17.33 %, р < 0.01-0.001).
Morphological characteristics were studied in adult and embryonic Amidostomum anseris (Zeder, 1800) obtained from domestic goose Anser anser domesticus Linnaeus, 1758. The studied characters included species-specific morphometric indices of male and female specimens and differential characters of sex-related dimorphism in that species. Stages and periods of embryonic development, and viability of the nematodes were studied at laboratory conditions. Size dimorphism in A. anseris was considerable, females were significantly larger (by 10.09–27.98 %) than males by 11 parameters. Additional metric characters were proposed to enhance effectiveness of differentiation of female and male A. anseris specimens. Under laboratory conditions, embryonic development of A. anseris occurs in four stages: blastomere cleavage; larval formation; formation of non-infective larvae I and II; formation of infective larva III which hatches from the egg. Infective larvae develop at 23 °С in six days, and their viability was up to 78.33 ± 2.08 %.