[The role of embryoid bodies in the development of germinogenous tumors of complex structure and of the teratoma].

250 germinal gonadal and extragonadal tumors were studied in children and adolescents under 16 years of age. Germinal tumours of complex structure were found in 42 patients and in 36 of them embryoid bodies of various types (full, not-full, amorphous) were distinguished. Certain features were revealed indicating the development of the immature teratoma by means of maturation of preexisting embryoid bodies. The arguments in favour of complex germinal tumour development due to the loss of maturation and differentiation capacity of one or several structural elements of the embryoid bodies are presented. The observation of mature, immature embryonal tissues and proliferating elements of the embryoid bodies in the composition of one and the same tumour may be explained by different biological potency of individual clones of atypical and primordial germinal cells which are the source of the development of these tumours.