[Determination of the activity of luteinizing hormone in PMSG preparations using testosterone synthesis in vitro]. / Stanovení aktivity luteinizacního hormonu v preparátech PMSG podle syntézy testosteronu in vitro.

The activity of luteinizing hormone (LH) in serum gonadotropin (PMSG) was studied by a bioassay in vitro, using the cells of mouse testes prepared by the combination of enzymatic and mechanical diffociation. The activity of individual preparations was calculated according to the amount of produced testosterone measured by radioimmunoassay. Comparison with the 2nd international standard of PMSG (WHO) showed that in the PMSG substandard (Dessau) the activity of LH was twice lower, and in three charges of the commercial PMSG preparation (Bioveta, Ivanovice in Haná) four-and-a-half times lower than declared. No great variability of LH activity was observed among the charges of the commercial PMSG preparation.

[The effect of different cell concentrations and incubation time of testicular tissue testosterone synthesis]. / Vliv ruzných bunecných koncentrací a doby inkubace varletní tkáne na syntézu testosteronu.

The cells of the testes of mice were enzymatically separated and the amount of Leydig cells was determined in different stages of dispersion and after washing the separated tissue. This amount ranged from 2 to 9%. The largest quantity of Leydig cells (9%) was obtained when separated tubuli were washed. The response of cell suspensions at seven concentrations stimulated by human chorion gonadotrophin (HCG) was tested. Cell suspension concentrations from 5.3 x 10(5) to 1.4 x 10(6) cells/ml were found to be satisfactory. After two to three hours of incubation, the values of testosterone could be used for the determination of the activity of gonadotropic preparations.

[Determination of the gonadotropin activity of biological preparations by testosterone synthesis in mouse testes in vitro]. / Stanovení gonadotropní aktivity biopreparátu podle syntézy testosteronu mysími varlaty in vitro.

The ability of mouse testicular tissue to respond to stimulation by a commercial preparation of human choriongonadotropin (Praedyn Spofa) was tested in vitro, using whole testes, fragments and cell suspension. In each experiment seven gonadotropin concentrations ranging from 0.06 to 50 i. u. per litre were tested, and the results were compared with the group of control samples without gonadotropin. The incubation of whole testes with gonadotropin of different concentrations was performed in five vessels, each containing one testis; the fragments were incubated in four vessels, each containing four fragments from different testes, and the cell suspension in triplicates containing 1 . 10(6) cells per ml. All three types of tissue reacted to the increasing concentrations of stimulating agent by the increasing production of testosterone, the concentration of which was determined by radioimmunoassay. For the suppression of the individuality and for achieving a uniform response of the individual samples with each stimulation, the cell suspension of testes from several animals appears to be most suitable.