Table 12

Quotient and 95% confidence limits of mean growth rates of Tetrahymena under continuous or periodic T² treatment.

(Csaba, G., Németh, G., Juvancz, I., Vargha, P. Involvement of selection and amplification mechanisms in hormone receptor development in a unicellular model system. BioSystems 15, 59-63, 1982)

Continuous schedule

Period of treatment (days)	1	3	6	9	12	18	24
Mean growth rate(treated/cont)	1770	1658	1670	1650	1677	1632	1644
Limit values
upper	1978	1873	1917	1904	1905	1850	1846
lower	1593	1476	1465	1442	1486	1448	1472

Periodic schedule

Day of last treatment	1	3	6	12	24
Mean growth rate(treated/control	1512	1813	1781	1536	1710
Limit values
upper	1691	1982	1987	1687	1896
lower	1358	1664	1606	1404	1550

Conclusions:

1. Though T₂ equally enhanced cell division during continuous or periodic treatment, the populations differed in structure.
2. During continuous treatment the population tended to become inhomogeneous, while during periodic treatment the variance was the same as in the control group, however the 2^nd and 3^rd exposures were more effective.
3. Continuous treatment leads to a selection process, while periodic treatment leads to hormonal imprinting.
4. Selection and amplification mechanisms promote hormone receptor development by joint rather than alternate action.