THE association between neoplasia and age is well seen in human prostatic cancer. In this disease, although the incidence increases with age, there is often a marked decline in biological malignancy (Franks, 1956), but it is uncertain whether the change is due to an alteration in the tumour or to endocrine or other changes in the host, which are known to accompany ageing. In addition the mechanism by which hormone-induced changes are produced in tumours or normal tissues in the intact animal remains obscure. By using the organ culture technique in which tissue can be maintained in an organised form in vitro for several weeks, it is possible to study the local tissue (or tumour) factors in isolation, and to observe the direct effects of specific hormones. There have been few reports however of studies of this type on adult tissues, except for those of Lasnitzki who, in a series of papers (Lasnitzki, 1951(Lasnitzki, , 1954(Lasnitzki, , 1955a, has described the effects of methylcholanthrene, oestrone, testosterone propionate and vitamin A on organ cultures of mouse prostate. The present paper records the effects in vitro of oestrogens and testosterone on the ventral prostate of mice of different ages, and is preliminary to a more detailed study of the human and rodent prostate.
MATERIAL AND METHODSC57 mice were used in all except one series of experiments and killed by neck dislocation. The ventral prostate was removed and each lobe of the paired gland was divided into two, or occasionally, if the lobe was very large, into four pieces. Tissue from each mouse thus provided material for four or eight cultures, which were divided into four groups-one group grown on control medium and three on hormone-containing media. The cultures were explanted on rayon (4 pieces on 1 cm. squares) by Shaffer's (1956) modification of the standard watch glass technique (Fell and Robison, 1929). Each watch glass contained 2 pieces of rayon, i.e., 8 cultures, on 1.5 ml. of clotted medium, composed of 0.5 ml. each of chicken plasma, chick embryo extract and human serum. The hormones used were dissolved in the human serum, to which was also added sufficient chloromycetin to give a final concentration in the medium of approximately 003 mg./ml. Cultures were incubated at 37°C and the medium changed every 3 or 4 days. Eight cultures from each group were fixed after 1, 3, 7, 10 and 21 days in experiments 1, 2 and 3. The media used in each of these experiments were: 1. Control medium.2. Control medium + oestrone 2