Mammary gland morphology and responsiveness to regulatory molecules following prenatal exposure to diethylstilbestrol.

Female ACI rats were exposed to diethylstilbestrol (DES) in utero to evaluate the effects on the peri-pubertal mammary gland with respect to 1) mammary gland morphology, 2) sensitivity to natural and synthetic estrogens, and 3) sensitivity to endogenous epidermal growth factor (EGF). Pregnant rats were injected with vehicle (sesame oil) or DES (total dose, 8.0 micrograms) on days 15 and 18 of gestation. DES-exposed and control offspring were ovariectomized at 34 days of age and sacrificed at day 53 to ascertain the morphology of the mammary glands in peri-pubertal rats. Elvax pellets containing 5 or 11 ng 17 beta-estradiol (E2) or DES were implanted subcutaneously adjacent to the third mammary gland pair. Furthermore, additional groups of rats were subjected to bilateral sialoadenectomy at the day of ovariectomy to remove the major source of endogenous EGF. A significant proportion of mammary glands of DES-exposed animals exhibited atypical mammary gland morphology, with approximately 25% displaying hypo-differentiation, and about 5% with aberrant hyper-proliferation. From the pellet implantation experiments, the DES-exposed glands were found to be refractory to stimulation by 5 and 11 ng DES; however, there was no significant difference in the degree of local stimulation elicited by either dose of E2. Sialoadenectomy at d34 had no apparent effect on mammary gland morphology in either the DES-exposed or vehicle-exposed groups. These data support the premise that the mammary gland of the peri-pubertal ACI rat is morphologically and physiologically aberrant as a function of transplacental exposure to DES, with a significant percentage hypo-differentiated and refractory to subsequent hormonal stimulation.

Morphological and physiological correlates of unilateral agenesis of the urogenital system in young ovariectomized ACI rats.

ACI rats are distinguished by a polygenic trait resulting in unilateral agenesis of the urogenital system in 20-30% of animals of both sexes. This report details additional features, both morphological and physiological, which distinguish ACI rats with unilateral agenesis of the reproductive and urinary tracts from the majority of ACI rats that have intact urogenital systems. Young female ACI rats were ovariectomized at 34 days of age and sacrificed 19 days later. A preliminary determination of the urogenital morphology was made at the time of ovariectomy and then confirmed by careful abdominal inspection at necropsy. Data on the time of vaginal opening were obtained at selected intervals prior to sacrifice. At necropsy, the mammary glands were removed and were prepared as stained whole mounts for morphological evaluation; the remaining portions of the reproductive tracts were excised, weighed, fixed, and sectioned for microscopic examination. A majority of animals with unilateral agenesis had mammary glands that had higher degrees of glandular proliferation than the mammary glands of intact rats. Unilateral agenesis animals also possessed significantly thicker and heavier uterine horns, despite having been ovariectomized. Furthermore, rats with unilateral agenesis were found to have an earlier time of vaginal opening than that of their intact counterparts. These features of ovariectomized ACI rats with unilateral agenesis are consistent with an active, extra-ovarian source of endogenous estrogen. Further investigation of the endocrinological state of animals with unilateral agenesis of the urogenital tract is warranted.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of reciprocal changes of diets differing in fat content on pulmonary metastasis from the 13762 rat mammary tumor.

The effect of changing the amount of polyunsaturated fat in the diet of aged female Fischer 344 rats at the time of tumor implant on metastasis from the 13762 transplantable mammary tumor was studied. Three experiments were performed. (a) Retired breeders, maintained on standard commercial chows until 10 to 12 mo of age, were transferred to high fat (HF, 23% corn oil) or low fat (LF, 5% corn oil) diets for 4 wk; at tumor implant, half of each group were kept on their original diets, while half were changed to the other diet (i.e., HF----HF, HF----LF, LF----LF, LF----HF). (b) Aged virgins, 14 to 16 mo old, were fed HF and LF diets from weaning; at tumor implant, the LF group stayed on the LF diet, while half the HF group remained on the HF diet and half were changed to LF. (c) Retired breeders were fed Purina rodent chow (5% mainly saturated fat) until tumor implant when they were placed on either the HF or LF diets. Six wk after tumor implant, all rats were necropsied, and the extent of pulmonary metastasis was determined. Data were expressed as volume of pulmonary metastases. In Experiment 1, animals maintained on a HF diet or changed to a HF diet at implant had significantly more pulmonary metastases than those animals kept on a LF or changed to a LF diet. Likewise in Experiment 2, pulmonary metastasis was less in rats which were fed a HF diet from weaning and then changed to LF at tumor implant than in the animals maintained on a HF diet both before and after tumor implant. Finally, in Experiment 3, when rats were changed from Purina rodent chow to either the HF or LF diet at tumor implant, there was no significant difference in the extent of pulmonary metastasis between the two groups; in both, the extent of metastasis was comparable to that seen in animals maintained on the LF corn oil diet. Data on metastasis were also examined in light of body weight, growth of the primary tumor, and food disappearance. These results suggest that the amount of fat consumed by aged rats after tumor implant is an important determinant of the extent of pulmonary metastasis from the 13762 mammary tumor. However, a period of prefeeding the semipurified diets appears to be required in order for the HF corn oil diet to stimulate metastasis in this system.

Effect of the quality of dietary fat on tumor growth and metastasis from a rat mammary adenocarcinoma.

Experiments were performed to investigate whether the type of dietary fat might affect metastasis from the 13,762 mammary tumor. Female Fischer 344 retired breeder rats were placed into one of five dietary groups: 23% (wt/wt) and 5% (wt/wt) corn oil (HFCO, LFCO), 20% (wt/wt) and 5% (wt/wt) olive oil (HFOO and LFOO), or 20% (wt/wt) beef tallow (HFBT). After four weeks on the diets, each rat had a 2-mm3 piece of the tumor subcutaneously implanted. Primary tumor growth and body weight were monitored weekly for 40 days. At necropsy, the average volume of pulmonary metastases in the HFCO animals (n = 30) was significantly greater than in the other four groups. Among the four groups that did not differ significantly from each other, the rank order in average volume of pulmonary metastasis was as follows: HFOO (n = 25), HFBT (n = 26), LFOO (n = 25), and LFCO (n = 18). Growth of the primary tumor did not vary appreciably among the five groups despite the significant difference in pulmonary metastasis volume. The diets varied considerably in fatty acid content; the most salient difference was that the HFCO diet, which stimulated metastasis significantly more than the other diets did, contained about four times more linoleic acid (18:2) than the other diets. The relevance of this difference and other fatty acid differences is discussed. These results suggest that the quality of dietary fat can be an important determinant of pulmonary metastasis from the 13,762 mammary tumor in retired breeder rats.

Effects of diethylstilbestrol exposure in utero on the genital tracts of female ACI rats.

Aspects of development and morphology were studied in the reproductive tract of female ACI rats exposed prenatally to diethylstilbestrol (DES) and followed to 10 months of age. Pregnant ACI rats were injected with vehicle or DES (0.8 microgram = low DES or 8.0 micrograms = high DES) on Days 15 and 18 of gestation. At 12 weeks of age, half of the female offspring in each prenatal exposure group received a subcutaneous implant of a pellet containing 2.5 mg DES and 17.5 mg cholesterol; the remaining offspring received a control cholesterol pellet. Maternal reproductive performance was significantly impaired in DES-treated dams compared to controls. In female offspring mean time of vaginal opening was accelerated from 50.3 +/- 2.7 days in the vehicle-exposed group to 46.2 +/- 2.6 and 47.1 +/- 2.3 days in the low and high DES groups, respectively. Prior to pellet implantation, none of the rats exposed to DES prenatally was in "persistent estrus." At necropsy, rats exposed to DES in utero and implanted with the cholesterol pellet showed an increased frequency of atypical uterine epithelia, cystically dilated uterine glands, and a thickened vaginal epithelium. Among groups implanted with the DES pellet, prenatal exposure to DES increased the incidence of squamous metaplasia of the luminal epithelium and of cystically dilated uterine glands. Collectively, groups implanted with the DES pellet had higher incidences of squamous metaplasia of the uterine lumen, cystically dilated uterine glands, and patches of multilayered uterine epithelium than groups bearing the cholesterol pellet. DES pellet-bearing rats were also found to display a pronounced thickening and vacuolation of the vaginal epithelium. Cervical tissue from 98% of the DES-treated litters was characterized by a markedly convoluted epithelium with numerous squamous cell nests. There were no apparent effects of prenatal DES exposure or postnatal DES treatment on ovarian or oviductal histology. However, ovarian wet weights were significantly reduced as a result of postnatal DES treatment. Thus, the epithelial tissues of the uterus, cervix, and vagina in the ACI rat show a sensitivity to DES whether administered prenatally, postnatally, or in combination.

Stimulatory effect of high polyunsaturated fat diet on lung metastasis from the 13762 mammary adenocarcinoma in female retired breeder rats.

The effect of a high-fat (HF) diet (23% corn oil) on the growth and metastasis of the 13762 mammary tumor in Fischer 344 retired breeder (RB) and young virgin (YV) female rats was studied. The RB (10-12 mo old) and YV (8 wk old) rats were fed the HF or low-fat (LF) diet (5% corn oil) prior to and following tumor implantation for a total of at least 10 weeks. The growth rate of the primary tumor in the intact RB and YV was not affected by the HF diet. In RB rats ovariectomized 4 weeks prior to tumor implantation, the tumor grew significantly faster in the HF group as compared to the LF group. The total volume of metastatic tumor nodules in the lungs of the HF groups was significantly higher than that in the the lungs of the LF groups in both the intact and ovariectomized RB. In the YV, there was no difference in pulmonary metastatic burden between the HF and LF groups. The weights of the HF intact and ovariectomized RBs were higher than those of the LF animals. However, when pulmonary metastatic tumor burden was compared to body weight at implant or at sacrifice, there was no significant correlation in either the HF or LF groups. These results suggest that an HF diet enhanced the growth of pulmonary metastases in the intact and ovariectomized RB but not the YV rats and that the effect of the HF diet on pulmonary tumor burden cannot be attributed entirely to increased body weight.

Transplacental effects of diethylstilbestrol on mammary development and tumorigenesis in female ACI rats.

Female ACI rats were exposed to diethylstilbestrol (DES) transplacentally and followed to 10 months of age to assess the effect of the drug on mammary development and tumorigenesis. Pregnant rats were given injections of vehicle (sesame oil) or DES (total dose, 0.8 micrograms = low DES or 8.0 micrograms = high DES) on days 15 and 18 of gestation. Pellets containing 2.5 mg DES + 17.5 mg cholesterol (DES pellet) or 20 mg cholesterol (chol pellet) were implanted s.c. into 12-week-old female offspring, creating 6 experimental groups: vehicle exposure + chol pellet (1) or + DES pellet (2); low DES exposure + chol pellet (3) or + DES pellet (4); high DES exposure + chol pellet (5) or + DES pellet (6). At sacrifice, representative mammary tissue and all palpable mammary tumors were removed for histopathological analysis. Each of the 6 experimental groups contained a minimum of 32 rats from at least 14 litters. In computation of data, the unit of analysis was the litter. Groups which had received any DES (prenatally or postnatally) were found to have elongated nipples and enlarged pituitaries. The mammary gland whole mounts from all rats in groups 4 and 6 displayed extensive lobuloalveolar proliferation comparable to that seen in DES pellet controls (group 2). Mammary glands of approximately 75% of rats in groups 3 and 5 were categorized as showing the lowest grade of differentiation while this undifferentiated condition was seen in only 36% of group I controls. No palpable mammary tumors were found in rats exposed to vehicle in utero (group 1). But in group 5, a total of 6 tumors in 5 animals derived from 4 different litters were obtained, a difference shown to be statistically significant. Group 3 had 1 rat with 8 tumors. Among rats bearing the DES pellet, tumor latency was shortened significantly in both groups exposed to DES in utero. By 22 weeks after pellet implantation, 100% of the DES-exposed litters (groups 4 and 6) contained at least 1 tumor-bearing rat compared to about 50% of the tumor-bearing litters in group 2. Tumor multiplicity at sacrifice was increased significantly in the group exposed prenatally to the higher dose of DES. Histologically, the overwhelming majority of palpable mammary tumors from all tumor-bearing treatment groups were classified as adenocarcinomas. Prenatal exposure to DES did not alter the ratio of malignant to benign lesions observed, nor did it affect the degree of differentiation noted in the adenocarcinomas.(ABSTRACT TRUNCATED AT 400 WORDS)

Resistance to biological and chemical challenge in rodents treated with xerosin II, a natural product of Achromobacter xerosis.

The biological response-modifying activity of acid-precipitable material from Achromobacter xerosis was first described as suppression of viral pneumonia in mice. Later, this acid-precipitable material (xerosin) was found to have antiinflammatory activity and to induce tumor regression in chickens infected with Rous sarcoma virus. Here, we report further purification of xerosin resulting in a product (xerosin II) that retains high biological activity against viral and endotoxin-induced pneumonia in mice. In addition, we describe new activities of xerosin II in two rat tumor systems. Female CD rats received gastric intubations of 7,12-dimethylbenz(a)anthracene; 2 weeks later, half began 4 weeks of treatment with xerosin II, while others received saline only. Xerosin II treatment significantly delayed the appearance of the first palpable mammary tumors per rat. In female F344 rats implanted with the 13762 mammary tumor, 4 weeks of xerosin II treatment prolonged the survival of rats by an average of 5-11 days (12-24%) in two separate trials. Tumor growth and incidence of metastasis appeared unaffected by xerosin II treatment. Thus, this refined bacterial extract proved to be a potent biological response modifier in four different rodent systems.

Genital tract abnormalities in female rats exposed to diethylstilbestrol in utero.

Genital tract morphology in 14-month old female rats exposed prenatally to diethylstilbestrol (DES) was analyzed as part of an examination of the effects of transplacental exposure to DES on estrogen sensitive tissues. Pregnant Sprague-Dawley rats were injected with sesame oil alone or with DES in sesame oil on days 10 and 13 of gestation (total dose 1.2 micrograms DES) or on days 15 and 18 (total dose 1.2 micrograms or 120 micrograms DES). Female offspring (9-15 per group) were sacrificed at 14 months of age. Effects of DES exposure varied with the dose given and with the stage of differentiation of the fetal tissues. In the ovaries of rats exposed to 120 micrograms of DES on days 15 and 18 of gestation, follicular elements were reduced and replaced by dense sheets of stromal cells; oophoritis was noted in five of nine rats. Hypercellularity of oviductal stroma was another common feature, as was suppurative salpingitis. Ovaries of rats exposed to 1.2 micrograms DES on days 10 and 13 of gestation were more likely to contain numerous corpora lutea than the other DES-exposed groups of controls. An increased incidence of benign uterine abnormalities was observed in DES-exposed offspring, including squamous metaplasia and suppurative endometritis. In the cervices of all nine rats exposed to 120 micrograms DES on days 15 and 18 of gestation, the epithelial surface showed a convoluted pattern, lined by stratified squamous and stratified cuboidal cells. Thus, prenatal exposure to DES, especially at the higher dose used, has long-term consequences on reproductive tract morphology in Sprague-Dawley rats.

The influence of dietary fat on mammary tumor metastasis in the rat.

Young, virgin female Fischer 344 rats bearing the 13762 transplantable mammary tumor were fed diets containing either 5% (low-fat group) or 23% (high-fat group) corn oil for five weeks before and six weeks after tumor implantation. Animals in the two diet groups gained weight at comparable rates throughout the experiment. There was no significant difference between the low-fat and high-fat groups with respect to average tumor diameter measured twice per week for six weeks. At the time of death (6 weeks after tumor implantation), the lungs of all rats in both diet groups contained some metastatic tumor deposits; the volume of the metastases in the lungs varied widely in both groups. Numbers of metastases to regional lymph nodes and kidneys appeared unaffected by the fat content of the diet. Thus, both growth of the 13762 mammary tumor itself and metastatic spread from the tumor were comparable whether the young rats were fed a high-fat or a low-fat diet.

Transplacental action of diethylstilbestrol on mammary carcinogenesis in female rats given one or two doses of 7,12-dimethylbenz(a)anthracene.

Aspects of the development, morphology, and estrogen binding capacity of mammary tumors in rats exposed prenatally to the synthetic estrogen, diethylstilbestrol (DES), and treated postnatally with 7,12-dimethylbenz(a)anthracene (DMBA) were analyzed as part of a project aimed at understanding the effects of transplacental exposure to DES on estrogen-sensitive tissues. Pregnant Sprague-Dawley rats were given injections of DES (total dose, 1.2 micrograms) or vehicle alone on Days 15 and 18 of gestation. All female offspring were given gastric intubations of DMBA, either a single 10-mg dose on Day 50 or two doses (10 mg each) on Days 50 and 57. Among rats treated postnatally with 10 mg of DMBA, the DES-exposed group had a significantly greater incidence of palpable mammary tumors than did the vehicle-exposed controls. In addition, there was an earlier time of appearance of palpable tumors in the DES-exposed group. When the data from rats treated postnatally with two 10-mg doses of DMBA were analyzed, there were no significant differences in palpable mammary tumor incidence or tumor latency between the DES-exposed and vehicle-exposed groups. When the pathology of the mammary tumors produced in rats treated with 10 mg of DMBA was analyzed, the DES-exposed group had a significantly higher proportion of benign tumors (fibroadenoma, adenoma, lobular hyperplasia) than adenocarcinomata compared to vehicle-exposed controls. Both exposure groups had similar numbers of nonpalpable mammary lesions discovered at necropsy. Estrogen binding capacities of representative adenocarcinomata did not differ significantly between the two prenatal exposure groups treated postnatally with 10 mg of DMBA. These results demonstrate the importance of the dose of the challenge carcinogen in revealing the effects of transplacental drug exposure and may have special significance for women who were exposed to DES in utero.

Influence of prenatal exposure to diethylstilbestrol on estrogen and progestin binding proteins in uteri and dimethylbenzanthracene- induced mammary tumors of the rat.

Various characteristics of steroid binding proteins from mammary tumors and uteri of rats exposed prenatally to diethylstilbestrol (DES) were examined. Pregnant rats were treated with no hormone (group A) or with a total dose of 1.2 micrograms DES during the second (group B) or third (group C) trimester of gestation. Female offspring received 7,12-dimethylbenz[a]anthracene (DMBA) at d 50 +/- 1. Animals with large mammary tumors were subjected to bilateral ovariectomy. Seven months after carcinogen treatment, the experiment was terminated. High-affinity binding sites for [3H] estradiol-17 beta and [3H]R5020 were found in all mammary tumors assayed. On sucrose gradients of low ionic strength both 8S and 4S forms of the estrogen receptor were identified in mammary tumors, regardless of prenatal treatment. In addition, progestin receptors sedimenting at 4S were identified in these tumors. However, the 7-8S form of the progestin receptor was found only in tumors from intact animals. Levels of progestin receptors were diminished after ovariectomy, both in mammary tumors and in uteri; ovariectomy also resulted in a significant reduction in uterine wet weight in the hormone exposure groups, as expected. Unlike groups A and B, rats exposed to DES during the third trimester had uterine progestin binding capacities and uterine wet weights that did not decrease proportionally ater ovariectomy. Furthermore, progestin binding capacities in mammary tumors from group C ovariectomized rats were higher than those in the other two groups. In intact rats from group C, cytosol from mammary tumors also had elevated levels of progestin binding; however, no differences in progestin binding were observed in the uteri from these animals. Small differences in estrogen binding capacities in tumor tissues were observed among the three groups; uterine estrogen binding capacities did not vary significantly. Prenatal exposure to DES during the third trimester appeared related to persistent biochemical alterations in rat mammary tumors and uteri; earlier exposure did not have this effect.

Prenatal exposure to diethylstilbestrol: ovarian-independent growth of mammary tumors induced by 7,12-dimethylbenz[a]anthracene.

The effects of ovariectomy on the growth of 7,12-dimethylbenz[a]anthracene (DMBA)-induced mammary tumors were investigated after rats ahd been exposed prenatally to diethylstilbestrol (DES). Pregnant rats were inoculated with either DES (total dose: 1.2 micrograms) in sesame oil or with the vehicle alone on days 10 and 13 of gestation. Female offspring were given 2 gastric intubations of DMBA (10 mg each) 1 week apart beginning at 50 plus or minus 1 days of age. When the average diameter of a mammary tumor exceeded 2 cm, the animal was ovariectomized. The initial response of most tumors in both the DES-exposed and control groups to ovariectomy was size regression. The growth of 7 tumors that arose soon after DMBA treatment in each group was studied for 12-20 weeks after ovariectomy. Whereas only 1 tumor from the control group resumed active growth after the initial regression period, 6 tumors in the DES-exposed group overcame the initial effects of ovariectomy and began to grow again. Thus ovariectomy appeared to be less effective in producing sustained control growth in DMBA-induced mammary tumors in rats exposed prenatally to DES.

Mammary tumorigenesis in the rat following prenatal exposure to diethylstilbestrol and postnatal treatment with 7,12-dimethylbenz[a]anthracene.

Pregnant rats were injected with vehicle or 1,2 microgram diethylstilbestrol (DES) during wk 2 or 3 of gestation; their female offspring ( approximately 50 d old) were fed 7,12-dimethylbenz[a]anthrocene (DMBA). The survivors (27 per group) were sacrificed 30 wk later. The three groups did not differ in the number of tumor-bearing animals; however, significantly more palpable mammary tumors arose in both DES-exposed groups than in controls. When DES was given during the second trimester, palpable tumors appeared earlier than in the other two groups. Thus, transplancental exposure to DES potentiated the action of a known carcinogen (DMBA) on rat mammary tissue. These results raise the possibility that, for young women, DES exposure in utero may have affected tissues other than the vagina. Further investigation is warranted, with special emphasis on the effects of DES on mammary and other estrogen-sensitive tissues.

Morphology, growth characteristics and oestrogen-binding capacity of DMBA-induced mammary tumours from ovariectomized rats.

The morphology of 20 mammary adenocarcinomas induced by 7,12-dimethylbenz(a)anthracene (DMBA) in Sprague-Dawley rats was compared with their growth characteristics and oestrogen-binding capacity following ovariectomy. The capacity to bind (3H)oestradiol-17B did not appear to be related to the growth characteristics, time of appearance after DMBA administration, or time between ovariectomy and assay for specific oestrogen-binding proteins. Furthermore, different tumours appeared to have oestrogen-binding capacities unrelated to the percentage of neoplastic cells within the tumour, amount of inflammation, mast cell infiltration, or the presence of fluid-filled cysts. The only morphological features which appeared to be correlated with oestrogen-binding capacity were the number of mitoses and the lipid content of the tumour; that is, the oestrogen-binding capacity tended to be lower in tumours with moderate or large numbers of mitoses and in tumours with much lipid in the epithelial cells. Six of the 19 adenocarcinomas found prior to sacrifice either continued growing or remained static following ovariectomy, while the others underwent regression. In 5 of the regressing tumours a new growth phase was observed, usually beginning 2 months after ovariectomy. Tumours other thus osteosarcoma as well as fibroadenomas and Zymbal-gland tumours.

PIP: Tumors were induced in 46 of 52 female Sprague-Dawley rats by gastric intubation of 5 mg of DMBA, dissolved in 1 ml of sesame oil, given weekly for 5 weeks. From 4 weeks after the final dose tumors were recorded and measured. Bilateral ovariectomy was done 3 days before sacrifice and assay. Excised tumors were immediately immersed in ice-cold Tris-EDTA buffer. Sections were prepared for histological examination. The assay was done by sucrose density centrifugation after administration of (2,4,6,7-tritiated)-estradiol-17beta in vivo 3 minutes before killing, and/or in vitro. For specific estrogen-binding proteins the capacity to bind (tritiated)-estradiol-17beta was not related to the growth characteristics, time of appearance, or time between ovariectomy and assay. Different tumors had estrogen-binding capacities unrelated to the percentage of neoplastic cells in the tumor, amount of inflammation, mast cell infiltration, or presence of fluid-filled cysts. The number of mitoses and the lipid content of the tumors were correlated with the estrogen-binding capacity in that it was lower in tumors with many mitoses and in those with much lipid in the epithelial cells. Of 19 adenocarcinomas, 6 did not regress after ovariectomy. In 5 of the regressed tumors a new growth phase was seen, beginning 2 months after ovariectomy. Tumors encountered, other than mammary adenocarcinomas, were an extraosseous osteosarcoma, fibroadenomas, and zymbal-gland tumors.

Specific estrogen binding in rat mammary tumors induced by 7,12-dimethylbenz(a)anthracene.

Experiments were undertaken with 7,12-dimethylbenz(q)anthracene-induced mammary tumors of the rat to determine whether ovarian-dependent and ovarian-independent tumors could be distinguished on the basis of differences in the estrogen binding capacity of the tumors in vitro and in vivo. Our results confirm reports showing that ovarian-depentent tumors undergo interaction between ovarian-dependent tumors undergo interaction between 17beta-(3H)estradiol and specific estrogen binding components both in vivo and in vitro, as described for other estrogen target tissues. However, our results also demonstrated that certain 7,12-dimethylbenz(a)anthracene-induced tumors, which continue to grow after ovariectomy of the host, contained significant amounts of 17beta-(3H)estradiol bound to cytoplasmic as well as nuclear components. The sedimentation properties of these components were indistinguishable from those of either ovarian-dependent 7,12-dimethylbenz(a)anthracene-induced tumors or rat uterus. The cytoplasmic binding components of both classes of tumors exhibited similar specificities for estrogens. There did not appear to be an absolute correlation between estrogen-binding capacity of a tumor and its growth response to ovariectomy.