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PubMed1992

The histology and development of hepatic nodules and carcinoma in C3H/He and C57BL/6 mice following chronic phenobarbitone administration.

Male C3H/He and C57BL/6 mice were given diets containing sodium phenobarbitone (PB) to allow a daily intake of 85 mg/kg. Control and treated animals were killed at 5, 30, 40, 60, and 80 wk. Other mice were killed in extremis or at the end of the respective experiments: 91 wk for C3H/He and 100 wk for the C57BL/6 animals. A basophilic nodule was found in 1/5 control C3H/He mice at 30 wk; these nodules increased in number with time so that nodules of this type were found in approximately 70% of animals by 91 wk. Nodules were not found in control C57BL/6 mice until 80 wk, when they were found in 4% of mice. PB treatment markedly increased the number of hepatic nodules in both strains of mice. The additional nodule burden was due to the development of a second nodule type formed of large cells with a predominantly eosinophilic cytoplasm. C3H/He animals given PB for 60 wk and then returned to a control diet bore fewer nodules at 91 wk than treated mice killed at 60 or 91 wk. The cumulative incidence of carcinoma in control C3H/He and C57BL/6 mice was 28 and 4%, respectively. The incidence of carcinoma was not increased by PB treatment in either strain. It is concluded that both strains of mice behave in a qualitively similar way to PB administration, although they show considerable quantitative differences in terms of the time and number of nodules that develop. Furthermore, the increased nodule numbers associated with PB treatment were not accompanied by an increase in the number of carcinomas.

Animals↗

PubMed2004

Intrapulmonary lymph nodes: thin-section CT findings, pathological findings, and CT differential diagnosis from pulmonary metastatic nodules.

We compared the thin-section CT findings of 11 intrapulmonary lymph nodes with pathological findings and evaluated the possibility of CT scan differential diagnosis from pulmonary metastatic nodules. First, we retrospectively reviewed CT scan and pathological findings of intrapulmonary lymph nodes. The median size of these nodules was 6.2 mm. The nodules appeared round (n=3) or angular (n=8) in shape with a sharp border, and they were found below the level of the carina. The median distance from the nearest pleural surface was 4.6 mm, and 3 of the 11 nodules were attached to the pleura. On thin-section CT scan, linear densities extending from the intrapulmonary lymph nodes were frequently visualized, and were pathologically proven to be ectatic lymphoid channels. We then compared the thin-section CT findings of 8 metastatic nodules less than 1 cm in diameter with those of the 11 intrapulmonary lymph nodes. The median size of these nodules was 6.8 mm, and the median distance from the nearest pleural surface was 16 mm. All nodules appeared round in shape. None of the nodules had linear densities extending from the nodules. The linear densities on thin-section CT scan may be the most useful characteristic of intrapulmonary lymph nodes, when differential diagnosis from metastatic nodules is necessary.

Aged↗

PubMed1983

Absence of Kupffer cells in carcinogen induced liver hyperplastic nodules: demonstration by intravenous injection of indian ink.

Absence of Kupffer cells in rat liver hyperplastic nodules induced by a chemical carcinogen was demonstrated by intravenous injection of indian ink. Hyperplastic nodules appeared 4 weeks after diethylnitrosamine (DEN) was administered, and the nodules continued growing and became eosinophilic hyperplastic nodules after 5 to 6 weeks. After intravenous injection of indian ink, hyperplastic nodules were observed as carbon-free white nodules, which were macroscopically distinguishable from the black surrounding tissue. As observed by light microscopy, Kupffer cells were absent in hyperplastic nodules in contrast to being present in the surrounding tissue. Scanning electron microscopy confirmed these findings and furthermore revealed that the sinusoidal endothelium of hyperplastic nodules had no fenestrae. Injection of indian ink is a useful method for delineation and enucleation of hyperplastic nodules in the study of morphological and chemical changes of nodules.

Animals↗

PubMed1992

Rat liver nodules induced by 2-acetylaminofluorene lose an ability to take up indocyanine green in the process of hepatocarcinogenesis.

Indocyanine green (ICG) was injected into rat liver nodules induced by 2-acetylaminofluorene (2-AAF) via portal vein. The relationship between ICG staining and cell atypism of liver nodules was examined by means of histology and DNA flow cytometry. After 2-AAF administration, many small nodules appeared on the liver surface. All hyperplastic nodules were ICG stained until 10 weeks after the administration, but some nodules were not stained after 14 weeks. ICG-stained nodules histologically consisted of benign tissues and borderline lesions, and many of them showed "diploidy" in DNA cytometry. ICG-unstained nodules consisted of hepatocellular carcinoma (HCCs) and borderline lesions, and many of them showed "aneuploidy". In this way, it has been suggested that HCC could derive from hyperplastic nodules and that they might lose an ability to take up ICG in the process of hepatocarcinogenesis. Immunohistochemical staining for glutathione-S-transferase alpha (GST-alpha), a carrier protein of ICG in hepatocytes, was well correlated with ICG staining in the nodules, suggesting that the loss of ICG uptake in HCC was partly due to the decrease of GST-alpha. Moreover, the appearance of ICG unstained and aneuploid nodules was significantly inhibited in rats which were fed on diet containing Syosaiko-to after the administration of 2-AAF. Chemopreventive effect of Syo-saiko-to on hepatocarcinogenesis was identified.

2-Acetylaminofluorene↗

PubMed1990

Regenerating nodules in hepatic cirrhosis: MR findings with pathologic correlation.

To establish clearly the pathologic basis for small low-intensity nodules seen on MR images of the cirrhotic liver, we obtained MR images in 26 patients with cirrhosis in whom partial hepatectomy for hepatoma (15 patients), laparoscopy for cirrhosis (10 patients), or autopsy (one patient) was subsequently performed. Small low-intensity nodules were seen on gradient-echo images with short TEs (10-13 msec) in 13 of the 26 patients. In 12 of these 13 patients, small low-intensity nodules appeared larger and clearer as the TE was prolonged (14-25 msec). On T2-weighted spin-echo images, small low-intensity nodules were seen in 12 of the 13 patients, but not seen as well as on gradient-echo images. Pathologic correlation in these 13 patients revealed that the nodules on the MR images corresponded to iron deposits in regenerating nodules. Small low-intensity nodules were observed only on T2-weighted spin-echo images in two of the remaining 13 patients, in whom microscopic examination of the liver revealed marked inflammatory cell infiltration in the fibrous septa and no iron deposition. We conclude that small low-intensity nodules observed on MR images are caused by iron deposits in regenerating nodules, and that gradient-echo images with short and prolonged TEs are useful to confirm the presence of iron deposits in regenerating nodules.

Adult↗

PubMed2003

Nondysplastic nodules that are hyperintense on T1-weighted gradient-echo MR imaging: frequency in cirrhotic patients undergoing transplantation.

OBJECTIVE: Our objective was to determine the frequency and MR imaging findings of nondysplastic nodules that are hyperintense on T1-weighted gradient-echo imaging in patients with cirrhosis who undergo liver transplantation. MATERIALS AND METHODS: Two observers retrospectively evaluated in-phase (4-5 msec), opposed-phase gradient-echo (2.0-2.4 msec), and turbo short tau inversion recovery (STIR) MR images in 68 patients with cirrhosis--but without dysplastic nodules or hepatocellular carcinoma--who underwent MR imaging at 1.5 T within 150 days before liver transplantation. The size, number, signal characteristics, and arterial enhancement pattern of nodules that appear hyperintense on T1-weighted gradient-echo images were evaluated as well as the presence or absence of signal loss on opposed-phase imaging. These imaging findings were correlated with pathologic findings of whole explanted livers. RESULTS: Eleven (16%) of 68 patients had at least one nondysplastic nodule that was hyperintense on T1-weighted MR imaging. Three patients had diffuse nondysplastic hyperintense nodules (>10 nodules) measuring less than 0.5 cm, and the remaining eight patients had 22 nondysplastic hyperintense nodules ranging in size from 0.5 to 2.5 cm (mean, 1.2 cm), of which 13 were isointense and nine were hypointense on turbo STIR images. No lesion lost signal on opposed-phase imaging or enhanced during the hepatic arterial phase. CONCLUSION: In cirrhotic patients undergoing liver transplantation, nondysplastic nodules that are hyperintense are common findings on T1-weighted gradient-echo MR imaging and do not lose signal intensity on opposed-phase imaging or enhance during the hepatic arterial phase. These nodules may be indistinguishable from dysplastic nodules.

Adult↗

PubMedDate not supplied

Lung nodule detection on chest CT: evaluation of a computer-aided detection (CAD) system.

OBJECTIVE: To evaluate the capacity of a computer-aided detection (CAD) system to detect lung nodules in clinical chest CT. MATERIALS AND METHODS: A total of 210 consecutive clinical chest CT scans and their reports were reviewed by two chest radiologists and 70 were selected (33 without nodules and 37 with 1-6 nodules, 4-15.4 mm in diameter). The CAD system (ImageChecker CT LN-1000) developed by R2 Technology, Inc. (Sunnyvale, CA) was used. Its algorithm was designed to detect nodules with a diameter of 4-20 mm. The two chest radiologists working with the CAD system detected a total of 78 nodules. These 78 nodules form the database for this study. Four independent observers interpreted the studies with and without the CAD system. RESULTS: The detection rates of the four independent observers without CAD were 81% (63/78), 85% (66/78), 83% (65/78), and 83% (65/78), respectively. With CAD their rates were 87% (68/78), 85% (66/78), 86% (67/78), and 85% (66/78), respectively. The differences between these two sets of detection rates did not reach statistical significance. In addition, CAD detected eight nodules that were not mentioned in the original clinical radiology reports. The CAD system produced 1.56 false-positive nodules per CT study. The four test observers had 0, 0.1, 0.17, and 0.26 false-positive results per study without CAD and 0.07, 0.2, 0.23, and 0.39 with CAD, respectively. CONCLUSION: The CAD system can assist radiologists in detecting pulmonary nodules in chest CT, but with a potential increase in their false positive rates. Technological improvements to the system could increase the sensitivity and specificity for the detection of pulmonary nodules and reduce these false-positive results.

Diagnosis, Computer-Assisted↗

PubMedDate not supplied

Characteristics of Lisch nodules in patients with neurofibromatosis type 1.

PURPOSE: To assess the prevalence and location of Lisch nodules among patients with neurofibromatosis type 1. PATIENTS AND METHODS: This was a prospective observational case series in which 369 consecutive patients from a neurofibromatosis clinic participated. Predetermined inclusion and exclusion criteria were applied to these participants. The presence of Lisch nodules was determined by one of the authors (SMC). The percentage of patients with neurofibromatosis type 1 with Lisch nodules was calculated. Lisch nodules were characterized as being distributed superiorly, inferiorly, or equally in each eye. The percentage of eyes in each group was ascertained. RESULTS: Among patients of all ages with neurofibromatosis type 1, 63.2% had Lisch nodules, whereas 92% of postpubertal patients had Lisch nodules. Among eyes with Lisch nodules, 80% had an inferior distribution. CONCLUSIONS: This study corroborated previously reported data regarding the prevalence of Lisch nodules in patients with neurofibromatosis type 1 and found that Lisch nodules were predominantly located inferiorly on the iris. The authors propose that exposure to sunlight may be the mechanism for this distribution of hamartomatous nodules.

Adolescent↗

PubMedDate not supplied

The hemodynamics of dysplastic nodules in the liver evaluated by CT angiography and immunohistochemistry.

BACKGROUND/AIMS: Dysplastic nodules diagnosed pathologically exhibit various hemodynamic patterns. To evaluate these differences in their hemodynamics, we observed basement membrane formation of sinusoids. METHODOLOGY: For 12 low-grade dysplastic nodules, 24 high-grade dysplastic nodules and 16 hepatocellular carcinomas, both computed tomography during arterial portography and CT arteriography were performed preoperatively. Resected specimens were examined immunohistochemically for COL IV (type IV collagen) and laminin to observe basement membrane formation. We compared their hemodynamics on computed tomography during arterial portography and CT arteriography with the expressions of COL IV and laminin. RESULTS: All of the low-grade dysplastic nodules were not hypervascular on CT arteriography, and negative for COL IV and laminin. All of the hepatocellular carcinomas were hypervascular on CT arteriography, and positive for COL IV and laminin. High-grade dysplastic nodules exhibit four hemodynamic patterns on CT during Arterial Portography/CT arteriography. All of 7 iso/iso and 5 iso/hypo nodules were negative for COL IV and laminin. Of the 9 hypo/hyper nodules, which exhibited hemodynamics similar to hepatocellular carcinoma, COL IV was identified in 7 and laminin identified in 8 nodules. Of the 3 hypo/hypo nodules, COL IV and laminin were identified in one. CONCLUSIONS: In high-grade dysplastic nodules, most cases exhibited a correlation between the hemodynamic patterns and the degree of the sinusoidal basement formation.

Aged↗

PubMed2002

[Outcome of hepatic nodules less than 10 mm in size detected by ultrasonography in patients with chronic liver disease].

The number of hepatic nodules detected by ultrasonography in patients with chronic liver disease has increased. Although it potentially is important to understand the outcome of small solitary hepatic nodules, they have not been fully investigated. In this study, we evaluated retrospectively the outcome of 35 solitary hepatic nodules smaller than 10 mm in 35 patients with chronic liver disease. The follow-up period ranged from 24 to 94 months, and, during follow-up, 8 of 35 nodules (23%) increased in size, 17 nodules (49%) showed no change, and 10 nodules (29%) disappeared. It took less than 12 months for 5 nodules to increase in size, and less than 24 months for 3 nodules. There was no significant difference between the ultrasonographic findings (echogenicity and size) of the nodules and their outcome. We conclude that follow-up observation of at least 24 months is essential to evaluate the outcome of solitary hepatic nodules.

Aged↗

PubMed2002

[Role of high resolution CT in diffuse pulmonary nodules].

OBJECTIVE: To evaluate high resolution CT (HRCT) in the diagnosis of diffuse pulmonary nodules. METHODS: Fifty normal chest radiographs, conventional CT and HRCT were used to evaluate the visualization of pulmonary lobule. The configuration, distribution and intrinsic structure of lesion in 38 patients with diffuse pulmonary nodules were analyzed by HRCT. RESULTS: The chest radiographs were not able to show the structure of pulmonary lobule. The visualization rates of pulmonary lobule were 20% by conventional CT and 50% by HRCT (P < 0.05). Of 38 patients with diffuse pulmonary nodules, 19 had interstitial nodules which were located in the pulmonary intestities, the lobular septa and under the pleura. HRCT could clearly show their para-bronchial distribution with clear cut margin. Four had airspace nodules, chiefly shown as solidification of the air spaces. There was no nodule beneath the pleura or in the lobular septa. HRCT revealed even density and hazzy margins. Fifteen had randomly distributed nodules, with the nodules scattered at random. HRCT showed nodules with high density, sizes varying greatly but the margin was clear. CONCLUSION: High resolution CT is able to show the pattern of distribution, intranodular structures and background of the diffuse pulmonary nodules, which is valuable in the diagnosis and differential diagnosis of this disease.

Adult↗

PubMedDate not supplied

Histopathologic differentiation of the main nodule determines outcome after hepatic resection for synchronous multicentric hepatocellular carcinomas.

BACKGROUND/AIMS: Clinicopathological features and outcome after surgery in patients with synchronous multicentric hepatocellular carcinoma were examined in relation to the histopathological grade of differentiation of the main nodule. METHODOLOGY: Two hundred and sixty-five patients with synchronous multicentric hepatocellular carcinoma (total, 683 nodules) who had undergone curative hepatectomy from 1988 through 1999 were studied retrospectively. In multicentric occurrences of hepatocellular carcinoma, the tumor with the largest dimension was defined as the main nodule, and the others as accessory nodules. RESULTS: The histopathological grade of differentiation of the main nodule was assessed to be well differentiated in 72 patients (27.2%), moderately differentiated in 160 patients (60.4%), and poorly differentiated in 33 patients (12.4%). Tumor size of the main nodule was significantly smaller in patients with well differentiated hepatocellular carcinoma than in patients with moderately or poorly differentiated hepatocellular carcinoma. Alpha-fetoprotein levels were significantly lower in cases in which the main nodule was diagnosed to be well differentiated hepatocellular carcinoma than in other cases. The 5-year survival rate and recurrence-free survival rate were significantly greater in cases in which the main nodule showed well differentiated hepatocellular carcinoma (78.1% and 33.8%, respectively) than in other cases [moderately differentiated 49.0% (p<0.0001), 11.6% (P=0.0002); poorly differentiated 37.4% (p<0.0001), 8.3% (P=0.0002), respectively]. Multivariate analysis identified the histopathological grade of the main nodule as significant independent prognostic factors. CONCLUSIONS: There were differences in surgical outcome in relation to the histopathological grade of differentiation of the main nodule in patients with synchronous multicentric hepatocellular carcinoma.

Aged↗

PubMed2005

Clinical and genetic significance of unilateral Lisch nodules.

PURPOSE: Bilateral Lisch nodules are highly characteristic for neurofibromatosis type 1 (NF1). We wished to study the clinical and genetic implications of unilateral Lisch nodules. METHODS: Retrospective study of the clinical data of 59 patients who received genetic counselling for neurofibromatosis type 1 (NF1) or type 2 (NF2) and were examined at the department of ophthalmology. RESULTS: Unilateral Lisch nodules were observed in 4 cases: one child with NF1 initially presented unilateral Lisch nodules but developed bilateral Lisch nodules by the age of 9. In 2 cases segmental NF1 was the most probable diagnosis and in one case isolated Lisch nodules were observed. Of the 35 NF1 patients 28 ultimately developed bilateral Lisch nodules. Seven NF1 patients did not demonstrate the nodules. At follow-up no Lisch nodules were detected in 2 neurofibromatosis type 2 patients, in 4 patients in whom the diagnosis of NF1 remained doubtful and in 15 patients without NF1. CONCLUSION: Because isolated Lisch nodules are very rare, their presence warrants a thorough patient history and clinical examination to either confirm or exclude generalised or segmental neurofibromatosis type 1.

Adult↗

PubMed1991

[Tumor hemodynamics in hepatic nodules associated with liver cirrhosis: relationship between cancer progression and tumor hemodynamic change].

Tumor hemodynamics including arterial vascularity (AV) and portal perfusion (PP) were evaluated in histologically confirmed 55 hepatic nodules associated with cirrhosis using ultrasonographic (US) angiography during intraarterial carbon dioxide microbubbles injection and CT during arterial portography. Tumor hemodynamic patterns were classified into 6 types as follows: Type I (n = 10): PP (+), AV (hypo); Type I' (n = 2): PP (+), AV (iso); Type II (n = 5): PP (-), AV (hypo); Type III (n = 8): PP (-), AV (iso); Type IV (n = 25): PP (-), AV (hyper), Type V (n = 5): PP (partially +), AV (vascular spot in hypovascular). Eight nodules of Type I were diagnosed as benign nodules histologically including adenomatous hyperplasia (AH) (n = 6) and regenerative nodule (n = 2). Hundred percent (5/5) of Type II and 88% (7/8) of Type III nodules were well-differentiated HCC, in contrast to 8% (2/25) of Type IV nodules, typical HCCs. Fatty metamorphosis was observed in 75% (6/8) of Type III nodules, in contrast to 16% (4/25) of typical (classical) HCC nodules (Type IV). We concluded that at the malignant transformation from AH to HCC, reduction of portal blood flow in the nodule precedes the initiation of the increase of the arterial tumor vessel. Moreover, early stage HCC could exhibit hypovascular (Type I, II), isovascular (Type III), or vascular spot in hypovascular pattern (Type V) compared with a typical HCC (Type IV). It was also suggested that the more mature as a neoplasms the HCC becomes, the more the arterial tumor vessel in the nodule increases and fatty metamorphosis of well-differentiated HCC is highly related with tumor hemodynamic condition, i.e., hypoperfusion state from both arterial and portal vessel.

Carcinoma, Hepatocellular↗

PubMed1989

Diagnostic efficacy of dynamic radiothallium uptake in thyroid nodules determined by computer-assisted scintigraphy. Reevaluation of a radioisotopic procedure.

Radiothallium (201Tl) has been proposed as a tracer in nuclear medicine for the diagnosis of cold thyroid nodules. Its potassium-mimetic characteristics, like those of 131Cs, can provide information on its turnover in the thyroid nodules; this serves as a basis for the distinction between benign and malignant thyroid tumours. The author presents a study on the diagnostic efficacy of 201Tl as a tracer for thyroid nodules with the aim of evaluating the dynamic uptake and the biodistribution of 201Tl after intravenous injection of 555-740 kBq/kg. A quantitative analysis was made by continuous scanning of 201Tl distribution during the first 20-30 min following thallium injection, with further surveys from 40 to 60 min or more when fixation in a nodule was demonstrated. The ratio between 201Tl uptakes in the nodule and in healthy tissue (density index) was calculated and a multiparametric analysis of the corresponding activity/time curves was performed. This study included 176 patients. Concordance between clinico-histological diagnosis and radio-isotopic findings was demonstrated in 102 out of 106 colloidocystic goitres, in 42 out of 48 benign nodules including thyroiditis, and in 21 out of 22 malignant tumours; a significant statistical difference in the density index between solid and cystic nodules, but no difference between benign and malignant nodules; and a different 201Tl dynamic behaviour in nodules of different nature, with a clear statistical difference in the thallium release between malignant nodular and healthy tissue (nodular disappearance index). This method can improve the diagnosis value of scintigraphy for thyroid nodules enhancing the sensitivity of the radioisotopic applications in comparison with other non-invasive techniques.

Adenocarcinoma↗

PubMed1983

Studies on nodules and adult Onchocerca volvulus during a nodulectomy trial in hyperendemic villages in Liberia and Upper Volta. I. Palpable and impalpable onchocercomata.

In hyperendemic onchocerciasis areas of West Africa nodulectomy trials were performed. 163 nodule carriers from four villages in the Liberian rain-forest and 52 nodule carriers from a savanna village in Upper Volta were operated on. During the surveys in the villages in Liberia and Upper Volta, an average of three and five nodules respectively per patient were palpated. Before each operation a further palpation was done and two more nodules per patient from both countries were found. The nodulectomies revealed 75% more nodules in the Liberian patients and 53% more in the patients from Upper Volta than were palpated immediately before. Half of these additional subcutaneous nodules extirpated in Liberians were superficially located, the other half deeper and impalpable through the skin. In the patients from Upper Volta two thirds of the additional nodules were seated in the depth of the subcutis. In both countries an average of three deep subcutaneous nodules per patient were found and this was equivalent to 20% of all extirpated onchocercomata. Most of these deep subcutaneous nodules were at those sites where most of the superficial nodules were located.

Adipose Tissue↗

PubMed1983

Effect of size on portal circulation of hepatic nodules from carcinogen-treated rats.

The portal circulation of diethylnitrosamine-initiated nodules (0.5 to 7 mm in diameter) was studied in rat livers perfused exclusively via the portal vein. Microlight guides were placed on normal and nodular tissue on the capsular surface of the liver to measure pyridine nucleotide fluorescence (366 leads to 450 nm). When oxygen tension of the inflow perfusate was lowered, fluorescence in both normal tissue and small nodules (less than 2 mm in diameter) increased sharply due to the reduction of pyridine nucleotides, indicating previous normoxia. In contrast, similar manipulations did not increase fluorescence in nodules greater than 2 mm in diameter, demonstrating that nicotinamide adenine dinucleotide was reduced maximally previously; i.e., the nodules were anoxic. Direct measurements of nodule oxygen concentrations with a miniature oxygen electrode confirmed these results. 7-Hydroxycoumarin or fluorescein could be detected with micro-light guides in normal tissue and nodules less than 2 mm in diameter but not in nodules greater than 2 mm in diameter. Furthermore, fluorescent microscopy indicated an absence of fluorescein in nodules greater than 2 mm in diameter. Therefore, with four independent optical and polarographic techniques, we have demonstrated reduced portal circulation in nodules greater than 2 mm in diameter; however, smaller nodules could not be differentiated from normal tissue.

2-Acetylaminofluorene↗

PubMed1978

Effect of parity on recovery of inapparent nodule-transformed mammary gland cells in vivo.

Inapparent nodule-transformed cells were recovered from five late-pregnant, first-pregnancy BALB/cfC3H females 4 months of age and from five late-pregnant multiparous females 6 to 7 months of age. Mammary tissues were removed from each donor and dissociated by means of the enzyme collagenase (0.1%), hyaluronidase (0.1%), and pronase (1.25%). Aliquots of 100,000 viable cells in 0.01 ml of media were injected into the gland-free mammary fat pads of 3-week-old syngeneic host mice. Ten weeks after the injection the outgrowths were classified as ductal, nodule, tumor, or combinations of these types of outgrowths. The recovery of nodule outgrowths indicated the presence of nodule-transformed cells in the cell suspension that was injected. All donors yielded nodule outgrowths, and the percentage of outgrowths was significantly greater than was the percentage recovered from virgin BALB/cfC3H females of the same age groups. The latent period for the emergence of nodules and tumors was reduced from 8 to 9 months in virgin females to 4 months in parous females. The incidence of both nodules and tumors was greatly increased. The data suggest that parity significantly increases the numbers of nodule-transformed cells in donor tissue, decreases the time required for the emergence of nodules and tumors, and increases the number of overt nodules and tumors.

Age Factors↗