Isooctadecanoic acid, mono- and diesters with glycerol

Repeated dose toxicity: oral

Administrative data

Endpoint:

chronic toxicity: oral

Type of information:

migrated information: read-across based on grouping of substances (category approach)

Adequacy of study:

key study

Study period:

04 Nov 2008 - 12 Feb 2010

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

GLP - Guideline study. According to the ECHA guidance document "Practical guide 6: How to report read-across and categories (March 2010)", the reliability was changed from RL1 to RL2 to reflect the fact that this study was conducted on a read-across substance.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2011

Report date:

2011

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 452 (Chronic Toxicity Studies)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.4100 (Chronic Toxicity)

Deviations:

no

Test guideline 3

Qualifier:

according to guideline

Guideline:

EU Method B.30 (Chronic Toxicity Studies)

Deviations:

no

Test guideline 4

Qualifier:

according to guideline

Guideline:

other: JMAFF, Testing Guidelines for Toxicology Studies (2-1-14), 12 NohSan No.8147, November 24, 2000

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

736150-63-3

EC Number:

616-005-1

Cas Number:

736150-63-3

IUPAC Name:

736150-63-3

Details on test material:

- Name of test material (as cited in study report): trade name
- Chemical name: Glycerides, castor-oil-mono-hydrogenated, acetes
- Main component: 12-Acetoxy-octadecanoic acid 2,3-diacetoxy-propyl ester, 12-Acetoxy-octadecanoic acid 2-acetoxy-1-acetoxymethyl-ethyl ester
- Physical state: amber coloured liquid
- Analytical purity: 95.0% (definition of purity based on content of fully acetylated monoglycerides of 12-hydroxystearic acid, stearic acid and palmitic acid)
- Purity test date: 2007-11-21
- Lot/batch No.: item 175540 batch 4010534806
- Expiration date of the lot/batch: 2009-12-31
- Storage condition of test material: room temperature in the dark

Test animals

Species:

rat

Strain:

other: Wistar HsdHan™:WIST

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Harlan Laboratories U.K. Ltd., Oxon, UK
- Age at study initiation: 6 weeks
- Weight at study initiation: 178-234 g (males) and 138-183 g (females)
- Housing: animals were housed in groups of up to 3 by sex in solid floor polypropylene cages with stainless steel mesh lids and softwood flake bedding (Datesand Ltd., Cheshire, UK). Environmental enrichment was provided in form of wooden chew blocks and cardboard fun tunnels (Datesand Ltd., Cheshire, UK).
- Diet: ground diet (Rat and Mouse SQC Ground Diet No.1, Special Diet Services Ltd, Witham, UK), ad libitum
- Water: mains drinking water, ad libitum
- Acclimation period: at least 10 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 2
- Humidity (%): 55 ± 14
- Air changes (per hr): at least 15
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:

oral: feed

Vehicle:

unchanged (no vehicle)

Details on oral exposure:

DIET PREPARATION
- Rate of preparation of diet: prior to treatment and then twice monthly
- Mixing appropriate amounts with: basal laboratory diet
- Storage of food: stored in labelled, double plastic bags in labelled, covered plastic bins

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Samples were taken of each dietary admixture and were analysed for concentration twice monthly for the first two months, monthly for the next two months and thereafter every three months. The concentration of the test material in the dietary admixtures was determined by gas chromatography using an external standard technique. The results indicate that the mean prepared dietary admixture concentrations were within ± 18% of the nominal concentration.

Duration of treatment / exposure:

52 weeks

Frequency of treatment:

daily, 7 days/week

Doses / concentrations

Doses / concentrations 1

Remarks:

Doses / Concentrations:
1500, 6000 and 15000/25000 (from Week 10)/30000 (from Week 41) ppm
Basis:
nominal in diet

Doses / concentrations 2

Remarks:

Doses / Concentrations:
98, 392 and 1333 mg/kg bw/day
Basis:
other: Group mean achieved dose level calculated on actual values for food consumption and body weight with calculated test material intake.

Doses / concentrations 3

Remarks:

Doses / Concentrations:
87.1, 348.5 and 1116.5 mg/kg bw/day
Basis:
other: Group mean achieved dose level of males calculated on actual values for food consumption and body weight with calculated test material intake.

Doses / concentrations 4

Remarks:

Doses / Concentrations:
109.3, 435.0 and 1549.8 mg/kg bw/day
Basis:
other: Group mean achieved dose level of females calculated on actual values for food consumption and body weight with calculated test material intake.

No. of animals per sex per dose:

21

Control animals:

other: diet treated with Arachis oil to achieve comparable calorific intake

Details on study design:

- Dose selection rationale: The dietary concentrations were chosen based on toxicity data and consultation with the Study Sponsor (no further information).
- Dietary concentration: In order to achieve a high dose level that approximated a test material intake equivalent to 1000 mg/kg bw/day, the dietary concentration of the test material in the diet was reviewed and periodically adjusted. High-dose concentrations were changed at Week 10 (25000 ppm) and Week 41 (30000 ppm).

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: once daily

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: once per week

BODY WEIGHT: Yes
- Time schedule for examinations: at Day 1 and at weekly intervals for the first 13 weeks and subsequently, every 4 weeks until study termination.

FOOD CONSUMPTION: Yes
- Food consumption for each cage group was determined at weekly internals from Week 1 to Week 13 and subsequently for one week in each four week period until termination.

FOOD EFFICIENCY: Yes
- Food efficiency and chemical intake was calculated for the food consumption periods.

WATER CONSUMPTION: Yes
- Time schedule for examinations: daily, for each cage group by visual inspection of the water bottles for any overt changes.

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: prior to testing and during Week 50
- Dose groups that were examined: all animals prior to testing and 10 females and 10 males from the control and high-dose groups during Week 50 were observed.

HAEMATOLOGY: Yes
- Time schedule for collection of blood: at 3, 6 and 12 months
- How many animals: 10 females and 10 males from each group
- Parameters checked: Haemoglobin (Hb), Erythrocyte count (RBC), Haematocrit (Hct), Erythrocyte indices, Total leucocyte count (WBC), Differential leucocyte count, Neutrophils (Neut), Lymphocytes (Lymph), Monocytes (Mono), Eosinophils (Eos), Basophils (Bas), Platelet count (PLT), Reticulocyte count (Retic), Prothrombine time (CT), Activated partial thromboplastin time (APPT)

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: at 6 and 12 months
- How many animals: 10 females and 10 males from each group
- Parameters checked: Urea, Glucose, Total protein (Tot. Prot.), Albumin, Albumin/Globulin (A/G) ratio (by calculation), Sodium (Na+), Potassium (K+), Chloride (Cl-), Calcium (Ca++), Inorganic phosphorus (P), Aspartate aminotransferase (ASAT), Alanine aminotransferase (ALAT), Alkaline phosphatase (AP), Creatinine (Creat), Total cholesterol (Chol), Total bilirubin (Bili), Triglycerides (Tri), Gamma glutamyltranspeptidase (γGT)

URINALYSIS: Yes
- Time schedule for collection of urine: at 3, 6 and 12 months
- Parameters checked: Specific gravity, volume, pH, protein, glucose, ketones, bilirubin, urobilinogen, reducing substances, blood, microscopic examination of sediment

NEUROBEHAVIOURAL EXAMINATION: Yes
- Time schedule for examinations: prior to the start of treatment and at monthly intervals and during Week 51
- Dose groups that were examined: all animals
- Battery of functions tested: sensory activity / grip strength / motor activity

Sacrifice and pathology:

GROSS PATHOLOGY: Yes. Adrenals, brain, epididymides, heart, kidneys, liver, ovaries, pituitary, prostate, spleen, testes, thyroid with parathyroid (post fixation), uterus.
HISTOPATHOLOGY: Yes. Adrenals, aorta (thoracic), bone & bone marrow (femur including stifle joint), bone & bone marrow (sternum), brain, caecum, colon, duodenum, epididymides, eyes (with optic nerve), gross lesions including palpable masses, harderian gland, head (to include pharynx, nasopharynx and, paranasal sinuses), heart, ileum, jejunum, kidneys, larynx, liver, lungs (with bronchi), lymph nodes (cervical and mesenteric), mammary glands, muscle (skeletal), nose, oesophagus, ovaries, pancreas, pharynx, pituitary, prostate, rectum, salivary glands (submaxillary), sciatic nerve, seminal vesicles, skin (hind limb), spinal cord (cervical, mid-thoracic and lumbar), spleen, stomach, testes, thymus, thyroid/parathyroid, tongue, trachea, urinary bladder, uterus.

Statistics:

Data were processed to give group mean values and standard deviations where appropriate. Where appropriate, quantitative data were analysed by the Provantis™ Tables and Statistics Module. For each variable, the most suitable transformation of the data was found, the use of possible covariates checked and the homogeneity of means assessed using ANOVA or ANCOVA and Bartlett’s test. The transformed data were analysed to find the lowest treatment level that showed a significant effect, using the Williams test for parametric data or the Shirley test for non-parametric data. If no dose response was found, but the data showed non-homogeneity of means, the data were analysed by a stepwise Dunnett (parametric) or Steel (non-parametric) test to determine significant differences from the control group. Finally, if required, pair-wise tests were performed using the Student t-test (parametric) or the Mann-Whitney U test (non-parametric). Histopathology data were analysed using the following methods to determine significant differences between control and treatment groups for the individual sexes. Chi squared analysis for differences in the incidence of lesions occurring with an overall frequency of 1 or greater. Kruskal-Wallis one way non-parametric analysis of variance for the comparison of severity grades for the more frequently observed graded conditions. Probability values (P) are presented as follows: P < 0.001(+++ or --- or ***), P < 0.01 (++ or -- or **), P < 0.05 ( + or - or *), P < 0.1 ((+), (-), (*)), p > 0.1 (N.S. (not significant)). With plus signs indicating positive differences from the control group and minus signs indicating negative differences. Asterisks refer to overall between group variation which is non-directional.

Results and discussion

Results of examinations

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

High-dose group: one male was found dead on Day 280, multifocal necrosis in the liver, not treatment related

Mortality:

mortality observed, treatment-related

Description (incidence):

High-dose group: one male was found dead on Day 280, multifocal necrosis in the liver, not treatment related

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

higher mean body weight in males and females in different groups and time points (see Table 1 under "Any other information on results incl. tables"), non-adverse

Food consumption and compound intake (if feeding study):

no effects observed

Food efficiency:

no effects observed

Water consumption and compound intake (if drinking water study):

no effects observed

Ophthalmological findings:

no effects observed

Haematological findings:

effects observed, treatment-related

Description (incidence and severity):

all treatment groups males: reduction in PLT and Neut; high- and mid-dose males: reduction in WBC (see Table 2 under "Any other information on results incl. tables"), non-adverse

Clinical biochemistry findings:

effects observed, treatment-related

Description (incidence and severity):

all treatment groups males: increased urea, reductions in Tri; mid-dose group males: decreased AP; low-dose group males: increased ALAT; all treatment groups females: reduction in Cl-; mid-dose group females: increase in K+, non-adverse

Urinalysis findings:

no effects observed

Behaviour (functional findings):

no effects observed

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

all treatment groups males and low dose-group females: increased kidney weight, all treatment groups females: increased thyroid/parathyroid weight (see Table 3 under "Any other information on results incl. tables"), non-adverse

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

no effects observed

Details on results:

CLINICAL SIGNS AND MORTALITY
There were no toxicologically significant clinical signs detected throughout the treatment period. Episodes of fur loss, fur staining, scab formation, mass formations and wounds were evident throughout the treatment and control animals during the course of the study. Observations of this nature are commonly observed in group housed animals or in ageing rodents and are not considered to be related to treatment.
One male treated at the high dose level was found dead on Day 280. Histopathological examination of this animal revealed a marked severity of multifocal necrosis in the liver which would have significantly contributed towards death. Acanthosis and hyperkeratosis of the fore stomach were also observed. In the absence of similar effects being detected in terminal kill animals the microscopic changes identified in the decedent were considered not to be an effect of test material toxicity. There were no further unscheduled deaths.

BODY WEIGHT AND WEIGHT GAIN
Overall bodyweight gain for males from all treatment groups was comparable to control values. Overall bodyweight gain for females from all treated groups was higher than controls. For males treated at the high dose group and at 6000 and 1500 ppm overall bodyweight gain was 94%, 99% and 97% of control values respectively. Occasional statistically significant differences in bodyweight gain were evident during Weeks 3 (mid-dose group) and 7 (high-dose group) and between Weeks 22-25 (mid- and high-dose groups), 35-38 (high-dose group) and 39-43 (mid- and high-dose group) for males and between Weeks 48-51 (low-dose group) for females. There was no obvious treatment related trend in the intergroup differences and in the absence of an overall effect on bodyweight the intergroup differences were considered not to be of toxicological importance.

FOOD CONSUMPTION/EFFICIENCY AND COMPOUND INTAKE
There were no treatment related effects on food consumption values or food efficiency for animals of either sex from any treatment group throughout the course of the study.

OPHTHALMOSCOPIC EXAMINATION
There were no treatment related ocular effects detected.

HAEMATOLOGY
During Month 3 evaluations, males in the low-dose group showed a statistically significant reduction in platelet count (p < 0.05). The effect on platelet count continued into the Month 6 assessments and extended to males in the remaining treatment groups (mid-and high-dose group, p < 0.05). During the final evaluations during Month 12 males treated at the high- and mid-dose level showed a statistically significant reduction in total leucocyte count (p < 0.05). Males from all treatment groups also showed a statistically significant reduction in neutrophil count (p < 0.05-0.01). There were no dose related responses in the intergroup differences detected and therefore were considered not to be of toxicological significance (see Table 2 under “Any other information on results incl. tables”).

CLINICAL CHEMISTRY
During Month 6 evaluations, males from all treatment groups showed statistically significant increases in urea (p < 0.05 - < 0.01) and statistically significant reductions in triglycerides (p < 0.05). Males in the mid-dose group showed a statistically significant reduction in alkaline phosphatase and males in the low-dose group showed a statistically significant increase in alanine aminotransferase. The effect on urea in males (p < 0.01) continued during the final evaluations at Month 12. At Month 12, females from all treatment groups showed statistically significant reductions in chloride concentration (p < 0.05). Females in the mid-dose group showed a statistically significant increase in potassium concentration (p < 0.05). There were no dose related responses in any of the parameters measured and therefore were considered not to be of toxicological significance (see Table 2 under “Any other information on results incl. tables”).

URINALYSIS
There were no treatment related findings detected in urine volume, urine specific gravity, urine sediment or the remaining urinalytical parameters examined.

NEUROBEHAVIOUR
Monthly open field arena observations did not reveal any treatment-related effects for treated animals when compared to controls. There were no treatment related changes in functional performance and in sensory reactivity.

ORGAN WEIGHTS
In the study, there were no toxicologically significant effects detected in the organ weights measured. Males from all treatment groups and females in the low-dose group showed statistically significant increases in kidney weight both absolute and relative to terminal body weight. Females from all treatment groups also showed statistically significant increases in absolute and relative thyroid/parathyroid weight (see Table 3 under “Any other information on results incl. tables”). In the absence of a dose related response or any associated histology correlates the intergroup differences were considered not to be of toxicological importance.

GROSS PATHOLOGY
There were no treatment-related macroscopic changes observed for either sex amongst animals at scheduled kill or the decedent animal. Macroscopic observations were identified as reddened lungs, pale or dark foci on the lungs, masses in various tissues, sloughing in the stomach or an enlarged thyroid. Observations of this nature are those typically observed for laboratory animals of this type and the occurrences of these observations were recorded for both control and treated animals. In the absence of any significant histology correlates the findings were considered to be associated with ageing animals and of no toxicological importance.

HISTOPATHOLOGY
There were no treatment related microscopic abnormalities detected. All morphological changes were those commonly observed in laboratory maintained rats of the age and strain employed and, since there were no meaningful differences in incidence or severity between control and treatment groups, all were considered not to be treatment related. In Table 4 under “Any other information on results incl. tables” conditions that warrant specific mention are given.

Effect levels

Dose descriptor:

NOAEL

Effect level:

>= 1 333 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: NOAEL corresponding to the highest dose tested

Target system / organ toxicity

Critical effects observed:

not specified

Any other information on results incl. tables

Table 1. Significant increases in body weight gains in comparison to the respective control group (g).

Group	Week 3	Week 7	Week 25	Week 35	Week 39	Week 48
Mid-dose group (M)	17.3 ± 9.1**	-	4.2 ± 3.5*	-	7.9 ± 6.2*	-
High-dose group (M)	-	11.1 ± 4.8*	-	9.5 ± 5.9**	7.1 ± 7.3*	-
Low-dose group (F)	-	-	-	-	-	9.7 ± 8.7*

*: P < 0.05

**: P < 0.01

-: no significant change in comparison to the respective control group.

Table 2. Significant changes of haematology/clinical examinations.

Group	PLT 10^9/ L	WBC 10^9/ L	Neut 10^9/ L	Urea mg/dL	ALAT IU/L	AP IU/L	Tri mg/dL	K+ mmol/L	Cl- mmol/L
Males
Low-dose group	558.5 ± 79.4*(M3) 615.5 ± 59.8* (M6)	-	1.005 ± 0.356* (M12)	35.0 ± 2.0 *(M6) 30.8 ± 2.9** (M12)	55.7 ± 20.7* (M6)	79.1 ± 11.3* (M6)	153.4 ± 33.1* (M6)	-	-
Mid-dose group	632.5 ± 51.6* (M6)	4.11 ± 0.49** (M12)	0.860 ± 0.274** (M12)	37.0 ± 3.9** (M6) 29.7 ± 4.0** (M12)	-	-	183.6 ± 59.8* (M6)	-	-
High-dose group	638.7 ± 56.4* (M6)	4.73 ± 0.74* (M12)	0.879 ± 0.341** (M)	35.6 ± 5.4** (M6) 29.5 ± 4.0** (M12)	-	-	168.7 ± 39.4* (M6)	-	-
Females
Low-dose group	-	-	-	-	-	-	-	-	103.5 ± 1.3* (M12)
Mid-dose group	-	-	-	-	-	-	-	4.428 ± 0.190* (M12)	103.8 ± 1.0* (M12)
High-dose group	-	-	-	-	-	-	-	-	103.6 ± 1.8* (M12)

*: P < 0.05

**: P < 0.01

M: Month

-: no significant change in comparison to the respective control group.

Table 3. Group mean kidney/thyroid weights with corresponding relative (% of Body weight) organ weights.

Group	Low-dose	Mid-dose	High-dose
Organ	Males
Kidney Mean ± S.D. (g) Mean ± S.D. (%)	2.45836 ± 0.25241** 0.453 ± 0.051*	2.55051 ± 0.25241** 0.462 ± 0.038**	2.46595 ± 0.35788** 0.461 ± 0.037**
	Females
Kidney Mean ± S.D. (g) Mean ± S.D. (%)	1.87500 ± 0.22877* 0.572 ± 0.059*	-	-
Thyroid/Parthyroid Mean ± S.D. (g) Mean ± S.D. (%)	0.02643 ± 0.00551* 0.008 ± 0.002*	0.02479 ± 0.00475* 0.008 ± 0.002*	0.02648 ± 0.00776* 0.008 ± 0.002*

*: P < 0.05

**: P < 0.01

-: no significant change in comparison to the respective control group.

Table 4. Summary of incidence of histopathological findings.

Organ/Tissue	Histological Finding
Bone marrow	Adipose infiltration of the marrow is an indicator of changes in marrow cellularity (higher grades of severity among ageing rats). No differences were seen between control and treated groups.
Adrenal glands	Cortical vacuolation is commonly seen among laboratory rats (especially males). Foci of altered cortical cells are also commonly seen among ageing rats and are characteristically hypertrophic and vacuolated. Isolated instances of haemorrhagic foci were seen among female rats. No evidence of a treatment-related distribution of incidence for any adrenal pathology.
Eyes	Retinal atrophy was observed for a few animals. No treatment-related distribution was observed.
Heart	Focal myocarditis was seen frequently among male rats and rarely among female rats. This is a common background entity in laboratory rats; the severity of the condition was never greater than 1 or 2 foci and should not be interpreted as being indicative of any significant ongoing myocardial disease.
Liver	Scattered mononuclear cell foci were observed in the majority of animals examined in the study. Such are commonly observed in the rodent liver and the severity was rarely greater than minimal or 1 or 2 foci. Centrilobular hepatocyte lipid vacuolation was seen among male rats without a treatment-related distribution of incidence and hepatocyte enlargement and periportal lipid vacuolation were seen occasionally among female rats. Foci of altered hepatocytes are commonly seen in the liver of ageing rats and foci in this investigation foci were typically clear-cell and basophilic. There was no neoplastic liver pathology in this study.
Lymph nodes	Isolated instances of spontaneously arising conditions were seen. Lymphoid neoplasia was not observed in this investigation.
Spleen	Extramedullary haemopoiesis is a normal background condition in the rat spleen. The severities observed were considered to be within normal limits for maintained rats of this age and strain and there was no treatment-related distribution of incidence or severity grades in this investigation.
Kidney	Isolated groups of basophilic/dilated tubules are frequently encountered in the renal cortex as spontaneous change in laboratory maintained rats of this age and strain and have no pathological significance at the severities or frequencies reported in this study. Similarly pelvic corticomedullary mineralisation is a commonly observed background condition amongst ageing female rats and was of no toxicological significance. Hyperplasia of the pelvic/papillary epithelium was observed for a few animals.
Lung	A minimal severity of perivascular/peribronchiolar lymphoid tissue was reported for all animals examined in the study and is not indicative of respiratory disease. Accumulations of alveolar macrophages, cuboidal cell metaplasia, haemorrhage/oedema, and congestion were also seen without significant group distribution of incidence or severity.
Mammary gland	Glandular and secretory hyperplasia were seen among control and high dose female rats and there was no evidence that the incidence or severity of either condition was related to treatment. A mammary fibro-adenoma was seen for one control female rat and a mammary adenocarcinoma was seen for one high dose female rat; these are relatively common spontaneous neoplasms in ageing female rats.
Ovary	Follicular/fluid-filled cysts, cystic corpora lutea, and haemorrhagic cysts are seen with increasing frequency among ageing female rats as spontaneous conditions. There was no relationship to treatment for ovarian cysts in this investigation.
Pancreas	Exocrine atrophy and islet cell hyperplasia were seen for several rats as spontaneous change and without toxicological significance.
Pituitary	Benign adenomas of the pars anterior were seen for a few control and treated rats of either sex. These are relatively common spontaneous neoplasms of laboratory rats (incidence increasing with age). Isolated instances of focal hyperplasia, haemorrhage, and developmental cysts were also seen.
Prostate	Interstitial chronic inflammatory cell infiltrates and prostatitis are commonly observed spontaneous conditions in laboratory rats. Variations in secretory content are also seen relatively frequently.
Thyroid	Parafollicular or C-cell hyperplasia was observed for 3 control and 3 high-dose male rats and follicular cell hyperplasia was seen for 1 control male rat. A few thyroid neoplasms were seen, notably a follicular cell adenoma for 2 animals and a follicular cell carcinoma for 2 animals. There was no treatment-related distribution of incidence.
Seminal vesicles	Variations in secretory content are seen relatively frequently.
Thymus	Lymphoid atrophy is common in the thymus of ageing rats (especially males) and there was no evidence of a treatment-related distribution of incidence or severity in this study.
Uterus/Vagina	Dilatation of the uterine horns and keratinisation of the cervical epithelium are commonly observed cyclical conditions in laboratory female rats, as is keratinisation of the vaginal epithelium. Isolated instances of a few other age-related conditions were also seen without toxicological significance.
Tissue masses	Nodules of fat necrosis were observed for a few animals; these are relatively commonly seen among ageing laboratory rats.