Expression of cyclooxygenase-1 and cyclooxygenase-2, syndecan-1 and connective tissue growth factor in benign and malignant breast tissue from premenopausal women.

Stromal factors have been identified as important for tumorigenesis and metastases of breast cancer. From 49 premenopausal women, samples were collected from benign or malignant tumors and the seemingly normal tissue adjacent to the tumor. The factors studied, with real-time polymerase chain reaction (PCR) and immunohistochemistry, were cyclooxygenase-1 and cyclooxygenase-2 (COX-1 and COX-2), syndecan-1 (S-1) and connective tissue growth factor (CTGF). COX-1 and S-1 mRNA levels were higher in the malignant tumors than in normal and benign tissues. The COX-2 mRNA level was lower in the malignant tumor than in the normal tissue, while CTGF mRNA did not differ between the groups. COX-1 immunostaining was higher in stroma from malignant tumors than in benign tissues, whereas COX-2 immunostaining was higher in the malignant tissue. Glandular S-1 immunostaining was lower in malignant tumors compared to benign and normal tissues, and the opposite was found in stroma. Conclusively, mRNA levels of COX-1 and COX-2 were oppositely regulated, with COX-1 being increased in the malignant tumor while COX-2 was decreased. S-1 protein localization switched from glandular to stromal cells in malignant tissues. Thus, these markers are, in premenopausal women, localized and regulated differently in normal/benign breast tissue as compared to the malignant tumor.

Oxytocin receptors in dioestrous and anoestrous canine uteri.

The aim of the study was to localize oxytocin receptors (OTR) and measure mRNA expression of OTR in the canine uterus with and without the influence of progesterone. Uterine samples were taken from nine anoestrous and eight dioestrous bitches during ovariohysterectomy. Histological changes were evaluated in haematoxylin and eosin (HE)-stained samples. Purified polyclonal antibody for OTR was used in immunohistochemistry to localize receptors in uterine layers. Relative mRNA concentration of OTR was evaluated with real-time PCR from full-thickness uterine samples taken from the middle horn and the body. Myometrial smooth muscle cells, endometrial luminal epithelium (LE) and deep and superficial glandular epithelium were positively stained for oxytocin receptors in non-pregnant animals. No significant difference in staining intensity was detected between uterine middle horn and body. However, the staining intensity of LE was significantly higher in dioestrous than in anoestrous uteri (p < .05). Leucocytes and endothelium of blood vessels were also positively stained for OTR. Real-time PCR showed no significant differences in OTR mRNA expression between the middle horn and the body of the uterus, or between anoestrous and dioestrous uterus. No correlation was noted between OTR mRNA expression and blood progesterone concentration. In conclusion, despite the apparent inactivity, the uterus of the non-pregnant bitch expresses OTR. The distribution or relative expression of OTR does not differ between uterine horn and body in dioestrus or anoestrus except in LE. LE may have more oxytocin-dependent activity during dioestrus than anoestrus.

Placental IGF-I, estrogen receptor, and progesterone receptor expression, and maternal anthropometry in growth-restricted pregnancies in the Swedish population.

BACKGROUND/AIMS: Fetal growth restriction is a complex problem of pregnancy arising from multiple etiologies. Key regulatory elements of growth are the insulin-like growth factor (IGF) axis, and estrogen and progesterone receptors. The aims were to determine the relations of expression of IGF-I, estrogen receptors α and ß (ERα and ERß, respectively), and progesterone receptor (PR), with maternal anthropometry, focusing on birth weight outcomes. METHODS: Placental samples were obtained from 33 patients following delivery. mRNA expression was determined by a solution hybridization technique. Samples were divided into normal control (NC) and growth-restricted (GR) groups. RESULTS: IGF-I expression was lower in the GR as compared to the NC group. PR levels correlated positively with IGF-I expression, infant anthropometry, and gestational age (GR). ERα correlated positively with PR expression (NC), and maternal BMI at delivery (GR). ERß correlated positively with maternal delivery weight and gestational age (NC). CONCLUSION: The differences in placental expression of IGF-I emphasize its key role in birth weight outcomes. We further suggest the importance of PR expression in the pathogenesis of intrauterine growth restriction, as there were direct correlations of PR expression with both IGF-I expression and infant anthropometric parameters, as well as gestational age.

Endometrial population of oestrogen receptors alpha and beta and progesterone receptors A and B during the different phases of the follicular wave of llamas (Lama glama).

The aim of this study was to characterize the distribution of oestrogen receptor (ER)α and ERß as well as both progesterone receptors isoforms progesterone receptor (PR) A and PRB in the luminal and glandular epithelia and stroma of the endometrium during the different phases of the follicular wave in llamas. Six llamas were examined by transrectal ultrasonography, and a transcervical biopsy was obtained when a follicle at the growing, plateau and regressing phase was recorded. Blood samples were collected at the time of biopsy for hormone determinations. An immunohistochemical technique was used to study receptor populations. Total positive area was evaluated in the different cell types by Image Analysis. Mean diameter measurements of the largest follicle were 6.9, 8.5 and 5.1 mm (p < 0.001) and mean plasma oestradiol-17ß concentrations were 27.9 ± 3.26; 30.0 ± 2.79 and 24.0 ± 1.78 pmol/l (p = 0.32) during the growing, plateau and regressing phases, respectively. Immunostaining of ERα was higher in the luminal epithelium during the plateau and regressing phases (p < 0.05) than during the growing phase. More positive cells to ERß were observed in the glandular epithelium of the growing and plateau phases (p < 0.05) than during the regressing phase. A higher percentage of cells positive to PRB was recorded in the luminal and glandular epithelia during the plateau phase (p < 0.05), while the PRA immunostaining was similar among phases. In brief, this study showed an increased population of ERα and PRB in the luminal epithelium, and only of PRB in the glandular epithelium at the time when an ovulatory follicle is present. The physiological importance of these changes in llamas remains to be elucidated.

Expression of the androgen receptor and syndecan-1 in breast tissue during different hormonal treatments in cynomolgus monkeys.

OBJECTIVES: To analyze the expression of the androgen receptor(AR) and syndecan-1 in breast tissue during long-term hormonal treatment in cynomolgus monkeys. METHODS: Sixty oophorectomized macaques were randomized to receive either tibolone, conjugated equine estrogens (CEE), CEE + medroxyprogesterone acetate (MPA) or no hormonal treatment. Breast tissue was collected at necropsy after 2 years and stained for AR and syndecan-1. RESULTS: Apparent differences were seen between treatment groups as compared to untreated animals. AR expression was markedly increased by tibolone and suppressed by combined CEE/MPA. Both treatments increased syndecan-1 in stromal tissue, whereas CEE alone had no significant effect. CONCLUSIONS: We found alternative regimens for hormonal therapy to differ in their influence on two markers of importance for the development of breast cancer. The results may be relevant for the ongoing clinical discussion on the long-term safety of different hormonal treatments.

Messenger RNA levels of estrogen receptors alpha and beta and progesterone receptors in the cyclic and inseminated/early pregnant sow uterus.

The aim of the present study was to investigate differences in the expression of mRNAs for ERalpha, ERbeta and PR in the sow uterus at different stages of the estrous cycle as well as in inseminated sows at estrus and during early pregnancy by use of solution hybridization and in relation to plasma levels of estradiol and progesterone. Uterine samples were collected at different stages of the estrous cycle and after insemination/early pregnancy. In the endometrium, the expression of ERalpha mRNA and PR mRNA was similar for cyclic and early pregnant groups. Both were highest at early diestrus/70 h after ovulation and ERalpha mRNA was lowest at late diestrus/d 19 while PR mRNA was lowest at diestrus and late diestrus/d 11 and d 19. The expression of endometrial ERbeta was constantly low during the estrous cycle but higher expression was found in inseminated/early pregnant sows at estrus and 70 h after ovulation. In the myometrium, high expression of ERalpha mRNA and PR mRNA was observed at proestrus and estrus in cyclic sows and at estrus in newly inseminated sows. Higher expression of myometrial ERbeta mRNA was found in inseminated/early pregnant sows compared with cyclic sows, although significant only at estrus. In conclusion, the expression of mRNAs for ERalpha, ERbeta and PR in the sow uterus differed between endometrium and myometrium as well as with stages of the estrous cycle and early pregnancy. In addition to plasma steroid levels, the differences between cyclic and inseminated/early pregnant sows suggest that other factors, e.g. insemination and/or the presence of embryos, influence the expression of these steroid receptor mRNAs in the sow uterus.

Effects of tibolone and conventional HRT on the expression of estrogen and progesterone receptors in the breast.

OBJECTIVE: There is evidence that long-term hormone replacement therapy (HRT) is associated with an increased breast cancer risk. The aim of this study was to assess the effects of tibolone on estrogen and progesterone receptors in comparison to the effects of conventional HRT in the breast of surgically postmenopausal macaques. METHOD: Sixty macaques were bilaterally ovariectomized 3 months before hormonal treatment was initiated. The animals were randomized into four treatment groups, including tibolone (TIB), conjugated equine estrogens (CEE), conjugated equine estrogens+medroxyprogesterone acetate (CEE+MPA) and control animals (C). After 2 years treatment, breast tissues were collected, fixed and paraffin embedded. Immunohistochemistry assays with monoclonal antibodies for estrogen receptors (ERalpha and ERbeta) and progesterone receptors (PRA and PRB) were performed. RESULTS: The expression of ERalpha was markedly decreased in the CEE+MPA group as compared to C and TIB groups. The TIB group was not different from the C and CEE groups. No significant differences were found for ERbeta immunostaining. The expression of PRA was strongly increased in the TIB group as compared to the C and CEE+MPA groups. Immunostaining of PRB was increased in the CEE and TIB treated animals as compared to both C and CEE+MPA groups. CONCLUSIONS: Tibolone increased the expression of both PRA and PRB, without affecting ERalpha and ERbeta expression in the macaque breast. These findings indicate that the effects of tibolone in breast tissue could be mediated via differential regulation of PRA and PRB isoforms and therefore distinct from those observed with conventional HRT.

Gene expression analysis of human endometrial endothelial cells exposed to op'-DDT.

The endocrine disrupting chemical o, p'-dichlorodiphenyltrichloroethane (DDT) can affect reproductive organs, tissues and cells in several species. Treatment of human endometrial endothelial cells (HEECs) with 50 microM o,p'-DDT decreased their proliferation compared with the control. Microarray analyses revealed that o,p'-DDT affected biological processes such as the cell cycle, cell division, defence response and lipid and steroid metabolism, in cellular components such as the plasma membrane and chromosomes, with molecular functions involved in signalling, receptor and cytokine activity, confirming the results of the proliferation assay. Expression of five of the most differentially expressed genes identified in the microarray analysis was verified by real-time quantitative reverse transcription polymerase chain reaction in five HEEC cultures obtained from women in the proliferative phase and in five cultures obtained from women in the secretory phase of the menstrual cycle after treatment with o,p'-DDT. The present study supports our previous findings of decreased proliferation and increased cell death in response to o,p'-DDT and may offer important clues to the mechanisms of action of o,p'-DDT.

Expression of syndecan-1 in paired samples of normal and malignant breast tissue from postmenopausal women.

BACKGROUND: The mammary stroma is important for modulating epithelial breast cell response to sex steroid hormones. Proteoglycans, such as syndecan-1, promote the integration of cellular signals. MATERIALS AND METHODS: The immunohistochemical expression of syndecan-1 and of the androgen receptor (AR) was analyzed in paired samples of cancer and adjacent normal tissue from postmenopausal women. RESULTS: Normal and cancer tissue showed dramatic differences in the expression of syndecan-1. In malignant breast stroma, mean values were more than 10-fold higher than in normal tissue (p<0.001). There was also a marked redistribution from the epithelium to the stroma. The expression of AR was on average 2-fold higher in cancerous than in normal tissue (p<0.01). CONCLUSION: Breast cancer patients have very different prognoses. Syndecan-1 and the AR may be new molecular markers relevant to clinical outcome. The redistribution from the epithelium and the dramatic increase of syndecan-1 in cancerous stroma may be related to the natural history of the disease.

Expression of Syndecan-1 in histologically normal breast tissue from postmenopausal women with breast cancer according to mammographic density.

OBJECTIVE: To analyze the expression of Syndecan-1 in dense and non-dense human breast tissue. METHODS: Specimens of histologically normal tissue were obtained from postmenopausal women undergoing surgery for breast cancer. Each tissue block was subject to radiological examination and pair-wise samples of dense and non-dense tissue were collected. Semi-quantitative assessment of immunohistochemical staining intensity for Syndecan-1 and estrogen receptor subtypes was performed. RESULTS: The expression of Syndecan-1 in all tissue compartments was significantly higher in dense than in non-dense specimens. The strongest staining was recorded in stromal tissue. There was a strong correlation between epithelial estrogen receptor alpha and stromal cell Syndecan-1 expression in dense tissue (rs = 0.7; p = 0.02). This association was absent in non-dense tissue. CONCLUSION: An increase of Syndecan-1 in all tissue compartments and a redistribution from epithelium to stroma may be a characteristic feature for dense breast tissue.

Expression of sex steroid receptor subtypes in normal and malignant breast tissue - a pilot study in postmenopausal women.

Female sex steroids are implied in breast cancer development. The estrogen (ER) and progesterone (PR) receptor subtypes may have different roles to modulate the cellular response. Paired samples of cancer and adjacent normal tissue were collected from postmenopausal women at surgery for ductal breast cancer. The expression of ERa, ERss, PRA and PRB was quantified by immunostaining and digitized image analysis. We found ERss to be significantly reduced in breast cancer tissue (35% vs 50%; p?=?0.001) and there was also a decrease of the ERss/ERa ratio. Among women using hormones at the time of diagnosis tumor tissue showed higher values for both PRB and PRA, as compared to women without such treatment. The results extend previous animal data to be valid also in women. There is evidence that loss of ERss expression may relate to estrogen dependent tumor progression. Increased PR expression could possibly relate to breast cancer risk during combined estrogen/progestogen treatment.

Differential estradiol effects on estrogen and progesterone receptors expression in the oviduct and cervix of immature ewes.

In order to study the effect of estradiol-17beta (E2) on estrogen (E) and progesterone (P) receptors expression in oviduct and cervix of lambs, their respective transcripts (ERalpha mRNA and PR mRNA) were determined by solution hybridization and the receptor proteins (ER and PR) by binding assays after E2 treatments. Lambs (n=4 in each group) were not treated or treated with one, two or three i.m. injections of E2 (1 microg/kg) at 24 h of interval. Tissues were obtained 12 or 24 h after the last E2 injection. Estradiol treatments increased ERalpha mRNA and PR mRNA concentrations in an organ-dependent manner: transitory in the oviduct while maintained in the cervix. The E2 effect on the oviductal and cervical ER and PR concentrations were biphasic, with an initial reduction of receptors content that was followed by restoration. The ER restoration in oviduct was earlier than in the cervix. In summary, this study shows that E2 treatments may exert an inductive effect in ERalpha mRNA and PR mRNA levels and a biphasic effect in ER and PR concentrations in oviduct and cervix of immature ewe. These E2 effects varied in timing and strength depending on the organ of the reproductive tract.

Immunohistochemical studies on the progesterone receptor (PR) in the sow uterus during the oestrous cycle and in inseminated sows at oestrus and early pregnancy.

Physiological changes in the sow uterus involve the regulation by progesterone and its receptor proteins (PR). Therefore, the aim of the present study was to investigate the localization of PR during different stages of the oestrous cycle and in inseminated sows during early pregnancy by use of immunohistochemistry. Uterine samples were collected from cyclic and inseminated sows at different stages of the oestrous cycle and early pregnancy. The samples were fixed in 10% formaldehyde and embedded in paraffin. Immunohistochemistry was done by use of a mouse monoclonal antibody to PR. The highest PR immunostaining in the surface epithelium was observed at oestrus/5-6 h after artificial insemination (AI) and early dioestrus/70 h after AI. In the glandular epithelium, the highest level of PR was found at oestrus with the lowest at late dioestrus/d 19. Higher levels of PR were observed in inseminated groups compared with cyclic sows. In the myometrium, a high level of PR was found at oestrus, while stromal PR cells were constantly present throughout the oestrous cycle and at different stages of early pregnancy. In conclusion, this study shows that the immunopresence of PR in the sow uterus differed between uterine compartments at the same reproductive stage. Differences were also found for some uterine compartments between cyclic and inseminated/early pregnant sows. The relatively consistent immunostaining of PR in the stroma strengthens a stromal role in the regulation of physiological activities in the sow uterus during the oestrous cycle as well as early pregnancy.

Differential regulation of the progesterone receptor A and B in the human uterine cervix at parturition.

The concept of a blockade of progesterone during human pregnancy and withdrawal of this blockade at parturition remains controversial There is no sharp fall in serum progesterone before parturition, but treatment with an antiprogestin is successful for labor induction at term pregnancy. The human progesterone receptor (PR) exists in two isoforms (PR-A and PR-B), mediating different biological responses. Here, the hypothesis of a progesterone withdrawal at parturition in terms of a change in PR isoforms was tested. Cervical biopsies were obtained at term before the onset of labor, immediately after parturition and from non-pregnant women. Solution hybridization showed a tendency for the PR mRNA level to be decreased at parturition. Immunohistochemistry displayed decreased PR(A + B) and PR-B levels (p < 0.05) immediately after parturition. The relative importance of PR-A seemed higher immediately after parturition as compared to its importance in non-pregnant and term pregnant women. Our results are consistent with the concept of a functional progesterone blockade at the receptor level at term pregnancy, and withdrawal of this blockade at parturition. These observations may have important clinical and therapeutic implications.

Sex differences in oestrogen receptor levels in adrenal glands of sheep during the breeding season.

The concentrations of the oestrogen receptor (ER), and the mRNA levels of ERalpha, progesterone receptor (PR) and insulin-like growth factor I (IGF-I) were characterised in adrenal glands and uterine tissue of adult Corriedale sheep during the breeding season. The sheep were of different sex and gonadal status. Ewes had higher levels of cytosolic ER in the adrenals than the rams (mean+/-S.E.M.: 7.3+/-2.0 fmol/mg protein and 2.5+/-1.0 fmol/mg protein, respectively; P=0.0091) and gonadectomy increased ER (mean+/-S.E.M.: 2.9+/-1.2 fmol/mg protein and 8.6+/-2.3 fmol/mg protein, intact and gonadectomised sheep, respectively; P=0.0071). No differences could be observed in mRNA levels for ERalpha and IGF-I in the adrenal glands of all of the sheep. PR mRNA levels were reduced in ovariectomised ewes and enhanced in castrated rams (sex x gonadal status: P=0.009). PR mRNA levels tended to be higher in ewes in the follicular phase than in ovariectomised ewes and intact rams (P<0.1). All of the animals had positive nuclear staining for ERalpha in the adrenal cortex, but no differences were observed between the groups. In this study, we demonstrated the existence of ER in the adrenal gland of sheep and found varying sensitivity to oestrogens as the ER levels differed among sex and gonadal status. These findings indicate that oestrogens most likely affect steroidogenesis directly at the adrenal cortex and suggest that oestrogens are partly responsible for the sex differences in cortisol secretion in sheep.

Immunohistochemical determination of thioredoxin and glutaredoxin distribution in the human cervix, and possible relation to cervical ripening.

Thioredoxin (Trx) and glutaredoxin (Grx) are dithiol redox enzymes, catalyzing general thiol-disulfide oxidoreductions apart from being hydrogen donors for ribonucleotide reductase, an enzyme essential for DNA synthesis. In mammals, isoenzymes of Trx and Grx are found in the cytoplasm (Trx1 and Grx1) or in mitochondria (Trx2 and Grx2). Trx and Grx play a role in cellular defence against oxidative stress and in redox regulation of cellular function. The localization and levels of human Trx1 and human Grx1 have been determined in the human cervix by immunohistochemistry and image analysis. Cervical biopsies were obtained from five non-pregnant, five term pregnant and five postpartum women. The levels of both Trx1 and Grx1 were increased in the nuclei (after translocation from the cytoplasm) of stromal cells in cervices from the term pregnant group as compared to the non-pregnant group, but the levels in the postpartum group did not differ significantly from those of the other two groups. These results are in agreement with our previous data on the mRNA expression of these two redox enzymes. The increased levels of the redox enzymes in term pregnancy suggest that they can be regulating factors involved in the process of cervical ripening, e.g. transcription factors and enzymes. Secreted Trx may participate in removing inhibitors of collagen-degrading metalloproteinases.

Effect of estrogen and antiestrogens on the estrogen receptor content in the cochlea of ovariectomized rats.

Older women in the normal population tend to develop less severe hearing loss as compared to males in the same age. In Turner syndrome (45,X), estrogen deficiency is one of the predominant problems. Ear and hearing problems are common among these patients. Does estrogen have an impact on the hearing organ? Twenty-four rats were ovariectomized and treated with vehicle (controls), estradiol or selective estrogen receptor modulators such as tamoxifen and ICI182780, in order to study the effects on the estrogen receptor levels and distribution in the inner ear. The cochleas were stained immunohistochemically using antibodies against estrogen receptor alpha and beta. No major difference in estrogen receptor content in the cochleas was observed among groups. There was however a potential down regulation of estrogen receptor alpha in the marginal cells of stria vascularis in the rats that were substituted with ICI182780 (pure antiestrogen) as compared to those given estradiol or tamoxifen. When investigating the tissues with light microscopy no change in inner ear anatomy could be observed.

Effects of long-term HRT and tamoxifen on the expression of progesterone receptors A and B in breast tissue from surgically postmenopausal cynomolgus macaques.

Estrogen is a well-known mitogen in breast epithelium but the role of progesterone is complex and incompletely understood. In contrast to what is seen in the endometrium, combined estrogen/progestogen treatment for postmenopausal replacement (HRT) may carry a risk for breast cancer beyond that of estrogen alone. The ratio of the two progesterone receptor (PR) isoforms, PRA/PRB may define the response to progesterone in reproductive tissues. In a primate model for long-term HRT, surgically, postmenopausal cynomolgus macaques were treated for 35 months with conjugated equine estrogens (CEE), medroxyprogesterone acetate (MPA), CEE + MPA and tamoxifen (n = 5 in all groups). The immunohistochemical expression of PRA, PRB and the androgen receptor (AR) in breast tissue was quantified by image analysis. Over all, the total PR immunostaining in glandular epithelium was more abundant during CEE (mean 12%) and tamoxifen ( 1%) treatment as compared to CEE/MPA (5%), MPA (4%) and untreated controls (6%). Differences in PRB expression were observed between treatment groups (p < 0.05). In the CEE group levels of PRA were unchanged while there was a decline in the CEE/MPA group. The mean PRA/PRB ratio in the CEE group was 2.7 and in the CEE/MPA group 0.2. Treatment with tamoxifen had effects similar to those of estrogen. There was in all groups a weak positive nuclear AR immunostaining. This is the first in vivo study on the effects on long-term hormonal treatment on the expression of PR isoforms in normal primate breast tissue. The results suggest that hormonal treatments have a different influence on the PRA/PRB balance in the breast.

The effect of long-term treatment with steroid hormones or tamoxifen on oestrogen receptors (alpha and beta) in the endometrium of ovariectomized cynomolgus macaques.

The effects of oestrogen are mediated by two specific intracellular receptors, oestrogen receptors (ER) alpha and beta, which function as ligand-activated transcriptional regulators. Ovariectomized macaques (Macaca fascicularis) were used to study the regulation of ERalpha and ERbeta in the endometrium by immunohistochemistry and in situ hybridization after long-term hormone treatment. Animals were treated continuously for 35 Months with either conjugated equine oestrogen (CEE), medroxyprogesterone acetate (MPA), combined CEE/MPA, or tamoxifen (TAM). Treatment with CEE/MPA down-regulated ERalpha in the superficial glands. In the superficial stroma the ERalpha level was lower in the CEE/MPA group than in the CEE and MPA groups. ERbeta immunostaining was faint with minor variation in response to treatment, but increased in the superficial stroma after MPA treatment. The ratio of ERbeta/ERalpha increased in superficial stroma and gland after CEE/MPA treatment, and also in stroma after MPA and TAM. Cystic endometrial hyperplasia was observed in TAM-treated animals, in combination with a high level of ERalpha protein expression. The present data show that long-term hormone treatment affects the ERalpha and ERbeta protein levels in the endometrium. The balance between ERalpha and ERbeta seems to be important for the proliferative response to oestrogen.

Estrogen receptors alpha and beta in the inner ear of the 'Turner mouse' and an estrogen receptor beta knockout mouse.

Estrogen receptors have earlier been shown in the normal mouse, rat and human inner ear. If estrogens are important in normal hearing and development of presbyacusis in the normal population is not known. However it is known that patients with Turner syndrome, where a lack of estrogens is one of the main characteristics, commonly develop an early presbyacusis. A 'Turner mouse' has been developed, as a model for the ear problems in Turner syndrome, and it shows otitis media and a premature aging of the hearing. Estrogen receptors exist in an alpha and a beta form. In this study inner ear tissue, from the Turner mouse and an estrogen receptor beta knockout mouse (betaERKO), was investigated regarding estrogen receptor alpha and beta using immunohistochemistry. Results show that the Turner mouse has the same pattern of inner ear labeling, both concerning the estrogen receptor alpha and beta, as that of a normal CBA/Ca mouse, with positive staining in the organ of Corti and spiral ganglion. The betaERKO mice show close to normal inner ear morphology and positive estrogen receptor alpha immunostaining at the same locations as the CBA/Ca mouse.