Effects of melatonin and metformin on the ovaries of rats with polycystic ovary syndrome.

OBJECTIVE: To study the combined and isolated effects of melatonin and metformin in the ovarian tissue of rats with PCOS. DESIGN: Experimental study using a rat model of PCOS induced by continuous light exposure. INTERVENTION(S): Forty adult female rats were divided into 5 groups: physiological estrus phase (Sham); permanente estrus with PCOS induced by continuous lighting exposure for 60 consecutive days (control); with PCOS treated with melatonin; with PCOS treated with metformin; with PCOS treated with melatonin + metformin. After 60 days of treatments, all rats were killed, and ovaries were collected and processed for paraffin-embedding. Formalin-fixed paraffin-embedded sections were stained with hematoxylin and eosin or subjected to immunohistochemistry for proliferation (Ki-67) and apoptosis (cleaved caspase 3) detection markers. SETTING: Federal University of São Paulo, Brazil. ANIMALS: Forty adult female Wistar rats (Rattus norvegicus albinus). MAIN OUTCOME MEASURE(S): Number of corpus luteum and ovarian cysts, number of ovarian follicles (primary and antral follicles), number of interstitial cells, percentage of ovarian follicles (primary and antral follicles), and of interstitial cells immunostained to cleaved caspase-3 and Ki-67. RESULTS: Absence of corpus luteum, a higher number of cysts, and increased nuclear volume and area of interstitial cells, along with a decrease in primary and antral follicle numbers, were noticed in the control group compared with the Sham group. Melatonin and metformin treatments attenuated these effects, although the combined treatment did not mitigate the increased number of cysts and ovaries induced by PCOS. An increase in theca interna cell apoptosis was observed in the control group, whereas melatonina and metformin treatments reduced it significantly. A higher percentage of caspase-3-immunostained granulosa cells was noted in the Sham and all treated groups compared with the control group; no aditive effects on ovarian cell apoptosis were observed in the combined treatment. The percentage of Ki-67- immunostained granulosa cells was significantly higher in the control group compared with the Sham group. However, the combined treatment, not melatonin and metformin alone, mitigated this effect. A higher percentage of Ki-67-immunostained interstitial cells was observed in all treated groups compared with the Sham and control groups, whereas no additive effects in that immunoreactivity were observed in the combined treatment. CONCLUSIONS: Melatonin and metformin may improve ovarian function in rats with PCOS. The combined melatonin and metformin treatment is more effective in attenuating excessive granulosa cell proliferation, but it is not more effective in improving ovarian function than these drugs applied alone in rats with PCOS.

Electromyographic analysis of muscle activation of the trunk and lower limbs during human gait and hippotherapy using different ride mount materials.

OBJECTIVE: Activation of the trunk and lower limb muscles, namely the multifidus, rectus abdominis, rectus femoris, and tibialis anterior, was analyzed using surface electromyographyin 40 young, healthy, and sedentary individuals. METHODS: Data were collected from sneaker-clad subjects with independent gait and during hippotherapy using saddles and blankets, with the feet in and out of the stirrups. RESULTS: Surface electromyography results demonstrated a statistically significantly greater activation of the rectus femoris comparison to tibialis anterior muscle during hippotherapy. No statistically significant differences were observed when comparing variables related to the mount materials used in hippotherapy and human gait. CONCLUSION: In this study, similarities were observed between activation of the trunk and lower limb muscles during hippotherapy and human gait. In addition, the mount materials and practices used in hippotherapy did not influence muscle activity.

Histomorphometric and immunohistochemical changes in interstitial cells and ovarian follicles of rats with polycystic ovaries treated with clomiphene citrate.

OBJECTIVE: To evaluate the histomorphometric and immunohistochemical changes in interstitial cells and ovarian follicles of rats treated with clomiphene citrate during and after induction of permanent estrus. METHODS: Twenty four adult-female rats with regular estrous cycle were equally divided into three groups: (1) GCtrl-at estrous phase. (2) GPCOS-at permanent-estrous phase. (3) GCC-PCOS rats, which remained exposed to 60 days of continuous illumination and treated with Clomiphene Citrate. After that, the animals were euthanized, and the ovaries were removed and processed for paraffin embedding. Sections were stained with H.E. for histomorphometry or subjected to immunohistochemistry for Ki-67 and cleaved caspase-3 detections. RESULTS: The GPCOS showed lack of corpus luteum and several ovarian cysts, as well as interstitial-like cells. The presence of corpus luteum and a significant increase in primary and antral follicles were observed in GCC, which also showed a decrease in the number of ovarian cysts and in the area occupied by interstitial-like cells, as well as a decrease in nuclear volume of interstitial cells. The percentage of cell proliferation was significantly higher in granulosa cells of the GCC. On the other hand, the percentage of apoptosis was significantly higher in the granulosa cells of GPCOS than the GCC. CONCLUSION: The ovaries of rats treated with clomiphene citrate showed a decrease in the number of cysts, an increase in the number of ovarian follicles, the presence of corpus luteum along with a decrease in the nuclear volume in the area occupied by interstitial cells.

Melatonin may prevent or reverse polycystic ovary syndrome in rats.

OBJECTIVE: To evaluate the ovarian effects of melatonin (Mel) in a rat model of polycystic-ovary-syndrome (PCOS) before and after permanent estrus induction. METHODS: Thirty-two adult-female rats with regular estrous cycle were equally divided into four groups: 1) GCtrl - at estrous phase. 2) GPCOS - at permanent-estrous phase. 3) GMel1 - treated for 60 days with Mel (0.4 mg/Kg) during permanent estrus induction and 4) GMel2 - rats with PCOS and treated for 60 days with Mel. After that, the animals were euthanized, and the ovaries were removed and processed for paraffin embedding. Sections were stained with H.E. for histomorphometry or subjected to immunohistochemistry for Ki-67 and cleaved caspase-3 (Casp-3) detections. RESULTS: The GPCOS showed lack of corpus luteum and several ovarian cysts, as well as interstitial-like cells. The presence of corpus luteum and a significant increase in primary and antral follicles were observed in Mel-treated groups, which also showed a decrease in the number of ovarian cysts and in the area occupied by interstitial-like cells. These results were more evident in GMel1. The percentage of Ki-67-positive cells was significantly higher in the Mel-treated groups, mainly in the GMel2, as compared to GPCOS. On the other hand, the percentage of Casp-3-positive cells was significantly lower in granulosa cells of GMel1, whereas it was significantly higher in the interstitial-like cells of GMel2, in comparison to GPCOS. CONCLUSION: Melatonin administration prevents the permanent estrus state in the PCOS rat model. This effect is more efficient when melatonin is administered before permanent estrus induction.

Melatonin may prevent or reverse polycystic ovary syndrome in rats

SUMMARY OBJECTIVE To evaluate the ovarian effects of melatonin (Mel) in a rat model of polycystic-ovary-syndrome (PCOS) before and after permanent estrus induction. METHODS Thirty-two adult-female rats with regular estrous cycle were equally divided into four groups: 1) GCtrl - at estrous phase. 2) GPCOS - at permanent-estrous phase. 3) GMel1 - treated for 60 days with Mel (0.4 mg/Kg) during permanent estrus induction and 4) GMel2 - rats with PCOS and treated for 60 days with Mel. After that, the animals were euthanized, and the ovaries were removed and processed for paraffin embedding. Sections were stained with H.E. for histomorphometry or subjected to immunohistochemistry for Ki-67 and cleaved caspase-3 (Casp-3) detections. RESULTS The GPCOS showed lack of corpus luteum and several ovarian cysts, as well as interstitial-like cells. The presence of corpus luteum and a significant increase in primary and antral follicles were observed in Mel-treated groups, which also showed a decrease in the number of ovarian cysts and in the area occupied by interstitial-like cells. These results were more evident in GMel1. The percentage of Ki-67-positive cells was significantly higher in the Mel-treated groups, mainly in the GMel2, as compared to GPCOS. On the other hand, the percentage of Casp-3-positive cells was significantly lower in granulosa cells of GMel1, whereas it was significantly higher in the interstitial-like cells of GMel2, in comparison to GPCOS. CONCLUSION Melatonin administration prevents the permanent estrus state in the PCOS rat model. This effect is more efficient when melatonin is administered before permanent estrus induction.

RESUMO OBJETIVO Avaliar os efeitos ovarianos da melatonina (Mel) em ratas com síndrome dos ovários policísticos (SOP) antes e após a indução do estro-permanente. MÉTODOS Trinta e duas ratas com ciclos estrais regulares foram igualmente divididas em quatro grupos: 1) GCtrl - fase de estro. 2) GSOP - fase de estro-permanente. 3) GMel1 - tratadas por 60 dias com Mel (0,4 mg/kg) durante a indução do estro-permanente e 4) GMel2 - ratas com SOP e tratadas com Mel. Após eutanásia dos animais, os ovários foram processados para inclusão em parafina. Cortes foram corados com H.E ou submetidos à imuno-histoquímica para detecção de Ki-67 e caspase-3 clivada (Casp-3). RESULTADOS O GSOP mostrou ausência de corpos lúteos e vários cistos ovarianos, além de inúmeras células intersticiais. A presença de corpos lúteos e o aumento significativo dos folículos primários e antrais foram observados nos grupos tratados com Mel, os quais também mostraram diminuição no número de cistos ovarianos e na área ocupada pelas células intersticiais. Esses resultados foram mais evidentes no GMel1 do que no GMel2. A porcentagem de células Ki-67 positivas foi significativamente maior no GMel1 e no GMel2, sendo mais evidente no GMel2, em comparação ao GSOP. Por outro lado, a porcentagem de células positivas à Casp-3 foi menor nas células da granulosa do GMel1 e maior nas células intersticiais do GMel2, em comparação ao GSOP. CONCLUSÃO A administração de melatonina previne o estado de estro-permanente em ratas com SOP. Esse efeito é mais eficiente quando a melatonina é administrada após indução do estado de estro-permanente.

Anatomical description of retromolar foramina in dry human mandibles: incidence, morphometry, and topography / Descrição anatômica de forames retromolares em mandíbulas humanas maceradas: incidência, morfometria e topografia

ABSTRACT Objective: To carry out morphometric, topographic, incidence analysis of retromolar foramina in dry adult human mandibles, and relate the findings to Dental practice. Methods: 265 mandibles were evaluated simultaneously by two researchers. With the aid of metal wires, each retromolar foramen was classified regarding diameter. Foramina with a diameter smaller than 0.5mm were not taken into account. Results: Retromolar foramina were observed in 23.4% of cases, with a higher bilateral incidence (with distinction of both antimeres), and up to 4 of them located in the same mandible. Furthermore, most foramina had a diameter between 0.5 and 1mm. Conclusion: The retromolar foramina are clinically relevant findings and should never be underestimated by clinicians.

RESUMO Objetivo: Realizar análises morfométrica, topográfica e de incidência de forames retromolares em mandíbulas humanas maceradas de adultos, correlacionando os achados com a prática clínica odontológica. Métodos: 265 mandíbulas foram avaliadas simultaneamente por dois observadores. Com o auxílio de fios de metal, cada forame retromolar foi classificado quanto ao diâmetro. Forames inferiores a 0.5mm não foram contabilizados. Resultados: Observaram-se forames retromolares em 23.4% dos casos, com maior incidência bilateral (com distinção dos antímeros) e podendo ocorrer em número de até 4 em uma mesma peça anatômica. Além do mais, a grande maioria apresentou diâmetro entre 0.5 e 1mm. Conclusão: Os forames retromolares são achados consistentes e clinicamente relevantes, não devendo ser subestimados pelos clínicos.

Evaluation of retromolar canals on cone beam computerized tomography scans and digital panoramic radiographs.

PURPOSE: The purpose of this study was to carry out morphologic and topographic analyses of retromolar canals on cone beam computerized tomography (CBCT) scans, comparing findings to others obtained from the corresponding digital panoramic radiographs. METHODS: Sixty-one CBCT scans were analysed digitally, as well as their corresponding digital panoramic radiographs. The prevalence and distribution of these canals, foramen diameters, and intraosseous communications were also evaluated. RESULTS: On CBCT scans, we found that 24.6% of individuals had at least one retromolar canal. The mean foramen diameter was slightly higher than 1 mm and we could not determine the intraosseous anatomical connections in most cases. The morphology and topography of the retromolar canals were not affected by gender and antimere. In addition, only 22.2% of all tomographically identified canals could be confirmed on digital panoramic radiographs (26.7% of such patients). Regarding all sample, 6.6% of individuals showed retromolar canals on digital panoramic radiographs. CONCLUSION: We may consider that these structures are clinically relevant findings and, due to the low accuracy of the panoramic radiographs, high-quality tomographic exams should always be asked for presurgical treatment planning.

Tomographic Evaluation of Accessory Canals Penetrating at the Inner Side of the Anterior Region of Mandibles.

BACKGROUND: The anterior region of the mandible is generally considered to be a safe region to invasive procedures; however, on its internal face, uncountable penetrating canals may be encountered. OBJECTIVE: To perform morphometrical and topographical analysis of endosseous canals located at the inner side of the mandibular anterior region, using cone-beam computed tomography. METHODS: Forty-six examinations were digitally analyzed. Localization of canals in relation to the midline, trajectories, communications between other anatomic structures and relation with teeth were evaluated. Longitudinal and transversal diameters of the canals and distances to the lower edge and symphysis of the mandible were also measured. RESULTS: All individuals had at least 1 canal, with a mean of 2.3 and higher prevalence in the midline region. The adjacent teeth to the canals were usually the incisors but the authors could not determine the connected anatomical structure in most patients. Both the mean diameters were quite similar, about 1 mm; however, the trajectories and distances to the lower edge and symphysis of mandible showed a remarkable heterogeneity among the individuals. CONCLUSIONS: These endosseous canals are consistent and clinically relevant findings and should never be underestimated by professionals.

Immunohistochemical evaluation of proliferation, apoptosis and steroidogenic enzymes in the ovary of rats with polycystic ovary.

OBJECTIVE: to evaluate the immunohistochemical expression of proliferative, apoptotic and steroidogenic enzyme markers in the ovaries of rats with polycystic ovary syndrome (PCOS). METHODS: twenty rats were divided into two groups: GCtrl - estrous phase, and PCOS - with polycystic ovaries. The GCtrl animals were subjected to a lighting period from 7 am to 7 pm, while the animals with PCOS group remained with continuous lighting for 60 days. Subsequently, the animals were anesthetized, the ovaries were removed and fixed in 10% formaldehyde, prior to paraffin embedding. Sections were stained using H.E. or subjected to immunohistochemical methods for the detection of Ki-67, cleaved caspase-3, CYP11A1, CYP17A1 and CYP19A1. The results were analyzed using Student's t-test (p < 0,05). RESULTS: morphological results showed evidence of interstitial cells originating from the inner theca cells of degenerating ovarian cysts in PCOS. Immunoexpression of Ki-67 was higher in the granulosa cells in GCtrl, and the theca interna cells in PCOS, while cleaved caspase-3 was higher in granulosa cells of ovarian cysts from PCOS and in the theca interna cells of GCtrl. Immunoreactivity of CYP11A1 in the theca interna, granulosa and interstitial cells was similar between the two groups, while CYP17A1 and CYP19A1 were higher in the granulosa and interstitial cells in the PCOS group. CONCLUSION: the results indicate that the interstitial cells are derived from the theca interna and that enzymatic changes occur in the theca interna and interstitial cells in ovaries of rats with PCOS, responsible for the high levels of androgens and estradiol.

Immunohistochemical evaluation of proliferation, apoptosis and steroidogenic enzymes in the ovary of rats with polycystic ovary / Avaliação imunoistoquímica de proliferação, apoptose e enzimas esteroidogênicas no ovário de ratas com síndrome dos ovários policísticos

Objective: to evaluate the immunohistochemical expression of proliferative, apoptotic and steroidogenic enzyme markers in the ovaries of rats with polycystic ovary syndrome (PCOS). Methods: twenty rats were divided into two groups: GCtrl - estrous phase, and PCOS - with polycystic ovaries. The GCtrl animals were subjected to a lighting period from 7 am to 7 pm, while the animals with PCOS group remained with continuous lighting for 60 days. Subsequently, the animals were anesthetized, the ovaries were removed and fixed in 10% formaldehyde, prior to paraffin embedding. Sections were stained using H.E. or subjected to immunohistochemical methods for the detection of Ki-67, cleaved caspase-3, CYP11A1, CYP17A1 and CYP19A1. The results were analyzed using Student's t-test (p < 0,05). Results: morphological results showed evidence of interstitial cells originating from the inner theca cells of degenerating ovarian cysts in PCOS. Immunoexpression of Ki-67 was higher in the granulosa cells in GCtrl, and the theca interna cells in PCOS, while cleaved caspase-3 was higher in granulosa cells of ovarian cysts from PCOS and in the theca interna cells of GCtrl. Immunoreactivity of CYP11A1 in the theca interna, granulosa and interstitial cells was similar between the two groups, while CYP17A1 and CYP19A1 were higher in the granulosa and interstitial cells in the PCOS group. Conclusion: the results indicate that the interstitial cells are derived from the theca interna and that enzymatic changes occur in the theca interna and interstitial cells in ovaries of rats with PCOS, responsible for the high levels of androgens and estradiol. .

Objetivo: avaliar a expressão imunoistoquímica de marcadores de proliferação, apoptose e enzimas esteroidogênicas nos ovários de ratas com síndrome dos ovários policísticos (SOP). Métodos: vinte ratas foram divididas em dois grupos: controle (GCtrl), na fase de estro, e com síndrome dos ovários policísticos (GSOP). Os animais do GCtrl permaneceram com período de luz das 7 às 19 horas, e os do GSOP com iluminação contínua, durante 60 dias. Posteriormente, os animais foram anestesiados, os ovários removidos e fixados em formol a 10% para inclusão em parafina. Cortes histológicos foram corados pelo H.E. e outros submetidos a métodos imunoistoquímicos para detecção de Ki-67, caspase 3 clivada, CYP11A1, CYP17A1 e CYP19A1. Os resultados foram submetidos ao teste t de Student (p < 0,05). Resultados: a morfologia mostrou evidências da origem das células intersticiais a partir das células da teca interna dos cistos ovarianos em degeneração no GSOP. A imunoexpressão do Ki-67 mostrou-se aumentada nas células da granulosa no GCtrl e na teca interna do GSOP, enquanto a caspase 3 clivada se mostrou aumentada nas células da granulosa dos cistos ovarianos do GSOP e na teca interna do GCtrl. A imunorreatividade da CYP11A1 nas células da teca interna, bem como da granulosa e intersticiais, mostrou-se semelhante entre os dois grupos. As CYP17A1 e CYP19A1 apresentaram-se aumentadas nas células da granulosa e intersticiais no grupo SOP. Conclusão: os resultados indicam que as células intersticiais são oriundas da teca interna e que ocorrem alterações enzimáticas nas células da teca interna e intersticiais do ovário de ratas com SOP, responsáveis pelos altos níveis de androgênios e de estradiol. .

[Morphology of the interstitial cells of rat polycystic ovaries: an experimental study]. / Morfologia das células intersticiais de ovários policísticos de ratas: um estudo experimental.

PURPOSES: To evaluate the histomorphometry of ovarian interstitial cells, as well as the blood sex steroid concentrations of female rats with polycystic ovaries induced by continuous light. METHODS: Twenty female rats were divided into two groups: Control Group - in the estrous phase (CtrlG), and a group of rats with polycystic ovaries induced by continuous illumination (POG). CtrlG animals were maintained on a light period from 07:00 a.m. to 07:00 p.m., and POG animals with continuous illumination (400 Lux) for 60 days. After this period all animals were anesthetized and blood was collected for the determination of serum estradiol (E2), progesterone (P4), and testosterone (T), followed by removal of the ovaries that were fixed in 10% formalin and processed for paraffin embedding. Five-µm histological sections were stained with hematoxylin and eosin and used for histomorphometric analysis. Morphological analyses, cyst count, determination of concentration and of the nuclear volume of interstitial cells were performed with the aid of a light microscope adapted to a high resolution camera (AxioCam), whose images were transmitted to and analyzed by the computer using AxioVision Rel 4.8 software (Carl Zeiss). Data were analyzed statistically by the Student's t-test (p<0.05). RESULTS: Morphological analysis showed the presence of ovarian cysts in POG animals and corpora lutea in CtrlG animals, as well as evidence of the origin of interstitial cells from the internal theca of these cysts. POG animals presented increased serum estradiol levels (pg/mL) compared to CtrlG animals (POG=124.9 ± 4.2>CtrlG=73.2 ± 6.5, p<0.05), the same occurring with testosterone levels (pg/mL) (POG=116.9 ± 4.6>CtrlG=80.6 ± 3.9, p<0.05). However, progesterone levels (ng/mL) were higher in CtrlG than in POG animals (CtrlG=16.3 ± 2.0>POG=4.2 ± 1.5, p<0.05). Morphometry showed a significant increase in nuclear volume in POG animals (POG=102.1 ± 5.2>CtrlG=63.6 ± 16.5, p<0.05), as well as in the area occupied (%) by interstitial cells (POG=24.4 ± 6.9>CtrlG=6.9 ± 3.2, p<0.05) compared to CtrlG animals. CONCLUSION: The interstitial cells of the rat polycystic ovary probably originate from ovarian cysts due to the degeneration of granulosa cells and differentiation of the internal theca cells. The elevations of serum testosterone and estradiol were probably due to the significant increase in cell activity and in the area occupied by interstitial cells.

Morfologia das células intersticiais de ovários policísticos de ratas: um estudo experimental / Morphology of the interstitial cells of rat polycystic ovaries: an experimental study

OBJETIVOS: Avaliar a histomorfometria das células intersticiais dos ovários, bem como analisar a concentração sanguínea de esteroides sexuais de ratas portadoras de ovários policísticos induzidos pela luz contínua. MÉTODOS: Vinte ratas foram divididas em dois grupos: ratas na fase de estro (GCtrl ) e ratas portadoras de ovários policísticos induzidos pela iluminação contínua (GOP). Os animais do GCtrl permaneceram com período de luz das 7:00 s 19:00 horas, e os animais do GOP, com iluminação contínua (400 Lux), durante um período de 60 dias. Ao final desse período todos os animais foram anestesiados, foi coletado o sangue, para determinação dos níveis séricos de estradiol (E2), progesterona (P4) e testosterona (T), seguido da retirada dos ovários que foram fixados em formol a 10% e processados para inclusão em parafina. Cortes histológicos com 5 µm corados pela hematoxilina e eosina foram utilizados para análise histomorfométrica. As análises morfológicas, contagem de cistos, determinação da concentração e do volume nuclear das células intersticiais foram realizadas com o auxílio de microscópio de luz adaptado a uma câmera de alta resolução (AxioCam), cujas imagens foram transmitidas e analisadas em computador com software AxioVision Rel 4.8 (Carl Zeiss). Os dados obtidos foram submetidos ao teste t de Student (p<0,05). RESULTADOS: A morfologia mostrou a presença de cistos nos ovários pertencentes ao Grupo OP e de corpos lúteos no GCtrl, mostrando ainda evidências da origem das células intersticiais a partir das células da teca interna desses cistos. Com relação aos níveis hormonais o GOP apresentou níveis séricos de estradiol (pg/mL) aumentados em relação ao GCtrl (GOP=124,9±4,2>GCtrl=73,2±6,5; p<0,05), o mesmo ocorrendo com os níveis de testosterona (pg/mL) (GOP=116,9±4,6>GCtrl=80,6±3,9; p<0,05). Entretanto os níveis de progesterona (ng/mL) foram mais elevados no GCtrl em relação ao GOP (GCtrl=16,3±2,0>GOP=4,2±1,5; p<0,05). A morfometria mostrou haver aumento significante do volume nuclear no grupo GOP (GOP=102,1±5,2>GCtrl=63,6±16,5; p<0,05), assim como da área ocupada (%) pelas células intersticiais (GOP=24,4±6,9>GCtrl=6,9±3,2; p<0,05) em relação aos animais do GCtrl. CONCLUSÃO: As células intersticiais do ovário policístico da rata provavelmente provêm dos cistos ovarianos devido degeneração das células da granulosa e diferenciação das células da teca interna. As elevações dos níveis séricos de testosterona e de estradiol provavelmente provêm do aumento significativo da atividade celular e da área ocupada pelas células intersticiais.

PURPOSES: To evaluate the histomorphometry of ovarian interstitial cells, as well as the blood sex steroid concentrations of female rats with polycystic ovaries induced by continuous light. METHODS: Twenty female rats were divided into two groups: Control Group - in the estrous phase (CtrlG), and a group of rats with polycystic ovaries induced by continuous illumination (POG). CtrlG animals were maintained on a light period from 07:00 a.m. to 07:00 p.m., and POG animals with continuous illumination (400 Lux) for 60 days. After this period all animals were anesthetized and blood was collected for the determination of serum estradiol (E2), progesterone (P4), and testosterone (T), followed by removal of the ovaries that were fixed in 10% formalin and processed for paraffin embedding. Five-µm histological sections were stained with hematoxylin and eosin and used for histomorphometric analysis. Morphological analyses, cyst count, determination of concentration and of the nuclear volume of interstitial cells were performed with the aid of a light microscope adapted to a high resolution camera (AxioCam), whose images were transmitted to and analyzed by the computer using AxioVision Rel 4.8 software (Carl Zeiss). Data were analyzed statistically by the Student's t-test (p<0.05). RESULTS: Morphological analysis showed the presence of ovarian cysts in POG animals and corpora lutea in CtrlG animals, as well as evidence of the origin of interstitial cells from the internal theca of these cysts. POG animals presented increased serum estradiol levels (pg/mL) compared to CtrlG animals (POG=124.9±4.2>CtrlG=73.2±6.5, p<0.05), the same occurring with testosterone levels (pg/mL) (POG=116.9±4.6>CtrlG=80.6±3.9, p<0.05). However, progesterone levels (ng/mL) were higher in CtrlG than in POG animals (CtrlG=16.3±2.0>POG=4.2±1.5, p<0.05). Morphometry showed a significant increase in nuclear volume in POG animals (POG=102.1±5.2>CtrlG=63.6±16.5, p<0.05), as well as in the area occupied (%) by interstitial cells (POG=24.4±6.9>CtrlG=6.9±3.2, p<0.05) compared to CtrlG animals. CONCLUSION: The interstitial cells of the rat polycystic ovary probably originate from ovarian cysts due to the degeneration of granulosa cells and differentiation of the internal theca cells. The elevations of serum testosterone and estradiol were probably due to the significant increase in cell activity and in the area occupied by interstitial cells.