Chronic and unpredictable stress can disrupt the female reproductive system by suppression for secretion of gonadotrophin-releasing hormone (GnRH) and gonadotrophin, resulted in ovarian malfunction and infertility. In the recent days, kisspeptin has been highly highlighted as a hypothalamic peptide which directly stimulates synthesis and release for GnRH. However, in spite of the key role of kisspeptin in the female reproductive system, little information is still available on the changes of its expression during ovarian cycle under stressed condition. Therefore, we induced chronic and unpredictable stress series to the female mice to analyze kisspeptin expression in the brain and ovary. Stressed mice exhibited changes of behavior and body weight gain during the stress assessment, which suggested that the present stress model in mice was successfully established. In the brain level, kisspeptin expression was attenuated than control. In the ovary level, the stressed mice displayed irregularly shrunk oocytes with broken zona pellucida throughout the follicle stages, pyknotic granulosa cells, decreased number of developing follicles and increased number of atretic follicles than the control. In case of kisspeptin expression in the whole ovary tissue, the expression level was decreased in the stressed mice. In detail, the less intensity of kisspeptin expression in the antral follicles phase was observed in the stressed mice than control mice, indicating that local function of kisspeptin during ovary cycle is highly associated with development of ovarian follicles. We expect that the present study has important implications for the fields of reproductive biology.

This study aimed to recover the ovarian function through in vitro culture of preantral follicles from aged mice. First, we isolated the preantral follicles from ovaries of sixty-seven-week old B6D2F1 mice with decreased fecundity to know how many follicles were present in them, which was 6 preantral follicles including 2 primary, 2 early secondary and late secondary follicles from 8 aged mice. It was confirmed that a few follicles (~2) were present in aged mice through histological analysis compared to adult mice as control. The 9 days of in vitro culture of preantal follicles showed in vitro growth and induced maturation after treatment with hCG (2.5 IU/mL) and EGF (5 ng/mL). Cumulus cells in the cumulus-oocyte complexes (COCs) were removed using hyaluronidase and oocytes at the germinal vesicle (GV) and GV breakdown (GVBD) were obtained from preantral follicle culture of aged mice in vitro. In conclusion, these observations demonstrated that there still were a few preantral follicles in the ovaries of 67 week-old mice, which we were able to culture in vitro and oocytes were obtained from them. This study proposed an in vitro culture system using preantral follicle as a therapeutic strategy for fertility preservation in humans for assisted reproductive medicine.

Excessive intake of red meat has been associated with colon carcinogenesis. The effect of hemin and zinc on colon carcinogenesis was investigated in male ICR mice. After acclimation for 1 week, five-week-old mice received three s.c. injections (0-2nd weeks of the experiment) of azoxymethane (AOM; 10 mg/kg b.w.) weekly and were treated by 2% dextran sodium sulfate (DSS) in drinking water for the next 1 week to induce aberrant crypt foci (ACF). Mice were fed on AIN-76A purified rodent diet for 6 weeks. There were three experimental groups; control, hemin, and hemin + zinc groups. The daily oral doses of hemin and zinc were 534 mg/kg and 55 mg/kg b.w., respectively. After staining colonic mucosa with 0.2% methylene blue, the ACF, aberrant crypts (AC), and polyps were counted. Lipid peroxidation in liver was evaluated by thiobarbituric acid-reactive substances (TBARS) assay. The numbers of AC, ACF, large ACF (i.e., ≥4 AC/ACF), and polyps in the hemin group were higher than those in the control group. In hemin + zinc group, the numbers of AC, ACF, large ACF were significantly lower compared to the hemin or control groups (p < 0.05), and the number of polyps was also significantly lower compared to that in the hemin group (p < 0.05). The TBARS level in the livers of the hemin + zinc group was significantly lower than that of the hemin group (p < 0.05). These results suggest that hemin enhances colon carcinogenesis and that co-treatment with zinc can protect against the induction of colon carcinogenesis.

In this study, we examined the protective immunity of a combination of seven Brucella abortus recombinant proteins; superoxide dismutase (rSodC), riboflavin synthase subunit beta (rRibH), 50S ribosomal protein (50s rL7/L12), nucleoside diphosphate kinase (rNdk), malate dehydrogenase (rMDH), arginase (rRocF), and elongation factor (rTsf) cloned in a pMal vector system and expressed in DH5α. Mice groups were immunized thrice with a combined subunit vaccine (CSV-7) at 0, 2, and 5 weeks and subsequently challenged with B. abortus at 5 × 104 CFU at 6 weeks. At four weeks post-infection, the mice were sacrificed and the bacterial burden in their spleens was quantified. Results revealed bacterial log reductions of 0.63 and 0.34 in comparison to PBS and maltose-binding protein (MBP), respectively. Cytokine profiling revealed a marked increase in IFN-γ (interferon-gamma), MCP-1 (macrophage chemoattractant protein-1) and IL-6 (interleukin 6) cytokines at 5-weeks post-immunization. On the other hand, only TNF was heightened at 7-weeks post-immunization. In general, this cytokine profile is consistently reflective of a Th1 immune response, which is beneficial for host immunoresistance.

Gonadotropin releasing hormone (GnRH) centrally plays a role in control of the hypothalamicpituitary- gonadal axis-related hormone secretions in the reproductive neuroendocrine system. In addition, hormone receptors like luteinizing hormone receptor (LHR) are important element for hormones to take effect in target organ. However, ageing-dependent changes in terms of the distribution of GnRH neurons in the brain and LHR expression in the acyclic ovary have not been fully understood yet. Therefore, we comparatively investigated those ageing-dependent changes using young (1-5 months), middle (11-14 months) and old (21-27 months) aged female mice. Whereas a number of GnRH positive fibers and neurons with monopolar or bipolar morphology were abundantly observed in the brain of the young and middle aged mice, a few GnRH positive neurons with multiple dendrites were observed in the old aged mice. In addition, acyclic ovary without repeated development and degeneration of the follicles was shown in the old aged mice than others. LHR expression was localized in theca cells, granulosa cell, corpora lutea and atretic follicle in the ovaries from young and middle aged mice, in contrast, old aged mice had few positive LHR expression on the follicles due to acyclic ovary. However, the whole protein level of LHR was higher in the ovary of old aged mice than others. These results are expected to be used as an important basis on the relationship between GnRH and LHR in old aged animals as well as in further research for reproduction failure.

This study was performed to investigate the effect of types of oil (OVOIL vs. OIL) on B6D2F1 mice oogenesis. In this study, B6D2F1 F1 mice were used in order to maximize oogenesis. The expansion rate of cumulus cells (82.0%±0.2 vs. 78.0%±0.1), in vitro fertilization rate (92.0%±0.1 vs. 88.0%±0.1), developmental rate (91.0%±0.1 vs. 87.0%±0.2), blastocysts formation rate (56.0%±0.1 vs. 57.0%±0.1), and zona hatched rate(41.4%±0.2 vs. 24.0%±0.1) were not different between groups (NS; P>0.05). However, there was a significant difference in maturation rate; the OVOIL group showed higher maturation rate compared to that of the OIL group (96.0%±0.1 vs. 87.0%±0.1; P<0.05). In the blastocysts cell numbers, the total cell numbers (83.9±26.1 vs. 56.9±23.9), ICM cell numbers (15.7±8.8 vs. 6.3±3.5), TE cell numbers (68.3±25.7 vs. 50.7±24.1), % ICM (21.6%±0.1 vs. 12.7%±0.1), and the ratio of ICM:TE (1:6.2±6.5 vs. 1:10.3±7.0) were significantly higher in the OVOIL group than the OIL group (P<0.05). These results suggested that it is expected to achieve the more developmental ability of B6D2F1 mice depending on the type of oil (OVOIL vs. OIL). In addition, the results can provide essential information for culture condition on B6D2F1 mice. Henceforth, thus, it is expected that these results herein might be used for in vitro culture of human embryos.

Alcohol intake is known to affect various organs in the human body, causing reduction of salivation in the oral cavity. Hypo-salivation effect of alcohol is a common feature, but the mechanism in salivary glands is still poorly studied. Therefore, in this study, the changes in salivary secretion and water channel protein (aquaporin5, AQP5) in salivary glands of mice were investigated after ethanol administration. Animals were divided in to 4 groups with the control, 4 g/kg ethanol, 8 g/kg ethanol and 16 g/kg ethanol administration groups. One hour after ethanol administration, saliva was collected from the oral cavity, and the animals were killed and parotid and submandibular glands were extracted to analyze the histopathology, AQP5 immunihistochemistry and AQP5 protein level. According to the results, the salivation rate decreased irrespective of the ethanol dose in mice, and viscosities increased with increase in ethanol dose. However, there were no pathological changes in parotid and submandibular glands due to ethanol administration. Expression of AQP5 in parotid and submandibular glands decreased with increase ethanol administration These results indicate that the reduction of salivary secretion due to acute alcohol intake is closely related to decrease of the water channel protein such as AQP5 in parotid glands and submandibular glands, rather than the damage of salivary glands.

This study evaluated the protective effects of a combination of eight B. abortus recombinant proteins that were cloned and expressed into a pMal vector system and DH5α: nucleoside diphosphate kinase (rNdk), 50S ribosomal protein (rL7/L12), malate dehydrogenase (rMDH), DNA starvation/stationary phase protection protein (rDps), elongation factor (rTsf), arginase (rRocF), superoxide dismutase (rSodC), and riboflavin synthase subunit beta (rRibH). The proteins were induced, purified, and administered intraperitoneally into BALB/c mice. The mice were immunized three times at weeks 0, 2, and 5 and then infected intraperitoneally (IP) with 5×104 CFU of virulent B. abortus 544 one week after the last immunization. The spleens were collected and the bacterial burden was evaluated at four weeks post-infection. The results showed that this combination produced a significant reduction of the bacterial burden in the spleen with a log reduction of 1.01 compared to the PBS group. Cytokine analysis revealed induction of the cell-mediated immune response in that TNF (tumor necrosis factor) and proinflammatory cytokines IL-6 (Interleukin 6) and MCP-1 (macrophage chemoattractant protein-1) were elevated significantly. In summary, vaccination with a combination of eight different proteins induced a significant protective effect indicative of a cell mediated immune response.

This study investigated the characteristics of obesity induced by a high-fat diet (HD) over 13 weeks in Rhbdf2 gene knockout (KO) mice. Forty 7-week-old Rhbdf2 wild and KO mice were used and the mice were divided into 4 groups: Wild-ND (n=10, Rhbdf2 wild mice, normal diet (ND)), Wild-HD (n=10, Rhbdf2 wild mice, HD), KO-ND (n=10, Rhbdf2 KO mice, ND) and KO-HD (n=10, Rhbdf2 KO mice, HD). The relative epididymal fat weight in KO-HD was significantly increased compared with that in KO-ND (P<0.01). The relative liver and spleen weights in KO-HD were decreased compared with those in Wild-HD (p < 0.05) and KO-ND (p < 0.01). The mRNA expression of SOD1 in KO-ND was significantly reduced compared with that in Wild-ND (p < 0.05). In Wild-ND and HD, the mRNA expressions of TNF-α and IL-6 in epididymal fat were significantly increased compared with those in KO-ND and HD (p < 0.01). A significant increase of TNF- α and IL-6 mRNA expression was observed in KO-HD compared with KO-ND (p < 0.01). These results indicated that Rhbdf2 genes may regulate high fat diet-induced obesity damage by anti-inflammatory and anti-oxidative roles in fat tissue of mice.

Dopaminergic neurons are one of the major neuronal components in the brain. Mesencephalon dopamine (DA) neurogenesis takes place in the ventricular zone of the floor plate, when DA progenitors divide to generate postmitotic cells. These cells migrate through the intermediate zone while they differentiate and become DA neurons on reaching the mantle zone. However, neurogenesis and neuronal migration on dopaminergic neurons remain largely unexplored in the mesencephalon development. This study presents neurogenesis and neuronal migration patterns of dopaminergic neurons during mesencephalic development of the mouse. Neurons from embryonic day (E) 10–14 were labelled by a single injection of 5-bromodeoxyuridine and immunohistochemistry was performed. The neurogenesis occurred mainly at the E10 and E11, which was uniformly distributed in the mesencephalic region, but neurons after E13 were observed only in the dorsal mesencephalon. At the postnatal day 0 (P0), E10 generated neurons were spread out uniformly in the whole mesencephalon whereas E11-originated neurons were clearly depleted in the red nucleus region. DA neurons mainly originated in the ventromedial mesencephalon at the early embryonic stage especially E10 to E11. DA neurons after E12 were only observed in the ventral mesencephalon. At E17, E10 labelled neurons were only observed in the substantia nigra (SN) region. Our study demonstrated that major neurogenesis occurred at E10 and E11. However, neuronal migration continued until neonatal period during mesencephalic development.

Osteoporosis is a major worldwide public health problem that poses a great economic burden to society. Puerariae Radix, the dried root of Pueraria lobata (Wild.) Ohwi, has been widely used in Asia. This study investigated the effects of Puerariae Radix (PR) on bone loss in ovariectomized (OVX) mice. C3H/HeN mice (10 weeks old) were divided into sham and OVX groups. The OVX mice were treated with vehicle, 17β-estradiol (E2), PR (oral administration, 250 mg/ kg/day) or PR (intraperitoneal administration, 50 mg/ kg/every other day) for 6 weeks. Grip strength, uterus weight, serum alkaline phosphatase (ALP), estradiol concentration and osteoclast surface levels were measured. Tibiae were analyzed using microcomputed tomography. There were no significant differences in the degree of grip strength, body weight and uterine weight between OVX group and PR-treated group. As compared with the OVX group, the serum estradiol levels were significantly increased in the PR-treated group. PR (i.p.) significantly preserved trabecular bone volume, trabecular bone number, structure model index and bone mineral density of proximal tibiae metaphysic. The administration of PR lowered serum ALP and osteoclast surface levels in OVX mice, suggesting that PR can reduce the bone turnover rate in mice. The results indicate that the supply of PR can prevent OVX-induced bone loss in mice.

The Hippo pathway was originally discovered in Drosophila by genetic screening and it has been shown to be conserved in various organisms including human. Until now, the essential roles of Hippo pathway in regulating cell proliferation, apoptosis, tumorigenesis, and organ size control is extensively studied. Currently, Mats1/2 (Mob1a/1b), one of the important components in Hippo pathway, mutant mice were generated which has abnormal phenotype such as resistance to apoptosis and spontaneous tumorigenesis. Of note, Mats1/2 mutant mice also showed dental malocclusion. Therefore, in this study, we have evaluated the bone phenotype of Mats1/2 mutant mice. Although the mRNA expressions of Mats1 or Mats2 were observed in both osteoclastogenesis and osteoblastogenesis, the increase of Mats1 level was most prominent during osteoblastogenesis. The RANKL-induced osteoclast differentiation from bone marrow-derived macrophages (BMMs) was unaltered upon Mats1/2 mutation; however, the osteoblast differentiation using calvarial pre-osteoblasts was significantly reduced in Mats1/2 mutant mice compare to that of wild type mice. In accordance with in vitro results, Mats1/2 mutant mice showed decreased bone volume as well as increased trabecular separation in μCT analyses. These results may provide novel prospect of the probable linkage between Hippo pathway and bone homeostasis.

본 실험은 마우스를 이용해 급성신부전에 대한 WK 추출물의 효과를 알아보고자 하였다. 실험 종료 후, 대조군은 항암제 주입 후 정상 대조군에 비해 혈중 BUN 및 creatinine 수치가 상승된 것을 확인할 수 있었고, WK-50군, WK-100군 및 WK-200군은 대조군에 비해 수치가 감소된 것을 확인할 수 있었다. 그 중 WK-200군은 정상 대조군과 유의한 수준의 혈중 BUN 및 creatinine 수치가 관찰되었다. 조직학적 결과에서 적출한 신장 장기의 형태학적 손상을 알아본 결과, 대조군에서는 현저한 신손상이 관찰되었다. 반면, WK-50군 및 WK-100군에서는 신손상이 관찰되었으나 대조군에 비하여 그 정도가 심하지 않았고, 특히 WK-200군에서는 신손상이 거의 관찰되지 않았음을 알 수 있었다. 따라서 WK 추출물은 급성신부전에 유의한 효과를 보이는 것으로 생각된다.

Whole grain cereal (WGC)-rich diets provide macronutrients that are important for the regulation of energy metabolism. The current study evaluated whether WGCs had a preventive effect on sarcopenic obesity in high-fat diet (HFD)-induced obese mice. C57BL/6N mice were fed a normal diet (ND), ND+WGC, HFD, and HFD+WGC for 12 weeks. WGCs significantly reduced body weight gain, food efficiency ratio, fat mass, and adipocyte size in HFD-induced obese mice. WGCs attenuated HFD-induced nonalcoholic fatty liver disease by decreasing liver weight and hepatic fat accumulation. In addition, WGCs increased muscle strength and muscle mass in HFD-induced obese mice as well as in ND mice. Taken together, WGCs can be employed as functional food materials for the prevention of sarcopenic obesity by inhibiting fat accumulation and increasing muscle mass.

Recent research on stem cell conditioned medium (CM) has been revealed that CM could influence on the embryo development when supplemented to in vitro culture medium. However, the optimal basal medium for CM production has not determined although it is the fundamental factor of CM. The purpose of this study is to examine the effect of human derived adipose stem cell CM (hASC-CM) with different basal medium on mice embryo development after parthenogenetic activation (PA). hASC-CM was collected from 2 kinds of serum free basal medium, DMEM and KSFM, respectively on day 5 from the culture of hASC isolated from human fat tissue. Intra-peritoneal injection of PMSG and hCG was conducted into 7-week-old ICR mice for superovulation. The oocytes were recovered from the oviductal ampulla, 18 h after hCG injection, and denuded using 0.1% hyaluronidase. PA of oocytes was conducted with KSOM media including strontium chloride. The parthenotes were in vitro cultured in 3 groups: 100% KSOM (Control), 75% KSOM + 25% DMEM or KSFM without FBS (DMEM or KSFM group) and 75% KSOM + 25% hASC-CM from DMEM or KSFM (DMEM-CM or KSFM-CM group). Cleavage rate was assessed after 2 days post IVC and blastocyst formation rate was evaluated after 6 days post IVC both using stereomicroscope. Total cell number of blastocysts was counted by Hoechst staining. 1way ANOVA from Graphpad prism 5 was used for statistical analysis and the values are presented as means ± standard error of mean. As a result, blastocyst formation rate of DMEM-CM group (16.09±3.32%, P<0.05) was significantly lower than control and DMEM group (34.43±2.89% and 34.49±5.34%, P<0.05) but cleavage rate and total cell number of blastocysts showed no significant difference among groups. In case of KSFM, there was no significant difference in cleavage rate, blastocyst formation rate and total cell number of blastocysts among the control, KSFM group and KSFM-CM group. The sort of basal medium used for the CM collection affected the development of parthenotes during in vitro culture differently. Therefore, further research should be conducted to find out the alternative basal medium of CM able to improve the embryo development. This research was supported by Nature Cell (#550-20170028), Cooperative Research Program of RDA (CCAR, #PJ013954022018), Research Institute for Veterinary Science and the BK21 plus program.

Our study has analyzed whether inappropriate gonadotropin secretion affects the morphological changes due to the activation of intrauterine MMP. Methods A total of each 6 mice were injected with PMSG, Progesterone, and Androgen in 5 IU of intraperitoneal injection every 2 days after estrus synchronization, and morphological and MMPs expression patterns were compared after inducing hormone secretion. Also, cell survival and death related genes were compared and analyzed. The endometrium was highly developed in the PMSG, and the androgen was not developed at all. In particular, the diameter of the uterus of the Androgen group was also very narrow. MMPs activity assay in the case of PMSG was confirmed that showed low activity, whereas, progesterone and androgen In showed high activity and, in particular, very high activity of MMPs in the case of androgen in glandular cell. The expression of VEGF in the tissues of each group was different from that of MMPs. In the PMSG group, the activity of VEGF was increased in both the Myo-metrium and the endo-metrium, whereas the progesterone group showed low overall expression in the endo-metrium. Therefore, the present study showed that the activities of the endo-metrial cells and the restructuring of the endometrial cells differed according to the type of the abnormal secretory hormone. In particular, the secretion of androgen increased the activity of MMPs throughout the uterus, The endo-metrial epithelial cells are affected by the progesterone group. In conclusion, this study suggests that inappropriate gonadotropin secretion increases the functional changes of the uterus and this reconstruction may be caused by increased activity of MMPs

Mammalian oocytes are sensitive to psychological stress at each period of follicular development. Especially, thermal stress interfere with reproductive condition by inducing formation of reactive oxygen species (ROS) and oxidative stress (OS). ROS lead to oocyte apoptosis, weakening oocyte quality and lowering the fertilization rate. As a result, the pregnancy rate is lowered, leading to infertility. Thermal stress also seems to influence zygotes through physiological changes in the maternal environment surrounding them. Loss of developmental competence suggests hyperthermia-induced oxidative stress in embryos. Interest in organic Lonicera caerulea berries has increased in recent years. They are abundant in various health-improving materials. Berries that found from natural products can be as free as possible from the bioactive toxicity of the active ingredient without side effects, and it can be a big advantage because it can work. Mammalian oocytes are arrested at the first meiotic prophase stage and get their meiotic competence to produce offspring during the development of follicle. A series of nuclear and cytoplasmic maturations are involved in this process and these vary in temperature sensitivity. Our study demonstrated that L. caerulea can relieve the negative effects of maternal hyperthermia by reducing ROS level at the developmental stage.

Microenvironments surrounded with various extracellular matrix (ECM) components can decide specifically the fate of spermatogonial stem cells (SSCs) and integrin heterodimers recognizing directly ECM proteins play an important role in transporting ECM-derived signals into cytoplasm, resulting in inducing a variety of biological functions such as cell attachment, self-renewal and differentiation. However, to date, studies on type of integrin heterodimers expressed functionally on the undifferentiated SSCs derived from mouse with hybrid strain remain unclear. Therefore, we tried to investigate systematically what kind of integrin heterodimers are expressed transcriptionally, translationally and functionally in the SSCs derived from testis of hybrid (B6CBAF1) mouse. For these, magnetic activated cell sorting (MACS) using Thy1 antibody was used for isolating SSCs from testis, and real-time PCR or fluorescence immunoassay was conducted for measuring transcriptional or translational level of integrin α and β subunits in the isolated SSCs. Subsequently, antibody inhibition assay was conducted for confirming functionality of presumed integrin heterodimers. As the results, transcriptional levels of genes encoding total 25 integrin subunits were quantified, 7 integrin α (α4, α6, α7, α9, αV, αL and αE) and 2 integrin β (β1 and β5) subunit genes showed significantly increased transcriptional up-regulation, compared to the other integrin subunit genes. In contrast, integrin α3, α5, α10 and α11, and integrin β2, β3, β4 and β7 were weakly transcribed. When translational levels of the integrin α subunits showing high transcription level (α4, α6, α7, α9, αV, αL and αE) were measured, significantly strong translational up-regulation of integrin α6, α7, α9, αV and αL subunit genes were detected, whereas integrin α4 and αE subunit genes were weakly. In case of integrin β subunit, β1 evaluated more expression than β5. Based on these results, we speculated that the undifferentiated SSCs derived from B6CBAF1 mouse might express integrin α4β 1, α6β1, α7β1, α9β1, αVβ1 or αVβ5 on plasma membrane. Subsequently, the hybrid strain SSCs showed significantly increased adhesion to fibronectin, laminin, tenascine-C and vitronectin and functional blocking of integrin α4β1, α6β1, α9β1, and αVβ1 or αVβ5 in SSCs significantly inhibited attachment to fibronectin, laminin, tenascin-C and vitronectin, respectively. Accordingly, we could identify that the hybrid (B6CBAF1) mouse-derived SSCs had integrin α4β1, α6β1, α9β1, αVβ1 or αVβ5 on plasma membrane. Moreover, this information will greatly contribute to constructing non-cellular niche supporting self-renewal of SSCs in the future.

This study was conducted to examine the influences of two human chorion gonadotrophins (hCGs) being injected into young or aged (45- to 65-week old) outbred (ICR) mice on developmental capacity of oocytes retrieved. In vitro-culture and parthenogenetic activation of oocytes retrieved were employed for the assessment. Superovulation was determined as being induced when more than 25 oocytes were retrieved. No aged mice were superovulated, while in contrast, 67-100% were superovulated in the 6- to 8-week-old (young) mice. In the aged, hCG injection yielded better retrieval (5 vs. 13 to 14.8 oocytes/mouse). Overall, no significant difference between two hCGs was detected but between the young and aged, significant differences in maturational arrest (0% vs. 39% MI arrest and 46% vs. 15% degeneration) and developmental capacity (24% vs. 46% 8-cell embryo development) were detected. In conclusion, hCG injection contributes to increasing oocyte retrieval from aged outbred mice, but the kinds of gonadotrophin influenced the efficiency of hyperstimulation induction in specific ages.