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The maturation of oocytes is one of the most important steps determining their developmental competence. Due to the low percentage of oocytes of bitches that reach the MII stage, searching for reagents that may stimulate the growth and maturation of oocytes is still present in this species of mammals. The most important media supplements include gonadotropins (LH, FSH, hCG), growth factors (IGF, TGF, EGF, FGF), progesterone and follicular fluid. It is suggested that the supplement of EGF, and/or follicular cells may have an important influence on the percentage of cells that reach the MII stage. Despite plenty of research based on the improvement of bitch oocytes in vitro culture, the results obtained are still unsatisfactory. Moreover, in the long stages of canine oocytes maturation many molecular and morphological modifications (including changes in mitochondria structure and configuration in the cytoplasm) are involved. In this article, the influence of selected media supplements on the efficiency of bitch oocytes in vitro maturation was described. The molecular and morphological modifications during canine oocytes maturation were also considered in the text.
A field experiment was conducted to determine the influence of follicular profiles over 4 d prior to superovulation on superovulatory responses in terms of the number of large follicles (F; ≥ 7mm) at oestrus and in the number of the corpus luteum (CL) 7 d later. Ultrasonography was performed once daily over 4 d prior to gonadotropin treatment (day 0) and on the day of oestrus during superstimulation. Animals conventionally superovulated (400 mg Folltropin-V) between day 8 to 12 of the oestrous cycles and 88 superovulation cycles were considered in the present experiment. Data were analysed by means of the GLM procedure of the SAS. Each type of superovulatory responses was divided into three classes - low, medium, and high. The profiles of changes in the mean diameter of the largest follicle (F1) and in the mean differences between the diameters of F1 and the second largest (F2) follicle (F1-F2) during the 4 d prior to superovulation did not differ (P>0.1) among the three classes of follicular and ovulatory responses. The proportions of superovulation cycles with high follicular and ovulatory responses were 69% and 52%, respectively. The results of the present experiment suggest that high follicular or ovulatory responses are not associated with follicular profiles prior to the initiation of superovulation.
The studies were done on 30 heifers with synchronized oestrus. IFN-γ was found in sera of 4 heifers in luteal phase and in 1 heifer in follicular phase. Moreover, an increased level of serum haptoglobulin (Hp) and serum amyloid component (SAA) was found in 8 heifers in follicular phase. The presence of IFN-γ a proinflammatory cytokine may point to an active inflammation, whereas an increased level of Hp and SAA in oestrus could be connected with an approaching ovulation. It was also found that in pregnant heifers with a detected IFN-γ and TNF-α and an increased level of Hp and SAA retention of placenta and post parturient metritis was diagnosed.
The activity of monoamine oxidase (MAO) in cow serum undergoes considerable fluctuations in the course of the oestrous cycle. The aim of the study was to determine the activity of MAO and its isoenzymes A (MAO-A) and B (MAO-B) in cow serum near the parturition. The experiments were performed on 8 pregnant and clinically healthy cows of the Polish Black and White Breed. Peripheral blood samples were collected every 4 hours before, during and after parturition. MAO serum activity was determined with the use of the spectrofluorimetric technique according to Matsumoto et al. (1985) with own modifications. Analysis of serum samples showed that MAO activity increased rapidly near the delivery. MAO-B activity was significantly higher than MAO-A activity and determined the profile of total MAO (MAO-T) activity. It may be suggested that an increase in MAO activity observed near delivery protects against an excessive elevation of catecholamine concentration in blood. However, the control mechanism and physiological role of MAO during this period need further investigations.
The reversibility of anoestrus caused by long-acting GnRH analogue (deslorelin), and the effectiveness of GnRH analogue to induce standing oestrous, and in consequence to the retardation of breeding season, was investigated. During the transition period, 26 fat tailed breed ewes were randomly divided into 3 groups. GnRH analogue Ovuplant and Suprelorin were inserted under the neck skin in group I (n=7) and group II, respectively. No administration was applied in group III (control group, n=10). Suprelorin was removed 60 d after the implant's insertion. The initiation of sexual activities based on the day of progesterone increase, and the first standing oestrous were 12.9±1.86, 34.7±9.69, 81.9±6.31, and 27.3±1.94, 48.3±9.24, 96.9±5.76 in control, Ovuplant and Suprelorin was administered to groups; respectively (P<0.001). In conclusion, deslorelin administration resulted in reversible anoestrus in ewes. During the 60 d experimental period, Suprelorin effectively suppressed sexual activity; therefore, Suprelorin could be used to delay the breeding season.
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