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Reducing the interval between generations would significantly advance the efficiency of genetic selection, which is mainly important in species characterized by late puberty, long pregnancy and single offspring. Oocytes for in vitro embryo production can be obtained from calves, lambs, goats, foals and gilts well before puberty, either after slaughter or by less invasive methods, such as laparoscopy and transvaginal aspiration under ultrasonograph guidance. The latter two can be applied to females without greatly affecting their health and are therefore the preferred methods when animals are to be retained for breeding purposes. However, the use of transvaginal aspiration is limited to larger animals, such as 6-month old calves. The quality of oocytes from prepubertal females seems to be lower than that of adults. Although hormone stimulation of the animals and the use of enriched media improve embryonic competence of prepubertal oocytes following in vitro maturation and fertilisation, the efficiency of embryo production remains low. The is probably due to the immaturity of their cytoplasm.
The aim of the study was to develop new techniques for the repeated recovery of goat and sheep oocytes useful for culture and fertilization in vitro and cloning and the evaluation of the efficacy of the established method. Oocytes were aspirated with a syringe or an originally designed catheter for aspiration. The oocytes donors were 54 goats. The animals were premedicated, after which general anesthesia was induced. The general anesthesia lasted about 22 min. The endoscope was inserted into the abdominal cavity. Two trockars for putting the manipulators were inserted 15 cm below the udder. Oocytes were collected by the aspiration of the follicular fluid from the ovarian follicles. Depending on the size, a single aspiration of up to 8 follicles was performed. The collected oocytes were evaluated under a stereoscopic microscope. The following rules of the evaluation and classification of the oocytes were established: class I - homogenous cytoplasm, at least 3 layers of the granulosa cells; class II - homogenous cytoplasm, 1-2 layers of granulosa cells; class III - homogenous cytoplasm, no granular cells; class IV - heterogenous cytoplasm, independent of the granulosa cells. Oocytes class I, II and III were qualified for the culture. 363 ovarian follicles were aspirated, 183 (50.41%) oocytes were obtained. 56 were qualified as class I, 79 - class II, 31 - class III, 8 - class IV. 175 (95.36%) of the obtained oocytes were qualified for the culture, including: 35.52% in class I, 43.17% - class II, 16.94% - class III. 4.37% of the collected oocytes were disqualified for the culture. The proposed technique allows for the collecting oocytes of good quality that can be used for IMV/IVF techniques and cloning.
Currently ART (assisted reproductive technology) is assuming one of the most important places in animal reproduction. Till the present, the main interest concerned the oocytes and embryos in laboratory and in producing animals. Nowadays, with the improvement of ART, as well as gradually increasing interest in endangered species, the interest in using these techniques is shifting toward other animals. Because of this fact, ART procedures concerning domestic cats have progressed significantly in the last years. Domestic cats are a very suitable model for the investigation of endangered feline species. The following paper discusses the current procedures of obtaining oocytes from domestic cats as well as their in vitro development.
The article presents the present state of knowledge about obtaining in vitro embryos from farm animals. This biotechnique includes: in vitro maturation of oocytes, in vitro fertilizing matured oocytes and in vitro culture of embryos. The aim of in vitro production of embryos is to obtain more blastocysts and blastocysts of good quality which will determine the efficiency of embryo transfer and facilitate the production of a greater number of healthy offspring. Offspring were produced after transferring embryos produced in vitro in sheep, cattle, pigs, goats and horses. This biotechnique is used in farm animal breeding, biotechnology and basic research.
The aim of the study was to improve the methods of recovery, maturation and fertilization in vitro (IVМ/IVF) of lamb oocytes in order to get offspring from prepubertal donors. Oocytes were obtained from 4-9-week-old lambs, oocytes from slaughtered adult ewes were run in parallel as control. Ewe lambs received subcutaneous implants (1 mg norgestomet) for 5 days. At the time of implant removal the animals were injected with FSH and PMSG. After 24 h oocytes (60 per donor) were collected by laparotomy under general anesthesia. Oocytes were matured and fertilized in vitro 24 hours after IVЕ, presumptive zygotes were transferred to the intermediate recipients for 6 days. From 9 definitive recipients which received 18 blastocysts, 8 were confirmed pregnant by scanning performed on days 35 and 60. One sheep has already delivered two normal lambs.
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