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P Cappai

Publications and source records attributed to P Cappai.

26 records · Page 2Linked to original sources
PubMed1994

Improved development to blastocyst of ovine nuclear transfer embryos reconstructed during the presumptive S-phase of enucleated activated oocytes.

The timing of pronuclear formation and the initiation and duration of the DNA synthetic period (S-phase) were determined during the first cell cycle of electrically activated ovine oocytes matured in vivo. Reconstructed embryos were produced by electro-fusion-mediated nuclear transfer of unsynchronized single blastomeres. These were derived from embryos produced in vivo at the 16-cell stage (Day 4) and transferred to enucleated metaphase II oocytes at the time of activation or to enucleated activated oocytes during early, mid, and late stages of the presumptive S-phase. The frequency of development to blastocyst was greatest in embryos reconstructed during the presumptive S-phase of enucleated activated oocytes than in embryos reconstructed at the time of activation (mean 55.4% vs. 21.3%). No significant differences were observed when embryos were reconstructed during early, mid, or late stages of the presumptive S-phase (61.3%, 45.7%, and 57.7%, respectively). The results indicate that the use of enucleated activated oocytes as cytoplasts for embryo reconstruction can increase the frequency of development to blastocyst of embryos reconstructed from unsynchronized donor blastomeres.

Animals↗
PubMed1992

[Use of a protein-free medium for the in vitro development of sheep embryos].

The employment of protein-free medium for the culture of ovine embryos collected at the 1-2 cell stage from superovulated ewes was investigated. For this purpose sheep zygotes were randomly allocated in four treatment groups: T1) CZB medium + bovine serum albumin (BSA) on sheep oviductal monolayer (SOM), T2) CZB + polyvinyl alcohol (PVA) + SOM, T3) CZB + PVA + SOM supplemented with inositol (I) and serine (S), T4) TCM 199 + 10% fetal calf serum + SOM. Standard culture conditions were 2 ml of medium in 35 mm Petri dishes, under 5% CO2 in air at 39 degrees C. The percentages of morulae and blastocysts were recorded after 4 and 7 days of culture. After 4 days of culture there was no significant difference (P > 0.05) in the percentage of morulae between embryos cultured in T1 (86%), T2 (85%), T3 (88.8%), and T4 (87.5%). After 7 days the percentages of blastocysts were T1 (70%), T2 (50%), T3 (55.5%) and T4 (46.8%). These data suggest that a protein-free medium, CZB + PVA and CZB + PVA + I + S, can support ovine preimplantation embryo development in vitro; however CZB medium supplemented with BSA enhances development to blastocyst.

Animals↗
PubMed1992

[Microencapsulation in Na-alginate and in vitro development of sheep blastomeres].

Embryos at 4 cell stage obtained from Sarda ewes superovulated with FSHp (Sigma) were micromanipulated in order to obtain single blastomeres (1/4 E). The 1/4 E have been located randomly in two groups. In the first (Group A n. 30) the 1/4 E have been put back in empty zonae pellucidae; in the second (Group B n. 21) they have been microencapsulated in sodium alginate (1.1%) by dropping cell-alginate solution in a 1.5% CaCl2. Each capsule (1 mm diameter) contained four 1/4 E. The blastomeres have been co-cultured for 5 days in CZB medium on oviductal cell monolayer in a humidified incubator (5% CO2, 95% air, 38.5 degrees C). No differences were found between the groups reaching blastocyst stage after the end of the culture period (A 50%-B 47%).

Alginates↗
PubMed1990

[In vitro separation and development of sheep blastomeres].

Four cell embryos collected by laparatomy from Sardinian breed ewes superovulated with FSH-p (16 mg Sigma), were divested of their zonae pellucidae (ZP) by micromanipulation or chemical methods (pronase 0.5%, tyrode pH 2.2). The blastomeres were separated by pipetting using a flame polished pasteur pipette in a Ca free medium (PBS. Sigma) and were inserted into previously evacuated Z.P. using a Leitz micromanipulator. The Z.P. were removed either mechanically or with acid tyrode; pronase was unable to digest them after incubation at 30 degrees C for 120 minutes. The single blastomeres were cocultured on a monolayer of ovine oviductal epithelial cells in TCM 199 + 10 FCS at 38 degrees C in 5% CO2 for 60 hours. No developments were observed in blastomeres obtained by acid digestion of the ZP while 50% of the other blastomeres continued their development until the 16 cell stages. Our results suggest that coculture with oviductal epithelial cell monolayers can support in vitro development of single ovine blastomeres.

Animals↗
PubMed1989

[Post-partum ovarian activity in Sardinian ewes].

Ovarian activity, assessed by the plasma progesterone concentrations, were studied in four groups of Sardinian breed sheep with different lambing season. The resumption of ovarian activity was shorter and similarly the proportion of ewes which had resumed ovarian activity in response to introduction of rams was greater in sheep with November and December rather than January and March lambings. The resumption of oestrus activity was delayed in sheep with a high level of lactation.

Animals↗
PubMedDate not supplied

Embryo transfer and related technologies in sheep reproduction.

This paper reviews the status of embryo transfer and the major technologies applied to preimplantation of embryos in sheep. Embryo production from superovulated ewes is hindered by an unpredictable response to hormonal treatment. Progress in this area should be expected by an appropriated control of follicular development with gonadotropin-releasing hormone (GnRH) agonist or antagonist prior to gonadotrophin administration. Simple protocols for the cryopreservation of sheep embryos by vitrification are already available and the development of frozen-thawed blastocysts to term is close to the fresh ones. Further research is required to identify factors able to promote the maturation in vitro of oocytes, namely those obtained from prepubertal animals. Semen and embryo sexing procedures are available in cattle although much less attention was paid to their application to sheep. Among all the reproductive technologies, cloning with embryonic and foetal cells has progressed dramatically in sheep and nuclear transfer has been used to produce transgenic animals as an alternative to pronuclear injection. The production of the first lamb cloned from a somatic cell opened new opportunities in animal breeding as well as exciting lines of basic research. The overall conclusions are that, apart from superovulation, the application of in vitro technologies is likely to evolve rapidly and once applied, a great impact on traditional and new animal productions should be expected. However, a better understanding of the changes in gene expression, induced in embryos by different in vitro manipulation procedures, is necessary to prevent abnormal foetal development.

Animals↗
PubMedDate not supplied

In vitro viability of vitrified mouse morulae thawed at different temperatures.

The effect of thawing temperature on in vitro development of vitrified mouse morulae was investigated. The embryos were vitrified in a solution based on ethylene glycol as cryoprotectant, and Ficoll as macromolecule to assist vitrification. They were then thawed at 20 degrees, 37 degrees and 48 degrees C for 6 sec and at 48 degrees C for 2 sec. Among groups, there was no significant difference on the development at 72 h of culture when embryos were thawed at 20 degrees, 37 degrees C for 6 sec or 48 degrees C for 2 sec. At 48 h of culture the embryos thawed at lower temperature had a reduced resumption (69.5%) while the embryos thawed at 37 degrees and 48 degrees C for 2 sec had a higher resumption rate (80.0% and 82.5%). It was concluded that a high development in vitro of vitrified mouse morulae can be obtained at three different temperatures of thawing, although at higher temperatures there seems to be a tendency of an earlier resumption development.

Animals↗