Biomedical subjects

M Gallus

Publications and source records attributed to M Gallus.

5 recordsLinked to original sources

PubMed1997

Embryo cloning in sheep: work in progress.

We summarize here the procedures for nuclear transfer using S-phase cytoplasts and describe a new method for avoiding loss of reconstructed embryos from the oviducts during in vivo culture. We obtained 2 clones of 5 genetically identical animals following the transfer of blastomeres from 16-cell embryos into enucleated preactivated cytoplasts. Metaphase II oocytes and embryos were surgically collected from superovulated Sarda breed ewes 54 and 120 h after sponge removal, respectively. Oocytes were exposed for 15 min to 5 mug/ml of Hoechst 33342 and were micromanipulated at room temperature. Efficiency in embryo reconstruction was 100% for enucleation and 98% for fusion. Embryos were embedded in agar as separate clones and transferred into the oviducts of temporary recipients. The fimbriae were closed with glass-nylon made filters. Embryo recovery from the temporary recipients was 97.3%, with a cleavage rate of 81.4%; development to morula-blastocyst stage was 70.6%. A total of 29 Grade 1 blastocysts corresponding to 5 clones were transferred into 13 naturally synchronous ewes, and scanning was performed at 30 and 90 d. Ten ewes were pregnant at the first scanning and nine at the second for a final pregnancy rate of 71.4%; the survival rate at term was 48%. Overall, we obtained 4 clones of identical lambs: two sets of 5 (one male set and one female set) and two sets of twins (both sets male). Pregnancy length in recipients carrying clones was longer than the standard period in Sarda breed (153 vs 150 d, respectively). Weight at birth was higher for male lambs obtained from nuclear transfer than for normal males (4.1 vs 3.6 kg), while the weight for females was normal.

Journal Article↗

PubMed1994

Superovulatory response and quality of embryos recovered from anestrus ewes after a single injection of porcine FSH dissolved in polyvinylpyrrolidone.

The effects of a single injection of porcine FSH (pFSH) administered in long acting vehicle on the superovulatory response of milk (Sarda breed) sheep were determined during the anestrous season. The sheep (n=42), synchronized with intravaginal sponges (40 mg fluorogestone acetate -FGA- for 14 d) were submitted 24 h before sponge removal to three different superovulatory treatments. Group 1 (n=16) was treated with a single intramuscular (im) injection of 16 mg of pFHS dissolved in 30 % polyvinylpyrrolidone (PVP); Group 2 (n=12) was injected im with 6, 5, 3 and 2 mg of pFSH every 12 h over 2 d; Group 3 (n=14) was given 800 IU of PMSG and 12 mg of pFSH. All sheep were mated with a fertile ram. Embryos were recovered surgically at Day 7 of sponge removal and graded for the quality according to their morphology. The percentage of good quality embryos recovered was 84% in Group 1, 68% in Group 2 and 77% in Group 3. Data for the onset of estrus, number of corpora lutea (CL), number of unovulated follicles, embryo recovery rate, embryo quality and fertilization rate were recorded for the 3 groups. The onset of estrus, number of CL, number of unovulated follicles, fertilization rate and number of good quality embryos did not differ significantly among the 3 groups. The embryo recovery rate was significantly lower in the group treated with PMSG-FSH (Group 3) than in the 2 other groups. It is concluded that during the anestrous season a single injection im of pFSH results on average in a superovulatory response as good as the more traditional treatments like multiple injections of pFSH and PMSG-pFSH combined.

Journal Article↗

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↗