Development Of Ovine Embryos Research Articles

Normal ovine embryo development following in vitro oocyte maturation in a portable incubator in the absence of CO 2

Normal ovine embryo development following in vitro oocyte maturation in a portable incubator in the absence of CO 2

Arachidonic acid metabolism during early development of ovine embryos: A possible relationship to shedding of the zona pellucida

Two experiments were conducted to determine if early ovine embryos produce prostaglandins and if prostaglandins may have a role in the shedding of the zona pellucida, i.e., embryo hatching. For Experiment 1, embryos were collected on day (d) 4, 8, 10, 12 or 14 of pregnancy and incubated with 1 μCi of [ 14C] arachidonic acid (AA) for 24 h. Based upon high-performance liquid chromatography, embryos from all days converted AA to a number of compounds; the amounts produced differed with day. Primarily, embryos produced an unidentified polar compound, 6-keto-PGF 1α, PGF 2α, PGE 2, 13,14-dihydro-15-keto-PGF 2α and PGB 2. For Experiment 2, embryos collected on d 7 of pregnancy were incubated for a maximum of 6 d in 500 μL of medium containing either ethanol (control; 20 μL), indomethacin (INDO; 10 −4 M), PGE 2 (2 ng) or INDO (10 −4 M) + PGE 2 (2 ng). Embryos were evaluated daily for hatching from the zona pellucida. The hatching rates (percentage) for control, INDO, PGE 2 and INDO+PGE 2 were 46.4, 34.5, 60.0, and 30.0, respectively. There was a main effect (P < .09) of treatment, and the hatching rate for embryos treated with PGE 2 alone was greater (P < .05) than that for embryos in any group with INDO. The results indicate that early ovine embryos can convert AA to various compounds in vitro, and prostaglandins may have a role in the hatching of sheep embryos from the zona pellucida.

Culture of ovine embryos in the absence of bovine serum albumin

Bovine serum albumin (BSA), a relatively impure protein, is routinely used as a component of embryo culture media. Since media containing BSA are chemically undefined, it would be desirable to replace BSA with substitutes of similar activity which are either chemically better defined and/or better standardized than BSA. Two commercial products, Ultroser ® G (USG) and Solcoseryl ® (SOL), were evaluated as replacements for BSA in culture with respect to the development of ovine embryos in vitro. A total of 126 late 8-cell and early 16-cell embryos were distributed among modified Brinster's medium for ovum culture (BMOC-2) containing either 1.5% BSA, 2.0% USG or 2.0% SOL. All three culture media supported development of ovine embryos. Results indicate that 8- and 16-cell embryos will develop into blastocysts in a BSA-free medium containing either USG or SOL. A higher number of embryos developed into blastocysts in media containing BSA than in media containing USG or SOL, and more blastocysts hatched in media containing BSA. Although the overall degree of embryonic development was more advanced in BSA-supplemented media, the concentrations of USG and SOL that were used in this study may not have been optimal for ovine embryo culture.

The Effects of Plasminogen on in Vitro Ovine Embryo Development1

Plasminogen activator production by ovine embryos and the effects of plasminogen on ovine embryo development and zona pellucida integrity were evaluated. Eight-cell to sixteen-cell embryos were cultured in Whitten's medium containing 0, 60, or 120 micrograms/ml plasminogen. Plasmin and plasminogen activator concentrations in the medium were determined by a caseinolytic assay. More blastocysts hatched in medium containing 60 and 120 micrograms/ml plasminogen (33 and 21%, respectively) than 0 microgram/ml plasminogen (0%; p less than 0.05). Zona pellucida dissolution time in acidified phosphate-buffered saline was less after incubation in medium with 60 and 120 micrograms/ml plasminogen (7.2 and 5.9 min, respectively) than 0 microgram/ml plasminogen (9.4 min; p less than 0.05). Plasminogen activator production was low until the morula stage, increased during morula-blastocyst transition, and remained elevated through blastocoelic expansion and hatching. Zona pellucida solubility, plasminogen activator production, and plasminogen conversion to plasmin increased as embryonic stage advanced; however, plasminogen activator production and plasmin conversion to plasmin were poorly correlated with zona pellucida solubility. The results indicate that ovine embryos produce plasminogen activator, and plasmin can increase zona pellucida solubility; however, other factors may also be involved in altering zona pellucida integrity prior to hatching.

Physiologic role of plasminogen activator in early bovine and ovine embryo development

Physiologic role of plasminogen activator in early bovine and ovine embryo development

Development of one-cell ovine embryos in two culture media under two gas atmospheres

The objective of this study was to develop a successful system for culturing one-cell ovine embryos through several cleavage divisions. One hundred and four one-cell embryos were collected from synchronized, FSH-treated ewes 48 hr after the onset of estrus and randomly placed in one of four culture treatments. The effect of glucose supplementation and reduced oxygen tension (20% vs. 5%) on embryo development was studied. Embryo development was quantitated by a cleavage index based on the number of completed cell divisions. The number of embryos completing at least two cell divisions when cultured in Brinster's Pyruvate Medium (BPM) was 7 26 and 9 26 , under 5% CO 2 in air and 90% N 2, 5% CO 2, 5% O 2, respectively, while 22 26 and 20 26 embryos divided when cultured in BPM supplemented with 0.1% glucose (BPM-G) under similar atmospheres. Mean cleavage indices for embryos cultured in BPM were 1.2 and 1.6 under 5% CO 2 in air and 90% N 2, 5% CO 2, 5% O 2, respectively, while embryos cultured in BPM-G had mean cleavage indices of 4.6 and 4.0, respectively. Results of this study indicate that one-cell ovine embryos can be successfully cultured through several cleavage divisions. Glucose supplementation was beneficial for one-cell ovine embryo development. Reducing the oxygen tension from 20 to 5% had no effect on embryo development, and there was no media × gaseous atmosphere interaction.