Date of Award

1987

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Abstract

The objective of experiment (Exp) I was to develop and evaluate a simplified method for producing bovine demi-embryos (DE). Treatment (Trt) A and B were the bisection zona pellucida intact (ZI) and free (ZF) embryos, respectively, using a microscope slide micromanipulator. In Trt C and D, ZI and ZF embryos, respectively, were bisected with a hand-held razor blade method. More DE were produced by the razor blade method (Trt C and D) than by the microscope slide micromanipulator method (Trt A and B). More DE were produced from ZF embryos (Trt B and D) than from ZI embryos (Trt A and C). A greater number of DE developed to blastocysts in Trt C (82%) than in Trt A, B, or D. In Exp II, the in vitro development of bovine embryos cultured inside (Trt A) bovine trophoblastic vesicles (bTV) were compared with co-culture with bTV (Trt B) and with medium alone (Trt C). After 96 h of culture, 58%, 72% and 44% of the embryos in Trt A, B and C, respectively, were considered viable. The number of grade 1 or 2 embryos in Trt B after 96 h of culture was greater (50%) than the number in Trt C (17%), but similar to the number in Trt A (36%). In Exp III intact and bisected bovine embryos (n = 33/Trt) were cultured 96 h with bTV or in medium alone. The Trt were: (A) DE cultured in medium alone, (B) DE co-cultured with a bTV, (C) intact embryos cultured in medium alone, (D) intact embryos cultured with a bTV. Fewer DE (Trt A and B) were viable or of grade 1 or 2 than intact embryos (Trt C and D). More embryos co-cultured with bTV (Trt B and D) were viable and quality grade 1 or 2 at the end of 96 h culture than were embryos cultured in medium alone (Trt A and C). In Exp IV, the viability of DE produced before or after freezing were compared in two trials. The Trt in Trial I were: (A) DE formed before freezing, (B) DE formed after freezing-thawing, (C) intact control embryos, (D) intact control embryos. Embryos in Trt A, B and C were agar embedded before freezing. The Trt in Trial II were: (A) DE formed before freezing, (B) DE formed after freezing-thawing, (C) intact control embryos. One DE of each pair in Trt A was agar embedded to produce a ZI embryo (Trt A-I) and the other was frozen ZF (Trt A-II). In Trial I, more embryos were viable and transferrable in Trt C and D post-thaw than in Trt A or B. The number of viable and transferable embryos in Trt A and B were similar. In Trial II, the number of viable and transferable embryos in A-I and A-II of Trt A were similar. Also, the number of viable and transferable embryos in Trt A and B were similar. More embryos were viable and of transferable quality in Trt C than in either Trt A or B.

Pages

136

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