Masters Theses

Date of Award

12-2003

Degree Type

Thesis

Degree Name

Master of Science

Major

Animal Science

Major Professor

J. Lannett Edwards

Committee Members

F. Neal Schrick, James D.Godkin

Abstract

Addition of retinol may improve development of maturing oocytes stressed by culture. Objective was to evaluate retinol for improving development of heat-stressed oocytes. Cumulus oocyte complexes (COC) were matured for 24 h at 38.5 or 41.0°C (first 12 h) in 0 or 5 μM all trans-retinol. Ability of putative zygotes (268-297/treatment) to cleave and develop to blastocyst was assessed on days 3 and 8 after fertilization, respectively. Fixed effects in statistical model included temperature, retinol, and the interaction. Data were tested to ensure normality. Culture of COC at 4l.0°C did not affect lysis (1.6 and 2.1% for 38.5 and 41.0°C; SEM=0.8) or cleavage after fertilization (75.4 and 72.2% for 38.5 and 41.0°C; SEM=3.8). Within cleaved embryos however, culture of COC at 41.0°C increased 2-cell (10.6 versus 6.2% for 41.0 and 38.5°C; SEM= 1.3; P< 0.04) but decreased 8-16 cell (41.4 versus 51.1% for 41.0 and 38.5°C, SEM=4.7; P< 0.05) embryos and development to blastocyst (20.0 vs 27.5% for 41.0 and 38.5°C, SEM= 2.2; P<0.007). Blastocysts derived from heat-stressed COC had fewer nuclei (85.3 versus 94.0 for 41.0 and 38.5°C; SEM=6.7; P < 0.005; Hoechst staining). Addition of retinol during maturation did not improve development of COC regardless of culture temperature. In three replicates, effects of 41.0°C for reducing development of COC to blastocyst were minimal. When these replicates were deleted from analysis, a significant temperature x retinol interaction was observed (n= 4 reps; 189-197 COC/treatment) for development to blastocyst (P<0.01) and number of nuclei (P<0.004). Addition of retinol to COC compromised by heat stress during maturation prevented heat-induced reductions in development to blastocyst (24.6 versus 14.7% for 38.5 and 41.0°C; and 23.2 and 22.0% for 38.5 and 41.0°C cultured in presence of 5 μM retinol; SEM = 2.4). Also, culture of COC at 38.5°C in 5 μM retinol increased number of nuclei in blastocysts (102.6 versus 98.7 for 38.5 C and 41.0° C; and 120.5 versus 95.1 for 38.5 and 41.0°C cultured in 5 μM retinol; SEM= 5.0). Retinol may protect oocytes that are heat-stressed during maturation from the deleterious effects of elevated temperature.

Download
Files over 3MB may be slow to open. For best results, right-click and select "save as..."

Share

COinS