Evidence that glucose is not always an inhibitor of mouse preimplantation development in vitro

A factorial experimental design was used to examine the effects of 16 combi nations of four concentrations of glucose (0.20, 0.60, 1.8, 5.4 mmol/l) and four concentrations of potassium dihydrogen phosphate (KH2PO4; 0.05, 0.15, 0.45, 1.35 mmol/l) on the development in vitro of outbred CF1 mouse zygote s. Three responses were measured: (i) the number of zona-enclosed blastocys ts; (ii) the number of blastocysts that started to hatch; and (iii) the tot al cell counts in the blastocysts. General linear modelling was used to est imate the most parsimonious two-dimensional concentration-response surfaces that represent the three responses to the different concentrations of gluc ose and KH2PO4. There were no significant interactions between the effects of glucose and KH2PO4 in all cases. Thus, the effects of glucose and phosph ate are independent. No significant effects of glucose on blastocyst format ion and the initiation of hatching were observed. Increasing the concentrat ion of KH2PO4 inhibited slightly (less than or equal to 20%) the developmen t of zygotes into blastocysts and the initiation of hatching. The slight in hibitory effects of KH2PO4 appeared to be due to the inhibition of the deve lopment of a few sensitive embryos. No significant effects of glucose and K H2PO4 were observed on the total cell counts.