Lipoproteins in the preimplantation blastocysts in the rabbit.

Disc electrophoresis was used to study the patterns of lipoproteins in blastocoelic fluid, uterine fluid, peritoneal fluid, and blood serum of rabbits 6, 7, 7.25, 7.50, and 8 days postcoitum. Five bands of lipoprotein were detected in the maternal blood serum and peritoneal fluid. The blastocoelic fluid of 6- and 7-day blastocyst contained only pre-beta-lipoprotein. Lipoprotein patterns in the blastocyst were similar to those of blood serum at 7.5 days postcoitum and to uterine fluids at 6 to 7 days postcoitum. The possible role of lipoproteins in the implantation of blastocysts is discussed.