Expression of CD44 Gene in Goat’s Oocytes and Embryos

Abstract

The CD44 family belongs to a larger group of hyaluronic acid-binding proteins and plays important roles in oocyte maturation, fertilization and preimplantational embryo development. We analyzed the CD44 receptor in goat oocytes and embryos. Immature oocytes (N = 90) were obtained from a local abattoir; mature oocytes (N = 40) and embryos (N = 25) were obtained by laparotomy from adult hair ewes submitted to ovarian stimulation treatment. The CD44 mRNA was detected by PCR, after reverse transcription, while proteins were located by indirect immunofluorescence, using anti-human CD44 monoclonal antibody. Human lymphocytes and immature bovine oocytes were used as positive and negative controls respectively. Assessment of the oocyte nuclear stages as well as classification of the embryonic Growth phase were made with Hoechst 33342 staining. Indirect immunofluorescence detected CD44 expression on the surface of mature oocytes and embryos; immature oocytes did not take up the stain. These findings were supported by the RT-PCR data, which showed no mRNA templates for CD44, in material from immature oocytes and cumulus cells. The CD44 amplicons were detected after a second heminested PCR in mature oocytes and embryos. The finding of CD44 in mature oocytes and preimplantational embryos could reflect the expression profile of hyaluronic acid during terminal folliculogenesis and preimplantational embryo development in goats.