VPB 321: Animal Biotechnology (2+1)

EMBRYO COLLECTION

• In the bovine, embryos are recovered by non surgical methods.
• Special catheters(Foley’s catheters) are introduced via the cerevix into the uterine horn and embryos are flushed with 250 – 300ml flushing medium.
• Recovery rate is influenced by
  • The position of the embryos in the uterus
  • The flushing method
  • The time of recovery
  • Ovarian response
  • Embryo viability
• In other farm animals, Sheep, Pigs and Goats embryo recovery is performed by surgical methods. Disadvantage of the surgical method is the number of repetitions is limited by the occurrence of adhesions.
• After recovering embryos from the flushing medium their further developmental capacity has to be evaluated. Embryo viability can be evaluated by various methods.

Morphological evaluation

• Most frequently the morphological evaluation at various microscopical magnifications is used. Morphological criteria in embryo evaluation are shape, colour, number and compactness of cells, Size of the perivitelline space, number and size of vesicles and status of the zona pellucida. The ideal embryo is even, the perivitelline space is empty and of a regular diameter. According to their morphological appearance, embryos are classified into four groups.
  • Excellent embryos: Embryos in the appropriate developmental stage with a perfect morphology.
  • Good embryos: Embryos in the appropriate stage of development with slight morphological deviations. Eg. Minor damage of the zona pellucida and excluded blastomeres or vesicles in the perivitelline space.
  • Degenerated and / or retarded embryos: Embryos in the appropriate developmental stage with major morphological deviations (degenerated embryos)
  • Unfertilized ova.

Staining methods

• Embryo viability can be evaluated by various vital staining and fluorescence techniques.