Equis ISSN 2398-2977

Reproduction: oocyte transfer

Synonym(s): Oviductal transfer of oocytes

Contributor(s): Madeleine Campbell, Camilla Scott

Introduction

  • Oocyte transfer is the transfer of a donor oocyte into the oviduct of a recipient mare.
  • Oocyte transfer provides a method of achieving pregnancies and preserving genetics from mares whose reproductive capabilities are limited by some factor other than oocyte quality.
  • Oocytes can be collected from live donor mares, ovariectomized mares, or recently deceased mares Reproduction: oocyte collection.
  • Collected oocytes may be either mature or immature Reproduction: oocyte collection.
  • Mature oocytes may be directly transferred into the oviduct of a recipient mare.
  • Immature oocytes (which are resting in prophase I of meiosis) need to be cultured / matured in vitro before transfer into the oviduct of a recipient mare.
  • Techniques for oocyte culture, handling and transfer are described below.
  • Recipient mares should be young (ideally 3-10 years old), free from disease and reproductively sound.
  • The recipient mare must be in estrus: either natural, ie a cycling recipient, or induced, ie an anestrus recipient who has been treated with exogenous hormones, so that her reproductive tract provides a receptive environment for the oocyte at the time of transfer.
  • Methods of synchronizing cycling recipient mares with donor mares, and of inducing estrus in acyclic mares, are described below.
  • Following transfer of the oocyte to the recipient mare’s oviduct, the recipient mare is inseminated with fresh, chilled or frozen semen. Fertilization and subsequent embryo and fetal development occurs within the recipient mare’s reproductive tract.

Uses

  • Oocyte transfer provides a method of achieving pregnancies from mares who are capable of producing a viable oocyte, but who are unable to either produce an embryo for embryo transfer or sustain a pregnancy themselves, due to a variety of reasons including pathologies of the uterus, cervix, oviduct or ovary.

Advantages

  • Facilitates production of foals and the preservation of valuable genetics from otherwise infertile mares.

Disadvantages

  • Requires technical expertise.
  • Success rates are very variable and are dependent upon the quality of the oocytes being transferred (quality tends to decline with mare age), the quality of the sperm inseminated, and the technical expertise of personnel.
  • Risk of fertilizing the recipient’s own oocyte as complete control of the recipient’s follicular activity is difficult in cyclic mares.

Requirements

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Preparation

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Procedure

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Aftercare

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Carnevale E M (2016) Advances in collection, transport and maturation of equine oocytes for assisted reproductive techniques. Vet Clin North Am Equine Pract 32 (3), 379-399 PubMed.
  • Riera F et al (2016) Factors affecting the efficiency of foal production in a commercial oocyte transfer program. Theriogenology 85 (6), 1053-1062 PubMed.
  • Carnevale E M et al (2000) Comparison of culture and insemination techniques for equine oocyte transfer. Theriogenology 54 (6), 982-987 PubMed.
  • Hinrichs, K, Provost, P J & Torello E M (2000) Treatments resulting in pregnancy in nonovulating, hormone-treated oocyte recipient mares. Theriogenology 54 (8),1285-1293 PubMed.

Other sources of information

  • Carnevale E M (2011) Oocyte Transfer. In: Equine Reproduction. Eds: McKinnon A O, Squires E L, Vaala W E & Varner D D. Blackwell Publishing Ltd, Oxford. pp 2941-2944.
  • Colleoni S et al (2007) Application of ovum pick-up, ntracytoplasmic sperm injection, and embryo culture in equine practice. In: Proc Am Assoc Equine Pract. pp 554-559.
  • Carnevale E M (2003) How to collect and transfer oocytes. In: Proc 49th Am Assoc Equine Pract. pp 293-294.


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