New Bolton Center Kennett Square, PA
Emergencies & Appointments:
Ryan Hospital Philadelphia, PA
Mares in Field

Intracytoplasmic Sperm Injection (ICSI)

Oocyte Recovery for Intracytoplasmic Sperm Injection (ICSI)

For mares that are not suited for embryo transfer, oocyte recovery and subsequent ICSI is another option that can result in pregnancies. 

Oocyte aspiration and ICSI can be used for mares with chronic uterine infections, cervical problems, oviductal problems, and other issues that prevent them from conceiving or carrying a pregnancy. 

Additionally, oocytes can be recovered post mortem, thus allowing for foals to be produced even after the death of the mare.

The Hofmann Center offers oocyte recovery services for mares, both alive and deceased. 


Phone: 610-925-6364

Hofmann Center for Animal Reproduction
443 Bartram Road
Kennett Square, PA 19348

About Live Mares

For live mares, oocytes, or eggs, are recovered from the mare’s ovaries using ultrasound guided transvaginal follicular aspiration. Follicles on the mare’s ovaries are aspirated while the mare is standing in stocks under heavy sedation.  We boast an average 50% oocyte recovery rate per aspirated follicle – among the best recovery rates you can find.

The recovered oocytes are packaged and transported overnight to a facility specializing in intracytoplasmic sperm injection (ICSI).  There, the oocytes are matured, injected with a single sperm cell and then allowed to develop in culture for several days. 

Any resulting embryo(s) are transferred into recipient mare(s). 

About Deceased Mares

For deceased mares, the ovaries can be recovered by your veterinarian on the farm immediately following death or euthanasia. 

The ovaries are transported to the Hofmann Center for oocyte recovery.  Every follicle in the ovary is individually scraped multiple times to recover the oocyte. We have an excellent recovery rate of over 80% per scraped follicle.

Recovered oocytes are packaged and shipped to a facility specializing in intracytoplasmic sperm injection (ICSI).  The remainder of the procedure is the same as that described above.

If you are interested in oocyte recovery and ICSI, please contact our reproduction team today. 

ICSI: Intracytoplasmic Sperm Injection

Intracytoplasmic Sperm Injection

This video shows a laser gradually drilling a hole through the outer layer (the zona pellucida) of an equine egg. Once the zona pellucida is penetrated, a tiny needle is advanced through the hole in the zona, then through the egg's cell membrane and into the center of the egg.  A single sperm from a stallion is then gently injected and the needle is withdrawn.

Reproductive technology has been a strength of Penn Vet's since Dr. Ralph Brinster's groundbreaking research on mammalian embryo culture in the 1960s and transgenesis in the early 1980s. It is fitting that our clinical services continue in this tradition by offering advanced reproductive services for our patients. 

Meet Logan, one of our two newest Penn Vet Working Dogs:  and here's Quest, already too big for his britches.  Both are 8 weeks old, and already working!!
After the ICSI procedure, the newly fertilized egg is cultured under very special conditions in a  laboratory incubator for about eight days, so the embryos will develop.  This picture shows two horse embryos four days after fertilization using ICSI.  After another four days in the incubator, these embryos will be ready to transfer to a surrogate mare.