Background: The aim of this study was to evaluate the long-term outcome of autotransplantation of vitrified warmed hemi-ovaries into ewes.
Methods: Six hemi-ovaries from six ewes aged 6 to 12 months were vitrified. After dissection of the medulla, the hemi-ovarian cortex was stored at -196 degrees C in liquid nitrogen. Four to six weeks after the first laparotomy, the left ovary was removed and the vitrified-warmed hemi-ovary was sutured.
Results: Plasma progesterone concentration increased in a regular manner in all ewes. Three pregnancies occurred, from which four lambs were born. The first delivery of a normal lamb occurred in February 2003. The second delivery of two normal lambs occurred in March 2003 (a 2.5 kg male and a 2.8 kg female). The last lamb had a normal delivery but had a malformation of the left leg and the oesophagus. This lamb died two months after delivery from pneumariae. Histological examination of the grafted vitrified ovaries showed few primordial and antral follicles.
Conclusions: These three pregnancies in a ewe model may indicate that ovarian vitrification gives results as good as those from a slow cooling protocol in autograft. It is impossible to establish a link between the vitrification procedure and the malformation of the last lamb, and further studies are needed to evaluate the feasibility of ovarian vitrification.