Calves produced by nuclear transfer (NT) had higher mortality than those produced by egg transfer. About half calves the produced by NT grew normally. Materials from calves which were aborted or died were collected and examined pathologically. From Feb. 1999, to Sep. 2002, 146 materials from calves were examined histopathologically. Among them, 23 calves were destroyed as scheduled, and no lesions were observed in them. Sixty-four calves were aborted or stillborn, 13 calves died just after birth, 28 calves died within 5 days after birth. Eighteen calves survived more than 6 days. The absence or decrease of thyroidal colloid was seen in 27 cases. Large fetuses of more than 50 kg in body weight were seen in 22 cases. In 14 cases, major lesions were seen in the placenta. Immunodeficiency was seen in 21 cases in which lymphatic tissues were hypoplastic. Abnormalities were seen in the muscles in 16 cases, in the umbilical cord in 7 cases and in the hip joint in 3 cases. Alveolar proteinosis was seen in 2 cases. The lesions characteristic for calves produced by NT were abnormalities of placenta, abnormalities of umbilical cords and large fetuses. The umbilical cords were thick and fragile. Such lesions as thyroid, muscle, hip joint, lymphatic tissues, etc are considered recessive hereditary diseases, so that most lesions seen in the calves produced by NT were due to genes that did not function normally. (Diagnostic Section, Department of Epidemiology TEL +81-29-838-7774)
Reference:
Watanabe et al. (2002) J. Biol. Chem. 277:5090-5093.
