Fig. 3.
Telomere length of cloned and fertilized bovine blastocysts by Q-FISH. (A) Representative photographs of telomere spots in nuclei of blastocysts (day 8 of development) derived from cloning of adult and fetal fibroblasts and in vitro fertilization. Magnification bar, 20 μm. (B–D) Distribution of mean telomere length over all analyzed nuclei of blastocysts derived from in vitro fertilization (n = 129) (B), cloning from fetal bovine fibroblasts (n = 192) (C), and cloning from adult bovine fibroblasts (n = 126) (D). (E) Mean value of the mean telomere lengths determined for individual blastocysts derived from in vitro fertilization (19.53 ± 4.6 kb, n = 6) and from cloning using fetal fibroblasts (17.3 ± 2.66 kb, n = 6) and adult fibroblasts (21.67 ± 3.92 kb, n = 5). Note that telomeres were elongated in all groups compared to the morula stage and that in contrast to the differences in telomere length at the morula stage, there was no significant difference between the different groups of blastocysts. (F) A sequential analysis of telomere length in embryos derived from a single in vitro fertilization experiment showed telomere elongation at the morula–blastocyst transition, with an average of 15.8 ± 3.1 kb for morula stages (n = 6) and 28.7 ± 7.4 kb for blastocyst stages (n = 6). Dotted line in B–D indicates mean value.