| Abstrakt: |
Fertilized oocytes of the inbred genotypes AKR (AK), C57BL/6 (B6), DBA/2 (D2), and CBA (CB) and the hybrid genotypes F1(♀ AK × ♂ B6) and F1(♀ B6 × ♂ AK) were collected by flushing the oviducts of ♀ mice every 2 h from 2 until 26 h post coitum. Developmental stages of the embryos and DNA content of the pronuclei were estimated by morphological criteria and cytofluorometric measurement of the pronuclei (ethidium bromide-stained DNA), respectively. In all genotypes, S-phase started about 4 h post conception (h.p.c.). The duration of S-phase amounted to 5.9 h (F1[♀ B6 × ♂ AK]), 6.4 h (AK), 8.5 h (B6), 9.4 h (F1[♀ AK × ♂ B6]), 9.8 h (D2), and 11.4 h (CB). In each of the reciprocal F1hybrids, the length of S-phase differed from the maternal genotype (p < 0.01) and resembled closely the paternal genotype (p > 0.25). Cleavage from one-cell stage to two-cell stage occurred between 16 and 21 h.p.c. |
