This study examines the relationship between common morphological anomalies of cleaving embryos and their ability to form apparently normal blastocysts in vitro. The impact of cleavage rate, fragmentation, and multinucleation on compaction, cavitation, along with inner cell mass and trophectoderm formation has been assessed. The study population consisted of 102 patients who elected or were selected to have a day 5 embryo transfer. Clinical pregnancy and implantation rates were 66.7 and 49% respectively. Slow and fast cleavage had a significant negative association with normal blastocyst formation. Only 13.8% (67/484) of embryos with <7 cells and 27.5% (25/91) of those with >9 cells on day 3 formed blastocysts with apparently normal morphology, compared to 41.9% (252/602) with 7-9 cells on day 3 (P < 0.001). Fragmentation had a negative impact on normal blastocyst formation. Embryos with >15% fragmentation formed normal blastocysts at a significantly lower rate (46/279; 16.5%) than embryos with 0-15% fragmentation (311/935; 33.3%) (P < 0. 001). Furthermore, the pattern of fragmentation was associated with blastocyst formation. Type IV fragmentation led to a significant reduction in blastocyst formation (25/170 or 14.7%), compared to types I, II and III which performed much better (38.6, 32.9 and 32.4% respectively). Only 15.9% (22/138) of embryos with one or more multinucleate cells on day 2 and/or 3 formed normal blastocysts compared with 31.9% (335/1051) (P < 0.001) of those without multinucleation. Collectively, the data suggest that cleavage anomalies, some of which do not preclude development after short-term culture, may reduce the developmental competence of embryos after prolonged culture.
It is likely that there is an association between the fitness of mitochondria and their ability to support normal cellular function. Oocytes are greatly enriched in the number of mitochondria as they support essential developmental processes such as oocyte maturation and embryonic development, while their replication is deferred until gastrulation. The mitochondrial DNA (mtDNA) copy number in 87 human oocytes from 29 patients was evaluated after DNA extraction and real-time quantitative polymerase chain reaction (PCR). The average mtDNA copy number was 795,000 (+/- 243,000) in metaphase II oocytes. mtDNA content varied considerably between oocytes, even within the same patient. No relationship was found between mtDNA copy number and maternal age. The findings suggest that mtDNA replication is fully accomplished by the germinal vesicle stage in the fully developed oocyte.
Visual disability affects about 2 million Poles. This group includes people who have been diagnosed with Stargardt’s disease. This disease occurs in the general population with a frequency of one in 10,000. It leads to legal blindness with visual acuity lower than 5%. Visual disturbances in this disease may occur in children, i.e. 7–12 years of age, as well as in adolescents and adults. People suffering from this disease experience a significant reduction in visual acuity, difficulty in recognizing colors, impaired depth vision, difficulties with accommodation, impaired central vision and often severe photophobia. The aim of the research was to collect information about the assistive technologies used by people with Stargardt’s disease and to identify their ability to move independently despite a significant reduction in visual acuity. The research results show that most of the 102 surveyed people use various types of assistive technology and experience significant visual impairment. At the same time, a significant part of this group declares that despite the inability to read the black print text, they can still move quite freely.
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