Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0029713 (immaturity)
 4,335 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Abnormal embryo development represents the major cause of implantation failures and accounts for the low rate of human infertility in vivo or in vitro. Chromosome abnormalities are widely involved in this process. Indeed, 28.4% of oocytes carry a chromosome aberration, i.e. 25.6% aneuploidy and 2.8% structural anomalies. Fertilisation abnormalities (possibly increased by in vitro procedures) were recorded: 7 to 28% of oocytes from fertilisation failure showed a sperm premature chromosome condensation probably resulting from ooplasmic immaturity. Moreover, 1.6% and 3.8% of inseminated oocytes had either a single or 3 pronuclei demonstrating parthenogenesis or triploidy, respectively. In vitro developmental capacities of embryos depends on the degree of ploidy. Parthenogenetic embryos display a fairly normal development until implantation. Triploid zygotes show an original way of division: half of them divide first into 3 cells and then into 6 cells (via a tripolar spindle) whereas diploid zygotes divide into 2 and then 4 cells. As a consequence of either meiotic or mitotic non disjunctions or fertilisation anomalies, 25 to 71% preimplantation embryos carry a chromosome disorder. As an outgrowth of in vitro fertilisation and embryo transfer, detection of genetic and metabolic defects prior to implantation might be possible in the future. So far, 6 girls have been born in couples at risk of transmitting X-linked disease. This technic will increase the efficiency of IVF and avoid the trauma of repeated abortions.
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PMID:Cytogenetic analysis of oocytes and embryos. 130 24

We examined cytological and cytogenetic parameters of 1076 oocytes and 385 zygotes that failed to develop post in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI). Out of 1076 oocytes, 894 (83%) arrested oocytes showed a first polar body and were thus assumed arrested at metaphase II while the remainder showed no polar body. In the group of oocytes with a polar body, 20.5% had an abnormal karyotype. Cytologically, premature sperm chromosome condensation was noted in 28.3% of uncleaved oocytes. This high PCC can be explained by the different grades of oocyte maturity from one center to another. Oocytes from older women showed no increased aneuploidy but did show increased premature chromosome condensation. Analysis by classical technique of 220 uncleaved zygotes showed 91 with highly condensed chromosomes, 53 with asynchrony of condensation, 31 with pulverized chromosomes, and 45 arrested at the first somatic metaphase. Out of 385 arrested zygotes, 165 were explored by in situ hybridization. FISH using a set of 7 chromosome-specific probes showed aneuploidy in the chromosomes analyzed (13, 16, 18, 21, 22, X, Y) in 21.8% of blocked zygotes (19-25% depending on morphology). Extrapolating to other chromosomes, we expect that a vast majority of blocked zygotes and oocytes probably carry chromosome abnormalities. These data demonstrate the contributions of chromosome disorder in early embryo development blocking and implantation failure. Certainly, the issue of cytoplasm and nuclear immaturity and their relation to each other and to chromosome abnormalities provides a fertile area for future investigation in ART.
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PMID:Morphological and cytogenetic analysis of intact oocytes and blocked zygotes. 1274 38