Polarized light microscopy-detectable structures of human oocytes and embryos are related to the likelihood of conception in IVF

Abstract

Purpose To clarify if birefringent structures of human oocytes and embryos, measurable by polarized light microscopy, have any value in predicting the chance of pregnancy in human in vitro fertilization and may halp to identify the most competent oocytes and embryos. Methods The inner layer of the zona pellucida (IL-ZP) and the meiotic spindle (MS) were analyzed by polarized light microscopy in 258 oocytes and in the 209 embryos deriving from them. Data obtained from 102 ICSI cycles with conception were compared with those obtained in 156 cycles without conception. The retardance and area of the IL-ZP, as well as the retardance, length of the major axis, and area of the MS were measured. Furthermore, polarized light microscopy parameters were related to the embryo morphological score by multiple regression analysis. Result(s) The mean area of the IL-ZP of both oocytes and embryos was significantly lower in conception than in nonconception cycles (p00.0001 for oocytes and p00.002 for embryos). The area of the IL-ZP in embryos was significantly, inversely related to the embryo morphological score (p00.011). The area, the major axis length and the retarcance of the MS, as well as the retardance of the IL-ZP in oocytes and embryos were comparable in conception and non-conception cycles. ConclusionThe area of the IL-ZP of the human oocytes may represent a marker of oocyte competence, as oocytes with a low IL-ZP area are more frequently obtained in conception cycles. When measured in embryos, a low IL-ZP area identifies embryos with a high chance of implantation.

Pregnancy with oocytes characterized by narrow perivitelline space and heterogeneous zona pellucida: is intracytoplasmic sperm injection necessary?

“…Aberrant ZP composition or ultrastructure could result in fertilization failure due to ineffective spermatozoon-oocyte fusion [20]. To clarify the birefringent structures of human ZP, polarized light microscopy was usually used [18,22]. Proper thickness of the inner zona layer showed better blastulation rate [19].…”

“…The round transparent ZP around oocytes from different women may present different morphologies in IVF cycles. ZP morphological abnormalities reported were centered in shape or thickness variety [18][19][20][21][22]. No previous report has been focused on the ZP texture under inverted light microscopy.…”

Intracellular glutathione content, developmental competence and expression of apoptosis-related genes associated with G6PDH-activity in goat oocyte

“…Visual assessment of the compactness of the cumulus investment as well as the homogeneity of the ooplasm is routinely used for selecting the more competent oocytes in ART programs [3]. Although such morphological characteristics are practically used in determining the quality of oocytes, their overall accuracy for assessing developmental potential are poor and therefore the predictive value of these criteria are more likely controversial [4][5][6][7].…”

Assisted Reproduction

“…) led to development of alternative non-invasive approaches to assess oocyte quality. Use of polarized light to visualize the size and shape of the meiotic spindle, 209 and the thickness of the inner zona pellucida layer 210 have been correlated with outcome. 211 However, because of the cost of the polarizing system and the sensitivity of the results to oocyte positioning it is unlikely that this approach will be routinely adopted in the IVF laboratory.…”