Morphometrical assessment of the expanded porcine oocyte-cumulus complexes matured in vitro: comparison of measuring methods

Abstract

Our previous studies revealed that porcine oocyte-cumulus complexes that matured in porcine follicular fluid (pFF) and its active fraction resulted in a significant increase in the degree of cumulus expansion as compared with those matured in a modified Krebs-Ringer bicarbonate solution (mKRB) supplemented with bovine serum albumin. In this study, the dif f ereces between an image analyzer and calculation by a formula (LW π/4, where L and W is the length and width of cumulus, respectively) in measuring the degree of cumulus expansion were investigated. Photographs were taken of the oocyte-cumulus complexes matured for 24 h in the different medium and the areas were measured using these two methods. The areas occupied by expanded oocyte-cumulus complexes that matured in pFF-Top fraction were measured accurately only by the formula method. The image analyzer gave significantly lower values due to faint boundary of expanded cumulus. There was no significant difference between the two methods for those unexpanded or very little expanded complexes. Advantages and disadvantages of the two different methods were noted. The advantage in using the image analyzer is that it can measure the natural shape of the oocyte-cumulus complexes. The disadvantages of the image analyzer are: a) the well exp a nded cumulus cell layers can not be measured a ccuret ely, b) it has difficulty in measuring the oocyte-cumulus complexes in the presence of detached cumulus cells and c) only clearly taken photographs can be used for measurement. The advant ages noted for using the formula were: a) oocyte-cumulus complexes printed in the photographs can be measured separately from the detached cumulus cells that are present and b) photographs with either over-or under-exposed prints can be used as a subject for measurement.