Flexibility of Oolemma is an Important Factor for Oocyte Survival after ICSI.

Developmental ability of embryos produced from oocytes with fragile oolemma by intracytoplasmic sperm injection

“…In this study, the fertilization rate after ICSI of fragile oocytes was lower than that of normal oocytes because of the increased rate of degenerated oocytes. This result is consistent with previous reports in which oocyte degeneration was found to be closely related to the characteristics of the oolemma [7,8]. However, once fragile oocytes were fertilized without degeneration, the developmental ability into the blastocysts of resultant embryos was compared favorably with that of normal oocyte-derived embryos.…”

“…Van Steirteghem et al [6] reported that an average of 10 % of oocytes may be lost because of degeneration as a result of the procedure. Degeneration of oocytes is particularly evident when the oolemma is very fragile, resulting in sudden breakage of the membrane during ICSI [7,8]. The observation that oocytes with a fragile oolemma (fragile oocytes) degenerate easily can be explained by the absence of the protective effect of the funnel responsible for sealing the breach.…”

Evaluation of the effect of piezo‐intracytoplasmic sperm injection on the laboratory, clinical, and neonatal outcomes

“…These oocytes may have oolemma with weak stretching ability. Several authors have reported the reduction in survival rate of oocytes that have non‐stretchable oolemma during P‐ICSI . Two processes may be involved in resealing the hole created in the oolemma during ICSI .…”

“…Several authors have reported the reduction in survival rate of oocytes that have non‐stretchable oolemma during P‐ICSI . Two processes may be involved in resealing the hole created in the oolemma during ICSI . It has been postulated that resealing of the hole in the oolemma may be facilitated by direct contact with outer surfaces of the oolemma, which would take place during post‐ICSI recovery process in fully stretched oolemma .…”

Association of follicular fluid volume with membrane stretchability of human metaphase II oocytes following the gonadotropin‐releasing hormone agonist protocol during intracytoplasmic sperm injection

“…Oocyte degeneration following intracytoplasmic sperm injection (ICSI) occurs at a rate of ~5%‐15% due to risk factors involving oocyte quality, such as oocyte cytoplasmic viscosity, oolemma stretchability or flexibility, and oolemma fragility . One study showed that the injection funnel volume after conventional ICSI is greater in normal fertilized oocytes than in degenerated oocytes, while another study reported that the post‐piezo‐ICSI survival rate is lower with low oolemma stretchability than with high oolemma stretchability .…”