Giulietta Micara

Is the sperm-binding capability of the zona pellucida linked to its surface structure? A scanning electron microscopic study of human in vitro fertilization

The structure of the zona pellucida and the early interactions between human oocytes and spermatozoa were investigated in an in vitro fertilization program. Thirty-five mature (preovulatory) oocytes, 10 immature oocytes lacking a germinal vesicle, and 11 atretic oocytes which had not undergone fertilization at 10–20 hr after insemination were studied by light and scanning electron microscopy. Observed through employment of these techniques, the zona pellucida showed two basically different patterns: a mesh-like, spongy structure having wide and/or close meshes; and a compact, smooth surface. The smooth-surfaced zona was most commonly seen in the cultured oocytes belonging to the immature and atretic groups. These observations seem to show that the spongy appearance of the zona pellucida is related mainly to oocyte development and maturity. In this study, greater numbers of penetrating spermatozoa were noted on oocytes showing the mesh-like zona, in contrast to the presence of a few sperm flattened against its surface or the frank absence of sperm associated with oocytes having the more compact, smooth zona. It is likely that the condensation of the outer aspect of the zona pellucida causes a disorientation of sperm-binding sites, which would probably result in markedly reduced binding and penetration capacity with spermatozoa. These changes might ultimately lead to impairment of in vitro oocyte fertilizability.

Heterogenous distribution of fibronectin, tenascin-c, and laminin immunoreactive material in the cumulus-coronal cells surrounding mature human oocytes from IVF-ET protocols—Evidence that they are composed of different subpopulations: An immunohistochemical study using scanning confocal laser and fluorescence microscopy

Monoclonal antibodies and immunofluorescence microscopy, including laser confocal microscopy, were used in this study to point out the production of fibronectin, tenascin‐c, and laminin in the cumulus‐corona (CC) cells surrounding mature human oocytes from IVF‐ET protocols in view of their presumptive importance in the coordination of the processes leading to fertilization and early embryo cleavage, including the final maturation of the ovum, the sperm‐egg interaction, and the “complex biochemical dialogue” between the gamete and the oviduct through the tubal luminal environment.

Clinical complications after transvaginal oocyte retrieval in 7,098 IVF cycles.

We report the complications observed after transvaginal oocyte retrieval guided by ultrasound in 7,098 IVF cycles. The frequency of severe complications in our patients was 0.08%, of which four cases were intraperitoneal bleeding (0.06%) and two were cases of ovarian abscess (0.003%).

Term pregnancy and live birth subsequent to immediate uterine transfer of sperm microinjected oocyte in a natural cycle

Abstract It has been reported that it is possible to achieve a pregnancy after immediate uterine transfer of oocyte and sperm, before fertilization and cleavage were known to have occurred; there is an enormous amount of work about the optimal timing of embryo transfer, with no conclusive evidence of a gold standard satisfying patient age, endometrial receptivity, hormonal levels and embryological parameters. We hereby report a case of one 35-year-old nulligravid woman with longstanding tubal factor infertility and 3 previous failed ICSI cycles, treated with ICSI and immediate transfer of the oocyte microinjected with a spermatozoon in a natural cycle. A single oocyte was retrieved, injected with a spermatozoon and transferred 40 min after injection, resulting in an uneventful pregnancy and delivery of a healthy female infant weighing 3320 g at 40 weeks’ estimated gestational age. This case, certainly novel, should be interpreted with caution. Whether confirmed for efficacy and safeness in appropriate controlled clinical trials, our present observation could offer a simple, practical and cost-effective approach in ART programs in selected patients. Chinese abstract 据报道称，在卵母细胞发生受精和卵裂前即刻将卵母细胞和精子植入宫腔获得妊娠是可能实现的；考虑到患者的年龄、子宫内膜容受性、激素水平及胚胎学参数而无法找到符合这一金标准的有力证据，因此关于胚胎移植最佳时期的选择仍需要进行大量的研究工作。而我们的病案中报道了一份病例：35岁女性，长期输卵管因素不孕，先前卵泡浆内单精子注射（ICSI）3个周期失败，本次在自然周期中行ICSI后立即将单精子注射后的卵母细胞植入宫腔。植入40分钟后单个卵母细胞成功获卵，成功妊娠并于足月（40周）顺利分娩一健康女婴，体重3320克。该报道毋庸置疑是创新的，但解读时应慎重。无论在适当的临床控制试验中是否能证明该技术安全有效，我们在现有的观察性研究中至少可以为实施辅助生殖技术中某些特定的病人提供简单、有效、性价比高的方法。

Ultrastructural and morphometric evaluation of aged cumulus-oocyte-complexes

Maternal age is one of the most significant factors influencing oocyte quality (1). 35 years of age seems to be a watershed in reproductive potential. The aim of this study was to reveal the amount and distribution of specific ultrastructural organelles in human mature cumulus-oocyte-complexes belonging to women of different ages (<35 years old; ≥35 years old/ reproductive aging) and to evaluate their different response during 24 hours prolonged culture (defined as in vitro aging) (1). The samples were studied by light and transmission electron microscopy; a morphometric analysis of TEM data was performed (2). In all aged samples, the amount of mitochondria- smooth endoplasmic reticulum aggregates, cortical granules and microvilli decreased (p<0,05), while the amount of mitochondria-vesicle complexes increased up (p<0,05). Occasional vacuoles were found in oocytes from older women after in vitro aging. A significant (p<0,05) increase of zona pellucida thickness was linked to the donor age but not to in vitro aging. A re-compaction of cumulus cells was seen in in vitro aged samples. Morphometric data strongly confirmed our preliminary results (3) revealing that: i) reproductive aging and in vitro aging share specific ultrastructural features ii) In vitro aging can be consider a model for reproductive aging iii) young oocytes seem to be less sensitive to in vitro aging than older ones. The above results may represent a reliable background for further multidisciplinary studies regarding aged oocytes and may be also useful in clinical settings.