Fertilization in vivo is a complex process consisting of six steps, namely, penetration of the cumulus complex, binding of the sperm to the zona pellucida, fusion of oocyte and sperm, oocyte activation, sperm remodelling, and formation of the pronuclei. Since ICSI bypasses the first three steps any problem related to fertilization failure after ICSI arises from oocyte activation onwards. Accord...

Fertilized mouse eggs regulate their size principally by accumulating glycine as an intracellular osmolyte using the GLYT1 (SLC6A9) transporter, a mechanism of cell volume homeostasis apparently unique to early embryos before the morula stage. However, nothing was known of cell volume regulation in oocytes before fertilization. We show here that GLYT1 is quiescent in mouse germinal-vesicle-stag...

Background: During spermatogenesis the sperm nucleus exchange histones against cystein rich protamines, which stabilize the sperm chromatin and protects the DNA against damages. At ejaculation the age of the patient, handling routines, processing of the semen sample and the storage of the final sperm suspension might damage the DNA. Sperm chromatin stability and DNA damages are evaluated with d...

Cloning by somatic cell nuclear transfer (SCNT) subverts sperm-mediated fertilization that normally leads to physiological activation of the oocyte. Therefore, artificial activation is required and it is presently unclear what developmental consequences this has. In this study, we aimed to improve cattle cloning efficiency by utilizing a more physiological method of activating SCNT reconstructs...

BACKGROUND Before human MII oocytes are vitrified they are usually denuded from their cumulus cells. In this study we wanted to investigate the effects of an intact corona radiata on the vitrification and fertilization of human oocytes. METHODS The study comprised two different parts. In Part 1, 36 MII stage oocytes, from 6 patients, were randomly assigned into a control group, a group of vit...

Glycoproteins and lectin-like proteins mediate sperm-zona pellucida interaction. The present study analysed the participation of carbohydrates in the different stages of sperm interaction with the zona pellucida in hamster, by determining the effects of different monosaccharides. N-acetylglucosamine (GlcNAc, 1 mM) reduced sperm ability to bind to the zona pellucida. Surprisingly, spontaneous ac...

The meiotic spindle and the zona pellucida exhibit molecular order when imaged with polarized optics. This study aimed to investigate possible factors contributing to the zona pellucida birefringence score and meiotic spindle visualization, and to evaluate whether these structures may predict intracytoplasmic sperm injection outcomes. Oocytes were divided into groups according to zona pellucida...

The paper reports a histological and immunohistochemical description of oocyte growth and ultrastructural aspects of zona radiata (ZR) formation as well as the relationship between plasma estradiol-17beta, (E2) levels and ovarian development in swordfish (Xiphias gladius L.) from the Mediterranean Sea. Ovaries were inactive during March to mid April; maturation occurred during late April to Jun...