Search results for "Zona Pellucida"
showing 10 items of 18 documents
Genetic Analysis of Human Preimplantation Embryos
2016
Preimplantation development comprises the initial stages of mammalian development, before the embryo implants into the mother's uterus. In normal conditions, after fertilization the embryo grows until reaching blastocyst stage. The blastocyst grows as the cells divide and the cavity expands, until it arrives at the uterus, where it "hatches" from the zona pellucida to implant into the uterine wall. Nevertheless, embryo quality and viability can be affected by chromosomal abnormalities, most of which occur during gametogenesis and early embryo development; human embryos produced in vitro are especially vulnerable. Therefore, the selection of chromosomally normal embryos for transfer in assis…
Limited proteolysis by acrosin affects sperm-binding and mechanical resilience of the mouse zona pellucida.
2021
Abstract The encounter of oocyte and sperm is the key event initiating embryonic development in mammals. Crucial functions of this existential interaction are determined by proteolytic enzymes, such as acrosin, carried in the sperm head acrosome, and ovastacin, stored in the oocyte cortical granules. Ovastacin is released upon fertilisation to cleave the zona pellucida, a glycoprotein matrix surrounding the oocyte. This limited proteolysis hardens the oocyte envelope, and thereby provides a definitive block against polyspermy and protects the developing embryo. On the other hand, acrosin, the renowned and most abundant acrosomal protease, has been thought to enable sperm to penetrate the oo…
Mammalian plasma fetuin-B is a selective inhibitor of ovastacin and meprin metalloproteinases
2019
AbstractVertebrate fetuins are multi-domain plasma-proteins of the cystatin-superfamily. Human fetuin-A is also known as AHSG, α2-Heremans-Schmid-glycoprotein. Gene-knockout in mice identified fetuin-A as essential for calcified-matrix-metabolism and bone-mineralization. Fetuin-B deficient mice, on the other hand, are female infertile due to zona pellucida ‘hardening’ caused by the metalloproteinase ovastacin in unfertilized oocytes. In wildtype mice fetuin-B inhibits the activity of ovastacin thus maintaining oocytes fertilizable. Here we asked, if fetuins affect further proteases as might be expected from their evolutionary relation to single-domain-cystatins, known as proteinase-inhibito…
Outcome of intracytoplasmic sperm injection with and without polar body diagnosis of oocytes.
2008
Objective To compare the reproductive outcome of women undergoing intracytoplasmic sperm injection (ICSI) with or without polar body diagnosis of oocytes. Design Nonrandomized retrospective study. Setting University-based human genetic institute in collaboration with a private fertility center. Patient(s) Six hundred seven women undergoing ICSI with polar body diagnosis and 591 women undergoing ICSI without polar body diagnosis at the same time in the same fertility center. Intervention(s) Polar body testing of ICSI oocytes by five-color fluorescence in situ hybridization. Main Outcome Measure(s) Pregnancy rate (positive fetal heartbeats) and live-birth rate (of at least one child). Result(…
Collapse of blastocysts is strongly related to lower implantation success: a time-lapse study.
2015
Study question Is there an association between blastocyst collapse patterns and implantation potential? Summary answer Embryos that exhibit collapse are as likely to hatch as those that do not, but are less likely to implant and should not be replaced if alternatives are available. What is known already Studies of blastocyst collapse in different species of mammals have found that most blastocysts, that experience consecutive weak contractions, hatch successfully whereas those that exhibit strong contractions or collapse, fail to hatch. Study design, size, duration Retrospective cohort study. Seven hundred and fifteen transferred blastocysts were analyzed from July 2012 to May 2013. Partici…
Cellular and Morphological Traits of Oocytes Retrieved from Aging Mice after Exogenous Ovarian Stimulation1
2001
The present study aims to shed light on the origin of abnormal oocytes ovulated by aged females. In order to reach this goal, cellular and morphological traits of ovulated oocytes from hybrid (C57Bl/6JIco female x CBA/JIco male) female mice retrieved after exogenous ovarian stimulation at the age of 12, 40-42, 50-52, or 57-62 wk were analyzed. Aging of female mice was associated with 1) decreased number of ovulated oocytes; 2) increased percentage of cumulus-free oocytes; 3) raised percentage of oocytes with intracellular mitochondrial aggregates; 4) reduced percentage of oocytes displaying a normal distribution of chromosomes in the metaphase-II plate; 5) increased percentage of normal ooc…
Intracellular activation of ovastacin mediates pre-fertilization hardening of the zona pellucida
2017
Study question How and where is pro-ovastacin activated and how does active ovastacin regulate zona pellucida hardening (ZPH) and successful fertilization? Study finding Ovastacin is partially active before exocytosis and pre-hardens the zona pellucida (ZP) before fertilization. What is known already The metalloproteinase ovastacin is stored in cortical granules, it cleaves zona pellucida protein 2 (ZP2) upon fertilization and thereby destroys the ZP sperm ligand and triggers ZPH. Female mice deficient in the extracellular circulating ovastacin-inhibitor fetuin-B are infertile due to pre-mature ZPH. Study design, samples/materials, methods We isolated oocytes from wild-type and ovastacin-de…
Interference of antisperm antibodies with the induction of the acrosome reaction by zona pellucida (ZP) and its relationship with the inhibition of Z…
1997
Abstract Objective: To determine whether antisperm antibodies can interfere with the induction of the acrosome reaction (AR) by the zona pellucida (ZP) and whether this interference also can occur in the absence of an inhibitory effect on ZP binding. Design: Prospective in vitro study. Setting: A tertiary care center, the Andrologic Clinic, University of L'Aquila. Patient(s): Sera from 12 infertile patients with high titers of circulating antibodies directed against the sperm head were studied. Intervention: None Main Outcome Measure(s): The effect of antisperm antibodies on ZP binding was evaluated by matching antibody-exposed and nonexposed donor sperm suspensions labeled with fluorescein…
The molecular evolution of sperm zonadhesin.
2008
Based on pioneering work of Hardy and Garbers, zonadhesin has become one of the best studied sperm ligands in boreoeutherian mammals, both from a biochemical and evolutionary perspective. Zonadhesin is a mosaic-type protein that localizes to the apical head of spermatozoa. In pig, cattle, rabbit and primates, zonadhesin precursor essentially consists of two or three MAM (meprin/A5 antigen/mu receptor tyrosine phosphatase) domains, one mucin-like domain, one incomplete and four complete D domains (homologous to vWFD). Mouse zonadhesin is distinguished from this general pattern by 20 extra partial D3 domains. While concerted evolution drives the divergence of the mucin-like domain in the orth…
Subzonal insemination, partial zona dissection or intracytoplasmic sperm injection? An easy decision?
1995
This review aims to analyse and compare the results to date of subzonal insemination (SUZI), partial zona dissection (PZD) and intracytoplasmic sperm injection (ICSI) to evaluate critically whether it is now possible to replace SUZI and PZD by ICSI. It appears that ICSI is a much more efficient assisted reproduction technique than SUZI and PZD for resolving cases of severe male infertility and/or repeated failure of conventional in-vitro fertilization (IVF). For ICSI compared with SUZI and PZD, fertilization (49.4, 17.7 and 16.8% respectively), percentage of patients reaching embryo transfer (91.0, 55.1 and 23.3% respectively), percentage of transfers performed with two or three embryos (83…