The hydrodynamic basis for the accumulation of spermatozoa at surfaces has been investigated. The general conclusion is that when spermatozoa arrive at a surface, they will remain there if the vector of the time-averaged thrust is directed towards that surface. This can arise in two basic ways. First, consider spermatozoa that maintain a three-dimensional waveform and roll (spin) as they progre...

During spermatogenesis, spermatozoa lose many of the organelles that most somatic cells possess (such as endoplasmic reticulum, lysosomes, and most of the cytoplasm) reducing the “baggage” they need to carry en route to the oocyte. The primary function of a spermatozoon, fertilizing an oocyte, is an integrated set of processes, which require multiple cell attributes. Therefore, although the spe...

Criteria for assessing embryo vitality of denuded rabbit and mouse embryos in vitro were: volume of the embryo, number of cells and number of metaphase plates after 24 and 48 h in culture. Mouse embryos grew normally, with and without the zona pellucida, but denuded rabbit embryos showed reduced growth (volume and cell number) and failure to implant in synchronized recipients.

Sperm surface beta 1,4-galactosyltransferase (GalTase) mediates fertilization in mice by binding to specific O-linked oligosaccharide ligands on the egg coat glycoprotein ZP3. Before binding the egg, sperm GalTase is masked by epididymally derived glycosides that are shed from the sperm surface during capacitation. After binding the egg, sperm-bound oligosaccharides on ZP3 induce the acrosome r...

To facilitate our understanding of the role of zona pellucida glycoproteins during fertilization in humans, recombinant human zona pellucida glycoprotein-A (hZPA), -B (hZPB) and -C (hZPC) were obtained by using Escherichia coli and baculovirus expression systems. Analysis by SDS-PAGE and Western blot of the Ni-NTA affinity purified recombinant proteins revealed that the baculovirus-expressed hZ...

Although improved outcomes of IVF after transfer of blastocysts has been reported (1, 2), it remains uncertain which blastocyst can develop into a viable fetus. At present, expansion of the blastocyst is the most practical selection criterion. However, if extended culture of embryos produces many expanded-stage blastocysts, it is not easy to decide which blastocysts to transfer (Fig. 1A). In ad...

Binding to the zona pellucida of an egg stimulates the spermatozoon to undergo the acrosome reaction, a process that enables it to penetrate the egg. Before this binding, the spermatozoon undergoes a series of biochemical transformations in the female reproductive tract, collectively called capacitation. Only capacitated spermatozoa can bind to the zona pellucida and undergo the acrosome reacti...