BACKGROUND Sperm design varies enormously across species and sperm competition is thought to be a major factor influencing this variation. However, the functional significance of many sperm traits is still poorly understood. The sperm of most murid rodents are characterised by an apical hook of the sperm head that varies markedly in extent across species. In the European woodmouse Apodemus sylv...

Silkworm (Lepidoptera) males produce dimorphic sperm: nucleate eupyrene sperm and anucleate apyrene sperm. The eupyrene sperm are ordinary sperm to fertilise the eggs, while the function of apyrene sperm remains uncertain. After meiosis, 256 sperm cells are enclosed by a layer of cyst cells, forming a sperm bundle. We have previously documented that the nucleus of eupyrene sperm anchors to the ...

BACKGROUND Protein tyrosine phosphorylation (TP) of human sperm is related to sperm capacitation and zona pellucida (ZP) binding. The aim of this study was to determine whether the TP of capacitated sperm is a useful marker for the ability of sperm to bind to the ZP and undergo the ZP-induced acrosome reaction (AR). METHODS Semen samples were obtained from 115 subfertile men with sperm count ...

Among mammals sperm competition leads to selection for increased sperm numbers but it is not known whether it also leads to changes in sperm size. Two contrasting theoretical predictions have been made. The first hypothesis relies on the assumption that there is a trade-off between sperm numbers and sperm size and predicts that, in species confronting sperm competition, there will be a concomit...

This study explored the correlation between sperm ultrastructure in infertile patients with abnormal sperm morphology and DNA damage. Three unusual sperm morphologies were selected for the experimental group namely case 1 (95% headless sperm), case 2 (98% headless sperm), and case 3 (100% headless sperm), and the control group consisted of 2 subjects (20 and 15% headless sperm). For case 1, the...

Among mammals sperm competition leads to selection for increased sperm numbers but it is not known whether it also leads to changes in sperm size. Two contrasting theoretical predictions have been made. The first hypothesis relies on the assumption that there is a trade-off between sperm numbers and sperm size and predicts that, in species confronting sperm competition, there will be a concomit...

When ejaculates from rival males compete for fertilization, there is strong selection for sperm traits that enhance fertilization success. Sperm quantity is one such trait, and numerous studies have demonstrated a positive association between sperm competition and both testes size and the number of sperm available for copulations. Sperm competition is also thought to favor increases in sperm qu...

Centrosome integrity is critically important for successful fertilization and embryo development. In humans, the sperm contributes the dominant centrosomal material containing centrioles and centrosomal components onto which oocyte centrosomal proteins assemble after sperm incorporation to form the sperm aster that is essential for uniting sperm and oocyte pronuclei. Increasingly, dysfunctional...

BACKGROUND The aim of this study was to determine the relationship between human sperm hyperactivation (HA), sperm-zona pellucida (ZP) binding and the ZP-induced acrosome reaction (AR) of ZP-bound sperm in vitro. METHODS Sperm samples from 129 infertile men were studied. Motile sperm (2 x 10(6)) selected by Pure sperm were incubated with four oocytes in 1 ml human tubal fluid supplemented wit...

What is sperm storage? Sperm storage is most commonly defined as the maintenance of sperm inside a female’s reproductive tract for an extended period of time. Because the fate of sperm post-copulation is important for understanding sexual selection, sperm storage is a particularly interesting characteristic that may have drastic impacts on the operation of post-copulatory sexual selection. Sper...