OBJECTIVE To analyze cases in which no sperm could be identified after thawing among cryopreserved samples of rare or very low concentrations of sperm. DESIGN Retrospective, single-institution, cross-sectional. SETTING Male infertility clinic. PATIENT(S) We identified couples that underwent intracytoplasmic sperm injection (ICSI) with the use of either ejaculated or testicular cryopreserv...

The existence and evolutionary significance of sexual selection through sperm competition was first realized by Geoff Parker in a prescient and influential review published in 1970. Parker recognized that competition between males for fertilizations will continue after mating, if the sperm of two or more males overlap near the site of fertilization in females. The process of sperm competition w...

Fertilization is a cell-cell recognition process that occurs between two distinct cells: a small asymmetric and motile sperm cell and a large and nonmotile egg. The stages of fertilization can be divided into four processes: 1) sperm preparation, 2) sperm-egg recognition and binding, 3) sperm-egg fusion and 4) fusion of sperm and egg pronuclei and activation of the zygote. The specific structur...

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...

epoxy powder coatings containing zinc aluminum phosphate (zap) and zinc phosphate (zp), which are the 2nd and 1st generation of phosphate-based pigments respectively, were applied to the surface of mild steel sheets. the anticorrosive performances of the coated samples were studied using electrochemical impedance spectroscopy (eis). cathodic disbonding resistance and the adhesion performance of...

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...