We recently described a complex population of spermatozoal coding RNAs that are delivered to the oocyte on fertilization. These are derived throughout spermatogenesis, representing a record of past events. Recently, evidence has been provided that micro-RNAs are present in testes, suggesting that they might also be carried in ejaculate spermatozoa. To directly test this hypothesis, a unique mic...

Changes in profiles of serum luteinizing hormone (LH), follicle stimulating hormone (FSH) and testosterone and in mating performance and ejaculate volume have been determined in Finnish Landrace (F inn)and Managra Synthetic (Line-M) rams during the ovine breeding season. In early August, mid-September, early November and mid-December four rams of each breed were bled by venipuncture from the ju...

Copulation duration varies considerably across species, but few comparative studies have examined factors that might underlie such variation. We examined the relationship between copulation duration (prior to spermatophore transfer), the complexity of titillators (sclerotized male genital contact structures), spermatophore mass and male body mass across 54 species of bushcricket. Using phylogen...

In many species, males can make rapid adjustments to ejaculate performance in response to sperm competition risk; however, the mechanisms behind these changes are not understood. Here, we manipulate male social status in an externally fertilising fish, chinook salmon (Oncorhynchus tshawytscha), and find that in less than 48 hr, males can upregulate sperm velocity when faced with an increased ri...

Recent studies of the function of the polymorphic seminal fluid enzyme, esterase 6, of Drosophila melanogaster suggested that it may act in the process of sperm displacement (Gilbert, Richmond and Sheehan, 1981a). This report examines the competitive ability of ejaculates from males homozygous for null or active alleles of esterase 6 under three experimental conditions that model aspects of sex...

Artificial insemination (AI) can help to avoid inbreeding and genetic degeneration for sustaining genetically healthy populations of endangered species in captivity. Collection of a sufficient quantity of viable sperm is an essential first step in the AI process. In the present study, we examined the effects of frequent electroejaculation on semen characteristics in a Siberian tiger. We collect...

Interspecific studies indicate that sperm morphology and other ejaculatory traits diverge more rapidly than other types of character in Drosophila and other taxa. This pattern has largely been attributed to postcopulatory sexual selection involving interaction between the sexes. Such divergence has been suggested to lead rapidly to reproductive isolation among populations and thus to be an 'eng...

INTRODUCTION The aim of this study was to evaluate the effect of microsurgical subinguinal varicocelectomy on semen parameters in azoospermic men with clinical varicocele and to determine the predictive parameters of postoperative improvement. METHODS Twenty-three men with non-obstructive complete azoospermia and varicocele underwent subinguinal open microsurgical varicocele repair. The outco...

This study aims to determine the effect of adding melon (Cucumis melo L.) juice Lactated Ringer’s-egg yolk extender on intact plasma membrane (IPM) and morphological abnormalities native rooster spermatozoa. Five ejaculate each from two roosters (Gallus gallus domesticus) were divided into four equal volumes. Ejaculate was extended 1:10 (v/v) in Ringer's-egg without or with addition 2, 4, 8% fl...

Sperm competition theory predicts that males should increase their expenditure on the ejaculate with increasing risk of sperm competition, but decrease their expenditure with increasing intensity. There is accumulating evidence for sperm competition theory, based on examinations of testes size and/or the numbers of sperm ejaculated. However, recent studies suggest that ejaculate quality can als...