The endosymbiotic bacterium Wolbachia pipientis manipulates host reproduction by rendering infected males reproductively incompatible with uninfected females (cytoplasmic incompatibility; CI). CI is believed to occur as a result of Wolbachia-induced modifications to sperm during maturation, which prevent infected sperm from initiating successful zygote development when fertilizing uninfected fe...

Production of more than one morphological type of sperm in a common testis has been documented for a variety of invertebrates, including gastropods, spiders, centipedes, and insects. This unusual phenomenon is difficult to explain by current theory, particularly since available evidence indicates that one sperm type is often incapable of effecting fertilization. In this review we critically exa...

Males of many species exhibit sperm heteromorphism, in which multiple morphologies of sperm are produced in a common testis (see references in [1]). Polymegaly, a form of sperm heteromorphism, is found in the Drosophila obscura group and is characterized by the production of two size classes of nucleated sperm that differ only in head and tail lengths [1,2]. Both the length and the ratio of spe...

The objective of this study was to investigate the influence of various factors on blastocyst development in a bovine in vitro embryo production system. Two production systems were originally compared: Protocol 1, which utilized oocyte recovery by slicing, 20 % fetal bovine serum with FSH (FBS+) for oocyte maturation, and sperm preparation system 1 (F1), and Protocol 2, which utilized oocyte re...

Reactive oxygen species overgeneration as a side effect of semen cryopreservation may lead to lipid peroxidation, protein degradation, DNA fragmentation and cell death, resulting in a decrease of sperm survival and fertilisation ability. Lycopene has been proposed as a potential supplement to semen extenders because of its antioxidant properties. The aim of this study was to evaluate the effect...

Studies confirm that male sperm counts are declining, and environmental factors, such as pesticides, exogenous estrogens, and heavy metals may negatively impact spermatogenesis. A number of nutritional therapies have been shown to improve sperm counts and sperm motility, including carnitine, arginine, zinc, selenium, and vitamin B12. Numerous antioxidants have also proven beneficial in treating...

Sperm competition favors increases in relative testes mass and production efficiency, and changes in sperm phenotype that result in faster swimming speeds. However, little is known about its effects on traits that contribute to determine the quality of a whole ejaculate (i.e., proportion of motile, viable, morphologically normal and acrosome intact sperm) and that are key determinants of fertil...

Interest in the physiologic and pathologic effects of ROS on male fertility is growing. The controlled generation of very low amounts of ROS seems to regulate the acquisition of sperm-fertilizing ability. High levels of ROS endanger sperm function and viability. Oxidative stress can arise as a consequence of excessive production of ROS or impaired antioxidant defense mechanisms in semen. Oxidat...

Semen quality and its relationship to fertility are major concern in animal production. The aim of this study was to assess the relationship between frozen thawed sperm characteristics and fertility following in vivo fertility through Artificial Insemination(AI). Semen samples were collected from four buffalo bulls. Semen volume and sperm concentration appeared to be significantly different (P0...