Polyspermy is a major puzzle in reproductive biology. In some taxa, multiple sperm enter the ovum as part of the normal fertilization process, whereas in others, penetration of the ovum by more than one sperm is lethal. In birds, several sperm typically enter the germinal disc, yet only one fuses with the female pronucleus. It is unclear whether supernumerary sperm play an essential role in the...

At coitus, human sperm are deposited into the anterior vagina, where, to avoid vaginal acid and immune responses, they quickly contact cervical mucus and enter the cervix. Cervical mucus filters out sperm with poor morphology and motility and as such only a minority of ejaculated sperm actually enter the cervix. In the uterus, muscular contractions may enhance passage of sperm through the uteri...

A sperm-specific cation channel (CatSper) facilitates the entry of calcium necessary for rapid changes in sperm motility allowing the cell to navigate the hurdles of the female reproductive tract and successfully to locate the egg. Brenker and colleagues show that CatSper is (directly) activated by a diverse range of small organic molecules that are reported to evoke chemotaxis in human spermat...

With the advent of human assisted reproduction in the year 1978 numerous techniques were developed to isolate spermatozoa capable to fertilize oocytes. While early methodologies only focused on the aim of isolating viable, motile spermatozoa, with further progress of assisted reproductive technology, particularly for ICSI, it rapidly became clear that these two parameters are insufficient for t...

BACKGROUND Evidence supports the involvement of nitric oxide (NO) in a variety of male reproductive processes such as spermatogenesis, spermiogenesis, sperm motion, sperm metabolism and sperm capacitation. However, low concentration of NO is essential in biology and physiology of spermatozoa, but high amounts of NO is toxic and has negative effects on sperm functions. On the other hand, it is e...

Discovery of 5-hydroxymethylcytosine (5hmC) in mammalian genomes has excited the field of epigenetics, but information on the genome-wide distribution of 5hmC is limited. Globozoospermia is a rare but severe cause of male infertility. To date, the epigenetic mechanism, especially 5hmC profiles involved in globozoospermia progression, remains largely unknown. Here, utilizing the chemical labelin...

The fate of mosquito sperm in the female reproductive tract has been addressed sporadically and incompletely, resulting in significant gaps in our understanding of sperm-female interactions that ultimately lead to fertilization. As with other Diptera, mosquito sperm have a complex journey to their ultimate destination, the egg. After copulation, sperm spend a short time at the site of inseminat...

BACKGROUND A key role of estrogens in human sperm biology has been recently suggested by aromatase and estrogen receptor detection in human testicular germ cells and ejaculated spermatozoa. However, the involvement of these hormones in the sperm maturation process is still not defined. The aim of this work was to investigate the expression of estrogen receptors, ER-alpha and ER-beta, in human e...

The mouse is an established and popular animal model for studying reproductive biology. Epididymal mouse sperm, which lack exposure to secretions of male accessory glands and do not precisely represent ejaculated sperm for the study of sperm functions, have been almost exclusively used in studies. We compared ejaculated and epididymal sperm in an in vitro fertilization setting to examine whethe...

Observations on the sperm biology of Bunnei (Barbus sharpeyi), after hormone injection perm activity for injected fish ranged between 85 % - 100 %. The most amazing finding was collected semen from deceased one hour 90 %, and it has highest time(120 sec.), this time higher than that Al-Therthar reservoir during spawning season. volume very low (1- 0.4 ml). which is a characteristic species. con...