A study that analyzed sperm samples from nearly 43, men from around the world over a few decades found that sperm counts have dropped by more than half over the last 40 years. Although the definitive cause is unknown and additional research is needed to find the cause of the drastic decline in sperm counts , researchers have identified some habits and health conditions that may cause a decrease in sperm production. The Cleveland Clinic notes that 5-alpha-reductase inhibitors used to treat prostate enlargement and hair loss such as finasteride, dutasteride, and propecia, can reduce one's volume of semen and number of sperm within their semen. In some cases, this drop in semen production is temporary or reversible. Selective serotonin reuptake inhibitors SSRIs used to treat depression and anxiety may also harm sperm or prevent it from moving through the reproductive tract. Chemotherapy drugs will inhibit sperm production and other medications such as spironolactone, cimetidine, nifedipine, sulfasalazine, colchicine, and oral ketoconazole can also negatively impact male fertility.
An understanding of the relationship between altered sperm motion and sperm function fertility is important when interpreting the biological significance of toxicant-induced changes in sperm velocity in rodent test species. Previous studies showed that a brief 4-day exposure of male hamsters to the model chemical alpha-chlorohydrin ACH results in significant deficits in epididymal and uterine sperm velocity, which are associated with both a delay and a failure of fertilization in vivo. To characterize this effect in terms of fertility, similarly treated male hamsters were bred to untreated females and pups were counted the day before parturition. Cauda epididymal sperm from the same males were assayed for motion characteristics using computer-assisted sperm analysis CASA , and for fertilizing ability in vitro.
All rights reserved. Listen up, ladies: The deep timbre of a male voice may sound attractive, but low-voiced men actually tend to have lower sperm counts, a new study says. Multiple studies have found that women usually favor masculine features, such as prominent jaws, high muscle mass, and low-pitched voices.
Use the link below to share a full-text version of this article with your friends and colleagues. Learn more. There is increasing recognition that male—male competition can take many forms, but as yet the form is not predictable a priori. Many recent studies have focused attention on how males in disadvantaged mating roles compensate through sperm competition. However, mating systems in which subordinate males are reproductively suppressed, particularly through the stress of social interactions, may limit the ability of males to respond by increasing investment in sperm quality.