Production of sperm and androgens is the main function of the testis. This depends on
normal development of both testicular somatic cells and germ cells. A genetic program …

Over the past four decades, studies of various designs have reported spatial and temporal
trends in human semen quality. Several standardized-methodology studies in …

Although semen quality is an important determinant of fertility, defining clear thresholds for
normal ranges has proven difficult. According to'time to pregnancy'studies, fecundity starts to …

Background Since the 1970s, several studies found that sperm concentration (SC) and total
sperm count (TSC) constantly worsened over time, mainly in high‐income countries …

Background Sperm counts have been steadily decreasing over the past five decades with
regional differences in the Western world. The reasons behind these trends are complex, but …

The prevalence of low semen quality and the incidence of testicular cancer have been
steadily increasing over the past decades in different parts of the World. Although these …

Purpose Many studies have reported declines in semen quality mainly focused on total
sperm counts (TSC) and sperm concentration (SC), ignoring the importance of progressive …

STUDY QUESTION How does age affect various semen parameters? SUMMARY ANSWER
For most semen parameters, the nomogram of the entire population was biphasic, peaking …

Sperm motility and quality decline with stallion age and sperm preservation, but the
mechanisms of functional deficit have not been explained. We tested the hypothesis that …

Objective Gonadotropins (luteinizing hormone (LH) and follicle-stimulating hormone (FSH))
are released from the pituitary gland and stimulate Leydig cells to produce testosterone and …