Andrology

Biologically speaking, human development begins after the joining of a sperm and an egg. Around 100 years ago, the German biologist Theodor Boveri brilliantly summarised the unique contributions of each gamete, stating: “The ripe egg possesses all of the elements necessary for development save an active division-center. The sperm, on the other hand, possesses such a center, but lacks the protoplasmic substratum in which to operate. In this respect the egg and the sperm are complementary structures; their union in syngamy thus restores…

The ability of sperm to pass through both the uterus and the Fallopian tube and fertilise an egg depends on sperm motility and progression. The flagellum confers motility on the sperm but, sometimes, spermatozoa present an abnormal axoneme ultrastructure and so they cannot swim (asthenozoospermia). The axoneme, the “scaffolding” of the flagellum, is composed of 9+2 microtubules pairs and provided with dynein arms, which conforms the major motor protein and provides flagella with movement. Certain autosomal recessive genetic disorders affect the structure (hence function) of specific motor proteins and, therefore, they result in the impaired action of cilia and flagella.Kartagener syndrome (KS) is caused by different mutations in various genes that encode proteins necessary for ciliary structure and function. Not only these patients suffer from respiratory tract diseases, but also their sperm exhibit an abnormal structure of the axoneme that makes it impossible for the flagellum to beat. Consequently, these patients areinfertile.Motility in a sperm sample is one of the markers for viability

Figure 1. Schematic representation depicting one of the possibilities of Klinefelter syndrome development during meiosis in the mammalian testis. Modified from (1). The common sex chromosome dosage in mammals is XX for females and XY for males. This implies that under normal circumstances each one of the X chromosomes in XX females comes from one of the parents, whereas in XY males the only X chromosome is always maternal, because the Y chromosome always comes from the father. Even though both X chromosomes in an XX…