The spermatozoon is a highly specialized cell that is formed through a
complex cellular program of differentiation during spermatogenesis. It has a unique
structure and chromatin that reflects its vital function. Morphologically it comprises a
head, a midpiece and a tail. The sperm DNA is confined to the nucleus of the head and
it has a characteristic protamine-based chromatin that makes it the most condensed
eukaryotic DNA. This super compaction of sperm chromatin enhances the protection of
DNA from damage since this cell type do not possess robust repair mechanisms. The
midpiece is considered the “source of power” of spermatozoa, since it contains many
mitochondria, which are responsible for the energy production required for motility.
The tail, also known as flagellum, is crucial for spermatozoa movement and transit
until they reach the female gamete. The morphological integrity of spermatozoa is of
extreme importance for their responsiveness to testicular and epididymal factors
involved in maturation. One of the main features that spermatozoa acquire during the
maturational process is their motility capacity. This characteristic is not only dependent
on the communication of spermatozoa with their surroundings, but also on sperm
intrinsic factors, such as adenosine triphosphate (ATP) and specific membrane and
secretory proteins. In recent years, sperm epigenome has been a matter of debate
among researchers. Its importance is related to its impact on the embryo fate and
offspring development. This chapter will discuss the significance of spermatozoa
exclusive structure and function for human reproduction and the preservation of
generations.
Keywords: Activated motility, Assisted Reproductive Technologies, DNA
damage, Epigenetics, Fertilization, Histone, Hyperactivated motility, Protamine,
Offspring, Sperm Chromatin, Sperm DNA, Spermatozoa morphology.
