Mechanisms of Development of Sperm Defects.

The intention of this chapter is to provide insights on the possible causes and disruptive mechanisms in play of some commonly occurring bull sperm abnormalities. Consideration is given to mutations of genes, inhibition of enzymes, deficiencies of trace elements, toxins, simulated stress, hormonal changes, hypoosmolarity and cold shock that cause similar disruptive phenotypes in development and structure seen in commonly occurring bull sperm abnormalities. The possible causes and disruptive mechanisms of the following bull sperm defects, arising from the above research, are evaluated: Tail stump, Decapitations, Dag, Dag-like, Short tail, Pseudodoplet, Segmental aplasia of the mitochondrial sheath, Coiled tails, Knobbed and Nuclear vacuolation. In addition, the idea arising from murid research, that mutations affecting sperm head shape most always affect motility, while mutations affecting sperm tail formation rarely affect sperm head shape is considered. Examples of mutations in genes or inhibition of enzymes involved with the early stages of acrosome formation are given that lead to a variety of 'globozoospermic-like' sperm head phenotypes all of which are associated with various degrees of aberrant sperm tail morphologies.