**6.1 Activation of motility**

It is broadly acquired that precious motility of sperm is the chief component of fertility of male. During the beginning of progressive motility and origin of hyper activation of sperm, key factors are involved. These key factors are calcium (Ca2+), cyclic adenosine monophosphate (cAMP) and bicarbonate (HCO3 <sup>−</sup>). Olfactory and GABA receptors are the possible candidates which trigger the progressive and hyperactivated motility of sperm.
