Panspermia, an idea that is still a favourite for some astronomers, means

Panspermia is the hypothesis or idea that life exists throughout the universe and can be distributed from one planet to another through the transfer of spores, seeds, or microorganisms. According to this concept, life on Earth could have originated from microorganisms or spores that arrived on our planet through space, possibly via comets, meteorites, or other means of interplanetary transport. 
(1) Creation of life from dead and decaying matter is the concept of abiogenesis, which suggests that life can arise from non-living matter under specific conditions.
(2) Creation of life from chemicals relates to abiogenesis, the idea that life can arise from simple organic molecules and chemical reactions.
(3) The process of sperm production in the human body is termed spermatogenesis and is not related to
The concept of panspermia.