Table 1.

Cellular and molecular similarities between human brain and testis.

brain	testis
biochemical/physical support cells: astrocytes	biochemical/physical support cells: Sertoli cells
high energy demands
metabolic cooperation: astrocytes produce lactate, which is used by neurons	metabolic cooperation: Sertoli cells produce lactate, which is used by germ cells
dependence on selenium metabolism
high concentrations of polyunsaturated fatty acids
highly susceptibility to oxidative damage
blood–brain barrier	blood–testis barrier
neuroendocrine proprieties
cytoskeleton motors (kinesins and dyneins): essential role in neuronal function	cytoskeleton motors (kinesins and dyneins): essential role in spermatogenesis