Barrière hématotesticulaire (blood–testis barrier) et variations de perméabilité du compartiment gonial dans le follicule testiculaire de Locusta migratoria implanté en milieu dépourvu d'ecdystéroïdes

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Abstract
In Locusta migratoria, the testicular follicle is made on an apical compartment that contains the youngest germ cells and a basal one in which the spermatids differentiate. As soon as it is formed during the fourth larval stage, the latter compartment becomes impervious to exogenous macromolecules. This permeability barrier, which corresponds to the blood–testis barrier defined in mammals, depends on extensive septate junctions. In this paper, testicular follicles were cultured in vivo in adult males known to be free of hemolymphatic ecdysteroids. The permeability of the apical compartment to horseradish peroxidase, used as a tracer, varied as a function of implantation time. This apical compartment became impermeable as soon as the basal compartment cells were postmeiotic. Once implanted into an adult host, a follicle that contained only gonia completed normal spermatogenesis and established a blood–testis barrier, providing a tight compartment in which meiotic processes occurred. Septate junctions developed normally. These results show that ecdysterone controls neither the differentiation of septate junctions nor the establishment of the blood–testis barrier, which appear both to be conditioned by the initiation of meiosis.