Tunica A. helps in the maintenance of the interstitial pressure inside the testis. It is reasonable to assume that the observed differences in contractility reflect a function of the tunica. Contractions at regions distant from the rete testis, which are not spontaneous and which might be triggered in vivo by neuronal input, could play a role in maintaining the interstitial pressure inside the testis and in controlling the flow of blood through the testis because the diameter of blood vessels between the inner and outer zone of the tunica should be affected dramatically by contractions.

The tunica albuginea (the membrane surrounding the corpora cavernosa), helps to trap the blood in the corpora cavernosa, sustaining the erection and thus helps in ejaculation (part of spermatogenesis).