Figure 1. A schematic drawing illustrating the functional relationship between the apical and basal ES in the seminiferous epithelium of adult rat testes.

As noted herein, the ES is supported by conspicuous actin filament bundles, either at the Sertoli-spermatid interface (step 1–8 spermatids in the rodent testis) or at the Sertoli cell-cell interface, known as the apical or the basal ES, respectively. The basal ES, which together with the TJ constitute the blood-testis barrier (BTB), which divides the epithelium into the apical (adluminal) and the basal compartments. The relative distribution of the Par-, the Scribble, and the Crb3-based polarity protein complexes and their corresponding partner proteins that confer the apico-basal polarity of individual spermatids in the seminiferous epithelium to support spermatogenesis are shown. Besides these polarity proteins, PCP proteins, such as Vangl2, are also present to support the alignment of polarized spermatids across the plane of the seminiferous epithelium, conferring PCP to the developing spermatids in the testis. Studies discussed in the text have shown that there are cross-talks between apical and basal ES, but more importantly that are also cross-talks between apical and basal ES through the action of Vangl2 but also NC1 domain peptide as noted in recent reports discussed in text. In short, both NC1 domain peptide generated from collagen α3 (IV) chain, a structural component of the basement membrane, and/or Vangl2 expressed by Sertoli and/or germ cells can modulate the actin- and/or MT-based cytoskeletons, thereby modulating the apical and/or basal ES function, modulating spermatid apico-basal and/or PCP polarity.