Fig. 3. Transplantation of seminiferous tubule segments under testis capsules of XX/Sry and XY W/W^v males. (A-K) Segments of immature XY seminiferous tubules (2-3 weeks old, wild type) were transplanted under the testis capsules of recipient XX/Sry (A,C) and XY W/W^v (B,D) males. Tubule segments of the primary-recipient XX/Sry testes with EGFP-positive XY spermatogenic colonies (2.5 months after spermatogonial transplantation using Green mice as donors; E,F) were further transplanted under the testis capsules of the secondary XY W/W^v recipients (G-K). All grafts were then histologically examined at 4 weeks after transplantation. (A,B) PAS staining showing elongated spermatids inside transplanted XY seminiferous tubules (arrows) of both recipient testes. (C,D) Immunohistochemical staining with anti-HSC70T antibody visualizing normal elongated spermatids of donor seminiferous tubules transplanted in XX/Sry testes. Insets show higher-magnification images of the donor seminiferous tubules. (E,F) Fluorescent micrographs showing a primary XX/Sry recipient testis (E) and two isolated tubule segments (F) with EGFP-positive XY spermatogenic colonies. (G-K) Anti-HSC70T and anti-EGFP immunohistochemical staining (two serial sections in G,H; K) and PAS staining (I,J) showing the absence of normal elongated spermatids (broken arrow in G; H), and the presence of pyknotic (arrowhead in I,K; J) and abnormally large (arrow in I,K) spermatids of XY spermatogenic colonies inside the donor XX/Sry seminiferous tubules transplanted in the secondary XY W/W^v recipients testes. Scale bars: 50 µm in A-H; 10 µm in I-K.