Fig. 1. Spermatogenesis and teratogenesis from fetal germ cells and epiblast cells. (A) Embryos at 6.5 and 8.5 dpc, a mid-part of 10.5 dpc embryo, and a male gonad and mesonephros at 12.5 dpc. Dotted lines demarcate regions used for transplantation. At 10.5 dpc, the urogenital ridges (asterisk) and mesentery with gut (arrow) were dissected separately. (B) A section of a W male testis (control recipient) stained with HE. Spermatogenesis is absent. (C) W mouse testis after transplantation of 8.5 dpc PGCs. Spermatozoa (arrow) are present in the center of the seminiferous tubule. (D) Anti-SCP3 immunostaining (green) of W testis after transplantation of 8.5 dpc PGCs, counterstained with Hoechst 33258 dye (blue). Inset, higher magnification view of the same sample. (E) Transplantation of epiblast cells at 6.5 dpc. Spermatocyte (arrow) and round spermatid (arrow head) were found. Inset shows acrosomes stained with PAS (red) in round spermatids. (F) W mouse testis transplanted with 8.5 dpc PGCs from Green mice embryos. Colonization of the recipient seminiferous tubule by EGFP (+) donor cells (green) was observed (arrow). (G) A section of the same testis as in (F), stained with Rhodamine-PNA (red) for acrosomes and with Hoechst 33258 dye (blue) for nuclei. Spermatogenenic colonies derived from EGFP (+) donor cells are present (arrow). (H) Higher magnification view of (G), showing spermatogonia (arrowhead) residing at the base of the seminiferous tubule, and elongated spermatids (arrow) with acrosomes (red), shedding the EGFP (+) cytoplasm. (I) Teratoma from epiblast cells at 6.5 dpc. Muscle, dermoid cyst and neuronal tissue are observed. (J) Spermatozoa (arrow) clustered around a Sertoli cell, released from a recipient testis of 8.5 dpc PGCs. (K) An offspring developed from an oocyte injected with a sperm derived from 8.5 dpc PGCs. (L) DNA sequences of the Kit gene around the W (left panels) and W^v (right panels) point mutations of an offspring derived from transplantation of 8.5 dpc PGCs (upper panels) and a W/W^v mouse as a control heterozygote (lower panels). Scale bars: 1 mm in F; 10 µm in H; 20 µm in J; 50 µm in others.