a, Experimental model. Wild-type C57BL/Ka recipients either were pre-conditioned 1 day before transplant by injection of Cy/Bu or by total body irradiation (0.5 Gy), or were left untreated. Mice from each treatment group then received by intravenous injection 4 × 107 GFP-transgenic bone marrow cells or wild-type (GFP-) bone marrow cells, or received no cells as a control. Two months later, animals were euthanized for chimaerism analysis of haematopoietic cells and oocytes. b, Representative brightfield (left) and epifluorescence (right) images of oocytes collected from GFP-transgenic controls. Total numbers of GFP+ oocytes per total oocytes examined are summarized on the epifluorescence panel; all oocytes collected from GFP-transgenic animals were GFP+. c, Representative brightfield (left) and epifluorescence (right) images of oocytes collected from non-transgenic animals 2 months after transplantation of GFP- or GFP+ bone marrow cells. Recipients were untreated before transplant or pre-treated one day previously with Cy/Bu. Total numbers of GFP+ oocytes per total oocytes examined are summarized on the epifluorescence panels for each group (n = 2–6). No GFP+ oocytes were detected in either untreated or Cy/Bu-treated mice receiving GFP- or GFP+ bone marrow cells. d, Chimaerism (average ± s.d.) of peripheral blood cells in control mice receiving no cells, or in transplanted mice receiving GFP+ bone marrow cells or wild-type (GFP-) bone marrow cells. Animals were untreated or pre-conditioned by low-dose total body irradiation (0.5 Gy) or intraperitoneal injection of Cy/Bu 1 day before transplantation. Analysis of control GFP-transgenic blood cells demonstrates expression of GFP by 98–100% of circulating leukocytes. e, Effects of bone marrow transplant on ovulation in chemotherapy- or radiation-treated animals. Total numbers (average ± s.d.) of ovulated oocytes retrieved from untreated (n = 4–9) or radiation (0.5 Gy, n = 2–4) or chemotherapy (Cy/Bu, n = 3–7) pre-treated animals that either received no cells (n = 2–9) or bone marrow cells (n = 4–7) from GFP-transgenic or non-transgenic donors 1 day after treatment are shown. All control GFP-transgenic and untreated animals ovulated, whereas no irradiated animals ovulated. A subset of animals pre-treated with Cy/Bu ovulated (1 out of 3 receiving no cells and 3 out of 7 receiving bone marrow cell transplant). Differences were significant (P < 0.05) in comparisons of untreated versus 0.5 Gy- or Cy/Bu-treated groups, but differences in Cy/Bu-treated animals that did (bone marrow cell transplant) or did not (no cells) receive transplants were not significant (P > 0.05).