Co-localisation of OCT4 and DAZL. In 1st trimester ovaries (a, 61 d) and testes (b, 64 d) OCT4 (green) and DAZL (red) were co-localised to germ cell nuclei. In ovaries from the 2nd trimester (c, 14 wk) DAZL protein was almost exclusively cytoplasmic and was largely localised to OCT4 negative groups of cells (arrow); a few OCT4 positive cells had a low level of DAZL immunoexpression in their cytoplasm (arrowheads). Testes, panel b, 64 d; panel d, 16 wk; panel e, 19 wk gestation. In 2nd trimester testes (d, 16 wk; e, 19 wk) DAZL was still expressed in the nuclei of some OCT4 positive germ cells but this pattern of expression was variable with DAZL protein present in the cytoplasm of OCT4 positive and OCT4 negative (arrow panel e) cells.