Primordial germ cells (PGCs) have been studied since the 19th century with a few different methods.

Primordial germ cells (PGCs) have been studied since the 19th century with a few different methods. 

The early works are based on morphological criteria for these cells associated or not with a specific staining.  subcellular fractionation protocol Different markers have been proposed in the immunohistochemistry of which we can cite the stage-specific embryonic antigene-1 (SSEA-1), mouse embryonic antigen-1 (EMA-1) or a heat shock protein 90. Unfortunately, none of them are specific germline .

The Vasa protein is considered as one of the most reliable marker for PGCs by several authors with expressions that are considered restricted to germ cells. However, other studies have reported expression in somatic cells. Here, we describe the expression of heat shock protein, Hsp90, and Vasa protein in early chicken embryos.

Embryos from stage Hamburger-Hamilton (HH) 19, 21 and 28 were collected. Embryos dissected and fixed in this Serra media. The part is placed on a slide for PAS staining and immunohistochemical double with Hsp90 and Hsp90 VASA.VASA and expression has been observed in germ cells but also in other cell lineages with spatio-temporal gradient with respect to the developmental characteristics of each organ. The conclusion is that the Vasa expression is not limited to the germ line in the chicken embryo.