Early in your own development, a subset of diploid cells called began to develop within your pre-ectodermal tissue. These cells will eventually lodge in the gonadal ridge. Still later they will go through meiosis and give rise to primary oocytes or primary spermatocytes.

primary germ cells or  primordial germ cells

Explanation:

During the early stages of embryonic development , primary germ cell or  primordial germ cells develops within the pre-ectodermal tissue. they are  diploid like other somatic cells and found in the primary ectoderm (epiblast) in the second week.

Primary germ cell moves through the gut of an embryo in order to develop gonads. Further they undergo meiosis process followed by cellular differentiation and five rise to mature gametes, either sperms (primary spermatocytes) or eggs (primary oocytes).

Hence, the correct answer is primary germ cells.

i think the answer is

mass

chordata is the answer