germinal

1. Of, relating to, or having the nature of a germ cell.
2. Of, relating to, or occurring in the earliest stage of development: was active in the germinal stages of the space program.

[French, from Latin germen, germin-, sprout,bud.]

1. Of, relating to, or having the nature of a germ cell.
2. Of, relating to, or occurring in the earliest stage of development of an embryo or organism.

Pertaining to or of the nature of a germ cell or the primitive stage of development.

• g. crescent — the region of development of primary germ cells in the avian embryo.
• g. inclusion cyst — see ovarian serous inclusion cyst.

The adjective has one meaning:

Meaning #1: containing seeds of later development
  Synonyms: originative, seminal