Figure 1.

Loblolly pine zygotic (A) and somatic (B) embryos from the nine developmental stages. The earliest two to three stages of somatic embryos typically are grown in liquid suspension culture (LSC) maintenance medium (C); stages 3 through 9 are on gelled, semi-solid maturation medium. D, Tissue in liquid cultures is characterized by dense embryo proper-like cell clusters (red arrows) surrounded by abundant, vacuolated suspensor-like cells (white arrows). E, Stage 7 zygotic embryo being dissected from megagametophyte (arrows: 1, embryo; 2, suspensor; and 3, megagametophyte).