Morphology and cytology of pea embryos during histogenesis

Cytological examination showed that day 3 pea embryo cells were undifferentiated in terms of morphological or gross cytological appearance. Histogenesis had commenced by day 4 and was accompanied by cytological differentiation with a gradient in vacuolation apparent along the root/shoot axis. Day 3 embryonic cells were cytologically different from meristematic (day 4 and 5) cells of the shoot apex. Cells of the embryo base appeared to have an intimate association with the middle suspensor cells.