Abstract: The fertilization was processed by sperm in mature male gametophyte combining with egg cell on the top of archegonia on June 15 or so. Then fertilized egg made division of free nuclei and cell wall was began to form while 8 daughter nucleus forming. When they were divided again, proembryo containing 16 cells was formed. In succession, cell layer of suspensor rapidly grew, elongated and down proembryo was carried away cell wall of archegonial base, then get into corrosion cavity in endosperm. Proembryo absorbed nutrition in corrosion cavity and grew, developed. In the first stage, the number of embryoes were very much, but only one developed to mature as usual.

Key words: Pinus sylvestris var. mongolica, fertilization, embryo, endosperm, development