Connecting the Male and Female Pathways

MALE PATHWAY                           FEMALE PATHWAY
PMC (2n)                               MMC (2n)
    ↓ meiosis                              ↓ meiosis
Microspore tetrad (n)                  4 megaspores (n)
    ↓ 1 microspore develops                ↓ 3 degenerate; 1 functional
Pollen grain (2-celled)                Functional megaspore (n)
  - Vegetative cell (tube nucleus)         ↓ 3 free nuclear mitoses
  - Generative cell (n)                8 nuclei → 7-celled embryo sac
    ↓ generative cell divides
2 sperm cells (n each)

MEETING POINT: Double Fertilization
  Sperm 1 + Egg (n + n) → Zygote (2n) [syngamy]
  Sperm 2 + 2 Polar nuclei (n + n + n) → PEN (3n) [triple fusion]

OUTCOME:
  Zygote (2n) → mitosis → Embryo (2n)
  PEN (3n) → mitosis → Endosperm (3n)
  Integuments (2n) → Seed coat
  Ovary wall (2n) → Pericarp (fruit)
  → Complete Seed inside Fruit

Key Connection Points

• Both pathways use MEIOSIS to produce haploid cells
• Both pathways use MITOSIS after meiosis for gametophyte development
• The male pathway contributes 2 sperm (from 1 pollen grain)
• The female pathway contributes 1 egg + 2 polar nuclei (from 1 embryo sac)
• Together: 2 fusions → 1 embryo (2n) + 1 endosperm (3n)