How does a ginkgo female gametophyte develop inside an ovule?

In the ginkgophyte division, the development of the female gametophyte occurs entirely within the ovule of the parent sporophyte. The process follows these stages:12

• Megaspore Formation: Within the megasporangium, a single cell undergoes meiotic division to produce four haploid megaspores. Typically, one of these megaspores becomes functional and begins to enlarge.32
• Free Nuclear Division: The functional megaspore undergoes a series of free nuclear divisions—where the nucleus divides repeatedly without the formation of cell walls—eventually producing approximately 8,000 haploid nuclei.12
• Cellularization: Once the nuclei have multiplied, cell walls begin to form at the periphery and extend inward until the entire gametophyte becomes cellular.12
• Archegonia Initiation: After the tissue is cellular, usually two archegonia are initiated at the surface of the gametophyte toward the micropylar end. Each archegonium consists of neck cells and a large egg cell, which is then ready for fertilization by the ginkgo's unique, multiflagellated sperm.32