What structure is formed when the oral epithelium fuses with the reduced enamel epithelium?

The fusion of the oral epithelium with the reduced enamel epithelium leads to the formation of the junctional enamel epithelium. This structure plays a crucial role in the development of the tooth's attachment to the gingival tissue. The junctional enamel epithelium serves as the interface between the tooth and the surrounding periodontal tissues, primarily helping to secure the tooth in place and maintain the health of the gingiva.

The junctional enamel epithelium also contributes to the formation of the epithelial attachment that anchors the gingiva to the tooth surface. This attachment is essential for periodontal health, as it helps prevent bacterial invasion and supports the stability of the tooth within the alveolar bone.

The other options represent different structures that have distinct roles in dental anatomy and health. The acquired enamel cuticle, for example, forms after tooth eruption and helps protect the enamel surface. The secondary enamel cuticle is related to the processes occurring after enamel maturation, and cementum is the hard tissue that covers the roots of teeth but does not result from the fusion of these two epithelial layers.