Final answer:
Mucous cells predominantly make up the sublingual gland, secreting a thick saliva with minimal salivary amylase into the oral cavity via the lesser sublingual ducts.
Step-by-step explanation:
The cells that make up the sublingual gland are predominantly mucous cells. These mucous cells in the sublingual glands are responsible for secreting a thick and viscous type of saliva that contains the least amount of salivary amylase in comparison with the saliva produced by other major salivary glands such as the parotid and submandibular glands. The sublingual glands utilize the lesser sublingual ducts to discharge their saliva directly into the oral cavity.