Histological and ultrastructural characterization of developing miniature pig salivary glands

Salivary glands are a classic model of organ development and differentiation. Miniature pigs are considered as a unique animal model for salivary gland researchers in the fields of gene transfer, radiation damage, and functional reconstruction. However, there is little information about the development of miniature pig salivary glands. The present article was designed to study the developmental stages of salivary glands in miniature pigs using histological and ultrastructural methods. Sections from E40, E60, E80, E95 embryos, and P0 pups were stained with hematoxylin-eosin, Alcian blue, or periodic acid-schiff. Selected specimens were also processed for electron microscopy. The development of the miniature pig salivary glands can be divided into five different stages that refer to the stages of the developing mouse submandibular gland. The histological characteristics of the miniature pig salivary glands at different developmental stages were synchronously verified at the ultrastructural level. Interestingly, the development of the miniature pig parotid gland trailed that of the submandibular gland by approximately 15 days. Our study provides first-hand data regarding the morphological organogenesis of salivary glands in the miniature pig and provides a foundation for further research on this model.