1. Find
fragments of submandibular and sublingual salivary glands:
submandibular salivary gland is a complex alveolar-tubular branching organ; contains two types of terminal portions (acini): protein type (prevailing) and mixed type;
sublingual salivary gland is a complex alveolar-tubular branching organ; contains a predominantly mucous type of secretion – mucous secretory portions;
common opening with the excretory duct of the submandibular gland is located outside the glands and is lined with columnar/cylindrical epithelium.
2. Study the structure of the secretory portions and excretory ducts:
protein acini (submandibular salivary gland) are formed by serous cells, small cone-shaped cells with weakly basophilic cytoplasm and a round nucleus placed in the center;
mixed acini (submandibular salivary gland) and serous cells contain numerous mucous cells – large-sized mucous cells with clear cytoplasm which has the features of a cellular structure and a flattened nucleus in the basal part;
mixed acini contain serous cells that are located peripherally on the surface of acini where protein cells form groups shaped like crescents;
mucous acini (sublingual salivary gland) are made from mucous cells;
myoepitheliocytes - are flattened cells lying between the basal membrane and serous cells on the external surface of the acini;
in the layers within the interlobular fibrous connective tissue there are narrower intercalated ducts (lined with low cuboid or squamous epithelial cells) and wider intralobular (striated ) ducts (lined with cuboid epithelial cells characterized by basal striation).
3. Draw and sign:
I - submandibular salivary gland [1 – serous/protein type acini (serous cells); 2 – mixed secretory type (а - mucous cells, б - protein groups shaped like crescents/ serous cells), 3 – the nucleus of a myoepitheliocyte, 4 - intralobular (striated) duct, 5 – interlobular fibrous connective tissue];