Histologia das glândulas salivares

Summary

In this detailed lesson, the structure and function of salivary glands are explored, focusing on three major types: parotid, submandibular, and sublingual glands. The parotid is a purely serous gland, while the submandibular and sublingual glands are mixed, with the submandibular being serous-predominant and the sublingual being mucous-predominant. The script delves into the histological features, including cell types, secretion mechanisms, and the roles of duct systems in these glands. Various glandular cells are discussed, highlighting their unique characteristics such as protein production and enzyme synthesis, providing an in-depth understanding of salivary gland anatomy and histology.

Takeaways

• 😀 The human salivary glands are divided into three major pairs: parotid, submandibular, and sublingual.
• 😀 These glands are exocrine, composed of tissue capsules, and have a secretory function via ducts.
• 😀 The parotid gland is 100% serous, meaning it secretes a watery, protein-rich fluid.
• 😀 The submandibular gland is mixed, with a predominant serous secretion.
• 😀 The sublingual gland is also mixed, but it has a predominant mucous secretion.
• 😀 The glands are organized into lobes and lobules, separated by connective tissue septa.
• 😀 In the parotid gland, serous acini are surrounded by duct systems, and cells are characterized by large, round nuclei with pale cytoplasm due to protein synthesis.
• 😀 The mucous secretions in the sublingual gland are less stained in histological slides and have flattened nuclei at the base of the cells.
• 😀 Ducts in the glands vary in size and shape, with smaller ducts observed in the sublingual gland due to its proximity to the oral cavity.
• 😀 In addition to secretory cells, salivary glands may contain blood vessels and lymphocytes, which are part of the immune response in the saliva.

Q & A

What are the three major pairs of salivary glands?

The three major pairs of salivary glands are the parotid, submandibular, and sublingual glands.

What type of glandular secretion does the parotid gland produce?

The parotid gland is 100% serous, producing a secretion primarily composed of fluids and proteins.

What is the basic structural organization of salivary glands?

Salivary glands are exocrine and compound glands, surrounded by a connective tissue capsule with collagen fibers. The capsule divides the gland into lobes and lobules. The secretory portions are made up of acini, and ducts are organized to transport the secretion.

How are the secretory cells of the parotid gland characterized?

The secretory cells of the parotid gland are serous, with a round nucleus and loose chromatin. These cells are pyramidal in shape, and their cytoplasm is darkly stained due to the presence of rough endoplasmic reticulum and ribosomes for protein production.

What is the difference between serous and mucous secretion?

Serous secretion is watery and rich in proteins, whereas mucous secretion is more viscous and primarily composed of mucins, which do not stain well with typical histological dyes, leaving the cells pale.

What distinguishes the submandibular gland's secretion from other glands?

The submandibular gland is a mixed gland with both serous and mucous secretions, but it has a predominance of serous cells.

How is the sublingual gland's structure different from the parotid and submandibular glands?

The sublingual gland is a mixed gland with a predominance of mucous cells. It has fewer septa and is more organized, with clear differentiation between the mucous and serous portions.

What role do myoepithelial cells play in the salivary glands?

Myoepithelial cells are contractile cells located around the acini that help to expel the gland's secretion by contracting and pushing the fluid into the ducts.

How can you differentiate between a duct and a blood vessel in histological slides of salivary glands?

Ducts are lined by cuboidal or columnar epithelium, whereas blood vessels have a flattened, squamous epithelium. Additionally, blood vessels may contain red blood cells (hemocytes), which ducts do not.

What is the function of the septa within the salivary glands?

The septa, formed by invaginations of the connective tissue capsule, divide the gland into lobes and lobules. They also provide structural support and help organize the glandular tissue.