What is Glandular Epithelium?
Glandular epithelium is a specialized type of
epithelial tissue responsible for the formation and secretion of substances like enzymes, hormones, and mucus. These cells are organized into structures known as
glands, which can be classified based on their structure and function.
Exocrine Glands
Exocrine glands secrete their products into ducts that open onto a surface. Examples include
sweat glands,
salivary glands, and
sebaceous glands. Exocrine glands can be further classified based on the mode of secretion:
Merocrine Secretion: The product is secreted by exocytosis. Example:
pancreatic glands.
Apocrine Secretion: A portion of the cell membrane buds off with the secretory product. Example:
mammary glands.
Holocrine Secretion: The entire cell disintegrates to release its product. Example:
sebaceous glands.
Structural Classification of Glands
Glands can also be classified based on their structure: Unicellular Glands: Consist of a single cell, such as
goblet cells, which secrete mucus.
Multicellular Glands: Consist of multiple cells and can be further subdivided into simple and compound glands based on the branching of their ducts.
Histological Features of Glandular Epithelium
Glandular epithelium exhibits several key histological features: Cell Shape: Glandular cells can be cuboidal, columnar, or even squamous in shape.
Secretory Granules: These granules contain the substances to be secreted and are often visible under a microscope.
Basal Lamina: Like all epithelial cells, glandular cells rest on a
basal lamina that separates them from underlying tissues.
Functional Aspects
The primary function of glandular epithelium is secretion. This can include the production of enzymes for digestion, hormones for regulation, and mucus for lubrication and protection. The specific function is determined by the type of gland and its location in the body.Clinical Relevance
Understanding glandular epithelium is crucial in the diagnosis and treatment of various diseases. For instance,
adenocarcinoma is a type of cancer originating from glandular epithelium. Additionally, conditions like
hyperthyroidism and
hypothyroidism involve dysfunction of endocrine glands.
