How do exocrine glands release their products?
Onto an epithelial surface or through an excretory duct.
How do endocrine glands release their products?
Directly into the blood.
What defines a tubular gland's secretory portion?
It is organized as a tube, which may be simple straight, branched straight, or simple convoluted.
What shape characterizes an acinar gland's functional units?
Spherical units with narrow lumina assembled in grape-like clusters.
What are the three types of endocrine glands?
Trabecular, diffuse, and follicular glands.
Which glands are examples of trabecular, diffuse, and follicular endocrine glands?
Adrenal and anterior pituitary (trabecular), Leydig cells in testis (diffuse), thyroid (follicular).
What are key features of a serous cell's secretion and structure?
It produces protein-rich enzymatic fluid as proenzymes, with abundant rough ER and small apical secretory vesicles.
What does a mucous cell produce that is rich in glycoproteins?
Viscous mucus called mucins.
How does merocrine secretion release its product?
By exocytosis without loss of cellular material.
What is released during apocrine secretion?
An apical cytoplasmic fragment.
What does holocrine secretion release after degeneration?
Whole glandular cells.
What dual functions do amphicrine glands perform?
Both exocrine and endocrine functions.
What does the liver secrete and release into the blood?
Secretes bile and releases glycogen-related products.
Which hormones does the pancreas release along with pancreatic juice?
Insulin and glucagon.
What is a microvillus specialized for in epithelial cells?
Absorption.
How long and wide is a typical microvillus?
About 1 µm long and 0.1 µm in diameter.
What is a stereocilium and how long can it be?
An immobile, branched apical expansion related to microvilli that can reach 80 µm.
What cytoskeletal element is found in stereocilia?
Actin filaments.
What is the function of a cilium on epithelial cells?
To move fluid or particles.
What are the typical dimensions and number of cilia per epithelial cell?
6–10 µm long, 0.2 µm diameter, up to 200 per cell.
What cell shape and layering characterize simple squamous epithelium?
One layer of flattened cells.
Where is simple squamous epithelium typically found?
In vascular endothelium and serous mesothelium.
What is a key nuclear feature of pseudostratified epithelium?
Nuclei at different heights.
What distinguishes all cells in pseudostratified epithelium regarding the basal lamina?
Every cell rests on the basal lamina.
What cell types compose transitional epithelium?
Basal cuboidal, intermediate racket-shaped, and superficial umbrella cells.
What function does transitional epithelium serve in the urinary tract?
Allows stretching during filling.
What are the three major classes of intercellular junctions?
Tight junctions, anchoring junctions, and communicating gap junctions.
Which types of anchoring junctions are included among intercellular junctions?
Zonula and macula adherens.
What is one function of epithelial junctions related to cell cohesion?
They maintain cell cohesion.
How do epithelial junctions affect intercellular permeability?
They control intercellular permeability.
What role do epithelial junctions play in membrane protein distribution?
They prevent membrane proteins from diffusing between specialized membrane domains.
What main components make up the basal lamina?
Type IV collagen, laminin, entactin, fibronectin, and heparan sulfate glycosaminoglycan.
How does the basal lamina function as a molecular sieve?
Its glycosaminoglycan arrangement determines pore size allowing selective permeability.
What substances can pass through the basal lamina in the kidney?
Water, ions, and small organic molecules can pass through.
What are the main steps in paraffin histology preparation?
Fixation, dehydration, clearing with xylene, paraffin infiltration, and oriented inclusion block formation.
What thickness range do microtomy sections have for light microscopy?
2–10 micrometers thick.
What thickness range do ultramicrotomy sections have for electron microscopy?
50–70 nanometers thick.
What are the key features of epithelial tissue organization?
Cohesive, polarized cells in layers on a basal lamina, avascular.
Which functions does epithelial tissue perform?
Absorption, secretion, protection, and lining body surfaces or cavities.
How do glandular epithelia release their synthesized products?
Through a duct, onto an epithelial surface, or directly into blood.
Why are epithelial cells continuously renewed?
Because their life span is only a few hours to days and they are eliminated.
What are the three types of acini?
Serous, mucous, and mixed acini.
Which glands exemplify merocrine, holocrine, and apocrine secretion?
Salivary gland or exocrine pancreas, sebaceous gland, and lactating mammary gland respectively.
What structural components does the ciliary axoneme contain?
Nine microtubule doublets, a central pair, nexine bridges, dynein arms, and radial spokes.
What is the role of basolateral folds in epithelial cells?
They support active transport of water and electrolytes.
Name three functions of epithelial tissue.
Protection, absorption, and metabolic exchange.
Which epithelia line blood vessels, coelomic cavities, and body cavities communicating with the exterior?
Endothelium, mesothelium, and epithelium respectively.
How does the basal lamina support epithelial adhesion?
Through hemidesmosomes and focal contacts anchored to connective tissue.
What happens in bullous pemphigoid related to the basal lamina?
Autoantibodies target basal-lamina components causing skin detachment and blisters.
What is done to a slide after sectioning in histology?
It is stained to increase contrast and mounted with resin under a coverslip.
Which stain is used for nucleic acids in histology?
Hematoxylin.
Which stains color the cytoplasm in histology?
Eosin or erythrosine.
Which stains are used for collagen fibers in histology?
Safran or light green.
What controls epithelial renewal and influences epithelial appearance?
Growth factors control renewal; hormones, activity, or metaplasia change appearance.
What epithelial change can smoking cause in the respiratory tract?
Squamous metaplasia of the respiratory epithelium.
How do uterine and vaginal epithelia change?
They change under the female hormonal cycle.
Test your knowledge with 22 questions on Epithelial Tissues Histology.
1. How does an exocrine gland differ from an endocrine gland in the route used to release its products?
2. Which structural feature identifies a tubular gland?
Review the complete course in the study sheet for Epithelial Tissues Histology.
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