Histology Slide Identification Lecture

Overview

• Objective: Identify and differentiate histological tissues.
• Format: Series of questions; side-by-side comparisons and individual tissue identification.
• Resources: Timestamps for navigation, related playlists, videos, and upcoming handouts or mini-courses.

Epithelium Identification

Simple Epithelium

• Simple Cuboidal: Single sheet of square-shaped cells lining open spaces.
• Simple Squamous: Single layer of flat cells; flat nuclei.
• Simple Columnar: Single row of tall, rectangular-shaped cells; may have cilia (rare).
• Ciliated Pseudostratified Columnar: Appears multilayered due to nuclei at different heights, but all cells touch the basement membrane; presence of cilia.

Stratified Epithelium

• Stratified Cuboidal: Multiple layers; cuboidal cells.
• Stratified Squamous: Multiple layers of squamous cells; upper layers may be keratinized (flaky top).
• Transitional Epithelium: Bubbly top layer, adjustable shape; not cuboidal or squamous.

Connective Tissue Identification

Dense Connective Tissue

• Dense Regular: Collagen fibers in one direction; fibroblasts in between.
• Dense Irregular: Collagen fibers in multiple directions; looks like "hamburger meat."

Loose Connective Tissue

• Areolar: Mix of thin elastic and thicker collagen fibers; fibroblasts present.
• Reticular: Net-like appearance with reticular fibers.
• Adipose: Thin-walled bubbles (adipocytes).

Specialized Connective Tissue

• Cartilage
  • Fibrocartilage: Wavy fibers resembling ramen noodles.
  • Elastic Cartilage: Presence of elastic fibers.
  • Hyaline Cartilage: Smooth, glassy appearance between lacunae.
• Bone
  • Spongy Bone: Non-compact structure.
  • Compact Bone: Osteons as structural units; lacunae contain osteocytes.

Muscle Tissue Identification

• Skeletal Muscle: Striations with nuclei at the edge.
• Cardiac Muscle: Striations with intercalated discs.
• Smooth Muscle: No striations, nuclei inside fibers.

Nervous Tissue

• Neurons: Long extensions; glial cells present as support.

Common Confusions and Tips

• Smooth Muscle vs. Dense Regular Connective Tissue: Smooth muscle has nuclei inside fibers; dense regular connective has fibroblasts between fibers.
• Simple Squamous vs. Adipose: Simple squamous has cells forming circles; adipose is single stretched-out cells.
• Transitional Epithelium: Varies in appearance; use bubbly top and comparison tactics to identify.

Recommendations

• Use playlists and practice videos for repetitive identification.
• Compare tissues side by side to understand differences.