CIE A Level Biology复习笔记9.1.3 Recognising Tissues

Cartilage

Cartilage micrograph

Cartilage – electron micrograph

• The cartilage in the trachea has a ‘glassy’ appearance due to its translucent protoplasm
• It contains no nerves or blood vessels

Ciliated epithelium

Ciliated epithelium – photomicrograph

Ciliated epithelium – electron micrograph

• Ciliated epithelial cells are distinctive due to their narrow cell bodies and hair-like cilia located along the apical layer
• The cilia are tiny projections which greatly increase the surface area of the cell

Goblet cells

Goblet cell – light micrograph

Goblet cells – electron micrograph

• Goblet cells can be found scattered among the ciliated epithelium of the trachea and bronchi
• They are distinctive in the epithelium due to their lack of cilia (although they still have some microvilli projecting outwards)
• The nucleus is found towards the basal (bottom) layer of the cell, with a large Golgi apparatus and mucus granules found towards the apical layer

Squamous epithelium

Squamous epithelium – light micrograph

Squamous epithelium – electron micrograph

• Squamous epithelium is made of thin, flat squamous cells

Smooth muscle

Smooth muscle – light micrograph

Smooth muscle – electron micrograph

• The cells of smooth muscle are tightly packed and are found beneath the ciliated epithelium
• Unlike skeletal muscles, they are not striated and so don’t show any cross stripes under a microscope

Capillaries

Capillary – photomicrograph

Capillary – electron micrograph

• Capillaries are distinctive from other blood cells due to their tiny diameter (~4 μm)
• Their walls consist of a single layer of epithelial cells