Histology of Eye, Ear, Endocrine, and Parathyroid Structures

Cornea

Avascular (no blood vessels); smooth stratified squamous; provides most refraction (~⅔).

Retina Cell Layers

Ganglion → Bipolar → Photoreceptors (photoreceptors are at the back).

Müller Cells

Retinal cells that act like fiber-optic cables to transmit light.

Olfactory Epithelium

Lined by pseudostratified columnar epithelium (not stratified cuboidal).

Organ of Corti

Identified histologically by V-shaped hair cells beneath the tectorial membrane.

Thyroid Gland Histology

Hallmark is colloid-filled follicles (pink lakes).

Parathyroid Histology

Distinct for dense purple chief cells; lacks follicles.

Adrenal Cortex Zones

Three zones in order: Zona glomerulosa = balls, Fasciculata = columns, Reticularis = mesh (Salt → Sugar → Sex).

Anterior vs Posterior Pituitary

Anterior = pink and cellular; Posterior = lighter with axons.

Endocrine Pancreas Tissue

Recognized by pale round islets (endocrine) within darker exocrine tissue.