Endocrine Histology

For embyrological Origins please see anatomy ntbk

Thyroid

• Secretes 3 Hormones
• Secretory glands arranged around periphery of follicles, secrete Thyroid hormones. Simple cuboidal epithelial. Darker Staining.
• Parafollicular(C-cells) cells interspersed around follicles, secrete Calcitonin. Pale staining cytoplasm.
• Follicles store secretions as Thyroglobulin (Colloid)
• Active tissue = smaller follicles & tall cuboidal/columnar cells
• Less Active = larger follicle & smaller cuboidal.
• Collagenous septa run between follicles; Vasculature, Lymphatics and Innervation
• Images

Parathyroid

• Chief cell - arranged in clusters/cords, pale staining cytoplasm, secrete Parathormone. Small cells, Round, central nuclei. Darker stained cytoplasm = active.
• PTH Increases blood Ca2+ concentration.
  • Promotes Osteoclastic resorption(decalcification)
  • Stimulates kidney to reabsorb Ca2+ from tubules
  • Stimulates intestinal absorption Ca2+ indirectly - activates 1-alphahydroxylase kidney → 1,25dihydroxyvitD synthesis
• Oxyphil cell - No secretion, pale staining cytoplasm with numerous mitochondria.
• Rich capillary network
• Images

Adrenal(Suprarenal)

• Capsule, Cortex and Medulla
• Cortex divided into 3: