Histology of Adipose

Question 1

Describe Adipose Tissues

Answer 1

• multi depot organ with a complex shape
• significantly contributes a body homeostatic regulation

Question 2

What are the 2 main types of depot ?

Answer 2

subcutaneous & visceral

Question 3

Describe Brown Adipose Tissue (BAT)

Answer 3

• main function = thermogenesis
• burns lipids & glucose to generate heat
• requires activation of Uncoupling Protein 1 (UCP1)
• generally multilocular = multiple lipid droplets with centrally placed nuclei
• high content of mito. packed with cristae within cytoplasm

Question 4

How is BAT innervated ?

Answer 4

• innervated by noradrenergic fibres from the SNS where the noradrenergic fibres directly interface with the plasma membrane of brown adipocytes via incindental synapses

Question 5

When does the developement of BAT begin?

Answer 5

starts in 20th week of gestation & continues until shortly after birth

Question 6

Describe the vascular supply to the BAT

Answer 6

• rich vascualr tree dense with multiple capillaries

Question 7

Describe White Adipose Tissue (WAT)

Answer 7

• utilises TAGs to act as long term fuel source
• thermal insulator
• helps protect other organs from mechanical damage
• can be considered an endocrine organ

Question 8

Describe the Endocrine function of WAT

Answer 8

• major organ responsible for release of FAs
• other lipid moieties secreted include; cholesterol, retinol prostanoids & steroid hormones
• enzymes such as lipoprotein lipase are also secreted
• heterogenous

Question 9

Describe Adipokines

Answer 9

• part of the secretome of WAT includes a number of released proteins that are classed as adipokines
• cannot be described as being secreted by WAT

Question 10

What characterises a protein as a adipokine ?

Answer 10

• expressed at the mRNA level
• has to be secreted by white adipocytes

Question 11

Describe the morphology of white adipose tissue

Answer 11

• spherical with a diameter that can vary between 30-70 um depending on the depot site
• cytoplasm & nucleus are compressed into a thin visible rim
• lipids are usually organised into 1 unilocular droplet

Question 12

Describe Beige Adipocytes

Answer 12

• WAT can undergo a process known as ‘browning’
• multilocular lipid droplets
• phenotypic plasticity
• develop in WAT