The document discusses unilocular adipose tissue, which is made up of adipocytes containing a single large fat droplet. It is predominantly found in adult humans. Unilocular adipocytes are generally large, spherical cells that have a thin rim of cytoplasm surrounding a large lipid mass. White adipose tissue has important functions such as storing lipids, insulating the body, cushioning organs, and secreting hormones like leptin that regulate appetite and metabolism. The tissue develops from mesenchymal stem cells that differentiate into early and midstage multilocular lipoblasts before maturing into unilocular adipocytes.

1. The white adipose tissue
Unilocular adipose tissue

2. Unilocular adipose tissue
 Made up of unilocular adipose cells
 Unilocular adipose cells have one
large fat droplet in cell
 Predominantly in adult humans

3. Unilocular adipose tissue

4. Anatomy of Unilocular
Adipocytes
 Generally large cells 50-150μm
 Spherical when isolated,
polyhedral/oval in situ
 Large owing to lipid accumulation in
cell
 Flattened nucleus displaced to one
end of lipid mass
 Thin rim cytoplasm around lipid mass
 External lamina made of type IV
collagen

5. Anatomy of white adipose
tissue
 Grossly viewed as white/ yellowish
mass.
 Tissue has a rich blood supply
 Capillaries found where adjacent
adipocytes meet
 Numerous mast cells present
 Unmyelinated nerve cells present

6. FUNCTIONS OF WHITE
ADIPOSE TISSUE
SYNTHESIS, STORAGE AND
MOBILISATION OF LIPIDS
INSULATION
CUSHIONING OF VITALS
SECRETION OF HORMONES

7. 1. SYNTHESIS, STORAGE &
MOBILISATION OF LIPIDS
 Triglycerides are synthesised from
dietary fats.
 Dietary fats ~ VLDL, chlyomicrons,
free fatty acids, glycerol
 Chlyomicrons intestinal epithelial cells
product of digestion
 VLDL complexes of lipids and proteins
 Adipocytes secrete lipoprotein lipase
to hydrolyse VLDL & chlyomicrons

8. SYNTHESIS, STORAGE &
MOBILISATION OF LIPIDS
(contd) Free fatty acids absorbed into adipocytes
 Resynthesis into triglycerides
 Fusion with glycerol phosphate
triglyceride
 Triglyceride deposition into growing lipid
droplet
o Role of insulin;
 Stimulates uptake of glucose
 Increased synthesis of lipoprotein lipase
 Inhibits hormone sensitive lipase

9. MOBILISATION OF FATTY
ACIDS
 Hormonal or nervous stimulation e.g.
Glucagon; Growth hormone;
Norepinephine
 Activation of hormone sensitive lipase
 Breakdown of triglycerides at surface
of lipid droplet
 Triglyceride FFA glycerol
albumen bound liver bound

10. 2. Insulation
 Panniculus adiposus layer under skin
 Adipose tissue high concentration of
fat thus poor heat conduction
 Helps thermally insulate the body
 Concentration under skin of abdomen,
buttocks and thighs, breasts
 Distribution influenced by age and
gender
sex hormones and adrenocorticoid

11. Insulation image
#distribution of fat

12. 3. Cushion
 Internally cushions vital organs like the
liver, heart, kidneys etc
 The fat acts as a space filler bringing
stability to the organs
 Shield from ever mobile external
environment
 Preferential locations; greater omentum,
mesentry, retroperitoneal space
 Retains this structural function even
under stress
 Fat in these locations undepleted

13. 4. HORMONAL SECRETION
 Endocrine organ qualities
 Synthesis and secretion of growth
factors and cytokines
Leptin
 16 kDa peptide hormone
 Synthesised in unilocular cells
 Functions in regulation of energy
homeostasis
 Satiety factor that inhibits food intake

14. HORMONAL SECRETION
(Leptin contd)
 Communication of energy state of
adipose tissue to regulators
 Appetite killer
 Regulates the formation of new white
adipose tissue
 Stimulates the metabolic rate i.e.
Triglyceride catabolism

15. HORMONAL SECRETION
(contd)
OTHER HORMONES PRODUCED
 Angiotensinogen (AGE)
 Adiponectin
 Resisten
 Steroid hormones e.g. Testosterone,
oestrogen, glucocorticoids

16. HISTOGENESIS OF
UNILOCULAR ADIPOSE

17. HISTOGENESIS OF UNILOCULAR
ADIPOSE
MESENCHYMAL
STEM CELL
• PLURIPOTENT CONNECTIVE TISSUE CELL
(MESNCHYMAL)
• PEROXISOME PROLIFERATOR ACTIVATOR ACCEPTOR
(PPAR)
EARLY LIPOBLAST,
MIDSTAGE
LIPOBLAST
• EARLY LIPOBLAST RESEMBLES FIBROBLAST
• MIDSTAGE ASSUMES OVAL SHAPE
• BOTH ARE MULTILOCULAR
LATE LIPOBLAST
MATURE
LIPOBLAST
• THE LATE LIPOBLAST ASSUMES A POLYHEDRAL SHAPE
• COALESCENCE OF THE TRIGLYCERIDES UNILOCULAR

18. MEDICAL IMPLICATIONS