This document summarizes key aspects of panniculus, or subcutaneous fat. It discusses the structure and functions of adipose tissue, including its role in insulation, energy storage, and as an endocrine organ. The embryological development of brown and white fat is described. Histologically, adipocytes have a signet ring appearance with a large lipid vacuole displacing the nucleus. Adipose tissue is highly vascularized and innervated. The processes of adipogenesis and lipogenesis are outlined. Fat deposits in various internal organs in addition to subcutaneous fat. Adipose tissue secretes hormones like adiponectin and leptin that regulate metabolism and energy homeostasis.

1. Panniculus
Dr. Preethi chekuri
MD DVL

2. Introduction
 Occurs almost universally over the body
surface, between the skin and deep fascia
 Absent from eyelids and male genitalia
 It varies in thickness with the race, age,
sex, endocrine and nutrtional status
 In a normal person, fat constitutes 10% of
body weight

3. Functions
 Acts as an insulating layer
 Protective cushion
 Thermogenesis
 Store of readily available energy
 Major endocrine organ
 Provides support and has cosmetic function
(contours of face)

4. Embryology
 Pre – adipocyte appears in the mesenchyme at 14th
week of fetal life
 Pre – adipocyte terminally differentiate into either
brown adipocyte or white adipocyte
 Development of brown fat begins at the 20th week
of gestation, reaches maximum at birth

5. Brown fat
 It is multilocular and metabolically
very active with many mitochondria
 Surrounded by a greater capillary network than
white fat ( partly responsible for the brown
colour), such that heat can be rapidly tranferred
into the circulation
 Most prominent in neck and upper thorax of fetus
 Adults have supraclavicular areas of brown fat

6. Histology of adipocytes
 Have a diameter upto 100 microns
 Mature fat cell has a characteristic signet ring
appearance, because the oval nucleus is displaced to a
side by a single, large, intracellular, fat containing
vacuole, which is surrounded by perilipin

7.  Arranged in lobules, which are separated by
interlobular septa
 Each lobule consists adipocytes, stromavascular
tissue being macrophages, fibroblasts, mast cells,
pericytes, endothelial cells and pre-adipocytes

8. Blood, nerve and lymph supply
 BLOOD - Fat tissue has an abundant blood supply, each
lobule being supplied by a terminal arteriole running
along the septa
Then breaks up to form capillaries
 LYMPH - Also contains a rich lymphatic plexus
These lymph vessels penetrate deep fascia and drain
into regional lymph nodes
 NERVE - Innervated by noradrenergic fibres of
sympathetic nervous system and para sympathetic
fibres

9. Adipogenesis
 It refers to the recruitment from multipotent
stem cells in the mesenchyme and stromavascular
tissue, and proliferation of pre adipocytes
followed by their differentiation into mature fat
cells
 -Glucocorticoids -
growth hormone and
-insulin, stimulate cells to terminally
differentiate, but after a certain size, growth
occurs through hyperplasia rather than
hypertrophy

10. Energy homeostasis
 Catabolism and anabolism of fat depends on
-nourishment, endocrine and nervous activity
 Insulin inhibits hydrolysis and breakdown of
triglycerides, conserving the energy store
 Adipose tissue in vitro has a metabolic rate similar
to a kidney and half that of liver

11. Outline of lipogeneis in an adipocyte

13. Fat as an organ
 Apart from the subcutaneous fat,
20% of fat tissue occurs internally,
in mediastinal and retroperitoneal
tissues, mesentry, marrow and
other individual organs including
blood vessels
 In view of the recent obesity
epidemic, increase in the upper
body and visceral fat are
associated with an increase
cardiovascular and metabolic risks

14. Fat as an endocrine organ

15. Adiponectin
 Protein with structural similarity to collagen and C1q
 Has autocrine/paracrine effects locally and endocrine
effects distally
 Promotes pre adipocytes to become mature fat cells
with increase in size
 Serum adiponectin levels are lower with weight gain
and higher with weight loss
 Also exerts anti inflammatory properties

16. Leptin
 Adipokine involved in energy homeostasis
 Structural homology similar to other
cytokine proteinssuch as TNF alpha and IL-6
 Exerts main effect via satiety centres

17. Thank you