Bone marrow is found within bones and produces blood cells, containing two types - red marrow which produces blood cells throughout life and yellow marrow containing fat; it undergoes examination by aspiration and biopsy to evaluate blood cell production and detect abnormalities by analyzing cellular composition and bone marrow architecture.

1. Bone marrow
Anatomy, Functions, Aspiration & Reporting
Dr. Narender Kumar

2. Anatomy..

3. • Two types of bone marrow:
▫ Medulla ossium rubra (Red Marrow -
consisting mainly of hematopoietic tissue)
▫ Medulla ossium flava (Yellow Marrow -
consisting mainly of fat cells)

4. • On average, bone marrow constitutes 4% of the
total body mass of humans
• In adults weighing 65 kg (143 lbs), bone marrow
accounts for approximately 2.6 kg (5.7 lbs)
• The hematopoeitic compartment of bone
marrow produces approximately 500 billion
blood cells per day

6. Primitive Hematopoiesis
• Derived from the extra- embryonic
YOLK SAC;
• Consists mainly of nucleated erythroid
cells that carry oxygen to the
developing embryonic tissues… an early
circulatory system.
• Probably starts ~ 4 weeks in humans

7. Definitive Hematopoietic System
• As the embryo’s size increases,
primitive system superceded by
definitive hematopoietic system,
which originates in the embryo
itself and continues throughout
adult life.
• 1st definitive multipotent
hematopoietic stem cells are
generated within the
embryonic AGM region of the
para-aortic splanchnopleuric
mesoderm (day 30-37 in human)

8. Subsequent sites of Hematopoiesis
in fetal life
After birth, BONE
MARROW
becomes main
hematopoietic
organ.
• Throughout fetal life, the liver is the chief organ for production of
myeloid and erythroid cells

10. Pattern of distribution..
• At birth, all bone marrow is red.
• With age, more and more of it is converted to the
yellow type; only around half of adult bone
marrow is red
• In Adults Red marrow is found mainly in the
Flat bones and in the epiphyseal ends of
long bones such as the femur and humerus
• Yellow marrow is found in the medullary cavity,
the hollow interior of the middle portion of long
bones

11. Bone Marrow
• Bone marrow is specially designed to support the
proliferation, differentiation, and maintenance of
hematopoietic cells
• The stroma of the bone marrow is all tissue not directly
involved in the primary function of hematopoiesis.
• Cells that constitute the bone marrow stroma are:
• fibroblasts (reticular connective tissue)
• macrophages
• adipocytes
• osteoblasts
• osteoclasts
• endothelial cells, which form the sinusoids.

14. • Bone marrow examination refers to the
pathologic analysis of samples of bone marrow
obtained by bone marrow aspiration and
bone marrow biopsy (often called a trephine
biopsy)

15. • The aspirate yields semi-liquid bone marrow,
which can be examined
• under a light microscope as well as
• analyzed by flow cytometry,
• chromosome analysis, or
• polymerase chain reaction (PCR).
• Frequently, a trephine biopsy is also obtained,
which yields a narrow, cylindrically shaped solid
piece of bone marrow which is examined
microscopically (sometimes with the aid of
immunohistochemistry) for cellularity and
infiltrative processes.

16. How the test is performed…

17. How the test is performed…
• usually performed on the back
of the hipbone, or posterior
iliac crest.
• However, an aspirate can also
be obtained from the sternum
(breastbone).
• A trephine biopsy should
never be performed on the
sternum, however, due to the
risk of injury to blood vessels,
lungs or the heart.

18. • Sahla Bone Marrow Needle, iliac crest, with adjustable
stop
• 14 (2.0mm) x 50mm
• 16 (1.6mm) x 50mm
• 18 (1.2mm) x 50mm (in child)

19. Contraindications
• The only absolute reason to avoid is the
presence of a severe bleeding disorder
Complications
• While mild soreness lasting 12-24 hours is
common after a bone marrow examination,
serious complications are extremely rare.

20. Erythroid series
Myeloid series
Megakaryocytic series
Monocytic series

22. *Proerythroblast
**Early erythroblast (Basophillic )
***Intermediate erythroblast (Polychromatic)
****Late erythroblast (Orthochromatic )

23. Erythroid precursors
• Normal red cells are
produced in the bone
marrow from erythroid
precursors or
erythroblasts.
• The earliest
morphologically
recognisable red cell
precursor is derived from
an erythroid progenitor
cell which in turn is
derived from a
multipotent
haemopoietic progenitor
cell.

24. proerythroblast
• Normal proerythroblast
[dark red arrow] in the
bone marrow. This is a
large cell with a round
nucleus and a finely
stippled chromatin
pattern. Nucleoli are
sometimes apparent.
• The cytoplasm is
moderately to strongly
basophilic.

25. Basophilic erythroblast
• Spherical nucleus, nucleoli
not visible, basophilic
cytoplasm

26. Polychromatophilic erythroblast
• smaller nucleus –condensed
chromatin, baso- and
eosinophilia in the cytoplasm

27. Orthochromatophilic erythroblast
• small nucleus with highly
condensed chromatin, nucleus
extruded, eosinophilic
cytoplasm

28. Normal erythroblasts in the BM

30. Myeloid precursors
• Myeloblast promyelocyte myelocyte 
metamyelocyte  band form  mature
neutrophil.

31. credit -Dr. Lekst rom Hines, JEM 1999

32. Myeloid precursors
• Normal myeloblasts have no granules but
abnormal myeloblasts may have a few granules.
• Myeloblasts undergo one cell division and
mature into promyelocytes.
• Promyelocytes have primary or azurophilic
granules. They have a Golgi zone a pale area
adjacent to the nucleus that is the site of granule
production. The chromatin pattern of a
promyelocyte shows some condensation or
clumping, in contrast to the diffuse chromatin
pattern of a myeloblast, but nucleoli are still
visible.

33. Normal granulocyte precursors in
the bone marrow
• Note the myeloblast
[dark red arrow] with a
high nucleocytoplasmic
ratio, diffuse chromatin
pattern and nucleolus.
• There is a promyelocyte
[green arrow] which is
larger and has a lower
nucleocytoplasmic ratio
and abundant azurophilic
granules.

34. Myelocytes
• Myelocytes are smaller
than promyelocytes and
have specific granules
that indicate whether
they are of neutrophil,
eosinophil or basophil
lineage.
• The nucleolus is no
longer visible.

35. Eosinophilic myelocyte

36. A neutrophil metamyelocyte
• The metamyelocyte
differs from a
myelocyte in having
some indentation of
the nucleus
• It differs from a band
form in not having
any part of its nucleus
with two parallel
edges

37. Neutrophilic
metamyelocyte

38. Eosinophilic
metamyelocyte

39. Basophilic metamyelocyte

40. Band or juvenile Neutrophils
• There are smaller
numbers of cells of
neutrophil lineage
with non-segmented
nuclei. They are
referred to as
neutrophil band cells
or band forms. They
are less mature than
segmented
neutrophils.

41. Compare the different cell types:
basophilic (myeloid) eosinophilic (myeloid)
neutrophilic (myeloid) erythroid

42. *Megakaryoblasts
** Promegakaryocytes
***Megakaryocytes

43. Megakaryoblasts
• Megakaryoblasts are
the precursors of the
megakarycytes.
• They may show
cytoplasmic blebbing.

44. Promegakaryocyte

45. Megakaryocyte

46. Monocytopoiesis
- Monoblast
- Promonocyte
- Monocyte

47. Promonocyte

49. 19-
49
Hematopoiesis

50. Systemic scheme for Examining
aspirated BM films
• Low power (x10)
▫ Determine cellularity
▫ Identify megakaryocytes
▫ Look for clumps of abnormal cells
▫ Identify macrophages

51. Systemic scheme for Examining
aspirated BM films
• Higher power (x40, x100)
▫ Identify all stages of maturation of myeloid and
erythroid cells.
▫ Determine the M:E ratio
▫ Perform a differential count
▫ Look for areas of BM necrosis.
▫ Assess the iron content.

52. Assessment of BM cellularity
• Cellularity cannot be assessed without knowing
the age of a patient.
• A young child on average has about 80% of the
intertrabecular space occupied by haemopoietic
cells whereas in a 75-year-old the average has
fallen to around 30%.
• 100 – Age of Patient

53. Comparing normo, hyper, &
hypocellular marrows

54. M:E ratio
• The M:E ratio is the ratio of all granulocytic plus
monocytic cells (Myeloid) to all erythroblasts
(Erythroid).
• For all bone marrow aspirates examined, the
report should specify the M:E ratio and the
percentage of lymphocytes and plasma cells.
• A differential count of at least 200-300 cells
should be performed.
• If there is any borderline abnormality, e.g. in the
number of blasts, lymphocytes or plasma cells, a
500 cell differential count should be
performed.

55. • Only after the bone marrow has been
carefully assessed on low and medium power
the X100 oil should be used to assess cellular
detail

56. BM iron stores
• Once all normal and
abnormal bone marrow
cells have been assessed
on a routine stain an iron
stain should be
examined, using a
medium power objective
(X 40 or X 50). Storage
iron, which stains blue,
should be assessed in
bone marrow fragments.
This image shows
normal bone marrow
iron.

57. Reporting results
• List the various descriptive comments regarding
all the cell lines present in the BM
• Mention the striking abnormalities separately.
• Write your impression and any
recommendations to the clinician.

58. Cellular constitution of the red bone
marrow parenchyma

59. Trephine biopsy

60. • Jamshidi Type Bone Marrow Biopsy Needle,
• 8swg (4.0mm) x 100mm
• 11swg (3.0mm) x 100mm
• 13swg (2.3mm) x 90mm
• 14swg (2.0mm) x 90mm (In child)

62. Adequacy of biopsy
• should contain at least five to six intertrabecular
spaces and, after processing,
• should be at least 2–3 cm in length
• Others have considered that 1.5–2 cm is an
acceptable length

64. Indications or areas of controversy
• Inadequate or failed aspirate.
• Need for accurate assessment of cellularity,
whether increased or decreased.
• Suspected focal lesion (for example, suspected
granulomatous disease or lymphoma).
• Suspected bone marrow fibrosis.
• Need to study bone marrow architecture.
• Need to study bone structure or bone marrow
blood vessels