Relation between 59Fe incorporation and maturation of rat bone marrow megakaryocytes in vivo

472 RELATION

BETWEEN

OF RAT

BONE

5gFE INCORPORATION MARROW

S. K. BRAHMA, Departments

AND

MEGAKARYOCYTES A. BOSE

MATURATION IN

T/IV0

and S. BOSE

of Cell Research and Biophysics, Chittaranjan Calcutta, India

National

Cancer Research Centre,

Received September 12, 1961

IN continuation of the work reported elsewhere [a] on the incorporation of 59Fe by rat bone marrow megakaryocytes in vivo, a differential count with regard to radioiron incorporation by the nucleus and cytoplasm of the megakaryocytes at their different stages of maturation was made from one thousand cells. It may be seen from Table I that total grains per cell gradually increases with the increase in number of nuclear lobulations. Fig. 1 shows the number of grains in the nucleus, cytoplasm, and total grains per cell plotted against the number of nuclear lobes. The average curve through the number of grains recorded in the nucleus falls on a straight line passing through the origin. This shows that 59Fe incorporation in the nucleus is directly proportional to the number of lobes, while cytoplasmic incorporation remains more or less constant. Figs. 2 and 3 are the photomicrographs of megakaryocytes with different nuclear lobulations. “Primitive proliferative pool cells” [3] found in the proliferative tissue cells, like lymphopoietic, erythropoietic, myelopoietic cells, etc., are absent in the case of the megakaryocytes. The former cells have a maturative multiplicative phase resulting in fully differentiated non-dividing cells. But in the latter there is no such stage. All ‘I‘ABLE

I.

59Fe incorporution

Nuclear lobulation

1 2 3 4 5 6 7 8 9 10 II 12

lobe lobes lobes lobes lobes lobes lobes lobes lobes lobes lobes lobes

in megaknryocytes Nuclear uptake

2.1 kO.54 2.9 10.75 4.52 1.03 5.it1.12 6,X? 1.21 7.9f 1.26 9.3fl.41 9.9f1.58 11.8fl.64 12.6 f 1.50 13.8? 1.17 1fi7t2.11

during

the process

Cytoplasmic uptalic

10.7 k2.54 12.9 * 3.54 12.3i3.x7 11.7k3.1-1 l’L.(rk3.15 12.i +x.54 13.3 -t 4.85 12.6 + 3.69 13.5k4.11 12.x+3.34 13.3 k 2.96 13.i i 1.4x

of maturation. Total uptake per cell

12.x k2.26 15.8 i- 2.29 16.X1 1.26 17.1 f 3.67 18.X k <‘3.65 ;o.s+4.01 22.6 I!Z4.46 22.5 -t -1.4 25.3 i 5.66 25.4 t3.85 Xi.1 + 3.46 30.4 -I- 6.‘2’)

5sFe incorporation

and maturation of megakaryocytes

I;ig. I.--Sumber of grains rccortlcd in the nucleus, cytoplasm and total cell arc shosx against the number ol lOl,C~ per nucleus.

Figs. 2 and 3.-Autoradiographs grain level, (b) on the cell Icvel.

of megakaryocytes x 1250.

labelled

with

59Fe. (u) Photographs

Experimental

on the

Cell Hesearch 25

J. P. Revel and Elizabeth D. Hay

474

through its differentiation from the primitive stem cells till the platelets are produced there is no cellular division. As a result a large multilobed nucleus develops by endomitosis [4]. It is evident from the present study that total incorporation of radioiron per cell increases with an increase in the number of nuclear lobulation, suggesting a relation between differentiation and nuclear incorporation. The present experiment shows that iron is present in the megakaryocytes and it could be heme and/or ferritin, leaving aside the results [I] where it has been shown that hemosiderin is not associated with the megakaryocytes. We for his cherya Mr. N.

wish to record our gratitude to Dr. Subodh Mitra, Director of the Centre, interest in the work, to Dr. P. De, Dr. R. K. Neogy and Mr. K. L. Bhattafor valuable discussions, to Mr. R. K. Chatterlee for his co-operation and to Saha for preparing the illustrations.

REFERENCES

1. 2.

M., Cytology of the Blood and t3lootl-forming Organs (English translation), pp. 173. Grune and Stratton Inc., New York, 1956. BRAHMA, S. I<., BOSE, A. and BOSE, S., Naturll,issenschuften 11, 436 (1961). BESSIS,

3. CRONKITE,

E. P., FLIENDNER, T. M., BOND, V. I-‘., RUBINI, J. R., BRECHER, G. and QUASTLE~, Proc. 2nd U.N. Int. Conf. Peaceful Lses of Atomic Energy, Geneva. 25, 190 (1958). 4. SIMPSON, S. hf., Intern. J. Radiation Hiol. 1, 181 (1959). H.,

AUTORADIOGRAPHIC IN A SPECIFIC

LOCALIZATION

ULTRASTRUCTURAL INTERPHASE

J. P. REVEL Department

of Anatomy,

OF DNA

OF THE

NUCLEUS’

and ELIZABETH Harvard

SYNTHESIS

COMPONENT

Medical

D. HAY

School, Boston, Mass., U.S.A.

Received September 14, 1961 Is spite of the great strides which have been made recently in the application of autoradiographic techniques to the electron microscope [2, 4, 8, !I, lo], it has been necessary to accept “a certain sacrifice in image quality and resolution” [2], owing to the presence of a layer of emulsion over the tissue section. By small modifications of existing techniques, however, we have obtained autoradiographic specimens which show no impairment in electron optical resolution. 1 This research was supported by Special Fellowship Grant #SC;-13,979 and by Grant #C-5196 from the LT.S. Public Health Service. Experimental

Cell Research 25