AUTHOR’S ABSTRACT OF THIS PAPER ISSUED 
BY THE BIBLIOGRAPHIC SERVICE, DECEMBER 27 
THE RETICULAR MATERIAL AS AN INDICATOR OF 
PHYSIOLOGIC REVERSAL IN SECRETORY POLARITY 
IN THE THYROID CELLS OF THE GUINEA-PIG 
E. V. COWDRY 
Anatomical Laboratory of the Peking Union Medical College and the Laboratories 
of the Rockefeller Institute for Medical Research, New York 
TWO PLATES (FOURTEEN FIGURES) 
It can easily be observed by the application of Da Fano’s 
(20, p. 157) modification of Cajal’s silver-impregnation method 
to the thyroid glands of guinea-pigs that the reticular material 
is not always restricted to the zone of cytoplasm between the 
nucleus and the follicular cavity, as has been supposed by all 
previous workers (Negri, ’00, p. 61; ’00 a, p. 178; Holmgren, ’01, 
p. 314, and Kolster, ’13, p. 128); but is found, in about one cell 
in every five hundred, in the opposite pole near the peripheral 
blood vessels. Detailed reviews of the literature relating to the 
material are given by Duesberg (14) and Cajal (14). 
A group of follicular cells is reproduced in figure 1 to illustrate 
the average position assumed by the blackened reticular material 
between the nucleus and the lumen. Reversal may take place 
in single isolated cells, as shown at (A) in figure 2, or in large or 
small groups of cells, as is illustrated in figures 3 and 4. On the 
other hand, the reticular material may be found to be unusually 
close to the lumen, as shown in figures 6 and 7. In very rare 
cases, in which the epithelium is several layers in thickness, the 
reticular material is extremely variable in position (fig. 8) and no 
polarity can be distinguished. 
In the acinus cells of the pancreas of the guinea-pig (fig. 9) it 
is wholly different, because here the reticular material is, as far 
as I can ascertain, invariably located between the nucleus and 
the discharging pole of the cell, with strands sometimes extending 
up on either side of the nucleus, and has been recorded in this 
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