lipids cannot be excluded, the present
study demonstrating the phagocytic activity of this cell suggests that the
radioactive material was ingested by
the cell as a phospholipid lying free
in the alveoli.
Thus it is proposed that the nonciliated bronchiolar cell is the major
site of pulmonary phospholipid production (presumably surfactant), while the
large alveolar cell is a phagocytic cell
responsible for the clearance of lipids
as well as other materials from the
alveolar area.
ALBERT H. NIDEN
Department of Medicine,
University of Chicago,
Chicago, Illinois 60637
SG, secretory granule.
phagocytic activity. Ciliated cells are
present in the terminal bronchiole but
disappear in the respiratory bronchiole, well before the alveoli are
reached. Thus the major portion of
this bronchiolar secretion is not exposed to ciliary activity.
These
secretion
granules
did
not
stain with periodic acid-Schiff, Alcian
blue, or Sudan black, indicating the
absence of mucopolysaccharides, acid
mucopolysaccharides, and free lipids.
However, the granules did stain with
Sudan
black—acetone,
Baker’s
acid
hematin, and silver hydroxylamine in
an aqueous ‘solution (Fig. 4A), indicat-
(10) were observed within 5 minutes
at the apex of the Clara cells (Fig.
4B). The presence of positive granules
after tissue extraction of free lipids
demonstrates the ability of these cells
to synthesize phospholipids from fatty
acids.
Although pulmonary surfactant has
not been completely identified, it has
been characterized as a phospholipid
(71). Thus, until pulmonary surfactant
has been more precisely identified, it
is only a presumption that the phos-
pholipid produced by the Clara cell
is surfactant.
The large alveolar cell was the only
other cell which incorporated tritiated
palmitate and acetate. Although the
possibility that this alveolar cell is
also capable of synthesizing phospho- .
2. R. E. Pattle, Physiol, Rev. 48, 48 (1965);
M. E. Avery and S. I. Said, Medicine 44,
503 (1965).
3. J. A. Clements, Physiologist 5, 11 (1962).
4, C. C. Macklin, Lancet 1954-I, 1099 (1954);
M. Klaus, O. K. Reiss, W. H. Tooley, C.
Piel, J. A. Clements, Science 137, 750 (1962);
S. Buckingham, W. F. McNary, J. E. Sommers, ibid. 145, 1192 (1964); K. Bensch,
K. Schaefer, M E. Avery, ibid. p. 1318; K. E.
Schaefer, M. E. Avery, K. Bensch, J. Clin.
Invest. 43, 2080 (1964); M. M. Orzalesi, E. K.
Motoyama, H. N. Jacobson, Y. Kikkawa,
E. O. R. Reynolds, C. D. Cook, Pediatrics 35,
373 (1965); S. I. Said, R. M. Klein, L. W.
Norrell, Y. T. Maddox, Science 152, 657
(1966).
. M. Clara, Z. Mikrosk, Anat. Forsch, 41,
321 (1937).
C. C. Macklin, Lancet 1954-I, 1099 (1954);
M.Klaus, O. K. Reiss, W. H. Tooley, C. Piel,
J. A. Clements, Science 137, 750 (1962);
J. U. Balis and P. E. Conen, Lab. Invest.
13, 1215 (1964); K. Bensch, K. Schaefer,
M. E. Avery, Science 145, 1318 (1964); Y.
Kikkawa, E. K. Motoyama, C. D. Cook,
Am. J. Pathol. 47, 877 (1965).
. D. D. Sabatini. K. Bensch, R. J. Barrnett,
on
ing the presence of a phospholipid (9).
Following the injection of tritiated
palmitate or acetate intraperitoneally,
autoradiographically positive granules
References and Notes
. G. Popjack and M. Beekmans, Biochem. J. 47,
233 (1950); J. M. Felts, Physiologist 5, 139
(1962); R. J. Havel, J. M. Felts, C. M. van
Duyne, J. Lipid Res. 3, 297 (1962); J. M.
Felts, Health Physics 10, 973 (1964); W. R.
Harlan, Jr., S. I. Said, C. L. Spiers, C. M.
Banerjee, M. E. Avery, Clin. Res. 12, 291
(1964); H. O. Heinemann, Bull, N.Y. Acad.
Med, 40, 74 (1964); E. G. Tombropoulos,
Science 146, 1180 (1964); K. Nasr and H. O.
Heinemann, Am. J. Physiol. 208, 118 (1965);
J. M. Felts, Med. Thorac. 22, 89 (1965);
S. Buckingham, H. O. Heinemann, 8. C.
Sommers, W. F. McNary, Am. J. Pathol. 48,
1027 (1966); A. Naimark, J. Appl. Physiol.
21, 1292 (1966).
~
normal mouse. (A) Bronchiolar cells at left with
development of secretion granules (arrows). Brondroplets collecting at apex of cell (SG). C, ciliated
secretory granule from apex of bronchiolar cell.
nw
Fig. 3. Terminal bronchiole from
well-formed Golgi area and early
chiolar cell at right with secretory
cells; Ci, cilia. (B) Extrusion of
J. Cell Biol, 17, 19 (1963),
. A. B. Novikoff, in Lysosomes, A. V. S. de
Reuck and M. P. Cameron, Eds, (Little,
Brown, Boston, 1963), p. 36.
9, M. C. Berenbaum, Quart. J. Microscop. Sci.
99, 231 (1958); C. W. M. Adams, O. B. Bayliss, M. Z. M. Ibrahim, J. Histochem. Cy-
tochem. 11, 560 (1963).
10, L. G. Caro and R. P. van Tubergen, J. Cell.
Biol. 18, 173 (1962).
11. M. H. Klaus, J. A. Clements, R. J. Havel,
Proc. Nati. Acad. Sci. U.S. 47, 1858 (1961);
R. E. Pattle and L. C. Thomas, Nature 189,
844 (1961); M. E. Abrams and F. B. Taylor,
Jr., Physiologist 7, 78 (1964); E. S. Brown,
Am. J. Physiol. 207, 402 (1964); T. Fujiwara,
H. Hirono, T. Arakawa, Tohoko J. Exptl.
Med. 85, 33 (1965).
Fig. 4. (A) Nonciliated bronchiolar cells stained with silver-hydroxamate reaction,
embedded in Epon and counterstained lightly with Toluidine Blue. Granules at apex of
bronchiolar cell stain positive for phospholipid. (B) Autoradiography of terminal
bronchus 5 minutes after injection of tritiated palmitate intraperitoneally. Positive
granules are at apex of bronchiolar cell.
1324
12. Supported by grants from the National Heart
Institute (H-6918) and NSF (GF-189). I am
indebted to Professor E. Yamada, Kyushu
University, Fukuoka, Japan, under whose
guidance and encouragement this study was
initiated. I am grateful to Phyllis Fogel for
her technical assistance.
15 June 1967
SCIENCE, VOL. 158