AUTHOR'S ABSTRACT OF THIS PAPER ISSUED 
BY THE BIBLIOGRAPHIC SERVICE, DECEMBER 27 
ENDOTHELIUM IN TISSUE CULTURES 
WARREN H. LEWIS 
Carnegie Laboratory of Embryology, Johns Hopkins Medical School 
FIVE PLATES (TWENTY-FOUR FIGURES) 
INTRODUCTION 
It is but natural that investigators in the field of tissue cul- 
ture should have had and should still have more or less difficulty 
in identifying the various types of cells that grow out from ex- 
plants of embryonic tissues. Most explants contain several 
types of cells that migrate out into the medium, some of which 
are comparatively easy to identify. 
Nerve fibers from the central nervous system have been ob- 
served by Harrison (’07, ’10), Ingebritsen (13), and Levi (’16 a), 
and those from the sympathetic system by Lewis and Lewis 
(12a), and Matsumoto (’20). They are always quite charac- 
teristic. Endodermal membranes from the cells lining the ali- 
mentary tract and allantois were not at first identified as such 
(Lewis and Lewis, 711; Lambert, ’12), but later their origin was 
established (Lewis and Lewis, ’12b) and their recognition is 
now simple. Ectoderm from the skin (Lambert, 712) and the 
amnion (Lewis and Lewis, 712 b) grows out in the form of a 
membrane or sheet, as does also the pigmented epithelium from 
the retina (Luna, ’17, fig. 1; Smith, ’20). In the frog, likewise, 
the epithelial cells grow out as membranes (Uhlenhuth, 714, 
"15; Matsomoto, 718). Liver cells form membranes similar 
to the endoderm and are easily identified (Lynch, ’21). The thy- 
roid-gland cells grow out either as tubules or membranes (Car- 
rel and Burrows, ’11 a,’11b). Renal epithelium from the tubules 
likewise-grows out in the form of membranes or sheets (Lewis 
and Lewis, 712 b) and sometimes as tubules (Reinhoff!). Blood- 
: Unpublished. 
39 
