CHAPTER 4
Morphological Problems of Cell Type,
Shape and Identification
E. N. W I L L M E R
Physiological Laboratory, University of Cambridge, England
I. The Problem
143
II. The Importance of Cell Movement
145
III. The Main Cell Types
147
IV. The Significance of the Main Cell Types
148
A. Extrinsic factors
150
B. Intrinsic factors
157
C. Stages in the alteration of cells
157
V. The Possible Evolution of the Cell Types
159
V I . Some Physico-chemical Characteristics of the Cell Types
162
V I I . The Problem of Interconversion
164
VIII. Lessons from the Metaplasia of Naegleria
166
I X . Cells in Clones and Pure Lines
167
X . Tissue Culture and the Meaning of Differentiation
172
References
174
I. T H E P R O B L E M
A study of Fig. 1 will reveal, more clearly than any description, the
problem to be discussed in this chapter. The photograph represents
part of the outgrowth from a hanging-drop culture of a piece of thymus
from the rat, in a plasma medium. Cells have wandered out from the
central explant and have been fixed and stained. The thymus in situ
normally contains an epithelial reticulum, small and large thymocytes
(lymphocytes?), the cells of HassalPs corpuscles, macrophages, endothelial cells and a few fibroblasts and muscle cells from the rather sparse
blood vessels. Red and white blood corpuscles are also inevitably present.
In the photograph, it is clearly not an easy matter to say which cell
in vitro corresponds to which in vivo. Is it indeed possible?
A few general considerations concerning the reactions of cells to
Tissue Culture conditions may perhaps help to put the problems of the
recognition of cells in culture into some sort of perspective.
Morphological Problems of Cell Type,
Shape and Identification
E. N. W I L L M E R
Physiological Laboratory, University of Cambridge, England
I. The Problem
143
II. The Importance of Cell Movement
145
III. The Main Cell Types
147
IV. The Significance of the Main Cell Types
148
A. Extrinsic factors
150
B. Intrinsic factors
157
C. Stages in the alteration of cells
157
V. The Possible Evolution of the Cell Types
159
V I . Some Physico-chemical Characteristics of the Cell Types
162
V I I . The Problem of Interconversion
164
VIII. Lessons from the Metaplasia of Naegleria
166
I X . Cells in Clones and Pure Lines
167
X . Tissue Culture and the Meaning of Differentiation
172
References
174
I. T H E P R O B L E M
A study of Fig. 1 will reveal, more clearly than any description, the
problem to be discussed in this chapter. The photograph represents
part of the outgrowth from a hanging-drop culture of a piece of thymus
from the rat, in a plasma medium. Cells have wandered out from the
central explant and have been fixed and stained. The thymus in situ
normally contains an epithelial reticulum, small and large thymocytes
(lymphocytes?), the cells of HassalPs corpuscles, macrophages, endothelial cells and a few fibroblasts and muscle cells from the rather sparse
blood vessels. Red and white blood corpuscles are also inevitably present.
In the photograph, it is clearly not an easy matter to say which cell
in vitro corresponds to which in vivo. Is it indeed possible?
A few general considerations concerning the reactions of cells to
Tissue Culture conditions may perhaps help to put the problems of the
recognition of cells in culture into some sort of perspective.