DIFFERENTIATION
OF KIDNEY
MESENCHYME
IN
AN
EXPERIMENTAL MODEL
SYSTEM
LAURI SAXEN, OLLI KOSKIMIES, AITO LAHTI,
HEIKKI MIETTINEN, JUHANI RAPOLA, AND JORMA WARTIOVAARA
1
University of Helsinki, Helsinki,
Finland
I. Introduction
251
A. Tissue Interaction in the Development of the Kidney Tubules
.
. 253
B. The Experimental Setup
255
II. Formation of Kidney Tubules
259
III. Expression of Differentiation at Different Levels
261
A. Response at the Level of Ribonucleic Acid Synthesis
.
.
.
. 262
B. Response at the Level of Protein Synthesis
266
C. Response at the Morphological Level
275
IV. Discussion
281
A. Induction
281
B. Cell Division
284
C. Macromolecular Synthesis and Morphogenesis
285
D. Stabilization of Differentiation
287
V. Concluding Remarks
288
References
288
I. Introduction
Embryonic cells apparently contain all the information required for
their further differentiation
and individualization, characterized by
specialized metabolism and structural features. Yet a great number of
experiments have convincingly shown that this differentiation cannot
be initiated without exogenous, epigenetic stimuli and that even predetermined cells can alter their prospective course of differentiation
when exposed to such stimuli. In a number of instances, these stimuli are
known to be released by heterotypic cells in the vicinity of the respond1
The results of our group to be reported here were obtained in a series of experiments made during the years 1960 to 1967 mainly in the Laboratory of Experimental
Embryology, Department of Zoology, University of Helsinki. Although the constitution of the group of scientists involved in this project has varied during this period,
we should like particularly to mention the late Doctor Tapani Vainio, who initiated
several lines of our research, and was a most active member of the team until his
death in 1965.
251
OF KIDNEY
MESENCHYME
IN
AN
EXPERIMENTAL MODEL
SYSTEM
LAURI SAXEN, OLLI KOSKIMIES, AITO LAHTI,
HEIKKI MIETTINEN, JUHANI RAPOLA, AND JORMA WARTIOVAARA
1
University of Helsinki, Helsinki,
Finland
I. Introduction
251
A. Tissue Interaction in the Development of the Kidney Tubules
.
. 253
B. The Experimental Setup
255
II. Formation of Kidney Tubules
259
III. Expression of Differentiation at Different Levels
261
A. Response at the Level of Ribonucleic Acid Synthesis
.
.
.
. 262
B. Response at the Level of Protein Synthesis
266
C. Response at the Morphological Level
275
IV. Discussion
281
A. Induction
281
B. Cell Division
284
C. Macromolecular Synthesis and Morphogenesis
285
D. Stabilization of Differentiation
287
V. Concluding Remarks
288
References
288
I. Introduction
Embryonic cells apparently contain all the information required for
their further differentiation
and individualization, characterized by
specialized metabolism and structural features. Yet a great number of
experiments have convincingly shown that this differentiation cannot
be initiated without exogenous, epigenetic stimuli and that even predetermined cells can alter their prospective course of differentiation
when exposed to such stimuli. In a number of instances, these stimuli are
known to be released by heterotypic cells in the vicinity of the respond1
The results of our group to be reported here were obtained in a series of experiments made during the years 1960 to 1967 mainly in the Laboratory of Experimental
Embryology, Department of Zoology, University of Helsinki. Although the constitution of the group of scientists involved in this project has varied during this period,
we should like particularly to mention the late Doctor Tapani Vainio, who initiated
several lines of our research, and was a most active member of the team until his
death in 1965.
251