CHAPTER
VI
THE DIFFERENTIATION OF VERTEBRATE PIGMENT CELLS
CHARLES E. WILDE, JR.*
I. Introduction
267
II. The General Problem of Cellular Differentiation
269
III. Cell Division in Relation to Cellular Differentiation
273
IV. The Morphological Characteristics of Pigment Cells
274
A.
The Melanoblast
274
B.
The Mature Melanocyte
276
C.
The Migration of Melanoblasts
282
V. The Causal Analysis of Pigment Cell Differentiation
286
VI. Discussion and Conclusion
293
References
298
I. Introduction
The pigmented cells of vertebrates have been a favoured material for
investigation of cell behaviour and the processes of migration, distribution and differentiation. They constitute readily identifiable and
distinctive cell types. In particular, the brown or darkish pigmented
cells (melanocytes) which reside in the epidermal and dermal areas of
the vertebrate body have been studied in detail. Advantage has been
taken of the fact that these cells have a characteristic morphology, both
in shape and colour, which make them recognizable in diverse anatomical
areas. The homogeneous distribution of pigment in granular form
throughout the cytoplasm of these cells has permitted investigators to
follow this cell type in life, in the animal, in tissue cultures, and in fixed
preparations, both stained and unstained.
Pigmented cells have a discrete origin in the vertebrate embryo, from
the neural crest. The origin of the cells from this tissue was clearly
foreshadowed in the early investigations of Borcea (1909), and of
R. G. Harrison (1910). However, the definitive experimental analysis of
pigment cell origin was carried out by DuShane (1935) in a series of
extirpation and transplantation experiments in the amphibian embryo.
Further work by many other investigators has served to point out that
* Original wor.k from the author's laboratory has been supported in part by grants
from the National Science Foundation, the Research Grants Branch, National Institutes
of Health and the Muscular Dystrophy Associations of America, Inc.
267
VI
THE DIFFERENTIATION OF VERTEBRATE PIGMENT CELLS
CHARLES E. WILDE, JR.*
I. Introduction
267
II. The General Problem of Cellular Differentiation
269
III. Cell Division in Relation to Cellular Differentiation
273
IV. The Morphological Characteristics of Pigment Cells
274
A.
The Melanoblast
274
B.
The Mature Melanocyte
276
C.
The Migration of Melanoblasts
282
V. The Causal Analysis of Pigment Cell Differentiation
286
VI. Discussion and Conclusion
293
References
298
I. Introduction
The pigmented cells of vertebrates have been a favoured material for
investigation of cell behaviour and the processes of migration, distribution and differentiation. They constitute readily identifiable and
distinctive cell types. In particular, the brown or darkish pigmented
cells (melanocytes) which reside in the epidermal and dermal areas of
the vertebrate body have been studied in detail. Advantage has been
taken of the fact that these cells have a characteristic morphology, both
in shape and colour, which make them recognizable in diverse anatomical
areas. The homogeneous distribution of pigment in granular form
throughout the cytoplasm of these cells has permitted investigators to
follow this cell type in life, in the animal, in tissue cultures, and in fixed
preparations, both stained and unstained.
Pigmented cells have a discrete origin in the vertebrate embryo, from
the neural crest. The origin of the cells from this tissue was clearly
foreshadowed in the early investigations of Borcea (1909), and of
R. G. Harrison (1910). However, the definitive experimental analysis of
pigment cell origin was carried out by DuShane (1935) in a series of
extirpation and transplantation experiments in the amphibian embryo.
Further work by many other investigators has served to point out that
* Original wor.k from the author's laboratory has been supported in part by grants
from the National Science Foundation, the Research Grants Branch, National Institutes
of Health and the Muscular Dystrophy Associations of America, Inc.
267