276
C H A R L E S
Ε .
W I L D E
and dispersion to peripheral cytoplasm, the cell generally increases its
load of melanin granules without evidence of streaming or flow of
granules from the perinuclear space. Other evidence, which will be
discussed in detail later, is to be found in experiments which demonstrate
that pieces of cytoplasm containing no nucleus, are still capable of synthesizing melanin granules in the contemporary absence of the nucleus.
The degree to which maturing melanoblasts become dendritic
particularly in vitro is widely variable. The point has previously been
F I G . 2. Early melanogensis in differentiating pigment cell. Arrows point to parallel
arrays of melanin granules in the perinuclear cytoplasm. Phase contrast 400 χ .
made that this process is more or less separable from melanogenesis.
The yellow (xanthophores) and white (guanophores) pigment cells of
amphibia are also dendritic, and while there is indubitably some initial perinuclear melanin synthesis in these types, the cells do become
markedly dendritic. Occasionally, under experimental conditions, highly
branched cells of form completely resembling mature pigment cells, but
without any vestige of melanin are to be seen.
With the development of an even loading and the dispersal of
homogeneously sized melanin granules the melanoblast can be called a
mature melanocyte.
The mature melanocyte may still be capable of cell division although
there is no positive evidence of its occurrence. The melanocyte is a
B . T h e M a t u r e M e l a n o c y t e
C H A R L E S
Ε .
W I L D E
and dispersion to peripheral cytoplasm, the cell generally increases its
load of melanin granules without evidence of streaming or flow of
granules from the perinuclear space. Other evidence, which will be
discussed in detail later, is to be found in experiments which demonstrate
that pieces of cytoplasm containing no nucleus, are still capable of synthesizing melanin granules in the contemporary absence of the nucleus.
The degree to which maturing melanoblasts become dendritic
particularly in vitro is widely variable. The point has previously been
F I G . 2. Early melanogensis in differentiating pigment cell. Arrows point to parallel
arrays of melanin granules in the perinuclear cytoplasm. Phase contrast 400 χ .
made that this process is more or less separable from melanogenesis.
The yellow (xanthophores) and white (guanophores) pigment cells of
amphibia are also dendritic, and while there is indubitably some initial perinuclear melanin synthesis in these types, the cells do become
markedly dendritic. Occasionally, under experimental conditions, highly
branched cells of form completely resembling mature pigment cells, but
without any vestige of melanin are to be seen.
With the development of an even loading and the dispersal of
homogeneously sized melanin granules the melanoblast can be called a
mature melanocyte.
The mature melanocyte may still be capable of cell division although
there is no positive evidence of its occurrence. The melanocyte is a
B . T h e M a t u r e M e l a n o c y t e