THE ULTRASTRUCTURE OF THE CYTOPLASM OF THE
DEVELOPING AMPHIBIAN EGG
1
SAUL WISCHNITZER
Department of Biology, Yeshiva University, New York, New York
I. Introduction
131
II. Egg Envelopes
132
A. Historical Review
132
B. Terminology
133
C. Formation of the Egg Envelopes
134
D. Ultrastructure of the Egg Envelopes
137
E. Discussion
141
III. Cytoplasm
145
A. Oocyte Development
145
B. Cytoplasmic Organelles
151
C. Inclusion Bodies
I
58
D. Discussion
164
IV. Summary
5
References
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I. Introduction
The success in our search for a fuller understanding of the life processes
is dependent upon the selection and utilization of the most suitable biological material examined by means of the most appropriate scientific
techniques and instruments. It has long been recognized that the amphibian egg is an unusually useful material in embryological research.
Around the turn of the century, the amphibian egg was intensively
studied with the light microscope in an attempt to demonstrate chromosomal continuity during meiosis (see references in Wischnitzer, 1961). At
the same time, Roux (1905) established the field of experimental embryology with his pioneering investigation of cleavage in the frog egg. Somewhat
later, this field was expanded by Spemann (1919), who used the salamander
1
This study was supported by a Public Health Service research grant (GM-1270602) from the National Institute of General Medical Sciences and a research career
program award (K3-HD-5356-03) from the National Institute of Child Health and
Human Development.
131