Simmel, E B OBSERVATIONS ON THE UPTAKE OF TRITIATED THYMIDINE IN THE PRONUCLEI OF FERTILIZED SAND DOLLAR EMBRYOS. [electronic resource] - The Journal of biophysical and biochemical cytology May 1961 - 59-65 p. digital Publication Type: Journal Article ISSN: 0095-9901 Standard No.: 10.1083/jcb.10.1.59 doi