Science: Pincogenesis

A scientist who tricks Nature—for sound scientific reasons—is bushy-thatched Dr. Gregory Goodwin Pincus, formerly of Harvard, now of Clark University (Worcester, Mass.) Some years ago Dr. Pincus accomplished the first fertilization of mammalian ova in vitro—a polite way of saying that conception took place in a glass vessel. He took ova from a doe rabbit, sperm from a buck, mixed them in a culture flask, implanted the fertilized ova in another doe which, at term, produced a fine litter (TIME, March 12, 1934). Since then the scientist has been able, by skillful coddling, to keep fertilized ova alive for ten days in vitro before implantation in the mother.

Last week Dr. Pincus exhibited a further marvel—a fatherless rabbit, born from an ovum which had never encountered the male fertilizing element at all. This process, called parthenogenesis, occurs naturally among certain insects, has been artificially induced by man in sea urchins and frogs, but never before in a mammal. Dr. Pincus used high temperature, hormone treatments and hypertonic salt solutions* to fertilize the ovum, and his canny microsurgical technique got the egg well started toward normal development in the host mother’s reproductive tract.

Normally the male spermatozoon is what determines the sex of the offspring. If the spermatozoon has a male-determining chromosome pattern in its nucleus, the sex will be male; if not, female. Since there was no spermatozoon in the case of the fatherless rabbit, therefore no male-determining pattern, the Pincus rabbit is a female. She seems to be perfectly normal. Mated to an ordinary buck, she produced a normal litter. These bunnies are the first in rabbit history with no maternal grandfather.

Naturally a swarm of newshawks, callous to the delicate distinctions of science, bore down on Dr. Pincus to find out how soon mammalian parthenogenesis could be applied to humans. The scientist dodged these embarrassing queries. A spokesman for him huffed: “Dr. Pincus’ work will make possible certain manipulations and experiments which will aid in the study of cellular and biological growth. It is ridiculous to even think that such work could be done with human beings. This work will in no way affect the manner of living or customs.”

* Hypertonic: having a greater diffusion pressure than that of blood.