Pregnant Mice Prove Environment, Heredity Cause Deformities in Young

The Soviet theory that environment shapes most human qualities and the Nazi theory of inherited racial supremacy both "appear to be nonsense," according to a scientist who has produced cleft palate, misshapen brains and many other deformities in mice.

Nearly every physical deformity found at birth appears to have many causes, some inherited, others experienced in the embryo, Dr. Theodore H. Ingalls, associate professor of Epidemiology at the School of Public Health, said last night. "Environment and heredity are to be appraised as overlapping influences, with the first dominating in one situation, the second in another," he declared.

Ingalls delivered the New York Academy of Medicine's fourth lecture for laymen in the current series of six.

Studied Defective Children

He stopped into the 250-year-old controversy on heredity versus environment after four years of research on deformities in mice caused by injury to the embryo, and after studies of many defective children and their mothers at five Boston hospitals.

Even sunburn, which can occur for the first time long after birth, is the result of "an intricate sequence of reactions which involves both the genetic equipment of man and the environment in which he lives," he pointed out.

It depends on the agent (the sun), the inherited qualities of the victim (blonds are more susceptible than brunets) and the environment (climate, altitude, time of year).

Ingalls and co-workers have shown that many deformities previously thought to be inherited are brought on in large part by unfavorable environment before birth--by, injury, illness or some other defect in the pregnant mother.

Exposed Prognant Mice

They devised a vacuum chamber in which they have exposed hundreds of pregnant white mice, each for a period of five hours, to a shortage of oxygen similar to that 28,000 feet up, the height of Mt. Everest.

The mice produced a large percentage of defective offspring, and the defects varied according to the stage of pregnancy at which the mother breathed the rarefied air in the vacuum chamber.

"White mice," he explained, "had severe deformities of the brain, skull and skeleton when the mother had too little oxygen on the eighth day of pregnancy. Cleft palate was a common result of exposure on the 14th day, and a curious defect of the eye and eyelids--so-called 'open eye'--when the pregnancy had advanced to about sixteen days."

But Ingalls emphasized that the stage of pregnancy and the lack of oxygen were not the only factors in determining the nature and extent of the defect.

Many of the offspring of mice put in the chamber were normal, and the seriousness of the defects varied widely even in the same litter, indicating that some mice could resist the injury better than others.

Heredity Important

One striking experiment indicated that heredity can be a decisive influence. Ingalls said that when a completely different strain of mice--brown mice--were put in the vacuum chamber on the ninth day of pregnancy, more than 15 per cent of their offspring had hernias: yet there were no hernias in the offspring of several thousand white mice who had had the same experience.

"The probability is that constitutional susceptibility is inherited and that the specific defect is brought about by stress," he commented.

The studies on mice do not necessarily apply to humans, Ingalls emphasized; nor do the classic studies which showed how certain qualities are passed from generation to generation in flowers and insects.

Must Study Population

"The clinical case helps to point up the problem," he said. "Experimental genetics contributes to theory. Only through studying the population, however, can we hope to prove whether or not forces shaping sweet peas, fruitflies and white mice also govern the destinies of human beings."

At present, he admitted, it would be difficult to apply knowledge thus gained to improving the human race by improving mating habits.

"I have yet to see a young couple be introduced with the warning that the hand-some man is RH positive while the girl in the dress with the green sleeves is RH negative," he said.

But he felt that "outside the laboratory walls lies the real arena of life; the real challenge to use the forces determining health and disease to improve the quality of the newborn child rather than the quantity of our offspring."