CHAPTER 18

Reproductive Medicine

The Caesarean Operation

The Caesarean operation was performed at the New-York Post Graduate Medical School and Hospital yesterday for the first time in the history of that institution. This is a dangerous and a rare operation, and it is never resorted to unless the birth of a child cannot be effected by natural means. During the last year there were only eight recorded operations of this kind in the United States.

How many of these were successful there are no available statistics to show, but it is rare that both mother and child survive. It is an operation which has been performed only in desperate cases, although the recent advances in surgery have done much to decrease the danger.

Yesterday’s operation was entirely successful, in that both mother and child survived.

February 8, 1893

Birth Made Easy by the Use of Gas

By EMANIE N. SACHS

The doctor sat in a big chair back of a mahogany desk, and his nervous fingers fretted with a bronze paperweight.

“You want to know about the use of laughing gas during childbirth?” he asked, “and you’ve promised that my name will not be printed?

“Well, it is not new, you know, the use of so-called laughing gas, or nitrous oxide, during labor. As a matter of fact, Klikowitsh of Petrograd used it in twenty-five cases in 1880. It has been used in dentistry for some time, but it has only gradually come into general use in obstetrics. I am not at all certain that it is in general usage even now. Twilight sleep came along with its poetical name and its alluring promises. Eager women seized upon it. In some cases it seized upon them and their infants. It is a potent, dangerous drug. Successful under ideal conditions, but ideal conditions are dismally rare. However, women began to clamor for relief. The use of anesthetics increased and is increasing.”

Complete Anesthesia Harmful

“Ether is not evanescent enough. It has unpleasant after-effects, and should not be given for a prolonged period. Of course, an operative case creates a different situation. There ether may be necessary. Chloroform sends the patient into complete unconsciousness. Labor pains are diminished and the function stopped. The entire enterprise is delayed. Not only is that the physical effect of both ether and chloroform, but there is a psychic effect. The patient’s morale is lowered. She is not so inclined to help the physician. Laughing gas is immeasurably superior. It is evanescent. Kemp found that 20 per cent remaining in the blood after administration was reduced in two minutes to 6.09 per cent. The pains are not stopped nor are the uterine contractions which are the motor power for the birth of the child lessened. The woman has her intelligence left, but the edge of the pain is removed. I can say more than that. It is exactly comparable to having a tooth pulled under gas. The woman has no more consciousness of pain than the person in a dentist’s chair who may know that there are instruments in his vicinity, but who sinks almost into oblivion when the yank comes. I can conservatively say that the use of laughing gas renders childbirth practically painless.”

“This sounds like a cruel question, but I want to get your answer. Does the bearing of intense pain such as women have endured for so long have a bad effect on the woman physiologically?”

“Yes and no,” he answered. “The modern woman, of course, is much more highly organized nervously than her mother and her grandmother. Worry destroys some of her resistance.

“It is said that labor pains are soon forgotten. The average woman does not forget them. If she has more children it is under protest. However, I cannot say that there is any definite ill effect from the pain attendant on a normal delivery. I cannot say it definitely, but there are statistics showing that maternal mortality increases in ratio with the longer duration of the woman’s sufferings. I have a colleague who goes further than I. He says that the use of nitrous oxide, or laughing gas, not only brings relief to the patient, but that it shortens the duration of labor, permits the doctor to manipulate the child more satisfactorily, saves the tissues of the mother and hastens convalescence.”

Patient Can Give Herself Gas

“Must there be an expert anesthetist on hand during the administration of laughing gas?”

“There is a question for which there are several answers. With an expert anesthetist the birth can be absolutely painless. But there is the problem of the increased liability to use instruments, because the mother being completely unconscious is of no help. The expert mixes the gas with oxygen, which makes it more pleasant. Personally, if my patient is fairly intelligent I let her give it to herself.

“But it is necessary for a doctor to be on the premises at least. Some of my colleagues differ there, believing that the presence of a trained nurse is sufficient. Others even permit a member of the family to turn the plug on the gas tank.

“Have you ever seen a gas tank? Usually one to four tanks are provided on a portable platform about the size of a standard weighing scale. A flexible rubber pipe leads into a rubber bag resembling a football, and a smaller tube empties into an almond-shaped mask which fits over the nose and mouth. The patient feels the pain coming before it really hurts. She places the mask over her face, takes four or five deep respirations and escapes the suffering. It works automatically. She doesn’t get too much, because as soon as she is under the influence of the gas her hand relaxes and the mask drops. You know that labor pains usually come more or less rhythmically. One-half hour apart at first, increasing to every five minutes, every two minutes, and so on. For the last stage, the actual birth of the child, we all use a few whiffs of ether, a complete anesthesia.”

“Then the patient anesthetizes herself for each pain, with a lapse to consciousness in between?”

“Yes, she begins to come to as soon as the mask drops. The relief has an excellent effect on her morale. She feels that something is being done for her, that she is, in fact, helping herself. She is often willing to stand a few pains in between. You have no idea of the frenzy of pain into which women have at times been plunged. They don’t know what they are doing.”

“Well, if it’s a benevolent agent, why is it not used always?”

“There’s a question. The first answer is that the medical profession is the most conservative of bodies. The second answer is concerned with economics. I told you that I believe that a doctor must be present while the gas is in use, which is for the duration of ten or twelve hours possibly—used periodically, remember. And remember also that some of my colleagues do not agree with me on that point. I have a wife and four children to support. I am an attending physician at three hospitals. If I stayed ten or twelve hours with each patient I could not make a living for my family unless I charged a fee far beyond the means of the average person. The presence of a professional anesthetist would, of course, make my presence unnecessary until the very last stage, but it would add materially to the cost as far as the patient was concerned.”

“But in the hospitals and in the free wards?”

“If the hospitals are organized to give this service, it can be practically managed there, both for private patients and in the free wards. There are always resident anesthetics who give far more dangerous drugs, ether and chloroform. There are nurses on duty to watch the hearts, in any case. The only additional cost to the hospital would be the actual cost of the gas itself.

“The point, of course, is the time element. The gas is given intermittently for four or ten hours sometimes. I think a rough estimate might indicate that it would cost about $10 for each patient if given nine or ten hours. This means the actual cost of the laughing gas. Of course, if we gave it to each woman in a hospital I know, where we confine about 2,000 women a year, that would add $25,000 to our annual budget.

“A twenty-five-thousand-dollar addition to an annual hospital budget is not to be lightly undertaken, I am afraid,” he said gravely, “but when women clamor more and more for relief I am in hopes that the time will come eventually when relief will be freely offered them.”

February 5, 1922

Painless Method Is Devised for Childbirth; California Doctor Blocks Spinal Nerves

A method of providing painless childbirth by anesthetizing the nerves carrying pain fibers as they emerge from the spinal cord was reported today by the University of California.

Dr. Herbert F. Traut, chairman of the department of gynecology in the university’s Medical School, said that it had been used successfully in about 100 selected cases at the university hospital but he cautioned that it was still experimental. The principle was “very sound,” he asserted, adding, “this is why we have such hopes for it.” He said, however, that it required expert handling and might never be widely employed by the general practitioner.

Credit for the development of the method was given to Dr. Shiras M. Jarvis, former assistant resident physician at the hospital, who is serving with the Navy in the South Pacific. A news release from the university declared that blocking the pain by means of spinal anesthesia was dangerous to the patient and frequently stopped the progress of labor.

As for caudal anesthesia, which was developed some years ago, the statement quoted Dr. Jarvis as saying that this affected the nerve pathways but “anesthetizes the skin and lowers the muscle tone of the lower body” so that “spontaneous delivery is not the rule.”

“The new method, known as paravertebral sympathetic nerve block, affects the nerves that carry the pain to the brain, and at the same time accelerates the first stage of labor,” the announcement went on. “It is accomplished by one or more injections into the nerve chains near the spinal vertebrae in the lumbar area of the back.

“Complete safety for mother and baby is maintained at all times and the patient is free to move about in bed, and can sleep or read, as she wishes.”

No harmful after-effects have been observed in the experimental cases, it was stated.

June 3, 1944

Birth Control Pills Reported a Success

Successful human use of pills as a method of birth control was reported today by Dr. Benjamin Sieve, who, while asserting he had preliminary success with them, declared further extensive studies must be made “before the general use of this anti-fertility factor is warranted.”

The Boston doctor, in a paper in the technical journal Science, said 298 married couples had experienced complete lack of fertility during periods ranging from three to thirty months while taking the pills.

He emphasized that the anti-fertility action of the chemical prevailed only while it was being taken. He said 220 of the women have had a baby and had become pregnant since terminating a period of control.

He said that the chemical was first shown to have anti-fertility action in animals by other researchers, and later confirmed in such use by himself. It is called “phosphorylated hesperidin,” and Dr. Sieve said it had previously been employed as a chemical to counteract hemorrhage.

The substance “promises safe and controllable anti-fertility,” Dr. Sieve said, adding, it “can be taken indefinitely without toxic (harmful) effects or permanent inhibition of fertility.”

The pills are taken at breakfast, lunch and dinner in dosages regulated for particular persons—and are taken by both the husband and wife. The pills must be taken for ten consecutive days before their action becomes effective, must be taken continuously thereafter to insure lack of fertility but “fertility can be restored merely by omitting the drug for a forty-eight-hour period.”

October 10, 1952

Wider Detection of Prenatal Flaws Expected to Spur Abortions

By WALTER SULLIVAN

Prenatal identification of birth defects has reached the stage where an increasing number of mothers are expected to take advantage of liberalized abortion laws to avoid the birth of children with severe disabilities.

In the long run, mass screening and weeding out of defective fetuses may become possible, but troublesome ethical questions have already arisen.

Where birth defects are suspected, or identified, in a fetus, what are the rights and obligations of the mother, the father, the physician, and the society that may have to render lifelong support to the infant?

What are the rights of the unborn child?

For example it is already possible to identify before birth (and abort) any fetus that will be mongoloid. Since half of all mongoloid children are born to mothers of 35 or older, by screening all such mothers in early pregnancy it should be possible to halve the birth rate of such infants.

It has been estimated by public health specialists that by 1975, if present birth rates continue, the yearly cost of maintaining mongoloids in the United States will have reached $1.75 billion.

Parley on Problems

Last weekend a conference of specialists in law, genetic screening, obstetrics, abortion, public health and related subjects was held at Columbia University Law School to explore these problems. The subject was “The legal, social, and biological significance of prenatal genetic diagnosis.”

The meeting was organized by the Council for Biology in Human Affairs of the Salk Institute in La Jolla, Calif. The participants, many of them distinguished university professors, spoke freely on these delicate subjects since their remarks were “off the record.”

The extent of scientific concern in this area was also reflected in the testimony of Dr. Joshua Lederberg, winner of a Nobel Prize for his genetics research. Appearing before a House appropriations subcommittee on Wednesday, he urged formation of a national task force to identify and coordinate research in critical areas of genetics, particularly as they apply to genetic disease.

Prenatal screening depends on a procedure known as amniocentesis. A needle is inserted through the abdomen of the mother and a small amount of amniotic fluid is withdrawn from the sac in which the fetus is floating.

This fluid has special analytical value because it is normally swallowed by the fetus: which also discharges urine into it. The fluid thus contains cells washed from the interior of the fetus, plus cells from its exterior and from the sac.

Amniotic Fluid Test

All of these cells are genetically part of the baby. About one cell in a thousand is still alive in the withdrawn fluid and can be cultured in the laboratory. During cell division the genetic material forms into chromosomes that can be photographed and sorted to see if the fetus has the proper quota of 23 chromosome pairs, or 46 in all.

If it has 47, with three, instead of two, “No. 21” chromosomes, it will be mongoloid. If it has an abnormal quota of the sex-determining chromosomes, it may either be mentally retarded, prone to violence, stunted, very tall—or normal and even of above-average intelligence.

By allowing the cultured cells to multiply until they number in the millions (they double roughly once every 24 hours), it is possible to test their chemistry for inherited disorders such as those where a particular enzyme is missing and the body chemistry goes awry.

However, while there are some 1,200 genetic diseases—as noted by Dr. Lederberg, a number far larger than most physicians realize—only eight of those involving biochemical defects have been identified so far by prenatal screening.

According to participants in last weekend’s conference another 20 or 30 such defects seem within reach, including the enzyme deficiency known as phenylketonuria, or PKU, but the great majority will be difficult to identify in this way.

The reason is that cells found in the amniotic fluid tend to be of the type that evolve into connective tissue, rather than into more specialized organs. The chemical functions within such connective cells, by and large, are not those that figure in inherited disorders.

Challenge to Researcher

However, like other body cells, those found in the amniotic fluid carry instructions for all body chemistry, even though most of the instructions are latent. Some optimists hope the cells can somehow be coaxed into performing enough of this latent chemistry to show whether or not the person-to-be is destined for trouble.

Another approach is to identify latent genetic defects in the parents. If both parents, although healthy, carry the same latent defect, there is a one-in-four chance that it will appear as a disease in their offspring.

Such latent, or “recessive,” genes can now be identified in some cases by a series of chemical tricks. Each individual carries two genes, or bits of genetic instruction, for every human characteristic: one from each parent.

A recessive gene is thought often to be an inoperative part of the genetic code. If it is mated with a normal, or dominant, gene, the latter does the necessary job (such as making a certain enzyme) although usually at only half the rate, had there been two active genes of this type. However if both genes for the process are recessive, the function is not performed, and the person may be seriously affected.

Radioactive Tagging

Ways have now been found—for example at the University of Colorado—to look into the chemistry of a person’s cells and see if a particular recessive gene is there.

This is done in a sample of his body cells by tagging a starting substance with radioactive atoms and seeing if each step of the chemistry runs at full speed. If one step runs at half-speed, a hidden recessive is suspected.

This has already been done, for example, in the case of galactosemia, an inherited disorder in which the body lacks an enzyme needed to process sugars. Death or mental deficiency can result. If both parents carry the recessive gene for this disease, they can be warned of the danger to their offspring.

A major difficulty in performing abortions, once a defect has been identified, is the length of time required for the identification. While attempts to remove amniotic fluid have been reported in pregnancies only eight weeks old, the risk of injury to the tiny fetus at such an early stage is considered too great.

Time Running Out

By 14 weeks, with the fetus in a cupful of fluid, a skilled specialist can do the job, being careful to locate and avoid both fetus and placenta. By 18 weeks, according to specialists, “any experienced obstetrician” should ultimately be able to carry out the procedure.

However it then takes a week or more to culture the cells and identify their chromosomes. Furthermore in 10 per cent of the cases the procedure may have to be repeated. By then it is close to the 20th week, beyond which time many physicians are reluctant to abort.

The fetus may have begun to move at the 15th week and so the mother, too, may shrink from the procedure.

During the first 13 weeks an abortion is relatively simple, particularly using the suction method devised by the Chinese in the 1950s. Until recently the standard method was to dilate the cervix and scrape the uterus, being careful to remove the tiny placenta, lest prolonged bleeding ensue.

Many physicians now consider the suction method simpler, and kinder to the uterus. A small device inserted by way of the cervix sucks out all that needs to be removed without need for scraping.

A fetus more than 13 weeks old must be removed surgically or “salted out.” In the latter procedure some amniotic fluid is withdrawn and replaced with highly saline water. This causes death of the fetus and usually induces labor.

An experimental method, using a slow drip of prostaglandin into the bloodstream, is said to have induced labor in about 90 per cent of women less than 20 weeks pregnant. Prostaglandin is a product of both male and female reproductive systems. The process has to be closely watched, as it may induce vomiting and other side effects.

However, some physicians see it as an early step toward what might become a “do-it-yourself” method for early abortion.

The cost of prenatal genetic screening now exceeds $100, largely because of the laborious process of chromosome isolation. Furthermore, it has only been carried out in early pregnancy on a few hundred women and so recently (largely within the last 18 months) that latent ill-effects have not had much chance to appear.

Nevertheless the results reported so far have spurred optimism. At least partial automation of the analysis and economies from large-scale operation should bring down the cost, leading to forecasts that, at least with women over 35, such tests will become routine.

Should they be made mandatory, like vaccinations? What if a fetus is found to have a defect of the sex chromosomes that does not necessarily lead to an abnormal life? Who decides on abortion, the mother alone or she and the father?

Could an older mother who bears a mongoloid child sue her obstetrician for the cost of supporting such a child, if he did not perform a prenatal test? And to what extent should the Government take advantage of the new capabilities for preventing the birth of individuals destined to a life of misery and dependence?

The conferees last weekend examined these questions, but they were far from agreed on the answers.

June 13, 1970

Woman Gives Birth to Baby Conceived Outside the Body

By WALTER SULLIVAN

The first authenticated birth of a baby conceived in laboratory glassware and then placed in the uterus of an otherwise infertile mother occurred last night, apparently without complications.

Reports from Oldham General and District Hospital in Lancashire said the baby, a girl, was delivered by Caesarian section, appeared normal and weighed 5 pounds 12 ounces.

The birth culminated more than a dozen years of research and experimentation by Dr. Patrick C. Steptoe, a gynecologist, and Dr. Robert G. Edwards, a Cambridge University specialist in reproductive physiology.

Unable to Conceive

The parents are Mrs. Lesley Brown, 31 years old, and her husband, John, 38, a railway truck driver from Bristol.

Mrs. Brown in more than 10 years of marriage had been unable to conceive a child because of a defect in the oviducts, or Fallopian tubes, which each month carry egg cells from the ovaries to the uterus. It is during this passage that the egg cells are fertilized.

In the procedure that culminated in last night’s birth, an egg cell was removed surgically from Mrs. Brown’s ovaries last Nov. 10 and fertilized with sperm from her husband in a petri dish. After two or more days in a laboratory culture, the fertilized embryo was injected into Mrs. Brown’s uterus.

More conventional methods had been attempted in an effort to get Mrs. Brown to conceive, including surgical reconstruction of her oviducts. But the efforts failed, and about two years ago she turned to Dr. Steptoe and Dr. Edwards for treatment.

There have been previous reports of so-called “test-tube babies” but none have been authenticated. The Steptoe-Edwards efforts, which failed a number of times, have been followed closely by the medical profession.

While the experimenters have often been frowned upon, they also are highly regarded by many in the field of obstetrics.

Working with a succession of patients, Dr. Edwards has gradually improved his ability to manipulate the hormones that control the reproductive cycle.

Perfection of Technique

Dr. Steptoe has used a surgical procedure known as laparoscopy to enter a woman’s abdomen at the appropriate moment in her monthly cycle to retrieve one or more egg cells. The device, placed through a small incision near the navel, illuminates the target area and allows the surgeon to identify and withdraw by suction early mature egg cells.

Once the egg cells have been exposed to sperm, and once microscopic examination after a few days has shown that an embryo is developing normally, the embryo is placed in the uterus with a tube inserted through the cervix.

It is estimated that one-fifth of one-half of women who are sterile are unable to bear children because of absent, defective or blocked oviducts. Because of that, it can be assumed that there will be considerable pressure on physicians to repeat the performance of Drs. Steptoe and Edwards, even though their work is still at a very experimental stage.

The chief problem encountered by the two doctors has been obtaining a satisfactory implant of the embryo in the wall of the uterus.

Problems with Hormones

In normal reproduction, the embryo lingers a day or more in the oviducts after fertilization and does not implant itself until, through cellular division, it has reached a multi-celled stage.

This process is controlled by hormones issued from various organs, including the ovaries, and from the embryo itself. The early efforts of Drs. Steptoe and Edwards were frustrated because their performing part of this process outside the body upset the hormonal signaling system.

Furthermore, the woman in many of the attempts was given added hormones to induce multiple egg production. The doctors hoped that this would give them more egg cells, improving their chances of success, but the added hormones seemed to throw the normal reproductive system off-balance.

Another fear was that culturing the embryo in glassware for four and a half days, as had been done, might place too severe a strain on it.

Experiments on Monkeys

Shortly before their removal of one or more egg cells from Mrs. Brown last Nov. 10, it was learned from experiments at the University of Birmingham Medical School that rhesus monkey embryos inserted into the uterus after only one or two cell divisions could survive.

This suggested that the embryos of primates, including man, might differ from other mammals in being able to withstand implantation into the uterus at so early a stage.

Some specialists therefore suspect that Drs. Steptoe and Edwards may have decided to implant Mrs. Brown’s embryo after only two days, allowing it to enter the uterus well before its normal implantation stage.

Reports from the hospital, this morning said that the baby was born just before midnight and that its condition was “excellent.” Mrs. Brown and her husband were reported to be jubilant.

Once the fetus began developing, its own hormonal signals generated all the effects of a normal pregnancy. Mrs. Brown is reported to have experienced the sort of cravings often reported by pregnant women—in this case, a yearning for mints!

July 26, 1978

Scientists Study Freezing and Storing of Embryos

By WALTER SULLIVAN

The freezing and storing of embryos, already routine with cattle, could provide an infertile woman with “a whole family” of children after a single egg-harvesting procedure, according to the two doctors who brought such a patient to the successful delivery of a baby girl late last night.

As Drs. Robert G. Edwards and Patrick C. Steptoe have done in previous attempts to overcome infertility over the last 12 years, a doctor would use hormones to stimulate “superovulation,” or the simultaneous production of many mature egg cells instead of the usual single cell. The eggs would be surgically removed, exposed to the husband’s sperm and cultured briefly in the laboratory.

Then—and this has never been done with humans, as far as is known—the egg cells that showed signs of normal development as fertilized embryos could be frozen.

A month or two later, and at intervals of a year or more, the embryos could be implanted one by one in the woman’s uterus and allowed to mature into babies in the normal manner. In this way, according to Drs. Edwards and Steptoe “a whole family could be established.”

In the case of Lesley Brown, whose daughter was born last night, only one egg was removed and it was implanted two days later, according to an article on Monday in the Daily Mail. This implied that the superovulation technique was not used. The London newspaper and its parent organization, Associated Newspapers, have bought the exclusive rights to personal accounts by those involved.

Mrs. Brown, who will be 31 years old on Monday, and her husband, John, 38, a railway truck driver from Bristol, had been trying for more than a decade to have a child. The difficulty was diagnosed as a defect in the oviducts, where egg cells are fertilized and through which they descend to the uterus.

After various unsuccessful attempts, including surgery, to correct the condition, the Browns turned to Drs. Edwards and Steptoe. Over a two-year period, Mrs. Brown made a number of visits to Dr. Steptoe’s clinic in Oldham, a Lancashire mill town, and there may have been several implantation attempts before the successful one, last Nov. 10.

While Drs. Steptoe and Edwards have shunned interviews on the Brown case, they have spelled out to colleagues their idea of producing a number of embryos from one egg-cell harvest. They described the procedure, for example, in a published account of a symposium on embryo freezing that was organized last year by the Ciba Foundation.

Many similar procedures, except for laboratory fertilization, have been used with livestock for some time. Breeders have no reason to produce offspring from an infertile female, so fertilization is achieved in the normal manner, with the embryos flushed out of the uterus.

Survival for Years

Scientists working with the freezing of animal embryos believe that once an embryo has been chilled to the temperature of liquid nitrogen (minus 321 degrees Fahrenheit), it will survive indefinitely. Lambs have been developed from embryos frozen for two and a half years.

However, the optimum cooling rate and stage of embryo development for freezing varies from one species to another and can be learned only through experimentation.

The freezing technique has already led to extraordinary juggling of generations, including a case in which a lamb was born to its sister. After both embryos were flushed from the uterus of a ewe that had been stimulated to superovulate, one was implanted in a foster mother. The other was frozen until its sister was full grown, whereupon it was thawed and implanted in the sister. It developed into a healthy lamb.

Experiments with freezing livestock embryos have been intended primarily to facilitate shipment of new, highly productive strains. Another goal, however, is establishing deep-frozen “embryo banks” that would preserve the genetic diversity of domestic animals, laboratory mice and endangered wildlife.

Establishing such banks is a goal of Dr. Christopher Polge of the Animal Research Station of Britain’s Agricultural Research Council near Cambridge, England. In a recent interview, he said that normal young had developed from once-frozen embryos of cows, sheep, goats, rabbits, rats, and mice.

Concerns Over New Strains

Embryo banks could be the answer to fears that new livestock strains, while highly productive, may be more vulnerable to new diseases or environmental changes than those being allowed to pass out of existence. Similar fears have led to the creation of international repositories for grain seeds.

In the freezing experiments with animals, variations have been shown in the procedures required for successful freezing and thawing of embryos. For example, early experiments with mice by Drs. Peter Mazur and S. P. Leibo of the Oak Ridge National Laboratory in Tennessee, working with Dr. David G. Whittingham of Britain, showed that survival rates are high only when the embryos are cooled and thawed very slowly.

Routine implantations of thawed cattle embryos have been initiated in recent months by a Lincolnshire company, T. H. Saul Embryos of East Heckington, working with a veterinary group. According to Dr. Polge’s colleagues, the concern has already done 200 implants; most of which involved an exceptionally productive strain of Friesian dairy cattle, the embryos are inserted through the foster mother’s flank, with a 50 percent success rate.

This is said to be the first commercial application of the method, although some efforts have also been reported from New Zealand. Researchers hope to develop nonsurgical insertion, which has been done with humans—in Dr. Steptoe’s method, the embryo is placed into the uterus through a tube inserted in the cervix.

The shipping of frozen embryos has largely supplanted an earlier practice, in which rabbits were used to transport cattle embryos. The chemistry of the rabbit uterus is sufficiently similar to that of a cow to sustain such an embryo for four or five days, long enough to fly samples of exotic strains as far as Australia.

Today, however, such shipments are ruled out by quarantine regulations against such ailments as foot and mouth disease. Only frozen embryos can be stored long enough to demonstrate that its parents were disease-free.

Freezing human embryos, as Drs. Steptoe and Edwards have proposed, would provide enough time before implantation to screen the embryo for genetic defects.

Such screening could also be used to determine the sex of the embryo. This, according to Dr. Polge, has already been done in cattle, sheep and rabbits. Only embryos of the desired sex would be implanted.

As noted by Dr. Polge, efforts have been made to “determine” the sex of an embryo by exposing an egg cell only to male sperm. Segregating sperm that carry the male and female “signals,” however, has proved difficult.

July 26, 1978