Withdrawal of the liquor amnii and yolk sac fluid from the rabbit's uterus: its effects on foetus and placenta

Abstract

Among the problems of development that still await solution none has occupied a more prominent place, so far as wealth and variety of investigation are concerned, than the origin of the liquor amnii. The literature on the subject is voluminous as it has been approached from many different standpoints. Some have endeavoured to arrive at a solution from observations of pathological conditions, such as hydramnios and oligohydramnios in the human subject; others have made exhaustive researches into the chemistry of the amniotic and allantoic fluids in the lower animals; others again. have investigated their physical properties; while yet others have relied upon experimental work , such as the injection of substances into the mother and the recovery of them in the liquor amnii. Yet the solution of the problem seems to be almost as far off as ever.

In looking over tie literature of the subject I could find no record of experiments made by tile artificial withdrawal of the fluid and the observation of Its effects. Such a line of investigation seemed to be a promising one, and I accordingly carried it out.

The results which I have obtained have been definite , so far as the effects on the foetus and placenta are concerned and as showing that no re-secretion occurred; but the first result of the aspiration of the fluid has been in all cases the death of the foetus , so that the deductions to be drawn regarding the origin of the fluid cannot be equally definite.

I have however, in my series of experiments been able to study the changes occurring in the placenta and foetus after intra-uterine death, due to an uncomplicated cause.

Thus it is that the greater part of what follows is concerned with the changes which occur in the retained placenta subsequent to the death of the foetus. I do not know of any similar observations on the lower animals. My results are interesting from the light which they throw on the pathology of the retained human placenta and on the changes which the foetus undergoes when it is retained in utero after its death.

The animals selected for observation were rabbits. They were chosen because of the facility with which they can be obtained and bred, and also because the normal structure of the placenta has been very fully worked out, especially by Minot, Duval and Chipman. To the work of the latter I am especially indebted as giving the most minute and detailed account of the whole gestation period. In my own specimens of normal placentae I nave also been able to follow out the series oi changes which occurs from the 8th day onwards - observations which it was essential to make, in order to interpret properly the pathological appearances induced by the experiments carried out. Though a short description will be given of the normal structure of the placenta of the animals operated on, both at the time of operation and at the post mortem, it may be well here to summarise the facts known regarding the anatomy of the genital organs of the rabbit and the development of the foetus and placenta.