Part 4
86. The decidual vessels derive their fluid from the uterine vessels. The arteries which convey uterine blood to the decidual vessels, are tortuous and very small; they are the adventitious produce of the _membrana propria_ of the womb acting under the influence of a peculiar stimulation which produces the decidual membrane, as inflamed surfaces produce organized exudations. Though the latter be formed in the uterus, even when the embryo is lodged, by aberration, in some other part of the abdomen, its presence must not be deemed, on that account, unessential to the embryo; for a vascular membrane, as nearly alike to it in texture as can be, has invariably been found to connect, by blood-vessels, the embryo to some vital part nearest to where that embryo has been casually deposited, that part having, at the same time, its circulation and vascularity greatly increased, and becoming, in fact, the parent of the connecting vascular membrane in question.
87. Nothing proves more distinctly, (it might be said, almost to demonstration,) the accuracy of the views (82, 83, 84, 85) which tend to establish the fact of a vascular communication between the arterio-venous system of the mother and the placenta (by intermediate decidual circulation) and to shew the fallacy of those who deny such a communication, than the very phenomenon just noticed (86). Here, morbid anatomy again comes to the assistance of normal anatomy and physiology, and affords evidence which is not liable to the errors that have been unjustly affixed to experimenters with injected fluids. Of the many examples that might be quoted in support of this proposition, the one which is stamped with the authority of Lallemand may be selected as the most striking[18]. In a case of ventral aberrant fœtation, which had proceeded to the end of the sixth month, before it destroyed the patient, a vascular and tomentous membrane had been formed on the surface of the peritoneum, to which adhered the regular placenta and chorion of the fœtiferous ovum. This membrane resembled in every respect the decidua, at six months—it was thicker, and more red and vascular where the placenta was adherent than any where else. “Vessels as visible as those of the inflamed conjunctiva,” observes the author, “passed from the highly injected peritoneum, opposite the placenta, into the membrane which lay between them; while other vessels from the placenta reached as far as the same membrane, and were lost in it where they probably anastomosed by their very minute terminal ramifications.” (Lallemand). The conclusion which this really eminent physiologist and good man has come to, upon this subject, is striking, and truly to my purpose. “The decidua,” says he, “has no other function to perform than that of serving as a capillary system, intended to be the medium of communication between the blood-vessels of the mother and those of the fœtus” (page 21).
88. It is possible that the venous blood of the decidual vessels may be returned through the great uterine sinuses, the large open orifices of which, covered with an almost valvular flap, have been described by the best anatomists, as being applied to the surface of the decidual placenta. Magendie[19] thus states his opinion on this subject. “In women large openings, which communicate with the uterine veins, are observed on that part of the uterus to which the placenta adheres; but it is not clear whether these venous orifices are destined to absorb the blood of the fœtus, or to suffer that of the mother to escape on the surface of the placenta. I am inclined to admit the latter idea—but no proof whatever exists of its correctness.” (page 554).
89. Such is the real structure of the human placenta (77 to 88, inclusive). Its description is founded on positive and direct experiments, first-rate authorities, and anatomical inquiries, which may be repeated, referred to, or ascertained any day, and to which many can bear witness: any other description differing from it and not so grounded, must be erroneous. This view of the real structure of the placenta differs from that of Dr. Hunter only in the non-adoption of that great man’s notion that continuous vessels go from the uterus, _through_ the decidua, direct into appropriate cells or laminæ, where he supposed that the arteries deposited their blood, which the veins pumped back into the uterine system of the mother, after it had served the purpose of bathing the terminal or cotyledonic vessels of the fœtus. The existence of cells, however, has been frequently denied, and by none more stoutly than by Professor Lauth, of Strasburgh, and others; but as these individuals deny, at the same time, that which a hundred anatomists of great skill and veracity have seen, namely, the transmission of fluids, by means of decidual vessels, from the uterine system into the placenta, their opinion is liable to suspicion. However, it is unquestionably true, that on looking at the appearance exhibited by the fluid injected from the uterine vessels, in those portions of the placenta which it reaches, (Experiment at the Middlesex Hospital, 85,) we feel more inclined to consider it as dendritic and ramose, than extravasated or diffused. I entertain the former opinion. I submitted a thin section of the injected placenta (March, 1833) (85) to a powerful magnifying lens before a very strong flame of an argand burner, and could not perceive any sensible difference between the appearance of the red and that of the yellow injection. Now, that the latter, which was thrown in through the umbilical vessels, had been deposited within minute vessels, and not within cells, no one doubts. It is, therefore, likely that the other fluid is also so deposited. If Hunter and his followers were wrong in their conclusions, (though accurate in their experiments,) Professor Lauth, and the author of a paper on the placenta, inserted in the Philosophical Transactions for 1832, (who, by a most singular coincidence repeats all that Lauth had said long before him respecting the non-existence of cells and of continuous vessels from the uterus in the placenta) are not less chargeable with even greater errors; inasmuch as they have denied anatomical facts which have been observed and ascertained by many. They have overlooked the function of the decidual vessels, and they have said not a word of that beautiful arrangement of the fœtal vessels of the placenta which Dr. Hunter compared to the “vascular portion of the chorion forming part of the placentulæ in a calf,”[20] and which I have succeeded in demonstrating in a human placenta prepared for that purpose, and still in my possession (79, note). It is evident that under such negative circumstances their view of the structure of the human placenta, and its connection with the uterus, will be repudiated.
90. The circulation of the blood in the Ovum is independent of that of the mother (personal experiment (59), and all the more recent physiologists). The embryo creates its own blood, and through it, sustains its own existence. But its blood, like that of all other animals, whether during its intro or extra-uterine life, requires to undergo certain changes at every minute period of that life—and those changes it experiences through the influence of the blood of the mother. (Magendie, Mende, Pockels, Baer, Chaussier).
91. The function of the Placenta, therefore, seems to be to facilitate, and in good truth to effect, the necessary changes in question (90). The decidual vessels receive the arterial blood of the mother. This is spread over a very considerable surface of tubular structure, which being, in its distribution, made to come in apposition with the infinite ramifications of the umbilical placental vessels, at innumerable points, (like the inspired air distributed through the bronchial passages is made to come in apposition with the myriads of vascular rami of the lungs); the required changes in the blood of the fœtus are produced, just as the changes called for in the pulmonic blood, are produced by the peculiar arrangement of that part of the animal economy. When the arterial blood of the mother has produced the desired effect on that of the fœtus—it is returned by the decidual veins to the uterine sinuses applied, like absorbing mouths, to the surface of the decidua, when it enters into the general venous system of the mother (Magendie; Personal Observations).
92. Of the two vascular systems, forming the machinery of the utero-decidual and fœto-placental circulation, (82 and 77,) that of the former is the smallest and least extensive (See injections in all the Museums). In point of origin, also, the latter has precedence. The Umbilical vessels unite the fœtus to the chorion before any regular placenta is formed outside of the membrane. Up to the tenth week the decidual vessels are as yet slender, straight, and insulated; while the umbilical vessels begin already to arrange themselves into minute cotyledons[21]. The reason of these arrangements is obvious. The embryo needs growth. This it gets through the maternal blood. But as its gossamer frame, for the space of two and three months, requires but little assistance from such a source for the promotion of growth; and as a large supply of maternal blood, at that early period, would overwhelm, instead of enlarging, the embryonic fabric, such an arrangement of means only obtains, in the reciprocal circulation, as is calculated to ensure the desired effect (Personal Observations).
93. This effect is nutrition. “Considering the power which the Ovulum displays when it first reaches the uterine cavity, of imbibing matter for its growth, together with the facility with which, according to Dutrochet, fluids may be drawn through animal membranes, it is not difficult to believe that nourishment is directly imbibed from the vessels of the mother by the circulating fluid of the embryo, through the fine intervening membranes.” (Mayo’s Outlines of Physiology, p. 437. 3d. Edit.)
94. It is possible, also, that other means may be at play in the promotion of such an effect (93) in the fœtus, besides the one before mentioned (91). We may instance as a probable one, lymphatic absorption. The probable existence of lymphatics in the placenta was admitted by Dr. Hunter. “It is most probable that it (the fœtus) is nourished by thousands of small lymphatic vessels which absorb nourishment from the blood of the mother and carry it along the navel-strings. It is true we cannot see any lymphatics running upon the navel-string, _yet it is reasonable to conclude they do_.”[22] Hunter’s conjecture has since been realized (Chaussier, Fohman, Uttini, Lauth). The second of these anatomists has delineated them in rich profusion, extending from the placenta along the funis, leaving the funis at the navel, and directing their course to the groin (Mayo).
95. Some have ascribed the nutrition of the fœtus to a regular deglutition and digestion of the amnionic fluid. Many facts render this opinion probable (Meckel). But there are also facts which would make nutrition by such a means impossible (Dr. Hunter). 1st. An embryo, at an early period, cannot be nourished by the mouth. 2dly. The amnionic fluid is mere water with a vestige only of albumen, the only nutritive quality in it. 3dly. A fœtus was seen whose intestine, a little below the duodenum, was impervious and divided through, and the lower end began at some distance from the higher portion. (Dr. Hunter’s MS. Lect.) 4thly. A full grown child was brought into the world without head, heart, lungs or intestines (Dr. Cooper, in Dr. Hunter’s MS. Lect.) 5thly. A kitten was sent to the Royal Society, full grown, born without either nose or mouth. (Dr. Hunter, ibid.) 6thly. I have the drawing of a pig (the preparation of which I exhibited at the Med. Ch. Soc. in 1814,) which was born, at the proper period, and full grown, without any vestige of the under jaw, and consequently without either mouth or any passage into the stomach.
96. Some have thought that the amnionic fluid was absorbed through the pores of the skin (Osiander), others through the mammæ of the fœtus (Oken). That the vesicula intestinalis (umbilicalis) contributes to the growth of the embryo is a great deal more probable (Blumenbach, Sœmmering, Lobstein, Joerg.) It is also not improbable that the gelatine of Wharton, contributes to that object (Lobstein). But these are all conjectures, for the probability or improbability of which as many arguments and real facts have been alleged on equally unquestionable authority. “Ce sujet,” observes Magendie, “a souvent exercé l’imagination des physiologistes, sans aucun profit réel pour la science.”
97. I am more inclined to believe in the existence of respiration in the fœtus as an additional means of facilitating growth and entertaining inherent life (Geoffroy St. Hilaire, Müller). The presence of air, analogous to atmospheric air, in the amnionic fluid, has been detected (Lassaigne). I once had in my possession an intact ovum at five months (30th June, 1826,) which served me for the purpose of studying more particularly the real structure of the placenta, and which contained, besides the amnionic fluid, a bubble of air about the size of a small plumb. Only a portion of this was, through the awkwardness of my assistant, received in a glass tube containing distilled water, while I punctured, under water, the membranes in the centre of the bubble. This portion was afterwards made to pass through a saturated solution of lime in water, and produced a visible cloudiness denoting the presence of carbonic acid. The respiration of the fœtus is supposed to be effected by the cutaneous pores, as in aquatic insects (Geoffroy St. Hilaire). In addition to which the placenta is looked upon as performing the office of lungs (Müller). Dr. Edwards’s experiments on the asphyxia of the _Batraciens_, may serve to throw light upon this question (Breschet).
98. The nature of the changes which the blood in the fœtus may be supposed to undergo from arterial to venous, and the converse, has not been satisfactorily ascertained. The colour of the blood in the umbilical vein is something lighter than that in the umbilical arteries (Mayo). This alleged change is not admitted by others (Meckel). I have never been able to detect the least difference between the arterio-umbilical and venous-umbilical blood, in the many cases I have examined. But the absence of any change of colour does not necessarily imply the absence of any inherent change in the blood of the two systems. The globules of the fœtal blood do not resemble those of the blood of the mother (Experiments alluded to by Dr. Breschet).
99. Connected with the subject of the nutrition of the fœtus and the changes which take place in the blood of it, may be mentioned certain recent discoveries[23], which would lead to the belief, that the function of the placenta is probably analogous to that of the liver during the intro-uterine life of the fœtus, and that the presence of bile in the blood of the placenta, discovered by modern chemists, is necessary to the maintenance of fœtal life (Breschet).
100. It is of the utmost importance to bear in mind the great distinction which exists between the independence of the fœtus, _quoad_ life, and its dependence, _quoad_ nutrition, in respect to the mother. The former state is secured by a total separation of the two circulations (maternal and fœtal). The latter by the close reciprocal contact of the organs of those circulations. Thence is it that we find the fœtus to live on, notwithstanding that its connection with the mother has been partially and sometimes even wholly, severed;—while on the other hand we cannot help admitting that, albeit this independence, the influence of the mother over the fabric of her offspring is unquestionable.
101. Here are two important positions. I have mentioned my experiments on the intact ova of the genus cat, (59,) to illustrate the first of them, and Dr. Prevost has since come to my assistance with as strong a case in further support of it[24]. This gentleman having observed an ovum still alive in the uterus of a ewe, which was a short time advanced in gestation, removed it and placed it upon a warm glass plate exposed to the rays of the sun, and attentively examined it with the microscope. The beatings of the heart became more lively. He noticed the blood arise to the surface of the chorion from the fœtus, there ramify plentifully, and by anastomosing vessels, return to two of the larger trunks which were the veins of the embryo. He concluded, therefore, that the ovum was an isolated substance.
102. In proof of the accuracy of the second position, we have equally strong evidence founded on experiments. Magendie introduced camphor into the veins of a pregnant bitch, and he found that the blood of the fœtus had, at the expiration of a quarter of an hour, acquired distinctly the smell of that drug (Physiology, 2d Edit. 1825). Quadrupeds carrying young were made to take with their food four ounces of madder-root. The colouring matter of that substance was found to have passed from the mother to the fœtus; as all the serum of the blood of the latter, the urine, the liquor amnii, the teeth and the bones were tinged with it (Dr. Mussy, 1829)[25]. In 1827, I undertook, at the request of Sir E. Home, a set of experiments on the human subject, with a view to ascertain the truth of my second position. Six gravid patients of one of the lying-in institutions under my direction, who required the constant use of aperient medicines, were instructed, towards the close of their time of gestation, to take at night, for a period which averaged about a week, from ten to fifteen grains of rhubarb in powder. After two or three days the effect was visible in the colour and smell of the urine of the patients previous to their confinement, and in one of them, in the colour and smell of the transpiration also. During the labour care was taken to preserve part of the amnionic fluid in a cup, the umbilical vessels were suffered to bleed on the side of the child after their recision, and the blood set apart so as to separate the serum, which was obtained in small quantity only.—Lastly, the first urine of the child was collected in sufficient portions. Each of these secretions appeared distinctly tinged by the yellow root, and bore the smell of it. When carbonate of magnesia was mixed with the fluids their colour became lateritious, and a reddish sediment was thrown down, evincing the presence of the drug which the mother had ingested. (MS. notes.)
ERRATA.
PROLEGOMENA.— Page iii, Prop. 20, _for reference_ (16), _read_ (17).
Page vii, Prop. 39, _for_ Haygton, _read_ Haighton.
———— idem, _for_ Embryoni, _read_ Embryonis.
Page viii, Prop. 46, 1st line, _dele_ (5).
PLATE III.— Page 9, Exp. of Fig. 13, _for_ membrane proper, _read_ membrana propria, and the same mistake occurs at pages 11, 14, and 26.
The following letter from the artist to whose skill and patience I am indebted for the principal part of the engravings, and the entire colouring of the present collection, is inserted in this place, with the hope of increasing that confidence in the reader, with which it is desirable that graphic representations of extraordinary or anomalous objects should be received.
9, Warren Street, Fitzroy Square, January 27, 1832.
DEAR SIR,
In sending you the last of the series of engravings on stone which I have executed under your directions for your work on Abortion, &c., I cannot omit stating, that I have endeavoured, to the best of my abilities, to copy in every instance and every minute particular the anatomical preparations which you placed before me and explained to me as I proceeded in my designs. The figures, in every case, have been drawn of the natural size, and are perfect facsimiles of the originals.
It gives me great pleasure to learn that they have given you satisfaction, and I am not a little flattered at having been assured by several medical gentlemen of eminence, who have seen my drawings, that the manner in which they are executed, and the work altogether, meet with their unqualified approbation.
I have the honour to be, Dear Sir, Your obedient servant, JOSEPH PERRY.
To DR. GRANVILLE, &c., &c., &c.
GRAPHIC ILLUSTRATIONS
OF
ABORTION
AND
THE DISEASES OF MENSTRUATION.
EXPLANATIONS,
ETC.
PLATE I.
SPECIMENS OF VERY EARLY MISCARRIAGES.
Fig. 1. Ovulum bigeminum lanuginosum.
(Four weeks after menstruation.)
This twin Ovulum has lost its outer shell or _cortex_, within which it originally made its way from the Ovarium into the womb.
The mossy or filiform vessels which, like an efflorescence, surround the present surface of the Ovulum, are, as yet, deprived of that extremely delicate membrane, which at a more advanced period of utero-gestation will cover them, and dipping amongst them, (after the fashion of the inner membranous envelope of the brain,) will separate them into vascular groups or cotyledons, having a single principal trunk in each, and many short and tortuous branches besides, constituting the placenta.
The slit visible in one part of the Ovulum leads to a small cavity from which the embryo escaped. In the second cavity to the left, which is still intact, the embryo is visible when the Ovulum is placed before a strong light.
Fig. 2. Ovulum semi-lanuginosum.
(Three weeks and a half after menstruation.)
In this specimen of an early miscarriage, the Ovulum exhibits the filiform vessels as in No. 1; but one half of its circumference is denuded of them, and the diaphanous involucra are distinctly visible in that part. They are represented flaccid owing to the escape of a part of the liquor amnii. In size the embryo (which required to be viewed in a very strong light) resembled that of No. 6.
Fig. 3. Ovulum lanuginosum.
(Three weeks after menstruation.)
A mossy Ovulum, shewing the inner or secreting membrane, within which I could not discover any embryo at the time of the miscarriage occurring. On searching among the coagula consequent on a very extensive hemorrhage, the Ovulum was found flat, and appeared like a confused mass. The liquor amnii had escaped, and probably the embryo along with it. The artist has most skilfully delineated the peculiar turns of the involucra where they have been divided so as to display those marked inflexions which are still more distinctly seen in No. 4.
Fig. 4. Ovulum semi-lanuginosum.
(Four weeks after menstruation.)
I look upon this as one of the most perfect specimens of mono-embryoferous Ovula at four weeks, I have seen; exhibiting as it does, not only the mossy or _nutritive_, but also the inner, amnionic, or _secreting_ involucrum, with its peculiar inflected turn, forming a _sacculum_ within which is lodged the embryo. The nutritive involucrum is separated from the middle membrane by the _allantoid_ cavity, and the middle membrane itself stands aloof from the amnion, owing to the _vesicula umbilicalis_. The existence of these various elementary parts of the human Ovum in the present specimen, shews its early development, and serves to fix its age, which I consider to be of about three weeks and a half.