Paper - Demonstration of a very young tubal ovum
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|ectopic pregnancy and early implantation in human.
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Demonstration of a Very Young Tubal Ovum
By Frances Ivens, Ms.
I am bringing this specimen before the notice of the Section as I believe it to be very young, and therefore possibly of some slight value in helping to throw light on points of interest in the early development of the ovum, especially the amnion, upon which, owing to lack of material, it has been necessary to theorize from the standpoint of comparative embryology.
Fig. 1. Complete section of tube with blastocyst, lyiug in blood-clot, and attached to muscular wall by plasmodial strand. (x 10.)
One cannot ignore the possibility that this ovum, which was found accidentally in the wall of the tube, may be pathological, and therefore an unreliable basis from which to draw correct conclusions, but as it presents no abnormal features the probability is that it is normal. The cells are clearly defined, as it was obtained fresh, it is complete, and the mesenchyme does not show the cellular appearance seen in some pathological ova. °
The specimen was obtained from the right Fallopian tube of an 8-para, aged 80, admitted to the Liverpool Stanley Hospital on April 22, 1910, for retroversion of the uterus. The last pregnancy had terminated in an abortion two years previously. Menstruation had been regular but profuse, and the last period occurred exactly a month before the .day of admission, when it began again as usual.
Fig. 2. Section 4. Mesoblastic connecting stalk, attaching embryo to wall of blastocyst. (x 450.)
Laparotomy was performed on April 25, three days after admission. The retroverted uterus was attached by filmy adhesions to the appendages and rectum. The left tubal fimbriæ were partially glued together. The right tube was pêtulous, showing a small dark red thickening in the middle. As it looked like a tubal pregnancy the tube was removed. The uterus was fixed in position by Gilliam’s operation.
Fig. 3. Section 8. Allantois tunnelling connecting stalk. (x 450.)
The tube was at once placed in 4 per cent. formalin, and after fixing the thickened portion was cut out, mounted in celloïdin, and cut into serial sections by Miss Wortham. The swelling measures l'4 cm. in its longest diameter through the mesosalpinx. The plane of section is rather oblique, but the ovum can be seen in every section cut, and the embryo completely traced through about twenty sections +66 mm. thick. The tubal lumen is rather flattened by a mass of clot, and the epithelial lining has disappeared for about one-eighth of the circumference. In the mesosalpinx there is extravasation of blood round the vessels. Anchored to the denuded muscular wall by a strand of plasmodium can be seen a triangular cyst—the ovum. There is no sign of decidual reaction in the tube, but some leucocytic infiltration, at the point of attachment. From each angle of the cyst a strand of trophoblast passes out into the surrounding clot. There is very little branching, but a mesoblastic core can be seen in some of the strands.
Fig. 4. Section 9. Yolk-sac lined by cubical epithelium and covered by mesoblast. Two cells free in cavity. Wall of blastocyst (lined by cellular mesenchyme) shows cubical cyto-trophoblast. (x 450.)
The cyst wall shows the typical structure of cyto-trophoblast and plasmodic trophoblast. The cyst cavity or extra-cœlom is filled with a granular, very slightly cellular material, the mesenchyme or magma reticulare, but that lining the cyst is more cellular. The cyst measures -0°8 mm. by 0‘6 mm. (internal measurements). The third dimension can only be roughly estimated by the thickness of the sections as about 0‘8 mm. The embryonic rudiment, about 019 mm. in diameter, is attached to the cyst wall by cellular mesoblastic tissue. In nearly every section taken through it a prominent object is an oval or rounded sac, lined by well-formed cubical epithelium, and covered by a single layer of meso- blast. This is undoubtedly the yolk-sac. A mesoblastic stalk connects it with the cyst wall. It contains granular material and two large cells can be seen. In one section in the wall of the yolk-sac is a vacuolated cell, probably the beginning of a blood-island, from which a future vessel is to be formed. The mesoblastic stalk is partially tunnelled by a canal lined by columnar epithelium, which can be traced into the yolk- sac, and is evidently the beginning of an allantois. The amnio-embryonic cavity is represented by a cleft in the mesoblast, situated between the wall of the ovum and the yolk-sac. It is lined by one layer of epithelium, ‘columnar towards the inner side, flattened towards the outer wall; this minute cavity can only be traced in about three sections. It shows no communication with the exterior through the chorion, the roof being attached to the lining wall by some mesoblastic tissue. The single layer of columnar cells in the floor of the amnio-embryonic cavity appears to be the ectodermal plate. Towards the caudal end (that near the allantois) is a lumen lined by columnar cells of which the nature is uncertain (? neurenteric canal). Strands of cells pass out into the mesenchyme from the mesoblast of the yolk-sac and connecting stalk, and vaguely indicate the formation of a cœlom.
Fig. 5. Section 12. Blood-island in wall of yolk-sac, lying between two layers. (x 450.)
Fig. 6. Section 13. Strands of mesoblast passing from yolk-sac out into mesen- chyme. (x 450.)
Fig. 7. Section 15. Embryonic rudiment with yolk-sac and amnio-embryonic cavity. (x 450.)
In determining the age of this ovum the history was of little value. Coitus had taken place at approximately weekly intervals, the last, five days before operation. Comparisons with the Teacher-Bryce and Peters’s ova would indicate that this ovum comes somewhere between the two in age, and is probably about a fortnight old (on the basis of Teacher’s determination). It is very slightly larger than the Teacher-Bryce  specimen (0‘77 mm. by 0‘63 mm.) but smaller than Peters’s (1°6 mm. by 0'8 mm. by 09 mm.). Protrusions of mesenchyme seen in the primary villi also indicate that it is rather more advanced than the former specimen, while the development of the amnion and ectodermal plate appears less than Peters’s, which also shows mesoblastic protrusions in the villi. ‘The very definite mesoblastic attachment seen between the embryo and wall of the blastocyst in this specimen would negative the assumption that a free stage exists as a normal phase even at this early age.'
Fig. 8. Section 17. ÆEmbryonic rudiment showing ectodermal plate, amnio- embryonic cavity, yolk-sac, ? neurenteric canal, and strands of mesoblast forming ? cœlom. (x 450.)
Fig. 9. Section 18. Yolk-sac (smaller in section) with strand of attached mesoblast. Trace of amnio-embryonic cavity. (x 450.)
Fig. 10. Section 22. A few cells showing termination of embryo. Branching cells of mesenchyme seen close to cellular wall of blastocyst. (x 450.)
Development of amnion
The appearances in the sections support the view held by Keiïbel , that the amnio-embryonic cavity arises by a splitting of the formative cell-mass, and that amniotic folds never occur in man. This author considers the traces of an amniotic duct or connexion between the epithelium of the amniotic cavity and surface of the chorion (described -by Beneke in human ova and Selenka in apes) to be only a ‘“ phylogenetic memory from dim ancestral times,” and not left by a process of inversion. The method of formation of the amnion as seen in these sections strongly resembles that described by Sobotta  as occurring in the mouse, where a cleft arises in the formative cell mass. In this tubal ovum the chorion is already so well developed, while the amnion is comparatively minute, that it is incon- ceivable that the amnio-embryonic cavity has been formed by the rising up of folds, or that the ectodermal plate (as such) could ever have been free on the surface of the ovum.
 Sobotta, “Die Entwicklung des Eies der Maus,” Arch. f. mikr. Anat., Bonn, 1903, Ixi, p. 274.
 Template:Ref-Teacher1908 p. 264.
THE PRESIDENT (Dr. Macnaughton-Jones) wished to convey the thanks of the Section to Miss Ivens for the very complete demonstration she had given them. Her devotion to research was on a par with her clinical and operative work, as shown in the paper she had just published on Hysterectomy for Myoma.