Book - Uterine and tubal gestation (1903) 1-3
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Bandler SW. Uterine and tubal gestation. (1903) William Wood & Company, New York.
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Part I. The Essentials of Uterine Gestation
Chapter III. The Embedding of the Human Ovum
A. The Uterus
For many years it had been taught that the human ovum in the uterus developed on the mucosa (decidua serotina) and was enveloped by mucosa growing up about it (decidua reflexa).
Fig. 13. — Cavity in ovum between embryonal sphere and placental pole has grown greatly, g, embryonal sphere. (v. Spee.) Rapidly growing, embedded guinea-pig ovum.
In the examination of young human ova Spee was never able to find uterine epithelium lining the bed in which the ovum rested, and he doubted the theory that the uterine mucosa and its epithelium grew up and surrounded the ovum. Hensen had made the observation that the ovum of the guinea-pig, on the seventh day post coitus, was no longer to be found free within the uterus, and that on the eighth day it was located in the uterine wall underneath the epithelial lining (Fig. 13). Selenka, on the other hand, supported the view that the ovum of the guineapig entered into a uterine gland whose epithelium was later destroyed.
The relation between ovum and uterus varies in different animals. There are forms in which the uterine epithelium is preserved at the point at which the ovum is attached. In all those cases in which the ovum grows before its attachment, it remains during its entire development within the lumen of the uterus or in a portion of the same. The closer relation between ovum and uterine wall develops later. In the case of ova which do not grow at that stage, the epithelium disappears. The smaller the ovum, and the smaller the area of uterine wall necessary for its attachment, the more intensely is the uterine tissue affected by the ovum, so that the area affected at this point becomes rapidly very large in proportion to the size of the ovum, and naturally the development of close connection between ovum and uterus occurs earlier than in the first class. Early attachment and small ovum are therefore favorable to the nourishment of the latter. A most favorable feature for the ovum is the form in which the fecundated germinal vesicle, without any increase in growth, is completely embedded in the subepithelial connective tissue of the uterus. Such is the case with ova of the rat, mouse, guinea-pig, and human being.
Decidua Menstrualis
In the menstrual decidua the superficial capillaries become greatly dilated, and serous infiltration of the endometrium takes place, which separates the meshes of the stroma, accompanied by a gradual but decided dilatation of all the blood vessels and lymph channels. There occur a growth of round cells in the inter glandular tissue and an entrance of leucocytes into the mucous membrane. The glands become larger and wider, being often filled with secretion (Fig. 14).
This swelling of the mucous membrane, the dilatation of the blood vessels, the production of round cells, and the growth of the superficial layer of the endometrium produce the so-called decidua menstrualis. Although in the connective tissue large cells, not to be distinguished from young stages of decidua cells, are found, it is to be noted that typical decidua cells do not, as a rule, develop at this time in the superficial layer. These round cells are the beginnings of the decidua cells. The endometrium is at this period from 6 to 7 millimetres in thickness.
Decidua Graviditatis in the First Week
On the occurrence of pregnancy, as will be noted below, the superficial portion of the mucosa is later composed mainly of cells and is called the compacta. The deeper layer is composed mainly of glands and is called spongiosa. In the first week, however, as may be seen from the description of Peters, there is a decided division into compacts, and spongiosa only near the ovum. There is at this time no real decidua elsewhere and no difference exists between the connective-tissue cells of the superficial and deep layers. The tissue between the glands, however, is thicker toward the surface. We find spindle-shaped connective-tissue cells mainly. The spaces between the cells are filled with a pale homogeneous plasma, and the tissue looks like reticular embryonal connective tissue. The nuclei in the more superficial cells are somewhat larger, and numerous small round cells are present which represent the early stages of decidua cells. The epithelium of the superficial glands and of the uterine surface is somewhat flattened. An hypertrophy of the glands, especially in the deeper layers, is present, and in transverse section they are lined with papillary projections on which are long, high, cylindrical cells, often looking like beaker cells. Numerous epithelia are found free in the glands. These glandular changes are marked mainly near the ovum.
Fig. 14. — Menstrual decidua. a, section through vessels surrounded by groups of round cells ; h. interglandular tissue consisting of normal cells with scattered round cells ; d, section of a gland somewhat dilated — its epithelia are somewhat smaller than normal. (Abel.)
Fig. 14a. — Decidua in intrauterine pregnancy (abortion) at the second month {curetting), a, section of a gland with flattened epithelia : b, interstitial tissue consisting of the so-called decidua cells, between which at certain points irregularly-scattered round cells are seen ; c, section of a vessel — in the wall are endothelia. (Abel.)
Decidua Graviditatis
These typical changes occur, chronologically, at a later period in the entire uterus. Since, however, they are marked in the first two weeks immediately about the ovum, they are mentioned now. It is especially necessary to consider the base in which the ovum develops, as it is difficult at all times, even as early as the first week, to distinguish in many areas between fetal and maternal cells. The mucosa of the pregnant uterus, at its thickest, increases to ten times its original depth by the growth of all its elements. At the end of the first month it is one centimetre thick. Its surface is uneven, deep grooves dividing into irregular fields. These changes are greatest at the fundus. In the region of the internal os the changes are less marked, the lining of the cervix, except for a high degree of hyperemia, having no part in these changes. The increase in the volume of the decidua depends greatly upon the growth of round cells in the endometrium and upon their change into decidua cells. The round cells of the connective tissue, situated in a meshwork of spindle- and star-shaped cells forming the stroma, enlarge. The protoplasm increases greatly in amount and the nucleus becomes larger. The cells are closely grouped, pale and epithelial in appearance (Fig. 14a). They are, like the connective-tissue cells of the normal uterus, infiltrated by capillaries and larger vessels whose endothelium borders immediately on the individual cells. The nuclei are round and long, 8 to 10 pi long and 10 to 12 ju wide. They stain lightly because their chromatin network is very fine. There are nucleoli. Mitosis is rarely observed, but two nuclei may be present. They generally retain their spindle-shaped form or are round polygonal. There is often a fine space between the individual cells, filled with a homogeneous intercellular substance. These cells appear at first in the upper layer, and so prominently that this layer of the gravid decichia is called the compacta. Later, as a result of pressure, the cells resemble squamous epithelium.
Fig. 14b. — A gland in the decidua graviditatis, showing the erroneously named "syncytial change" of the lining epithelium. Taken from the curetted mucosa of a uterus two weeks gravid.
The external layer near the muscle contains so many gland lumina that the interglandular tissue is in the background. This interglandular tissue disappears more and more, so that finally a tissue honeycombed by glands results. This layer, in contrast to the superficial, is known as the spongiosa. The compacta is thrown off with the ovum; the spongiosa remains to regenerate the glands.
The gland cells lose their cylindrical form and become cubical and spherical. The protoplasm grows and the nuclei are therefore further apart. Into the gland extend prominences covered with groups of epithelium (Fig. 145). Sometimes the eel] boundaries become indistinct, giving the so-called "syncytial change, ' ' which has nothing to do, however, with real syncytium.
Fig. 15. — Schematic representation of the earliest stage in the embedding of the human ovum. (Peters.)
The epithelium of the surface is subjected to pressure and is flattened, becoming later thin as endothelium.
B. The Embedding of the Human Ovum
Spee and von Herff have shown that in the guinea-pig the ovum forms an opening through the epithelial lining of the uterus, and that, after having passed entirely through the mucous membrane, it develops further in the region of the subepithelial connective tissue. The opening thus formed is closed by lymph exudation, and there results about the ovum a so-called lymph space, showing that an exchange between the ovum and the surrounding tissue exerts upon the latter a certain reaction. That the same process of centrifugal descent of the ovum into its bed occurs in the human being is to be expected, for the following reasons: 1. By analogy with the above process. 2. In human beings there is no epithelium, nor are there any gland openings on the surface of the so-called reflexa, facing the ovum. 3. The youngest human ova found in the uterus show no prominence into the uterine cavity, which would be the case if they developed upon the decidua vera and were surrounded by a decidua reflexa.
Ovum in the Earliest Stages
Peters examined a growingovum supposedly three clays old. The uterus was slightly enlarged and soft. The decidua at the fundus and on the posterior wall was 8 millimetres thick ; on the anterior, 5 millimetres. The lining of the cervix was hyperemia. On the posterior wall was a slight prominence, which proved to be the ovum, whose largest diameter was found to be 1.6 millimetres. The ovum was embedded in the compact part of the decidua, which portion, as before stated, showed only a slight prominence. The summit of the ovum was not covered by a capsule, but showed a spot of blood granulation.
Fig. 16. — Schematic representation of a centrifugally embedded human ovum. (Peters.) The summit of the capsularis is closed by a fibrin plug.
Only in the immediate circumference of the ovum was there a clear division into compacta and spongiosa. The nearer to the ovum, the more frequently were free red and white blood cells found between the cells of the stroma and in the plasma. Nowhere was there an evidence of fatty changes in the superficial layers. The mucosa was everywhere extremely vascular. The venous channels showed, superficially, often only a simple canal of thin endothelium, without adventitia. The arteries preserved their adventitia up to the covering epithelium. The nearer to the ovum, the greater was the vascularization. In this case fecundation took place shortly before the expected menstrual period. The fact that this ovum had made its way into the decidua, wherein it was firmly embedded, proves, analogous to the observation of Spee, that an ovum can develop only on a spot free of epithelium, and that, through reaction upon the surrounding tissue, an ovum sinks into the decidua, and that this reaction causes a dilatation of the surrounding lymph spaces, with a resulting localized edema (Fig. 20).
In the edges of the groove in which the ovum was embedded, and also deeper clown, a more decided hemorrhagic edema took place and minute blood extravasations forced their way up to the epithelium and lifted it off. The resulting coagulation, containing likewise the remains of these cells, serves to close the opening and to cover the ovum (Fig. 16).
Capsularis. — In place of the old view of a reflexa growing up and above the ovum supposedly situated on the epithelium lining the uterus, a centrifugal descent of the ovum must be taken for granted. In v. Spee's young ovum the capsularis had not yet united at the summit. In Leopold's case (ovum seven to eight days) union had already occurred. In Peters' case the summit was closed by fibrin. Leopold and almost all investigators find the structure at this point atypical. The same changes are found as Sanger remarked in the organization of hematocele capsules, i.e., fibrin, connective tissue, and capillaries. Keibel, Kollman, and Reichert say that at the summit of the capsule union results in the formation of what may be called a cicatrix, to which is given the name cicatrix of Reichert.
As proof of the ready and early connection between maternal blood and fetal tissues, it may be mentioned that the tissue which separates the capillaries from the uterine epithelium becomes extremely thin in the decidua menstrualis. The capillaries which run a twisted course between the glands of the spongy layer extend up to the epithelium under the mucosa. In the compacta or superficial layer they often possess only an endothelial wall. When the ovum sinks into the decidua the decidua basalis presents in addition a huge dilatation of the capillaries. The zone which surrounds the ovum is formed by the compacta. As the ovum descends, gradually more compacta surrounds it, forming the so-called enveloping zone.
The Enveloping Zone is the layer of the compacta immediately about the ovum. It furnishes the blood supply to the growing blastocyst. Through its edematous infiltration it renders the centrifugal descent of the ovum easy.
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Reference: Bandler SW. Uterine and tubal gestation. (1903) William Wood & Company, New York.
Cite this page: Hill, M.A. (2024, April 20) Embryology Book - Uterine and tubal gestation (1903) 1-3. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Book_-_Uterine_and_tubal_gestation_(1903)_1-3
- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G
