Paper - The physiological descent of the ovaries in the human foetus
|Embryology - 21 May 2019 Expand to Translate|
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Hart DB. The physiological descent of the ovaries in the human foetus. (1909) J Anat Physiol. 44(1): 27-34. PMID 17232822
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The Physiological Descent of the Ovaries in the Human Foetus
By D. Berry Hart, M.D., F.R.C.P.E., F.R.S.E.,
From the Laboratory of the Royal College of Physicians, Edinburgh. (1909)
Lecturer on Midwifery and Diseases of Women, Surgeons’ Hall, Edinburgh ; Hon. Fellow, Ameriean Gynceeological Society; Carnegie Research Fellow
Little attention has been paid to this subject, evidently for the reason that the normal descent does not go below the immediate vicinity of the brim of the pelvis, and that it is dwarfed by the more complicated question of the descent of the testes. The permanent position of the ovary, however, is of importance, as even after the ascent due to pregnancy it sinks normally to the same level. There are two other points of interest in addition, viz.: that while the ovary is never normally in the inguinal canal or labium majus, these are normally canalised to a certain extent by the round ligament, the analogue and homologue of the gubernaculum; abnormally, also, the ovaries may imitate the normal descent of the testes, and be permanently, usually on one side only, in the inguinal canal or even in the labium majus—the so-called hernia of the ovary. The question of their normal descent is thus of some scientific value. As two of the marsupial embryos I recently examined were. female, with the ovaries developing on the Wolffian bodies, and as the round ligaments had penetrated the abdominal wall, I was able to trace the process to a certain extent in them, and also in two human embryos at the 5th to 6th week (h. to b. measurement, 31 mm.).
I shall therefore consider: (1) The development of the round ligament and of the mammary pouch; and (2) The descent of the ovaries.
I. The Development of the Round Ligament and of the Mammary Pouch
On examining one of the marsupial embryos in serial section from above down (the other confirmed the findings), the first thing that struck one in the suprapubic region was the presence of an oblique chain of lymphatics lying in front of the pyramidalis muscle on each side; and lateral to the developing mammary pouch. They crossed the line of the future inguinal canal, were not so marked as in the male, and formed, in them, oval canals lined with thin spindle-celled fibres and round nuclei, the latter projecting into the lumen slightly. The connective tissue and unstriped muscle between and 11ear these sinuses was markedly increased. A distinct bundle, part of the round ligament in the abdominal wall, formed a curved band iii the lymph site round the outer side of the pyramidalis and marsupial bone. This appeared as a cone—shaped projection, probably the analogue of Klaatsch’s inguinal cone, bulging the peritoneal lining of the abdominal cavity in the neighbourhood of the point of entrance of the inguinal fold to be presently described. The round ligament had thus penetrated the muscular fibre of the internal oblique and transversales muscles, and had now in its substance striped muscular fibres. In its substance, too, can be seen some of the lymph sinuses, and near the abdominal wall there is a distinct cavity with a ridge on its inferior aspect. The round ligament here is bounded by the connective tissue of the abdominal wall, and nothing at present analogous to the tunica vaginalis except the cavity and ridge just alluded to is to be noted.
In one specimen, muscular fibres traceable to the internal oblique can be seen in the substance of the ligament, and loose connective tissue separates it from the denser connective tissue to the outside.
I have already described the nature of these lymph—sinuses in the male in a previous paper on the descent of the testes. They are the sinuses of the lymphatic system developing from the vein in the groin, budding off from them Dr Florence Sabin has already described, and I need not recapitulate this description therefore, except to say that the chains as seen on transverse section lie one on each side, in front of the pyramidalis, and each is joined to its fellow by a band of connective tissue as in the male. They form a ladder in the subcutaneous tissue running obliquely from below up, in this case above the level of the top sections which lay below the rib-level. The round ligament is at first the inguinal fold, i.e. before it begins to penetrate the abdominal wall. In two human embryos at the fifth to sixth week one sees the inguinal fold meeting the abdominal wall with the internal oblique and transversales muscles and tendon of the external oblique in front, but as yet there is no penetration. In one of these, prepared by Gulland in serial section, the lymph-sinuses are seen Well developed Where the round ligament meets the wall (fig. 2). They thus bear out the relations of lymph-sinuses to gubernaculum already shown in the case of the Marsupials.
In the part of the round ligament nearer the Wolffian body wall the unstriped muscle was well developed, but nearer the abdominal Wall its place was taken by round-celled connective tissue. One formed the impression that unstriped muscle was radiating into the round ligament from a posterior source. On tracing from below up the serial sections of one of the marsupial female embryos, which were at a later stage of development than the human specimens, so as to ascertain the relations of the round ligament as it passed through the abdominal wall, the appearances were as follows :—One came upon first the inguinal fold penetrating the abdominal wall (fig. 1) and forming a shallow peritoneal pouch. In this penetration, however, the peritoneum soon ceases to be active, but the unstriped fibres grow on and up, and mingled in them are the striped cremasteric fibres, not advancing with them paw} passu, and thus not forming part of the advancing wedge we see so well in the development of the cremaster associated with the male gubernaculum. The unstriped muscular bundle arrives at the lower end of the mammary pouch, and appears to end in the roundcelled connective tissue in which the mamma afterwards develops.
Fig. 1. Shows inguinal fold, future round ligament penetrating, and minor participation of peritoneum in it. (50/1.)
In adult marsupials, as Katz’s specimens show, the round ligament, or cremaster as Katz terms it, runs in front of the pouch well above its deep part; and thus, after the stage I have just described, the pouch must deepen below the level of the cremaster insertions.
The round ligament, like the gubernaculum, invades the lymphatic area in the groin; and this may determine its line of growth, as it appears to do that of the gubernaculum in the male, In its subsequent growth the round ligament does not pass through the stages the gubernaculum does, and thus the ovaries have only normally a descent in the abdomen, and not any further descent comparable to that of the testes.
Fig. 2. Trans. section, female embryo, 5th-6th week. (-‘f’—.) 1, round ligament; 2,. bladder; 3, lymph-sinuses.
The adult round ligament is very distinct. It is really equivalent to the developing gubernaculum prior to the descent of the testes, and not to the developed gubernaculum; it remains in the stage of the developing gubernaculum, and grows with the growth of the uterus. Not only that, but the ovarian ligament, the analogue of the caudal ligament of the testis, remains as a well-marked structure. ' We see on the anterior aspect of the broad ligament in the adult the origin of the round ligament very well. It arises at the junction of the uterus and tube in front, and is thus opposite the uterine end of the ovarian ligament. Its origin thus marks the spot corresponding to the origin of the gubernaculum in the early male embryo. The gubernaculum arises from the epididymis, where the globus minor is continuous with the vas deferens (Frankl), and we thus can make more precise the nature of the parovarium or epoophoron. The parovarium comprises the vertical tubes and the longitudinal tube which represent the epididymis, and has a free longitudinal duct which ceases at or near the origin of the round ligament. Thus this longitudinal tube must end at a point corresponding to where the globus minor and vas deferens in the male meet—any part of this duct remaining at the side of the uterus or in the vagina is equivalent to part of the vas deferens. The important point is that the epoophoron witl1 its duct found normally in the broad ligament is a definite part of the Wolffian body and its duct, 11.6. comprises the analogue of the epididy1nis, and a part of the VVolfiian duct down to the globus minor. So far as I know, this fact has not been pointed out.
We see, therefore, that the origins of the caudal ligament of the testes and that of the ovarian ligament are analogous.
As Hill’s specimen of the embryo male pig shows, the caudal ligament has its origin near the testis’ caudal end, at the junction of the epididymis and vas deferens, or beginning of the duct of the epididymis. It ends on the upper and inner surface of the genital ducts opposite the point where the gubernaculum arises. The ovarian ligament springs from the uterine end of the ovary, but whether its origin is exactly like that of the testicular caudal ligament is 11ot accurately known. It ends at the junction of tube a11d uterus opposite the point where the round ligament springs. They are thus equivalent in every respect.
The m(Lm7n.cm°y ynmclz. develops in a very simple manner (fig. In the suprapubic region, the deep and superficial epidermis passes back, laterally and dow11, to form a solid, flattened epidermic cone, the superficial cells being central. This cone penetrates the band of unstriped muscle joining the inner ends of the superficial lymph sinuses. In its upper part, this cone or plug is continuous with the free abdominal surface, but nearer the pubes it becomes snared off. It is evident that desquamation of the epidermis gives a pouch with its opening above. From the posterior aspects of this pouch the mammary structures bud out, but my specimens show only the early buds—Bresslau has, however, worked this out. The unstriped muscle of the intersinus band thus comes to lie in front of the pouch, where the epidermic plug is buried in the abdominal wall.
The development of the mammary pouch is thus related to lymphatic sinus development, inasmuch as it takes place between the inner ends of the sinuses; on the other hand, the round liga1nent and gubernaculum develop along the outer edge of these sinuses.
The chief conclusions may therefore now be summed up as follows :—
The round ligament of the adult human female is equivalent to the gubernaculum in the male embryo at the stage when the preformed inguinal canal has been made by the latter and the testes are still abdominal, and not to the fully developed gubernaculum when the testes are descending. It has thus no stage of involution.
The mamma, round ligament, Wolffian body and its duets, with the ovary, form a connected system—an anatomical unit in the body—analogous to what I have already described in the male. It comprises mamma, ovary, tubes, vagina, urogenital sinus, hymen, external genitals, epoophoron, upper part of Wolflian duct and lower end of Wolffian duct. This is the female urogenital and mammary unit—for shortness the female U.G.M. unit — and will be analysed along with the male U.G.M. unit in its elements and significance in a subsequent paper on “Mendelian Action on Differentiated Sex.”
Fig. 3. Epidermis, on anterior abd. wall, passing back and in, to form mammary pouch. (50/1)
II. The Descent of the Ovaries
The ovaries develop like the testes on the inner and anterior aspects of the Wolifian bodies (fig. 4).
There is a well-marked mesovarium, better marked than the primary mesorchium. They lie at first in the lumbar region, but about the 5th to 6th week their position is lower and behind the genital cord, where the mesovarium is well marked. In the adult female they lie on the posterior aspect of the broad ligament, on the lateral pelvic wall, in front of the sacroiliac joint, immediately below the iliopectineal line, and with the ureter curving behind. Their descent is thus purely from the abdomen into the upper strait of the pelvis. The question may be asked why the ovaries descend no further. It seems at first sight that they maybe arrested by the infundibulo-pelvic ligament, and also because the welldeveloped uterus and broad ligament lie in front, and may block further descent. The ovaries may, however, descend as far as the inguinal canal or’ into the labium—so-called hernia of the ovary—b11t this term masks the real condition, viz., that it is a descent analogous to the stages of the descent of the testes. The main cause .is the normally arrested development of the round ligament. This, as already pointed out, is the equivalent of the stage of the gubernaculum While the testes are still undescended. There is thus nothing more remarkable in normal descent of the ovaries in the adult than there is in the position of the testes with the gubernaculum in a condition similar to that of the round ligament.
Fig. 4. Six weeks’ human embryo. (1/50.) 1, ovary; 2, mesovarium ; 3, Wolffian body.
The round ligament passes into the solid labium majus, and this structure, the equivalent of a half scrotum, is a mammary area, shown, not only by the vascular and nervous supply of its upper part, which is, in common with that of the inguinal region, undoubtedly a mammary area, but also strikingly proved by the labial mamma ‘Harting has so fully described. The round ligament thus ends in a mammary area and connects the ovary through the ovarian ligament with it, just as the gubernaculum indirectly by means of the caudal testicular ligament joins the testes to a mammary area. It thus fulfils for the ovary the anatomical generalisation I have made for testicular descent, tic. the round ligament passes to a mammary area, modified only by the fact that it does not pass through the full development the gubernaculum does.
We have not the anatomical detail of the descent of the ovary that we have of the testes. The difficulty here is the Want of material, but in large maternities like those in our chief medical centres excellent investigations could be made, and these would throw light, not only on some points in testicular descent, but also on those of excessive ovarian descent usually imperfectly described as hernia. They are analogous to the cases of ectopia testis, but it is paradoxical and yet correct to say that inguinal and labial ectopia ovarii are normal stages for the testes, while pelvic ectopia testis is analogous to the normal ovarian position.
For literature see previous paper on “The Physiological Descent of the Testes,” and Hertwig’s Lehrbuch.
- Hart DB. The nature and cause of the physiological descent of the testes. (1909) J Anat Physiol. 43(3): 244-65. PMID 17232805 , fig. 8, p. 32
Cite this page: Hill, M.A. (2019, May 21) Embryology Paper - The physiological descent of the ovaries in the human foetus. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Paper_-_The_physiological_descent_of_the_ovaries_in_the_human_foetus
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