View source for Paper - Preliminary note on the development of the clitoris, vagina and hymen

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| [[File:Mark_Hill.jpg|90px|left]] This historic 1896 paper by Hart described the development of the female genital tract. Note the current understanding of the development of the vagina has changed since this historic paper. David Hart (1851-1920) published several papers on both male and female genital development.
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=IV. Preliminary Note on the Development of the Clitoris, Vagina, and Hymen=
[[File:David Berry Hart.jpg|thumb|300px|alt=David Berry Hart|link=Embryology History - David Berry Hart|David Berry Hart (1851-1920)]]
By [[Embryology History - David Berry Hart|D. Berry Hart]], M.D., F.R.C.P.E., 

Lecturer on Midwifery and Diseases of Women, School of Medicine of the Royal Colleges (Surgeons’ Hall), Edinburgh.

1 From the Laboratory of the Royal College of Physicians, Edinburgh.


While much has been done to put the development of the female genital organs on a satisfactory basis, there are certain points in which our knowledge is defective, as well as some outstanding facts which have not yet received a clear explanation, and can thus only be classed as anomalous. In the first place, so far as our present knowledge goes, it is remarkable that in the foetus at full time a hymen is always present; and still more remarkable that even in atresia vaginae the hymen, and occasionally a double hymen, is developed. Why should the hymen be always present in the full-time foetus? Why in atresia vaginae should the hymen escape the atresia?


Then, again, the structure of the vaginal mucous membrane is quite analogous to that of skin. We have many layers of a squamous and quite characteristic nature, the cells of the deeper layers being more oval and staining more deeply. The superficial layers desquamate like skin; there are practically no glands present, and in prolapsus uteri the everted mucous membrane takes on the appearance of the body skin. One would expect, therefore, an epiblastic origin for the lining of the va.gina and the outer covering of the vaginal cervix. The genital tract is stated. to be developed, however, from the ducts of Muller, the noncoalescing parts forming the Fallopian tubes, the coalescing portions the uterus and vagina. The ducts of Muller arise probably from the mesoblast, the Wolffian ducts from the epiblast. The received opinion is, therefore, that the vaginal lining is derived from Miil1er’s ducts, a mesoblastic source, and that the Wolffian ducts and bodies have only an important excretory function in the early foetus until the permanent kidneys develope. Their importance as active organs then ceases, and they are considered as possessing merely a pathological significance, as they provide the gynaecologist with the wellknown parovarian cyst, with some of the papillomatous tumours of the ovary and broad ligament, as well as some of the rarer vaginal and broad ligament cysts. Some observers assert that the Wolffian ducts enter into the formation of the lower part of the vagina; and Pozzi, in a very acute and able manner, gives most excellent reasons for considering the hymen as not vaginal. Whether he is right in stating that it is to be considered vulvar remains to be seen.


For some time past I have had prepared for microscopical examination the pelves of early foetuses, male and female, the paraffin method being employed and the material cut serially. I examined them at first for my own information and for teaching purposes, but the remarkable developmental changes roused my interest and induced me to go more thoroughly into the matter than I had at first intended. From the published works and papers of His, Waldeyer, Dohrn, Nagel, V. Miha1k0Vi0S, Blldin; Tourneux and Legay, Klein, Pozzi, Kollmann, Keibel, and from the suggestive text-book of Minot, I received much valuable information, but no answer to the initial difficulties I have stated. A prolonged and careful examination of my specimens seems to me to have cleared up these anomalous points, and this is my reason for publishing the present communication, and committing what the professed embryologist may consider a trespass.



Fig. l. Vertical mesial section of the female pelvis (modified from Foster). A cross marks the site of the hymen, and the lining of the vagina derived from the Wolffian bulbs has a. dotted outline.


The question to be considered will be clearly understood if figs. 1 and 2 be first studied. fig. 1 shows a vertical mesial section of an adult pelvis. One sees the hymen on section, and the vagina with its outline dotted where its lining is derived, as I hope to show, from the Wolffian ducts, and therefore epiblastic.

Farre and Cullingworth accurately describe the hymen as a pouting vertical slit, and there is no doubt that some of its various shapes are made by the method of examination.


Fig. 2.  From Keibel’s model of organs in foetus at about eighth week. The eminence of Muller where the hymen will develope is marked with a. cross, which also lies at the upper end of the sinus. (8.)

[[File:Keibel's model of urogenital organs.jpg|600px]]

'''Fig. 2''' Shows Keibel’s valuable model of the relations at the eighth week; it is practically the same as in the seven Weeks’ foetus, of which sections are given in the Plates. It is at Muller’s eminence that the hymen is developed, and the main object of this note is to determine some of the changes transforming fig. 2 into fig. 1.


The specimens I had for examination Were as follows :—(1.) Serial sections of a five weeks’ foetus, carefully prepared and stained, which I owe to the kindness of Dr H. J. Stiles. (2.) A seven weeks’ foetus, also serially cut. This was from a cancerous seven weeks’ pregnant uterus, successfully extirpated by me, and prepared and stained by Dr Lovell Grulland. (3.) A foetus at the third month, perfectly fresh and well preserved. (4.) A four and a half months’ foetus, and one at full time. I also examined several male pelves as well as those of foetal rabbits, but do not consider these at present.


The foetuses (3.) to (5.) were prepared by Mr Hume Patterson at the Laboratory of the Royal College of Physicians, where also the microphotographs and transparencies were made. I am greatly indebted to Mr Patterson for the skill he displayed in the preparation of the specimens and photographs.


The early foetuses were cut serially and transversely by the paraffin method; all the sections were mounted. The later foetuses were treated in the same Way, but only every sixth could be mounted, and the sections were cut in the sagittal mesial plane. Mr Stiles’ preparation had been stained in carmine in block; for all the rest, logwood and eosin were employed.

Based on this examination, and on the literature of the subject, I shall now consider (1.) The development of the genital tract prior to the formation of the hymen. This is well illustrated by the foetuses of the sixth and seventh week. (2.) The origin and development (a) of the prepuce of the clitoris, and (b) of the hymen. The foetuses of the third and fourth month illustrate this stage.


==1. The development of the genital tract prior to the formation of the hymen==

In the seven weeks’ foetus one finds, in the abdominal cavity, the peritoneal ridges, one on each side of the middle line, with the Woltfian bodies. Lower down, the outer ridges with the Wolffian and Mullerian ducts appear; and at the lower levels, the ovary with its characteristic pedunculated form comes into view, lying on what will be the posterior lamina of the future broad ligament. The Wolffian bodies have greatly lessened in size, and at the level of the ovary are much diminished in section. The outer ridge is hour-glass shaped on transverse section. In the outer segment the ducts of Wolff and Muller develope: the inner one becomes the ovary. The outer joins its fellow to form the broad ligament in front of the ovarian part, which thus comes to lie behind.


In the broad ligament we have the Wolffian ducts and ducts of Muller, and at a lower level the genital cord of Thiersch. In the five weeks’ foetus we find four canals in the genital cord, the two outer being the Wolfiian ducts, the two inner the ducts of Muller. In the six weeks’ foetus the ducts of Muller have coalesced into one canal, but the Wolffian ducts are distinct. Still lower we get the Woltfian ducts opening into the urino-genital sinus, while the ducts of Muller end in the eminence of Muller between these (v. Plates I. and III.).


Immediately before the Wolffian ducts so end they ﬂatten out laterally, and with the Mullerian ducts form an H-shaped appearance on transverse section (Pl. III., fig. 6). So far, then, it is certain that the Anlage of the greater part of the vagina is the ducts of Muller, with probably a part of the Wolffian ducts where the adult vagina is H-shaped on transverse section. (Hoffmann, quoted by Pozzi; but I have not been able to get the original paper.)


==2. The origin of (a) the prepuce of the clitoris and of (b) the hymen==

In the four and a half months’ foetus the coronal section of the glans clitoridis shows a remarkable horse—shoe like structure surrounding the glans tissue. The margins of the horse-shoe consist of a layer of active cells staining deeply, while between 
these we have less deeply stained cells (Pl. IV., figs. 7 and 8). So far as one can determine, they are epithelial cells. Their origin and nature are clearly determined in the sagittal sections of the glans in the three and a half months’ foetus, where one sees, at the lower part of the clitoris apex, the epidermis sending in two sickle-shaped processes whose apices do not meet (Pl. IV., fig. 7). This is really a thimble-like involution of epidermis, the open base of the thimble being at the corona. The superficial layers of the epidermis are necessarily in the centre of these involutions. The clitoris in the early foetus is bulbous and entire (Pl. V., fig. 10). The involution, as already described, takes place at or about the third month, and the separability of the prepuce is formed by the central cells, Which are really the superficial ones, desquamating; z'.e., the prepuce is now the movable hood We find in the adult.


To see the changes which bring about (b) the development of the laymen, we must examine sections at the third and fourth month respectively.


The specimens I examined were at the third and a half and fourth month, and the sections were cut sagittally in the former specimen, and in the axial transverse direction in the latter; 'i.e., from side to side, and in the axis of the brim in the four and a half months’ one.


Remarkable changes have taken place in the vagina. We have seen that in the early foetus the vagina was formed from the coalesced ducts of Muller, and that a lumen was present, the cavity being lined with a single layer of cells. What we now find is as follows :—At what we may term the site of the vaginal entrance one sees an ingrowth, the deeper layer of the vestibule lining passing in, and with it the superficial layers too. This passing in of the superficial layer is, as in the case of the clitoric prepuce, of great importance, as it is the desquamation of these superficial layers, however effected, that gives rise to a lumen. The passage is in the form of multiple tubular ingrowths, so that we see on section several canals the walls of which gradually disappear, and thus a single canal up to the outer aspect of the hymen is formed (Pl. IV., fig. 7). 


A little higher in the vaginal axis remarkable structures are now to be noted, viz., two oval collections of cells from which cords of actively proliferating cells pass in several streams, as it Were, to fill up the vaginal lumen as far as the cervix uteri, where in this specimen the posterior fornix is mapped out by a sickle-shaped prolongation of the cells. The vaginal lumen is solid below, but higher up a lumen has begun to form. The periphery of the bulbous collection of cells is mapped oil’ by actively growing cells, while the mass of the bulb is made up of epithelial cells exactly similar to those of the epithelial lining of the fully developed vagina, the peripheric cells being the same as those in the deeper layers of the vaginal epithelium. In regard to this bulb an examination of all the sections shows that the following conditions are present :—At a little distance from the middle line it is solid; in the middle line it has a lumen in the form of a vertical slit; while further out a second bulb is seen and with a duct, the Wolffian duct passing into it. One of the bulbs is the larger, and they lie laterally in relation to one another (Pl. VI., fig. 12; and P1. II., figs. 3 and 4).


I may anticipate here, for convenience of terminology, one of the chief conclusions of my paper, by saying that these bulbs are Wolffian in their origins i.e., are derived from the Wolffian duct and I shall now term them the Wolffian bulbs.


It is evident that we can now explain the hymeneal opening of the vagina, as we must distinguish between this and the formation of the fully developed hymen and its varieties. At present I only consider the former question.


The hymeneal opening is evidently formed by a vestibular involution from below meeting the bulbar distensions above, and causing a thinning, and ultimately a perforation, of the intervening tissue.


The four and a half months’ pelvis shows the fully-formed and coalesced bulbs with a vertical slit, and according to the obliquity of the section we get either one bulb or both. Between the lower ends of the bulb is a vertical spur, the rudiment of the posterior vaginal column (Plate V., fig. 9).


The full statement of the formation of the vagina and hymeneal opening seems to me to be as follows :—Up till the origin of the hymen the vagina is Mullerian and lacking its lower end. Then comes the formation of the Wolfiian bulbs by a proliferation of the lower ends of the Wolffian ducts. The epithelium of these ducts, epiblastic in their origin, forms the Wolffian bulbs, and, proliferating, passes up into the vaginal canal, filling up its lumen, mapping out the fornices, covering the vaginal portion of the cervix, and passing at first into the lower part of the cervical canal. The central cells are the least active and become shed; that is, a lumen is formed. The vaginal entrance is formed where the epiblastic ingrowth from below meets the bulbar distension above, and this is the developmental definition of the hymen and the vaginal entrance.


The view so ably advocated by some authors, that the fullyformed vaginal lining is derived from the ducts of Muller, is full of difficulties. It would make the vaginal lining mesoblastic, and give no explanation of the remarkable blocking of the vagina with cells while the hymen is being formed, as well as no reason for the different lining of the adult vagina, uterus, and tubes. The lining of the uterus is Mullerian and mesoblastic, that of the vagina is Wolffian and epiblastic.


The question of the relation of these ducts to the germ layers is, however, much disputed. In the Elasmobranchs they appear to have a common origin. So far as my reading and examination of specimens go, I am of opinion that the Mullerian duct is mesoblastic in the human foetus, but that at its very lowest part the vagina is Wolffian and therefore epiblastic, and that as the hymen is derived from the Wolffian bulbs, its inner surface is epiblastic. Its outer surface is really hypoblastic, being derived from the lining of the urino-genital sinus.


The view I advance seems to me to explain the development so far as the points stated in the beginning of the paper are concerned, and may be summed up as follows :—

# Before the hymen is developed—'£.e., up till the second and third month of foetal life—the vagina is formed by the coalesced ducts of Muller, but no lower aperture and no hymen are present; the vagina is Mullerian and blind. 
# At the beginning of the third month two bulbs form from the lower ends of the Wolffian ducts, the periphery of these bulbs being formed from the more active cells, the central of cells of a more squamous type. The cells are, in fact, the same as those of the adult vagina.
# By the proliferation and spread of these cells the Mullerian vagina has its lumen blocked, the fornices and vaginal portion of the cervix mapped out.
# The Wolffian bulbs coalesce, break down in the centre, and as the Wolffian cells in the centre of the Mullerian va.gina do the same, we get the normal vaginal lumen formed.
# The hymeneal opening is brought about by the epithelial involution from below meeting the distending bulbs above.
# The ducts of Muller determine the site of the vagina; the Wolffian ducts supply its lining and develope the hymen (72. also 5).


The bearing of these views on Atresia vaginae is as follows :—

# Atresia vaginae is atresia of the Mullerian vagina, but the hymen, being Wolffian in origin, is present.
# The reason a hymen is always present in the fully-formed foetus is as follows :—The Wolffian bulbs form the hymen and obliterate the lower ends of the ducts of the Wolffian bodies, and as these are the temporary kidneys of the foetus, they must of necessity have been present during the early life of a fully developed foetus.
# The double hymen is not due to a permanent duplicity of the ducts of Muller, but to a non-coalescence of the Wolffian bulbs. The vertical slit of the hymen is due to the apposition of the lateral Wolffian bulbs.
# In imperforate hymen the tissue between the involution from below and the Wolffian bulbs has not been perforated.


The real essence of all this development seems to be as follows :—In the fully-formed genital tract we have the lining of the uterus developed from the ducts of Muller, and having as its great function pregnancy and menstruation. Its single epithelial layer and delicate connective tissue fit it for these functions; but for the pressure of parturition which the vagina has to undergo, We need a multiple, squamous, in fact, skin—like structure, such as is supplied from an epidermic source. One can see the great difference in the mucous membranes of, say, an inverted uterus and prolapsus uteri. In the one we have a raw, bleeding surface, quite unfitted for friction; in the other a structure that soon becomes skin-like and horny. To give the vagina this skin-like structure we get the Mullerian lining replaced from the epiblastic Wolffian bulbs; these at the same time taking a part in the formation of the hymen, as already described.


==Literature==

BALFOUR, F. M. — On the Origin andgﬂistory of the Urino-genital Organs of Vertebrates. Memorial Edition, 1885.

BANKS, W. M. — On the Wolfiian Bodies «f the Fcetas, and their

Remains in the Adult. Edinburgh: Maclachlan & Stewart, 1864.

BUDIN. — “Recherches sur l’hymen et l’orifice vaginal,” Progrés Médicale, 1879.

CLELAND, J . — The Mechanism of the G'abernacalam Testis. Edinburgh: Maclachlan & Stewart, 1866.

CULLINGWORTH. -— “ A Note on the Anatomy of the Hymen,” Jonrn. of Anat. and Phys, xxvii., 1893.

DUNCAN, J. M. — Researches in Obstetrics. Edinburgh: A. & C. Black.

GERV1S. — “ Clinical Observations on the Anatomical Relations of the Hymen,” St Thomas’s Hosp. Reports, xiv.

HIS. — Anatomie menschlicher Embryonen. Leipzig, 1880.

KEIBEL. — “Zur Entwickelungsgeschichte des menschlichen Urogenital Apparates,” Archie fitr Anatomic and Physiologic. Anatomische Abtheilung, 1896, Heft i. and ii.

KLEIN.— “ Entstehung des Hymen,” Festschrift der Gesellschaft filr Gebartshillfe and Gynétkologie. Wien: Holder, 1894.

KOLLMANN. — “ Die Rumpfsegmente menschlicher Embryonen Von 13 bis 35 Urwirbeln,” Arehio fitr Anatomic and .E'ntwic/."elunggeschichte, 1891.

V. M1HALK0VICs. — “Untersuchungen iiber die Entwicklung des Harn- und Greschlechtsapparates der Amnioten,” Intern. Monats. filr Anat. and Hist, 1885, Bd. xi.

MlNOT. — Haman Embryology. New York: Wood & Co., 1892.

NAGEL. — “Uber die Entwickelungen des Uterus und der Vagina beim Menschen,” Archie fitr Mi/crosk. Anat., Bd. xxxvii. See also Arch. far Gyn., Bd. xlv. Heft 3.

P0zzI.—Te:ct—Booh of Gynaecology, Syd. Soc. Trans, p. 442, vol. iii. P 114 NOTE on THE DEVELOPMENT or THE CLITORIS, VAGINA,

TOURNEUX et LEGAY. — “ Mémoire sur le développement de l’ute'rus et du vagin,” Journal de l’/inatom/ie, 1884. WALDEYER.——Eie7°st0ck mwl Ed. Leipzig, 1870.

See Tourneux and Legay, and °Hertwig’s text-book for full literature. F .

==Description of Plates==

Pl. I., fig. 1.—T. S. of seven weeks’ foetus ; a is in Wolffian duct ; c points to summit of bladder. (5%) '

fig. 2.—T. S. at level where broad ligaments have formed. a is ovary ; 0 points to VVolffian relics ; d is Wolffian duct; e, duct of Muller. In both figures the spinal cord lies behind. ({&.) ’

Pl. II., fig. 3.——Shows Wolffian bulbs. The larger one shows the epithelium proliferating into the Mullerian vagina ; at the side is seen the second Wolffian bulb at its outer aspect, with the Wolffian duct passing into it. Wolffian duct has b in its lumen ; a is larger Wolffian bulb. (5-313-0.) ’

fig. 4.—Wolffian duct and Mullerian vagina. Mullerian vagina, a; Wolf/fian duct, b. (21119-.)

Pl. III., fig. 5.—T. S. showing genital cord. at points to the three canals in it; the central one is the coalesced Mullerian ducts; the outer are the Wolffian ducts. b points to the eminence of Muller in the urino-genital sinus. It is at the eminence of Muller that the hymen forms. (§.)

fig. 6.—T. S. shows genital cord as in fig. 5. In the urino-genital sinus the openings of the Wolffian ducts can be seen; a points to genital cord; b to urino-genital sinus. ($33-.)

Pl. IV., fig. 7.—Sagittal mesial section of pelvis of three and a half months’ female foetus, showing development of hymen and formation of prepuce of clitoris. e is epidermis passing to map out glans ; a is on Wolfiian bulb, which is breaking down centrally ; and b is involution from urino-genital sinus to meet distending Wolffian bulbs and make hymeneal opening. (5%)

fig. 8.—Coronal section of four and a half months’ foetus to show passing of epidermis to form prepuce. b, glans clitoriclis; a points to active layer of epidermis. (s;1.)

Pl. V., fig. 9.—Coronal section of pubic arch of four and a half months’ fcetus between the layers of triangular ligament. a is lower end of urino-genital sinus ; c is at upper end ; b is the lateral half of the hymen developed from one of the Wolffian bulbs ; the section has missed the other half, but one can see

the spur representing the posterior column of the vagina. dis on Bartholinian gland.

10.—lT. S. six weeks’ foetus (Stiles). Shows early clitoris and urinogemtal sinus, a, b. ($13.)
Pl. VI., fig. 11.—T. S. seven weeks’ foetus showing cloaca. Rectum, b; urino-genital sinus, 66. (§.)

fig. 12.—\_7erticaln_1esial section of three and a half months’ foetus. Wolffian bulbs, a b; c 1S Mullerian vagina, with ep1thehal proliferation in it, and posterior formx mapped out. Rectum, d ; symphysis, e. (£11.) PLATE L


Development Of Genital Tract And Hymen, By Dr D. Berry Hart.


Prof. Simpson said that the embryological researches were of the deepest interest, and threw quite a new light on the development of the vagina and vulva. That Dr Hart had been absolutely correct in his interpretation of the changes he had described would, of course, need fuller confirmation by further examination of other embryos and foetuses; but there was an air of‘verisimilitude in the demonstrations they had witnessed which must have made all feel that he was on the track of an important discovery. Dr Hart had found confirmation of his views in the presence of the hymen in cases where the vagina was completely atresic. He (the Chairman) would suggest that a study of the relations of the hymen in cases of duplicity of the vagina might give further important light on the subject.


Dr J. W. Ballcmtg/ne agreed with Prof. Simpson as to the special value and interest of the demonstration which Dr Hart had given. Even the best text-books on embryology gave a very uncertain sound on many of the points which Dr Hart had so clearly and ably demonstrated. As to the question whether or not the epiblastic Wolffian ducts and bulbs entered into the formation of the lining of the vagina a11d the hymen, he (Dr Ballantyne) felt that it was safe to leave it to the embryologists to thrash out; but whether or not there was agreement on this point, there could be no doubt that Dr Hart’s theory formed a splendid working hypothesis to explain the mode of origin of some of the most puzzling anomalies and malformations of the external genital organs in the female. After all, this fact should go a long way in itself to support the theory, for it had over and over again been found that the study of malformations threw much light on normal development, and the theory which best explained the anomalous cases Was probably also the most nearly correct as regarded the normal. Dr Hart’s views were especially interesting in their bearing upon so-called imperforate hymen, and he (Dr Ballantyne) believed that most of the cases regarded and reported as hymeneal imperforation were really instances of iinperforation of the lower ends of Muller’s ducts, the hymen being present, but overlooked on account of the projecting Mullerian pouch. It would be of interest, and might prove or disprove Dr Hart’s theory of origin of the vaginal lining membrane, if the nature of this epithelial lining in a purely Mullerian vagina could be microscopically determined. He thought also that this evening’s demonstration might throw light upon the nature and mode of origin of vaginal and hymeneal cysts. There was to him one difficulty in regarding the Wolffian bulbs as the analogue of the hymen and vaginal lining—viz., the cases in which the Wolffian ducts were regarded as permanently present in the form of Grartner’s ducts or Skene’s tubules, and in which the hymen and vagina were yet normally formed. He had hoped that Dr Hart would have thrown some light upon the question of the primary double character of the clitoris; he had recently met with a case of split clitoris and another of double penis, and had been much impressed with the idea that probably both these homologous organs were primarily double, but the embryological text-books gave no hint as to any such possibility. Yet in some of the lower anima1s—the reptilia and crocodilia for instance—the penis was either double or bifid; and it seemed to him as very probable that it would yet be found that in its earliest manifestations the sexually indifferent genital eminence might show signs of duplicity. In conclusion he thanked Dr Hart for his extremely profitable and suggestive demonstration.

Dr Berry Hart, in reply, thanked the Fellows for their kind and suggestive criticisms.

Meeting V. - February 12, 1896.

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