Paper - Origin, development and degeneration of the blood vessels of the ovary (1899)
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Clark JG. Origin, development and degeneration of the blood vessels of the ovary. (1899) Johns Hopkins Med. J 10:
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Origin, Development and Degeneration of the Blood Vessels of the Ovary
By J. G. Clark, M. D.,
Late Resident Gynecologist in the Johns Hopkins Hospital, Associate in Gynecology in the Johns Hopkins University.
(From the Anatomical and Gynaecological Laboratories of the Johns Hopkins University.)
Anatomical and physiological study of the vascular system of the ovary and its influence upon the successive states and accompanying phenomena occurring in the evolution of the Graafian follicle. also a consideration of the relationship of the corpus luteum to the conservation and to the final cessation of ovulation.
Presented before the Johns Hopkins Medical Society, December 19, 1898.
In February, 1896, at the suggestion of Prof. Mall, I began the study of the ovarian circulation, with a view of determining the normal distribution of the arteries and veins of the ovary and their relationship to-each other. At first sight the solution of this question did not appear to present greater difficulties than those encountered in the ordinary course of any research. A study of the sections of a few injected adult ovaries, however, at once demonstrated the futility of attempting to draw any conclusion from this source, for the close crowding together of the parallel vessels of the medullary portion, and the markedly irregular course of those in the cortex or follicle bearing zone, rendered impossible any accurate observations concerning the relative number and distribution of the veins and arteries, and the exact course followed by each system.
With a view, therefore, of securing ovaries possessing a simpler scheme, a study was made of the lower animals, such as the dog, rabbit, guinea-pig, sheep and pig, but with unsatisfactory results, and only after the injection of the generative organs of a monkey was a suggestive clue secured. Beyond this point, however, it was difficult to proceed, and only after the injection of a very large series of ovaries from individuals, ranging in age from a six-months fetus to a woman many years beyond the menopause, were final conclusions reached.
In the search for this normal scheme through an extensive number of serial sections, various questions directly dependent upon the circulation have presented themselves for solution, which have widened the scope of this work until it has developed into a composite anatomical and physiological research.
Thus the various vital phenomena have been considered which transpire within the follicle from its embryological origin aud progressive growth to the time of its disappearance, either through an obliterative process or through its rupture, organization as a corpus luteum and final retrogression as a corpus fibrosum. In this connection theories have been suggested as to the cause of ovulation, the synchronism of ovulation and menstruation, the mechanism of the rupture of the mature follicle and the final cessation of ovulation, which have been based upon observations made in the study of a very large number of sections.
Soon after beginning this work I was struck not only with the difficulty of arriving at a definite knowledge of the scheme, but also of determining the age at which this scheme may be taken as a standard for comparison.
This is certainly not possible after active ovulation is established for the constant changes in the vascular system induced through the maturation, rupture and organization of the follicle, introduce an element of variability into the circulation of this organ which, so far as I know, occurs in noother.
Failing to reach any satisfactory starting point in the adult, the ovary of a girl approaching puberty was next studied, but with little less success, for it was found that almost as constant variations occur in the follicular circulation before as after the inauguration of ovulation. In the hope of finally reaching a period in the life of the female individual, at which a definite standard for comparison might be found, numerous specimens from children of various ages were injected and closely studied. Finally the ovary of a six-months fetus was obtained, which furnished a definite clew as to the arrangement of the vessels, but as the follicular apparatus was still in process of development a new-born child in which the tunica albuginea was well formed was selected as the standard. Even here the solution of the question was not easy, for in order to trace the ramifications of the vessels from the point of their entrance into the ovary to their ultimate termini the study of the serial sections of many ovaries was necessary.
To briefly summarize the chief points in this investigation I have considered them under a skeleton outline, the main headings of which will conform in general to the arrangement in my forthcoming paper.
In this preliminary statement it is impossible to more than hint at the points which will, in the final publication, be developed through schematic demonstrations and many drawings from injected specimens, and for the same reason references to the numerous researches which have been made upon many of the subjects considered in this report must be omitted.
The primitive circulation of the Wolffian body will be dwelt, upon, and an explanation of the origin of the spermatic vessels as an independent system from that of the former will be offered. As is well known among embryologists the Wolffian and Miillerian ducts are well formed and the germinal eminence is of considerable size before visible signs of the differentiation of sex become manifest. Up to this point the embryo is said to be of the hermaphroditic or indifferent type.
In retracing the steps of development from the well-formed embryo back to this period some very interesting points concerning the differentiation of sex have been secured. The radical differences existing between the vascular system of the testicle and ovary have furnished a valuable sign for determining the gender of very young embryos, before the external differential marks are established.
The fact to which attention will be directed especially is that the testicular circulation is peripheral, the main artery of which courses over the dorsal .aspect of the organ, giving off in its course rib-like branches which in turn send penetrating brauches into the gland. Between the arteries are situated the collecting veins which unite at the base of the testicle to form the spermatic plexus.
In the ovary this scheme is exactly reversed, the arteries with their accompanying veins entering the center of the organ where they branch tree-like and terminate as a fine capillary anastomosis in the tunica albuginea.
Upon the peculiarities of each circulation the differential signs of sex are based — a visible dorsal vessel always indicating a male; an alabastic-like non-vascular white cortex a female embryo.
In microscopic sections the presence of large peripheral vessels also indicates the male, whereas large central vessels indicate the female sex.
The significance of the vascular arrangements in the testicle and ovary will also be discussed from the physiological standpoint, and to the radical differences existing between them will be ascribed the persistence of the testicular function in the male to old age, and the comparatively early abrogation of ovulation in the female. In the testicle the production of sperma is a more or less fixed and constant function like that of the pancreas, the parotid and other secreting glands, consequently the circulation is not subject to variations and is only interrupted through disease or through senile changes, whereas in the ovary there is a constant variation in the circulation incident to the obliteration or disappearance of follicles and the compensatory production of connective tissue which sooner or later begins to limit the peripheral circulation, and this in turn leads though secondary influences to a final cessation of ovulation.
Incidentally. I may remark that these wide differences in the circulation lead me to the conclusion that the origins of the ovary and testicle are not as generally believed the same, but are totally different, and that the expressions " asexual period," " hermaphroditic stage of the embryo," etc., merely serve to mask our inability to select the differential features of the sexes back of this point.
In view of the fact that the common progenitor of the ovary and testicle is the Wolffian body and that the atrophy or degeneration of the latter is coincident with the active growtli of the former, an endeavor has been made to discover the explanation of this apparent paradox. According to my observations upon this point, it lies in the fact that the vascular system of the sexual glands originates entirely independently of that of the Wolffian body, consequently the synchronous development and degeneration of the two sets of organs is j>ossible.
Having traced the development of the circulation in the ovary and testicle from the so-called asexual period to the point where they have formed systems diametrically opposite in their distribution and ultimate arrangement, the further consideration of the testicle will be dropped and the study of the ovary along the line of its development and progression to its ultimate history will be pursued.
Development of the Graafian Follicle
My study leads me to reject the Valeutine-Pfluger theory concerning the origin of the follicle and to accept, with some reservation, the general scheme of development as suggested by Waldeyer. So far as the genesis of the "egg nests" and their ultimate subdivision into follicles are concerned, I am in accord with the latter investigator, but as to the origin of the so-called follicle epithelium or membrana granulosa, I feel that the evidence in my hands is sufficient to put me at variance with Waldeyer's conception and to incline me towards that of Foulis, who believes that the, germinal epithelium only forms ova and that the lining membrane of the follicle is derived from the connective tissue stroma.
The Ovarian Circulation of the New-Born Child
With the completion of the fibrous covering of the ovary (tunica albugiuea) shortly after birth, the vascular system becomes fully developed, and this period, therefore, may be said to represent the typical scheme, for up to this point there has been no derangement of its central or peripheral branches, which will occur later through the progressive development and degeneration of follicles.
The secondary branches of the circulatory tree occupy a comparatively small medullary area, its tertiary branches being given directly off. into the follicle-bearing zone. The follicles are, as as rule, still in their primitive state, only a few of the many thousands as yet showing progressive development.
Even at this early period, however, isolated follicles undergoing progressive and retrogressive changes may be noted. These changes, as I shall hope to show, are closely analogous to if not identical with those occurring in the ovaries of older children, and in women after ovulation is inaugurated.
The arrangement of the circulation as established at this early age is shown in the following schematic way:
Vasa auastomotica superfieialia
Rami corticalcs ;
Rami folliculares ' Vasa auastomotica follicularia
Venae ovaricae propriae
Arteria ovarica propria
Arteriae parallelae ovarii
As will be seen from this sketch each follicle is provided with a vascular wreath, which is formed by the terminal twigs of the main cortical branches.
The development of this wreath and its final obliteration, along with the disappearance of the corpus luteum, does not affect the general scheme, for it merely represents one small terminal system, the destruction of which, so far as its effect upon the general system is concerned, is like the lopping off of an ultimate twig of the branch of a large tree.
For this reason the changes in the ovarian circulation incident to the progressive development and degeneration of the follicles, even in early womanhood, are local and not general. It is only in the later periods of the ovulating life of the female that the latter effect is noted. Beyond the follicular zone the terminal vessels break up into capillaries which form a fine parallel running anastomosis in the tunica albuginea, which hitherto has not been described.
The extensive anastomosis throughout the ovary renders easy the shifting of the circulation from one set of vessels to another, consequently the destruction of the function of the ovary is almost an impossibility before its final cessation through natural causes.
In the same way the persistence of the function in even tiny bits of the ovary, which are occasionally left after an ovariotomy, may be explained.
In order to conform to the new method of classification, recently decided upon by anatomists, a system of nomenclature has been adopted which is based upon the regional distribution of the vessels.
Classification of Vessels:
English. Ovarian artery.
Extra ovarian or liilus branch ' of artery.
Extra ov., or lulus branches of
Cortical branches. Peripheral anastomosis.
Latin. Arteria ovarica.
Vena? ovarica? or Vv. ovaricse.
Arteria ovarica propria or Aa. ovaricse propria (Ramus I, II, III, IV, V).
Vena- ovarica? propria?.
Rami meiiullares or arteria; parallela? ovarii.
Vasa capillaria anastomotica superficialia.
Vasa anastomotica follicularia.
Arteria anastomotica uterina.
In order to follow the progressive changes in the ovary from birth tii the climacteric, specimens from my collection representing the following ages have been selected : child of 2 years, girls of 9 and 12 years, and of 14 years, just after the establishment of ovulation, young woman of 24 years, middle-aged woman of 35 years, woman approaching the menopause at 42 years, and finally an old woman of 66 years, long after the menopause.
In these specimens an endeavor has been made to follow not only the changes incident to the circulatory system, but also the other progressive histological transformations.
The comparison of this ascending series has suggested certain hypotheses concerning the physiology of the ovary, which I trust have been strongly sustained, if not confirmed, by the specimens in hand.
The Ovary of a Child of Two Years
In the six-months foetus the main branches of the ovarian artery correspond in the general form of their distribution to the fasciculi of a widely spread folding-fan, the divisions between the arteries being filled with primitive follicles.
As the ovary grows in age the vessels with the connective tissue septa?, which form these divisions, change from a gently curved to a perpendicular course, the branches occupying the medullary portion being crowded into parallel lines (arterise parallels ovarii).
In the two year old child, through the development and retrogression of numerous follicles from birth up to this time, the medullary area comprises a much larger portion of the than that noted in the new-born.
As there is no increase in the number of follicles after birth t'je obliteration of each primitive or partially develop naturally decreases the total original number, which results in an increase in the medullary portion of the ovary at the expense of the follicle-bearing or cortical zone.
The law of development in the follicle is from within outward, that is the primitive follicles lying nearest the central circulatory tree arc the first to undergo development.
In the young child the developing follicles instead of moving towards the periphery, as occurs in the girl approaching puberty or in the adult, tend to maintain their primitive position, their enlargement being simply centripetal without any attempt at mobilization.
Having reached a certain stage in their development, a retrogressive change following the degeneration of the ovum is inaugurated; and the original Bite, occupied by the follicle, is replaced by a very minute addition of connective tissue to the stroma of the organ, which naturally builds up through successive accumulations the central area.
Follicles in various stages of development and retrogression are noted in all ages after birth, and according to my observations the same principle involved in the Obliteration of the unruptured follicles before puberty governs the organization of the corpus luteum after ovulation is inaugurated.
Briefly stated the changes consist in an increase in the vascular wreath around the primitive follicle and a coincident or dependent hyperplasia of the membrana propria and an accumulation of liquor folliculi.
What determines the cessation of these progressive changes and the beginning of the retrogressive or obliterative process remains unexplained. The fact remains, however, that with the degeneration of the ovum the liquor folliculi is absorbed and the cavity is filled in with large embryonic connective tissue cells arising from the theca interna.
Through the gradual diminution in the blood supplied by the follicular wreath the excess of connective tissue undergoes hyaline changes and absorption until finally only a mere trace of the new-growth remains.
In this way the size of the ovary is maintained within reasonable bounds. Were each mature or large follicle to be replaced by permanent connective tissue, the ovary would very early in life assume the proportions of a new-growth, which sooner or later would constitute fibromata of no mean dimensions.
Progressive Changes in the Ovary
In the progressive growth of the ovary the obliterative changes just referred to continue until the follicle-hearing area, reduced by many thousands in its numbers of primitive follicles, becomes a narrow zone compared with its width in the new-born child.
The crowding together in more or less parallel lines of the secondary and tertiary branches of the ovarian vessels is, to return to our antilogy, simulated by the partial closure of the fasciculi of the fan. The increase in the internal resistance through the building np of a denser medullary centre and the closer crowding together of the parallel vessels sooner or later breaks the equilibrium of forces and consequently the follicles no longer maintain their primitive position while enlarging but undergo mobilization towards the tunica albuginea, that being the direction of least resistance.
The actual rupture of the follicle, according to my opinion, is due to the influx of blood during the menstrual cycle into the medullary blood-vessels, which ba a double action, first to push the mature follicle rapidly towards the surface, and second, through the increased pressure, to close the parallel running anastomosis in the tunica albuginea, and thus permit a physiological necrosis and rupture of the follicle.
Concerning the question of ovulation and menstruation I shall endeavor to offer further evidence to prove that the rule of synchronism is the normal, and that deviations from this rule are probably due to modifications in the life habit incident to changes in environment and to departures from primitive methods of living and from primitive laws governing sexual congress.
A brief paragraph will be devoted to the processes through which the mature but unruptured follicles undergo obliteration. I shall assume that this is not a pathological condition, but is merely Nature's method of getting rid of a functionless cavity. The organization of the vascular system of the corpus luteum, followed by its retrogressive changes and final disappearance, will be considered, and I shall take the position that little or nothing of the follicular vascular system remains when the resorption of the corpora fibrosa is complete.
As a conclusion to this study the cessation of ovulation will be ascribed to the gradual impairment of the vascular systems, through first, densification of the ovarian stroma and second, through the retroactive effect of imperfectly removed corpora lutea, which as an end result diminishes the blood-supply to the cortical area to such an extent that the growth of the primitive follicles is retarded and finally completely inhibited. These final retrogressive changes lead up to and constitute the menopause or climaterium.
Cite this page: Hill, M.A. (2020, September 27) Embryology Paper - Origin, development and degeneration of the blood vessels of the ovary (1899). Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Paper_-_Origin,_development_and_degeneration_of_the_blood_vessels_of_the_ovary_(1899)
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