Licence: Public Domain Mark
Credit: Researches in embryology. (Second series) / by Martin Barry. Source: Wellcome Collection.
Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.
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![retinacula, Plate V. fig. 96. g^. and g'^.'] in which the ovum is imbedded is observed to be composed of a g-elatinous substance interspersed with grains, but as yet there appears no distinctly circumscribed envelope. T. Wharton Jones then refers to the views of Krause, and remarks-f-, From his [Krause's] observations on the ovum before impreg^nation, he has been led to form much the same opinion regard- ing- the origin of the chorion as is recorded in this memoir. This opinion of Krause appears to have been the following:|:. It may be conjectured that the ovulum on the bursting- of the folliculus passes with the disc and layer of albumen into the Fallopian tube, and that out of the granules of the former [i.e. the disc] the cho- rion is formed. My own observations do not realise the conjectures of T. Wharton Jones. On the contrary, they show that when the chorion first comes into view, it is not as a g-elatlnous coat§, but in the form of a thin lamina closely investing the thick transparent membrane or zona pelkicida (Plate VI. fig. 104. a and (3. cho.) ; and that this thin lamina—itself the incipient chorion—expanding from the zona pellucida, imbibes a quantity of fluid into its interior, thickens, and with the im- bibed fluid presents a gelatinous appearance,—but that the chorion is not formed out of the gelatinous-looking- coat*^, since the outer portion of this coat is from the first constituted by a membranous structure, the chorion,—and the imbibed fluid which formed the principal part of the coat (Plate VI. fig-. 105 to 113./'.) soon passes into the interior of the ovum, leaving the chorion again in close contact with the outer surface of the zona pellucida (Plate VI. fig. 11/, cho. and/.) The con- jecture of Krause, howevei, does not appear to me to coincide with that of Jones, so closely as tlse latter seems to have supposed. So far from this, I think it by no means improbable that—as conjectured by Krause—the so-called disc (my tunica granulosa and retinacula) may bring from the ovary the materials out of which the chorion is formed, and it is possible that the granules (vesicles) of the disc may coalesce to form it. Thus that portion of the tunica granulosa {g^) which in the ovum Plate IX. fig. 153. was seen surrounding the incipient chorion {cho.) on its rising from the membrane may have been destined to enter into the formation of the chorion, and to contribute towards the thickening of this memibrane, as well as to supply fluid for its imbibition (par. 150. 151.) ||. t L. c, p. 340. X Muller's Arcliiv. 1837, Heft I. pp. 28, 29. § See his fig. 1. I. c. plate xvi. See also figs. 109. and 110. in Plate VI. of the present memoir. II I am inclined to think that the very delicate albuminous membrane figured by Krause (/. c, Taf. I. figs. 4 to 6.) as surrounding a thin layer of fluid albumen, must have been the incipient chorion (from some cause making its appearance in the ovary) though Krause does not seem to have regarded it as such (compare with Plate IX. fig. 153. in the present memoir). On a former occasion (I. c, par. 49. Note.) I stated that an e.'camination of the ovum of the Goat enabled me to attest the accuracy of Krause ; but to a certain extent only; for I did not in any instance find the membrana vitelli surrounded by a fluid as described by Krause, but by the perfectly formed and consistent chorion (as I then called the membrane/.). From this, however, it will be obvious that the exceedingly distinct membrane, which I found to circumscribe the yelk in ova of this animal, cannot have corresponded, as I then believed, to the thick membrane figured by Professor Krause in the same situation.](https://iiif.wellcomecollection.org/image/b2197214x_0042.jp2/full/800%2C/0/default.jpg)
