Notice of the dissection of a case of lateral transposition of the viscera of the thorax and abdomen in a man / by Allen Thomson.

  • Allen Thomson
Date:
[1853?]
Catalogue details

Licence: Public Domain Mark

Credit: Notice of the dissection of a case of lateral transposition of the viscera of the thorax and abdomen in a man / by Allen Thomson. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

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    asoending and descending veins are at first placed on the left side cxclusivdy, or if there are two, the left is the largest. The open part of the alimentarjr canal, hy which it communicates with the cavity of the yolk, is placed more to the left; and ■ when the rotation is complete, the left side of the embryo is towards the surface of tlie yolk. V. Baer points out that in all animals in which the germinal membrane (toes not surround the yolk from the first, but extends gradually over it, the same sort of isolation of the foetus from the yolk takes place, and the same relative situation is observed in the earlier periods between the embryo and the yolk; at all events, in the sauria, ophidia, birds, and mammalia, the embryo is always, in the second stage of its development, placed with its left side towards the yolk. In several hun^eds of embryo-chicks, V. Baer has only observed two in a different position, or with the right side towards the vitellus. In one of these the turn was incom- plete, and the heart was natural; but in the other, in which the rotation was complete, the position of the heart was inverted, so that the part usually towards the left was turned towards the right, &c. “I cannot doubt, therefore,” says Von Baer, “that in° this case there was a commencement of transposition (situs invcTsus^,^ “I have,” continues this author, **more fre<][uently found the umbilical vesicle situated to the right of the embryo in mammalia, particularly in the pig, which may depend upon the less firm support which the membranes of the ovum receive fi*om the external coverings in viviparous than in oviparous animals. A considerable number of years ago, when investigating tlie phenomena of development of the bird on an extensive scale, I observed only once out of many hundred incubated eggs of the common fowl, the embryo on the third day lying on its right side. I did not in that case attend to the state of the heart. But m a goose’s egg of a corresponding period of advancement, I also once saw the same deviation from the natural position most distinctly, and in this case the position and form of the heart and vessels connected with it, were quite inverted; but the other viscera were not sufficiently advanced to enable me to observe whether the inversion had extended to them. , • i I have elsewhere* called attention to the fact, that in the c^e of double monstrosity, while the one of the united indi\nduals that is situated to the right of a person looking at them in front is na- turally formed, in the other the heart and non-symmetrical yscera are laterally transposed, as in the case of the man under considera- tion. The viscera in the two individuals of a double together therefore form a symmetrical whole; and I have adduced this fact, in confirmation of the suggestion of Von Baer as to the Monsters in the London and Edinburgh Monthly Journd. Recherches d’Anat. Transcend, and Isid. Geoff, bt. Hilaire Hist, des Anomalies. 1832. * Paper on Double 1844. See also Serres’