The anatomy and nature of two acardiac acephalic foetuses / by Arthur Keith.

  • Keith, Arthur, Sir, 1866-1955.
Date:
1900
Catalogue details

Licence: In copyright

Credit: The anatomy and nature of two acardiac acephalic foetuses / by Arthur Keith. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    posterior end of the blastoderm, which afterwards helps to form the allantois. The placenta remains in common, and the parasite draws its blood-supply directly from the placental circulation of the host twin. The parasite is reared and nourished as a bud on the placental circula- tion of the host. Its circulation is reversed ; the impure blood from an umbilical artery of the host enters the parasite by a single umbilical or hypogastric artery, and is returned to the circulation of the host by a single umbilical vein. The circulation in the parasite is de- pendent on the heart of the host. There is here the experiment made of rearing a human being as a bud (Plate XI). The outstanding lesions in a parasitic foetus are those of imperfect, arrested, and abnormal segmentation, and these lesions may be due in some degree to the abnormal circulation. But from experimental work we know that pathological processes antedate the appearance of an active circulation. The formation of blood islands and the fusion of these into blood-vessels, and the incursion of these vessels to form the leading blood-stems of the body are vitiated. We know, too, that unequal division of segmenting frog ova made artificially leads to formations similar to parasitic foetus. I therefore regard a parasitic foetus as the product of the lesser and imperfect part of a twin blastoderm. The origin of the condition is to be sought in the very earliest stages of segmentation of the ovum. Inquiry into the condition of the mother during the weeks following conception might throw some light on the cause. Besides the similarity in the nature of their circulation, another character iu which both specimens agreed was in the condition of the connective tissue of the body. In both it was thickly infiltrated with mucoid jelly-looking material, and greatly hypertrophied in amount. In both the thyroid gland was absent. The veins and arteries were equally thickly coated. Leucocytes were extremely abundant in theconnective tissue and in the blood-vessels—