A treatise on the science and practice of midwifery . ds of the amnion unite, thefree edge of each is bent outward andspreads around the ovum, immediately within the zona pellucida, form-ing a lining to it, termed by Turner the subzonal membrane, which isconnected with the development of the chorion. The amnion is themost internal of the membranes surrounding the foetus, and will pres-ently be studied more in detail. It soon becomes distended with fluid,the liquor amnii, and as this increases in amount it separates the amnionmore and more from the foetus. Changes in the Hypoblast.—During this
A treatise on the science and practice of midwifery . ds of the amnion unite, thefree edge of each is bent outward andspreads around the ovum, immediately within the zona pellucida, form-ing a lining to it, termed by Turner the subzonal membrane, which isconnected with the development of the chorion. The amnion is themost internal of the membranes surrounding the foetus, and will pres-ently be studied more in detail. It soon becomes distended with fluid,the liquor amnii, and as this increases in amount it separates the amnionmore and more from the foetus. Changes in the Hypoblast.—During this time the innermost layer ofthe blastodermic membrane or hypoblast is also developing two pro-jections at either extremity of the foetus, and these gradually approacheach other anteriorly. As the hypoblast is in contact with the yelk, whenthese meet they have the effect of dividing the yelk into two , and the smaller of the two, forms eventually the intestinal canalof the foetus; the other, and much the larger, contains the greater por-. ter of Development of the Amnion1. Vitelline membrane. 2. External layblastodermic membrane. 3. Internal layersforming the umbilical vesicle. 4. Umbilicalvessels. 5. Projections forming Embryo. 7. Allantois. CONCEPTION AND GENERATION 107 tion of the yelk, and forms the ephemeral structure known as the umbili-cal vesicle, from which the foetus derives most of its nourishment duringthe early stage of its existence. Its communication with the abdominalcavity of the foetus is through the constricted portion at the point of Fig. 56.
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectobstetrics, bookyear1
