. The cell; outlines of general anatomy and physiology. l vesicle is frequentlyfound in that place, where the absorption of material must ofnecessity take place. Thus, for instance, in one species of Coehn-terates, the ova are derived from the endoderm and are nourishedby the gastrovascular system by means of endodermal cells. Inconformity with the above-stated law the germinal vesicles ofyoung ova are situated superficially near to the surface of thatwall, which is turned towards the gastric cavity (Fig. 164). Inmany Actinice (Hertwig, VIII. 5b) the ova, for a considerable 328 THE CELL period
. The cell; outlines of general anatomy and physiology. l vesicle is frequentlyfound in that place, where the absorption of material must ofnecessity take place. Thus, for instance, in one species of Coehn-terates, the ova are derived from the endoderm and are nourishedby the gastrovascular system by means of endodermal cells. Inconformity with the above-stated law the germinal vesicles ofyoung ova are situated superficially near to the surface of thatwall, which is turned towards the gastric cavity (Fig. 164). Inmany Actinice (Hertwig, VIII. 5b) the ova, for a considerable 328 THE CELL period, protrude a stalk-like (peduncular) process right up to thesurface of the intestinal epithelium (Fig. 165). This process hasa regular fibrillary (rodded) structure, as is always seen, when anactive exchange of material takes place in definite directions;it may, therefore, he considered to be a special nutrient apparatusof the ovum. In this case, too, the germinal vesicle is alwayssituated in immediate contact with the base of the nutrient liiiip- Fig. 16 k
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Keywords: ., bookcentury1800, bookdecade1890, bookidcelloutlines, bookyear1895
