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Show 508 MR. F. E. BEDDARD O N THE DEVELOPMENT A N D [Dec. 7, Stage I.-The earliest stage of these bodies is represented in fig. 1 ; its different constituents are figured, highly magnified, m figs. 5, 14-20. The whole structure is situated near to the surface of the ovary, with which indeed it is still in continuity ; the germinal epithelium (ge), which is apparently not everywhere present as an external layer in the adult ovary, is here conspicuous by its presence; it forms a mass of cells, the nuclei of which are so large and so closely pressed together that I have found it impossible to detect any cell-outlines (see fig. 1). These thickly clustered groups of epithelial cells seem to correspond to the " epithelial islands " of many writers (see Iwakawa, G. J. M.S.I 882, p. 266). The nuclei of these cells are deeply stained by borax carmine, and for the most part rounded or oval in contour, though frequently (perhaps owing to the hardening-reagent) somewhat angular. The staining-fluid is not evenly taken up by the whole nucleus, but a peripheral layer, sometimes confined to one pole of the nucleus, is very deeply stained, the central regions being comparatively pale. The germinal epithelium is immediately continuous with a mass of cells which form a hollow sphere, partly occupied by a plug of cells of a somewhat different appearance ; tbe spherical mass of cells is quite close to the surface and connected with the germinal epithelium by a very short neck, which is as wide as the area occupied by the patch of germinal epithelium. The peripheral mass of cells is already differentiated into two distinct layers, which are distinguishable from each other by the characters of the component cells and more particularly of their nuclei. The outermost layer is of course the one that is in contact with the germinal epithelium ; the outlines of its cells are not very visible in m y preparations : between the nuclei of the cells is a fibrous substance moderately stained by borax carmine ; this appears to m e to be the slightly altered protoplasm of the germinal cells themselves, and not to be an inroad of connective-tissue stroma-cells. The germinal cells bear, however, a very striking resemblance to connective-tissue cells. Balfour has figured (Q. J. M . S. 1878, pi. xvii. fig. 10) and described (p. 390) a condition of the Elasmobranch ovary which is so far very similar to that which 1 have just described, and which gives me greater confidence in stating that the cells displayed in fig. \,f.e, of Plate LII. are really germinal and not stroma-cells. H e says (p. 391) : - " T h e surface of the ovarian region ... is covered by a distinct . . . pseudo-epithelium . . . The cells of the pseudo-epithelium have one peculiarity very unlike that of ordinary epithelial cells. Their inner extremities are prolonged into fibrous processes which enter the subjacent tissue, and, bending nearly parallel to the surface of the ovary, assist in forming the tunic spoken of above. This peculiarity of the pseudo-epithelial cells seems to indicate that they do not essentially differ from cells which have the character of undoubted connective-tissue cells, and renders |
