STUDIES IN MAMMALIAN EMBEYOLOGY. 533 



PLATE 36. 

 All the figures in this Plate X 480. 

 Fig. 66. — Part of the uterine wall opposite the mesometrium, in the phase 

 of Fig. 3 (of. Fig. 17). The stretching of the uterine wall is very consider- 

 able ; the blastocyst has not yet become attached. 

 Utr. Mus. Cat. n°- Sorex 2 a, 5 »*. 23 s. 

 Fig. 67.— Part of the same, one stage further (of. Figs. 4 and 19). Pro- 

 liferation of the uterine epithelium has commenced. Karyokinetic figures 

 demonstrate the participation of the epithelium cells. 

 Utr. Mus. Cat. n°- Sorex 52 b, 4, r. 20 *. 

 Fig. 68.— Section through another swelling of the same uterus, showing 

 the mouth of one of the uterine glands (cf. Figs. 4 and 21). 

 Utr. Mus. Cat. n°- Sorex 52 i, 3 r: 21 s. 

 Fig. 69. — Section through the same swelling from which Fig. 67 was taken, 

 somewhat further from the mesometrium (cf. Fig. 4). The proliferated 

 epithelium cells have commenced to arrange themselves in a radial fashion. 

 Uterine epithelium as yet continuous. A few cells in the border region, 

 between the epithelial proliferation and the connective tissue of the uterine 

 wall, are seen to become spindle-shaped in Figs. 68 and 69. This is later on 

 further accentuated into a special fibriform layer (cf. Figs. 72 — 74, and also 

 Figs. 22—25). 



Utr. Mus. Cat. n°- Sorex 52 b, 4 r. 15 s. 

 Fig. 70. — Section through a further stage of development. The prolifera- 

 tion forms already a thicker layer, the uterine epithelium breaks away from 

 under the radially arranged groups of cells, which are going to be the secon- 

 dary epithelial crypts. 



Utr. Mus. Cat. n°- Sorex 73/, 3 r. 22 s. 

 Fig. 71. — Another section through another swelling of the same uterus. 

 The passage of the uterine epithelium into that of the crypt is already more 

 complete, but quite different from the mouth of a gland. 

 Utr. Mus. Cat. n°- Sorex 73 e, 3 n 14 *. 

 Fig. 72.— The boundary region between the epithelial proliferation and the 

 connective tissue of the uterine mucosa. The blood-vessels in the latter are 

 more spacious than the capillary ducts in the former. Of the uterine glands 

 one is partly cut along the lumen, the other only tangentially through the wall. 

 Utr. Mus. Cat. n°- Sorex 73 6, 2, 3 r, 8 *. 

 Fig. 73.— The same, in a somewhat later stage. The proliferated epithe- 

 lium cells are more closely packed, and between them and the connective 

 tissue there is a layer of fusiform cells, first noticed in Fig. 69. This section 

 was somewhat too tangential to show the secondary crypts well (cf. Fig. 25, 

 which has reference to the same uterus). 



Utr. Mus. Cat. n°- Sorex 42 e, 2 r. 13 s. 



