26 R. W. NoYES, T. H. Clewe and A. M. Yamate 



from that observed in albino-to-albino transfers. However, after fourteen days 

 the tissue from the blacks became unresponsive to gonadotropins and began 

 to degenerate. The albino-to-albino transplants lasted indefinitely; several 

 animals being observed for as long as one hundred and eighty days without 

 regression of the transplants. 



The interspecific transplants often became vascularized, and one crop 

 of follicles sometimes developed. However, neither ovulation nor ovum 

 maturation was observed. The average period of viability of such grafts was 

 10 days. The details of these interspecific experiments are recorded elsewhere 

 (3, 10). 



Figures 1 and 2 are low and high power photomicrographs of ovarian 

 tissue from a 25-day-old rat. After four days in the eye, all of the original 

 antrum-containing follicles degenerated, and the few surviving primordial 

 follicles were located along the interface between the ovary and the iris 

 (Fig. 3). The earliest of the new antrum-containing follicles appeared on the 

 fourth day (Fig. 4). Fifty-six hours after castration and gonadotropin 

 injection of the host, the new follicles had enlarged greatly (Fig. 5) and the 

 ova had begun to separate from the mural granulosa. The nuclei in most of 

 the ova remained in the immature or germinal vesicle stage (see Fig. 2), 

 although occasional ova formed the first meiotic spindle (Fig. 6). Fourteen 

 hours following the injection of HCG, the follicles enlarged still further, and 

 an occasional follicle ovulated (Fig. 7). Ova in the maturing follicles usually 

 completed meiosis by this time and they were separated completely from the 

 mural granulosa. Mitotic activity in the cumulus cells was abundant (Fig. 8). 



Corpora lutea were formed 22 hr after the administration of HCG (Fig. 9), 

 and ova that had not been ovulated were found compressed among the 

 lutein cells (Fig. 10). The relationship of the transplant to the iris and to the 

 cornea is shown in Fig. 9. In this particular section the connection between 

 the iris and the ovary is narrow, but usually the transplant was attached to a 

 wide area of the iris. 



Figure 1 1 is a photograph of a transplant taken through the cornea at the 

 same magnification that was routinely used with the dissecting microscope. 

 A freshly ovulated ovum, still surrounded by cumulus oophorus, is visible. 



Plate I 



Fig. 1. Ovary from a 25-day-old rat. (x 20) 

 Fig. 2. An early antrum follicle from Fig. 1. Volume = 65 x 10® ^^ (x 90) 



Fig. 3. Half an ovary from a 25-day-old donor rat, 4 days after transfer to the anterior 

 chamber of the eye of a 25-day-old recipient rat of a different strain. ( x 20) 



Fig. 4. An early antrum follicle from Fig. 3. Volume = 4.6 x 10" ix^. ( x 90) 



Fig. 5. Rat ovarian transplant 56 hr after injection of the recipient rat with 

 15 I.U. pregnant mare's serum gonadotropin, (x 20) 



Fig. 6. Developing follicle from Fig. 5. Volume 110 x 10® fj.^. The ovum is 

 unusual in that it has formed the first meiotic spindle, (x 90) 



