BENIRSCHKE ET AL.: OVULATION IN DOLPfflNS 

 Table 7. — Group via: Experimental group with early corpora lutea. Specimen no. 1-19 Stenella longirostris; no. 20-28 S. attenuata. 



placed into Group VIb. Because of the potential 

 insight these specimens give into the dynamics of 

 ovarian/endometrial relationships, these speci- 

 mens are described in more detail. 



When the Graafian follicle has recently rup- 

 tured, stromal vessels infiltrate the granulosa 

 layer (Figure 16). The follicular lumen is filled 

 with serous fluid and fibrin but rarely contains 

 blood as in many other species. The corresponding 

 endometrial stroma is edematous, the glands are 

 tubular, lack secretory vacuoles and contain 

 mitoses (Figure 17). When the corpus luteum is 

 better established, the central cavity is more pro- 

 nounced, capillaries have penetrated the 

 granulosa layer, and, in contrast to its cells in 

 specimens from early pregnancy (Figure 11), they 

 possess less cytoplasm, being less plump (Figure 

 18). It should again be noted that the cavities 

 rarely contain red blood cells. The endometrial 

 glands at this stage are more crowded, have more 

 coiling, and still possess mitoses, but the earliest 

 appearance of epithelial cytoplasmic vacuoles oc- 

 curs (Figure 19). The vacuolization appears to 

 commence under the endometrial surface and 

 penetrates slowly throughout the entire thickness 

 of the endometrium (Figure 20). At the same time, 

 fibroblastic infiltration of the corpus luteum cav- 

 ity has taken place and the luteinized cell wall has 



folded remarkably. Very few mitoses were found 

 in superficial endometrial cells at this stage and in 

 the final stages before the central corpus luteum 

 cavity has been completely filled in by fibrous tis- 

 sue, the endometrial stromal edema disappears, to 

 be replaced by coiled secretory glands (Figure 21). 

 No mitoses exist, nor is secretion exuded into the 

 glandular lumina. Such corpora lutea are ex- 

 pected to be associated with early pregnancy par- 

 ticularly because of the conspicuous size of 

 granulosa luteal cells. Since no embryonic sacs 

 were found, it is then also not surprising that the 

 endometrium possesses different histologic fea- 

 tures from those whose comparable corpora lutea 

 were associated with early pregnancy (Figures 

 11-13). Perhaps this climaxes endometrial de- 

 velopment before regression of corpus luteum 

 occurs. 



One of these specimens from an October catch 

 (no. 20, Table 6) had a fresh corpus luteum with 

 fibrin-filled cavity and unusual endometrium. The 

 stroma beneath the surface epithelium had the 

 typical hyalinization of the post partum state, yet, 

 early secretory endometrium was found in deeper 

 layers (Figure 22). Moreover, hemosiderin pig- 

 ment was found. It would appear that this was the 

 first and infertile ovulation after a recently past 

 pregnancy which is further supported by the 



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