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Fig. 116. Comparative histological characters of corpora lutea at different stages of 

 pregnancy in Pacific walruses: (a) during initial luteinization of a recently ruptured 

 follicle (14 February); (b) in a 17-mm, fully luteinized corpus (17 March); (c) in a 

 25-mm corpus (1 April); (d) in a 27-mm corpus from a female with a 0.7-mm 

 unimplanted blastocyst (30 May); (e) in a 32-mm corpus, postimplantation (10 June); (f) 

 in a 44-mm corpus, about halfway through gestation (30 November); (g) in a 35-mm 

 corpus at full-term (24 May); and (h) in a 33-mm corpus, immediatelv postpartum 

 (12 May). (Photos by F. H. Fay) 



