Figure 23. — Genital tract of female fur seal showing implantation chamber (IC), right ovary (RO), left ovary (LO),and 

 OS cervix (OC). Specimen no. 66, 28 November 1965, age 17; ventral aspect of freshly thawed tract; scale = 5 cm. 

 (Photo VBS 6177.) 



IMPLANTATION OF THE BLASTOCYST 

 IN FUR SEALS 



In I960, Douglas G. Chapman estimated the 

 mean date of implantation of the blastocyst in 

 fur seals as early November. He based his 

 conclusion on extrapolation of the weights of 

 398 fetuses collected at sea from January to 

 June (In Scheffer, 1962). 



In 1965, the genital tracts of 70 adult, white - 

 whiskered females on St. Paul Island were 

 collected for a study of implantation. The 

 tracts were collected at about 6 -day intervals 

 from 13 September to 28 November, and 

 placed in a freezer within 1 hour after death. 

 In March 1966 they were thawed and examined. 

 The external diameter of each uterine horn 

 at its midpoint was measured, and each horn 

 was examined for the presence of a placental 

 scar (fig. 23). Each ovary was sliced by 

 scalpel, and the presence of a corpus luteum 

 or a corpus albicans was noted. 



General Conditions of Genital Tracts 



The right ovary of one tract was lost on the 

 killing field. Of the remaining 69 tracts, 66 

 (96 percent) had a normal corpus luteum and 

 were assumed to be pregnant (table 33). Data 

 for the three tracts showing no evidence of 

 parturition follow: 



Diameter 



of uterine 



horns 



Age Right Left Remarks 



Years Mm . Mm . ' 



4 10 10 Immature? 



17 11 14 Corpus luteum small, regressing (?) 



13 21 25 Corpus albicans in each ovary; cyst 



on right ovary 



36 



