Time of Implantation 



Seventeen tracts contained an implantation 

 chamber (table 33). The earliest was collected 

 on 4 November; in the last collection on 

 Z8 November all of the five tracts had im- 

 plantation chambers. In this small sample, 

 no relation between time of implantation and 

 age of seal was evident (table 34). 



Embryos 



Five embryos were identified in tracts 

 collected during the 19-day period 9-28 Novem- 

 ber. They ranged from 8 to 19 mm. in crown- 

 rump length, as follows: 



Date 



9 Nov. 

 23 Nov. 

 23 Nov. 

 28 Nov. 

 28 Nov. 



Crown-rump length 

 of embryo 



8? (broken) 

 10 

 14 

 19 



Table 33. --Percentage of genital tracts with a corpus 

 luteum and with an implantation chamber, by date of 

 collection 



Collection 

 date 



Tracts with 

 corpus luteum 



Tracts with 



implantation 



chamber 



Number Percent 



13 Sept. 

 22 



28 " 



6 Oct. 



13 " 

 20 " 

 24 " 



29 " 



4 Nov. 

 9 " 



14 " 

 19 " 

 23 " 

 28 " 



Total. 



Number 



Percent 



66 



96 



17 



24 



Persistence of Corpus Albicans 



Of 65 tracts having a new corpus luteum and 

 a corpus albicans of the 1964-65 pregnancy, 

 24 also had a corpus albicans of the 1963-64 

 pregnancy. The 24 tracts with both old and 

 new corpora albicantia were distributed as 

 follows: 



8 of 12 in September (67%) 



9 of 25 in October (36%) 

 7 of 28 in November (25%) 



The percentages suggest that the proportion 

 of corpora albicantia identifiable in gross 

 exarri:nations decrease progressively 4 or 

 more months after parturition. 



Placental Scars 



A placental scar (or its absence) was cor- 

 rectly identified in 41 of 70 tracts (table 35). 

 Identification was incorrect in 29 tracts mainly 

 through failure of the examiner to record a 

 doubtful scar. A placental scar cannot always 

 be recognized after early October. 



Diameter of Uterine Horns 



The diameter of the uterine horns is shown 

 in table 36 for 49 tracts in which one ovary 

 had a corpus albicans and the other had a 

 corpus luteum (excluding 17 tracts that had an 

 implantation chamber, 3 tracts that showed 

 no evidence of pregnancy, and 1 tract that 

 lacked an ovary). Presumably, for most of the 

 tracts, the horn on the side with a corpus 

 albicans delivered a fetus in 1965. 



■■■ One of the tracts probably, but not certainly, had 

 an implantation chamber. 



^ One of five tracts lacked the right ovary. 



Tablt; 34. — Number of female seals showing evidence of 

 implantation (I) and no evidence (NX), by collecting 

 date and age-'- 



Number 



2 



1 1 

 1 1 

 1 



1 -- 



1 -- 



Total 



10 



46 



68 



•'■ Excluding one 4-year nullipara and one adult for 

 which age was not estimated. 



^ Age estimated from examination of canine teeth. For 

 females 8 years old and older, estimates may be in error 

 by + 2 years. 



3 Probably, but not certainly, implanted. 



37 



