406 



DISCOVERY REPORTS 



chorionic vesicle extends itself into the corpus and into the other cornu. There appears, 

 however, to be no intimate union between the placenta and the uterine wall at any stage 

 in the development. The non-pregnant part of the uterus also undergoes considerable 

 enlargement with the size of the foetus, but the growth is far less marked than that of 

 the pregnant cornu. When the pregnant cornu contains a foetus 4-0-5-0 m. in length 

 and measures 90-0-95-0 cm. in diameter, the non-pregnant cornu may have enlarged 

 to the order of 70-0 cm. The uterus recovers quickly after parturition and in lactating 

 whales assumes its normal resting dimensions — namely about 17-0 cm. 



At their junction with the short corpus the cornua remain still separated by a median 

 tongue (Fig. 12/ 2 ). In the 2-1 m. foetus this measured 3-0 cm. in length. This tongue 

 projects backwards into the lumen of the corpus so that the cornua finally join together 

 very obliquely. The corpus uteri (Fig. 12/ 3 ) is very short. In the 2-1 m. foetus the 

 distance from the tip of the median tongue to the narrow entrance to the vagina was 

 3-0 cm. The lining mucous membrane of the cornua and of the corpus is raised into 

 very numerous short parallel ridges, longitudinal in direction, with depressions between 

 them. These ridges are firm and erect in the foetus, but in older whales, after weaning, 

 they take on the character of loose folds. The corpus has one or two very slight circular 

 constrictions (Fig. 12), foreshadowing, as it were, the vaginal pleats shortly to be 

 described. The longitudinal ridges of mucous membrane are continued over these 

 constrictions which do not make the complete circuit of the lumen of the corpus. 



Transverse sections of the cornua (Fig. 16) reveal 

 the ciliated epithelium intact only between the parallel 

 ridges. In the foetus 2-1 m. in length the glands were 

 not yet properly developed. As Turner remarked the 

 glands are probably not developed during intra-uterine 

 life and are not fully formed until sexual maturity. 

 Beneath the mucosa is a thick layer of circular muscles. 

 At this stage, at any rate, no longitudinal muscles were 

 found except those belonging to the broad ligament. 

 Outside the circular muscle layer is a serous coat. 



The entrance of the corpus uteri into the vagina is 

 marked by a circular constriction (Fig. 12) forming a 

 passage (0-9 cm. long in the 2-1 m. foetus) lined by 

 the same parallel ridges as are found throughout the 

 corpus and the cornua. At the upper end of this 

 comparatively narrow passage is the os internus which 

 is wider than the lower aperture which forms the os externus leading into the vagina. 

 Both these uterine apertures, however, are ill defined and take the form of narrowings 

 of the uterine lumen rather than of a definite os uteri. The position of this narrowing 

 is marked externally upon the uterine wall as a slight neck dorsally ; but ventrally it is 

 invisible. 





Fig. 16. Transverse section of part of 

 the wall of the uterine cornu in a 

 2-1 m. Fin whale foetus, (x 2§.) 



a. Circular muscle layer. 



b. Epithelium (intact only between 

 the ridges). 



c. Embryonic mucosa. 



d. Developing glands. 



