FEMALE GENITAL SYSTEM: INTERNAL ORGANS 405 



anterior pole of the ovary. A similar fold was described by Weber (1886) for Hyperoodon, 

 in which a groove, with fimbriae arranged on each side of it, was found running to the 

 ovary along the fold, as a continuation of the tuba mouth whose edges are drawn out to 

 form the fold. 



Within the oviduct itself a number of compound folds, covered with the same ciliated 

 epithelium, projects into the lumen, greatly reducing its area in transverse section 

 (Fig. 15). Around the canal is a layer of circular fibres, which spread out also into the 

 ligamentous attachments of the tube (Fig. 15c). No longitudinal muscles were found 

 belonging to the oviduct itself but the broad ligament has a superficial muscular lamina, 

 which, at the junction of the ligament with the oviduct, is brought into close proximity 

 with the circular muscles surrounding the tube (Fig. 15 a). 



The uterus 



The uterus (Fig. 12/ 1 ,/ 3 ) possesses two long cornua joining medianly to form a short 

 corpus. The cornua pursue a curved course from the ovaries and Fallopian tubes to 

 their junction with the corpus a little behind the level of the posterior pole of the left 

 kidney. While the right cornu, however, describes an almost perfect semicircle, the left 

 describes the arc of a circle of very much longer radius. In the foetus 2-1 m. in length 

 the right cornu measured 10-5 cm. along its curve from the junction with the oviduct to 

 the entrance into the corpus. The distance in a straight line between these two points 

 was 8-o cm. The left cornu, on the other hand, measured 9-5 cm. around its curve, while 

 the distance between its extremities in a straight line was 8-5 cm. The right cornu curves 

 forwards from the oviduct across the pole of the right kidney, after which it curves more 

 gently backwards towards the middle line (Fig. 12). The left cornu has no forward 

 direction at the beginning of its course, but runs backwards in a gentle curve across the 

 left kidney between the posterior first and second thirds of the organ (Fig. 12). 



In the foetus 2-1 m. in length each cornu was of even diameter and measured 1-25 cm. 

 in diameter at its middle. In young whales, just before the attainment of sexual 

 maturity, the diameter of the cornua, though varying considerably, averages about 

 4-0-5-0 cm. (in Fin whales 15-0-16-0 m. in length). At sexual maturity the diameter is 

 about io-o-i2-o cm. In Fin whales after sexual maturity the diameter of the uterus in 

 a whale which is neither pregnant nor lactating — that is a resting whale — averages 

 about 17-0 cm., although variations occur between 15-0 and 25-0 cm. Mackintosh and 

 Wheeler (1929, pp. 397-401) have dealt with the changes in size of the uterus at sexual 

 maturity and after. These authors find that when an ovulation occurs without fertilization 

 of the ovum increase in diameter of the uterus takes place (perhaps up to 40-0 cm.). 

 During pregnancy the uterus grows very greatly, and when a large foetus is present it 

 may attain a diameter of over a metre. The growth in size of the pregnant cornu is con- 

 siderably faster in the early stages of pregnancy than in the later, and there is a slowing 

 down by the time the foetus has reached a length of 3-0-4-0 m. This is connected 

 with the considerably faster growth of the foetus itself in the early stages of pregnancy. 



The development of the foetus takes place in one cornu of the uterus, but the large 



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