THE OVARIES 345 



kidneys and forwards to the diaphragm; a large pink-coloured lobe of fatty tissue arises from this 

 fold near to the anterior pole of the ovary. In the pregnant female it measured 42 x 25 x 10 cm. and 

 in the immature female about 33 x 21 x 7 cm. This reddish-pink fatty lobe is very conspicuous against 

 the grey-white peritoneum and serves as a useful landmark when searching for the ovaries on the 

 flensing deck. Rounded fatty lobes have also been noticed in the broad ligament. 



From the posterior pole of the ovary two conspicuous ovarian ligaments extend, one to the uterine 

 horn and the other along the broad ligament. In addition a broad fold representing the mesovarium 

 runs over the broad ligament carrying most of the blood vessels, lymphatics and nerves to the ovary. 



The differences between this account and the description given by Ommanney (1932) are the result 

 of comparing the foetal anatomy with the adult. The most important respect in which they differ is 

 the development of the ovarian sac in the sexually immature and adult female, whereas in the foetus 

 the ovary 'lies free on the ligamentum latum and is not enclosed in any sort of sac or pavilion' 

 (Ommanney, 1932, p. 444). 



GRAAFIAN FOLLICLES 



Foetal ovaries 



Chittleborough (1954, pi. 1) found abundant primary follicles up to 0-13 mm. in diameter in ovaries 



from near-term humpback-whale foetuses 4-54-4-66 m. long. The average neo-natal length in this 



species is 4-56 m. (Chittleborough, 1958). 



The neo-natal length of fin whales averages 6-4 m. (Laws, 19596) and of 956 foetuses of known 

 length in the present material none was above 6-o m. Only 0-9% are above 4-0 m. and only 0-4% 

 above 4-5 m. This is a result of sampling being restricted to a period when most females are in mid- 

 pregnancy, whereas Chittleborough's sample are in early or (the majority) in late pregnancy. Con- 

 sequently no near-term fin-whale foetal ovaries are available for examination. All foetal ovaries 

 examined including the largest, from foetuses measuring 3-8 and 4-16 m., show as yet no development 

 of primary follicles. The genesis of follicles must, therefore, begin in the last 2 or 3 months of gestation 

 as in man. 



Immature ovaries 

 Owing to the minimum size regulations for the antarctic pelagic catch in recent years only the larger 

 immature females are sampled. 



The cortex of two pairs of immature ovaries from females of length 54 and 56 ft. which have been 

 sectioned for histological examination contained very numerous primary follicles, most of which were 

 from 45 to 70 fi in diameter. These are already separated from the germinal epithelium by a tunica 

 albuginea which is about 150-250 fi in thickness (PI. IV, fig. 6). 



The size frequency distribution of the largest follicle in 80 pairs of immature ovaries in the material 

 is shown in Text-fig. 2. The majority, 66%, are less than 1 cm. in diameter; only 17-5 and 8-8% are 

 over 2-0 and 3-0 cm. respectively, the largest being about 5 cm. With few exceptions these follicles 

 appeared to be atretic with thick elastic walls, and when a sample was examined histologically it was 

 confirmed that they were in varying degrees of atresia. 



One immature female examined in 1954 (on 10 February, length 68 ft.) had ovaries of unusual 

 appearance. The body of each ovary was very thin and strap-like, measuring 22 x 6-5 x 1-5 cm. and 

 26-5 x 5-5 x i-o cm., the corresponding weights being 0-4 and 0-3 kg. Each ovary had several large 

 follicles projecting from the surface and often connected only by a small neck. The largest were 

 3-5 and 2-7 cm. in diameter. These follicles had very thin transparent walls in which the blood vessels 

 were very conspicuous. In view of their relatively small size and lack of turgidity it seems unlikely 



3-2 



