the ovaries 343 



Giant ovaries 

 Although the combined weight of a pair of fin-whale ovaries is usually less than 10 kg. and of blue- 

 whale ovaries under 16 kg., there are two records of ovarian hypertrophy. One is of an 83-ft. pregnant 

 blue whale with ovaries weighing in all 59-4 kg. (Laws, 1954). The other, previously unpublished, is 

 a lactating female fin whale with ovaries together weighing 52 kg. (26 kg. each), which were examined 

 at South Georgia in 1929. Both ovaries of this whale had a number of large bodies which appeared 

 like hypertrophied corpora lutea; they showed a corona-like structure and several of them had a 

 central cavity (see p. 359), but they were composed of white fatty tissues. There were four of these 

 bodies in one ovary, of mean diameter 30, 25, 18 and 13 cm., and six in the other ovary measuring 

 23, 22, 21, 17, 11 and 8 cm. In the first ovary there were four corpora albicantia but no macroscopically 

 visible follicles, and in the second ovary was a large protruding cyst 12 cm. in diameter. 



In both examples of giant ovaries there was excessive fat deposition, but the blue-whale ovaries 

 were otherwise normal. The fin-whale ovaries now described must be classed as pathological in view 



of the ten abnormal fatty bodies. 



Morphology 



The external appearance of the ovaries has been described and figured by Mackintosh and Wheeler 

 (1929) and Ommanney (1932). In the foetus they are small, compact, tending to taper posteriorly 

 with an irregularly grooved surface divided into a number of flattened lobes by branching sulci. In 

 sexually immature females the ovaries elongate, and the smaller grooves gradually disappear so that 

 the surface is smooth. Towards sexual maturity the development of Graafian follicles leads to the 

 formation of rounded protuberances. In the adult the ovaries usually have a flattened elongated 

 egg-shape, tapering posteriory, with many rounded follicles and corpora albicantia protruding, the 

 latter often attached by only a small area at the base. The corpora lutea usually project almost entirely 

 from the body of the ovary and are sometimes connected only by a narrow neck. The colour of the 

 ovary is a pink-grey-white, varying somewhat with the circumstances of death. 



The ovary is reduced in thickness at the hilum, where it is attached to the mesovarium. Blood 

 vessels and lymphatics enter and leave the ovary along this narrow connexion and the ovarian artery 

 divides into a number of branches before entering the ovary. In a 68 ft. non-pregnant mature female 

 there were respectively 1 5 and 1 6 arteries visible at the hilum of each ovary. 



The medulla is a dense mass of white fibrous tissue supporting the many tortuous arteries, veins 

 and large lymphatic sinuses. The larger arteries have a spiral configuration (Reynolds, 1950). A few 

 branches pass into the cortical layer which invests the medulla up to the hilum. This cortex is 1-6 cm. 

 in thickness and contains the developing and atretic follicles, the corpora lutea and corpora albicantia. 



At the periphery of the cortex of sexually immature females under 60 ft. long a thin layer of cubical 

 germinal epithelium rests upon a fibrous tunica albuginea which is already 150-250// thick. In 

 sexually mature females no germinal epithelium has been found and the tunica albuginea is usually 

 more than 1 mm. thick. The large follicles rest on the medulla and as they expand protrude from the 

 surface of the ovary, filling the full thickness of the cortex. It is probable that the protrusion of the 

 follicles and corpora as they mature is a consequence of the relatively rigid fibrous supporting nature 

 of the cortex and medulla of baleen whales. In the odontocetes Globicephala melaena (Harrison, 1949), 

 Pseudorca crassidens (Comrie and Adam, 1938), and Physeter catodon (Matthews, 1938a), the ovary 

 accommodates the growing follicle or corpus luteum so that the latter remains for the most part 

 invested by cortical tissue and the ovarian surface is smooth. In some fin-whale ovaries there are a 

 few small stalked mushroom-shaped bodies of fibrous tissue projecting from the hilus or from the 

 ovarian surface. 



