CORPORA ALBICANTIA, CORPORA ABERRANTIA AND CORPORA ATRETICA 365 



transformed luteal tissue, occupy relatively less space. All stages in regression are seen, from bodies 

 similar to the corpus luteum, to bodies in which the connective tissue septa have enlarged at the 

 expense of the pigmented tissue so as to fill almost the whole volume of the corpus (PI. VI, fig. 1). One 

 macroscopically visible feature which enables even the most recent corpora albicantia to be distinguished 

 from the corpus luteum is the relatively sudden change in the appearance of the luteal tissue from 

 an opaque yellow, to a hyaline brownish yellow. Occasionally a corpus luteum is found in which some 

 lobes are hyaline, others still characteristically luteal and others intermediate in condition. 



ra 



Text-fig. 12. Morphological variation in 'young' and 'medium' corpora albicantia. 



Table 3. Incidence of vesicular or radiate corpora in different groups 



With cavity 



( 



Tntnl Nn 



All corpora lutea pregnancy 



All corpora albicantia 



All corpora lutea + all corpo 



albicantia 

 ' Young' + ' medium' corpora albicantia 

 'Old' corpora albicantia 

 All corpora albicantia associated with 



a vesicular corpus luteum 



The most distinctive bodies are the corpora albicantia with a central cavity or core of connective tissue, 

 and a stellate structure with septa arranged radially (Text-fig. 12k and PI. VI, fig. 3). These clearly 

 represent the products of regression of vesicular corpora lutea and a consideration of their frequency is 

 confirmatory. If the corpora lutea and corpora albicantia samples are combined there is a sample of 2082 

 corpora and the incidence of the vesicular type is iy58± i-66%. The percentages of this type among 

 ' young ' and ' medium ' and ' old ' corpora albicantia (as defined below) are given in Table 3 , which shows 

 that the differences are not significant. It appeared likely that in ovaries where the corpus luteum was of 

 the vesicular type there was a higher proportion of radiate ' corpora albicantia (20-35 %) suggesting that 

 some females had more tendency than others to accumulate this type of corpora, but this difference 

 in the percentages is found to be not significant. 



We may conclude that the incidence of the vesicular type of corpora does not vary significantly 

 among different groups of corpora albicantia and corpora lutea. This also confirms that the incidence 

 of cavities is not appreciably different in corpora lutea of ovulation compared with corpora lutea of 

 pregnancy. Since the production of corpora of ovulation presumably equ?ls or outnumbers the 



