206 OVARY AND PAROVARIUM, BY W. WALDEYER. 



to a conclusion. (See also 141, 142.) Wagner, in his Prodromus 

 (121), instituted a comparison between the ova of all known classes 

 of animals. He had already depicted the micropyle of the ovum of 

 the Holothuriadse in his Icones Zootomicae. Doyere (143) appears 

 to have already seen it in 1850 in Syngnathus. J. Miiller (80) first 

 described it minutely in the ovum of the Holothuriadae, and com- 

 pared it with the micropyle of plants. Keber (55) then expressly 

 applied the term micropyle to this opening. We are indebted to 

 Valentin in 1838 for the first demonstration of branched and tubular 

 glandular structures in the ovary ; an observation that was soon 

 corroborated by Billroth (15), but to which little attention was paid 

 until it was rediscovered by Pfliiger (84), who in a detailed monograph 

 led to the development of a different view respecting the structure of 

 the ovary. 



We have already given in the text, as far as space would permit, 

 the views of Pfliiger on the mode of origin of the Graafian follicles 

 from tubes, on the development of the ova, their structure and their 

 continuous new formation in adults, and the peculiarities of the 

 ovarial epithelium. Formerly the follicles and ova were regarded as 

 descendants of the ordinary stroma cells of the ovary ; since Pfliiger' s 

 time, however, both have been considered to be independent epi- 

 thelial structures that are only imbedded in the stroma. It is never- 

 theless true that the demonstration of their first development still 

 remains a desideratum. 



Pfliiger's investigations led to the publication of numerous works 

 on the ovary. The tubular formations were soon also discovered in 

 the human subject, first by Spiegelberg (107), and then by Letzerich 

 (65), and Langhans (64) ; in the Fowl by Strieker (114) and many 

 others, and very recently by Plihal (87) in Mammals. It must be 

 confessed, however, that in opposition to Pfliiger, who lays so much 

 stress on the tubular structure of the ovary, stand the investigations 

 of Borsenkow (22), Bischoff (19), Henle (50), Grohe (49), and the 

 recent ones of His (52), who has paid especial attention to ovaries of 

 embryoes, and first impressively pointed out their cavernous structure, 

 with rounded and ovum- containing clusters of epithelial cells ; also 

 those of Kolliker (59). The work of Bornhaupt (21) must also be 

 mentioned here, who first described in Fowls the development of the 

 tubes of Pfliiger from the epithelium of the ovary. 



The statements made in the text upon the epithelium of the ovary, 

 as well as upon the formation of the follicles and ova from it, may be 

 compared with those given in No. 123 of the bibliography, with 



