126 GLANDS. 



ovary structure. The Ovary. The envelope of the ovary (tunica 

 albugined) is of the same nature as that of the testi- 

 cle, and like it, is covered everywhere, except at its 

 lower border (hilus), by a serous membrane. Its 

 inner surface is intimately adherent to, and continu- 

 ous with the parenchyma of the organ. This is com- 

 posed of an obscurely fibrous substance, traversed by 

 numerous blood-vessels, in the meshes of which the 

 ovisacs, or Graafian vesicles are found. At the lower 

 border of the ovary its fibrous element is denser than 

 elsewhere, and forms, with the tunica albuginea, a 

 sort of corpus Highmorianum, in which there are no 

 ovisacs ; but just outside of it, and throughout the 

 whole parenchyma to its outer surface, large numbers 

 of them exist, and of all dimensions the larger ones 

 always lying nearest to the surface of the organ. 



The outer envelope of the ovisac is a fibro-vascular 

 membrane consisting of the same material as the 

 parenchyma in which it is embedded, only more con- 

 densed. The external portion of this membrane, 

 which is loosely adherent to the surrounding tissue, 

 is less vascular than its deeper surface. In contact 

 with this is a stratified epithelium (inenibrana granu- 

 losa), which increases considerably in thickness near 

 the point which looks towards the surface of the 

 ovary, and constitutes the proligerous disc, in the 

 interior of which the ovule or egg is contained (PL 

 XXI. fig. VI. 2, 3, 4). The remaining cavity of the 

 ovisac is filled by an albuminous fluid which contains 

 cells, or the debris of cells, detached from the mem- 

 brana granulosa. 



The proper tunic of the ovule (vitelline membrane, 



