372 THE CORPUS LUTEUM OF DASVL^nrS, 



to be any trace of the future %itelline membrane or envelope of 

 the ovum. In the cytoplasm of this primordial ovum, usually on 

 opposite sides of the nucleus, are to be seen two dark bodies 

 situated in a clear space, possibly the "centrosomes," which later 

 on disappear. The cells of the ovarian stroma adjacent to the 

 primordial ovum do not at first show any peculiarity, but soon 

 cells make their appearance, which have a circular arrangement 

 round the periphery of the ovic cell. These cells are flattened 

 and epithelial in type, with a definite nucleus; their characters 

 are shown in fig. 1. These cells soon become sharj)ly marked off 

 from the ovum b}^ a membrane, the vitelline membrane. The}' 

 are not at first marked off from the connective tissue stroma 

 externally, but later on a membrane forms, which is the early 

 representative of the "Glashaut," "basal membrane," or "mem- 

 brana propria" of authors. The cells between the two membranes 

 become more cubical in form, and are the first representatives of 

 the cells of the mcmlDrana granulosa. At a very early stage, 

 therefore, there are formed the rudiments of the more important 

 structures of the ovarian ovum, with its surrounding cellular and 

 membranous structures. The subsequent development of the 

 ovic cell does not concern us further. Briefly, it increases in size, 

 it forms yolk granules, the bodies like centrosomes disappear, and 

 the nucleus becomes excentric or even peripheral. 



After a certain stage, the ova grow very little, and the sub- 

 sequent changes involve the membrana granulosa, which had 

 attained the form of a single layer of cells, placed between two 

 membranes. This single la3^er of cells multiplies to become a 

 zone of cells, two, three, then nine to twelve cells in thickness, 

 with nuclei showing many karj^okinetic figures. The cytoplasm 

 of the cells is lightl}' stained and the walls are indistinct, whilst 

 the most externally placed cells (adjacent to the basal membrane) 

 are regularlj' placed, and suggest an epithelial arrangement. The 

 same applies in some cases to the cells near the vitelline mem- 

 brane. At the angles between the cells are often to be observed 

 spaces, probably to be accounted for by the rapid cell-growth not 

 leaving time for the intercellular angles to be filled. These 



