368 DR FOULIS ON THE DEVELOPMENT OF THE OVA, ETC. 
ovary, in man and other mammals, which are about to burst to liberate the 
contained ovum, a great part of the wall of the follicle outside the membrana 
granulosa becomes again converted into large connective tissue corpuscles. 
When first formed, the membrana granulosa consists of a single layer of 
minute corpuscles arranged in the form of a capsule round the ovum (fig. 30, 7). 
As the young ovum enlarges, which it rapidly does after the formation of the 
membrana granulosa, it distends its follicle, and the corpuscles of the membrana 
granulosa increase greatly in number. In this membrane, when first formed, 
the corpuscles lie in close contact with each other, and when looked down upon 
from above they present a polygonal form from mutual compression (fig. 32, 7’). 
By the constant multiplication by division of its corpuscles, the membrana 
granulosa at last comes to consist of several layers. As a further stage in 
development, certain of the corpuscles, generally those in the middle parts of 
the membrana granulosa, break down, and, it appears to me, become dissolved 
in a fluid which afterwards forms the liquor folliculi. By the breaking down 
and solution of these corpuscles, a cavity, the follicular space occupied by 
fluid, is formed. In section, this space appears semilunar in form. After the 
formation of this space the ovum is not entirely separated from the membrana 
granulosa, but remains connected with the wall of the follicle by a heap of 
corpuscles which surrounds it. In good specimens a layer of corpuscles 
remains in contact with the zona pellucida round the ovum for a long time after 
the formation of the follicular space. When first formed, the corpuscles of the 
membrana granulosa in the human fcetal ovary of 74 months measure about __ 
sooth inch. ‘s 
For the complete demonstration of the development of the corpuscles of 
the membrana granulosa, the ovary of an adult rabbit is admirably suited. 
In a section of such an ovary, we first direct our attention to the structure 
of the stroma of the organ, and we find it consists entirely of very minute 
attenuated fusiform corpuscles. At first sight these appear as simple fibres, 
but each fibre is an elongated nucleus, having round it a minute quantity of 
protoplasm. The stroma of the ovary of an adult cat has an exactly similar 
structure. In the adult rabbit’s ovary, in a single section, we may find young 
ova in various stages of development. Ina very young ovum (fig. 33, m), we 
notice first the large germinal vesicle, with its germinal spot. Around the 
germinal vesicle is a small quantity of protoplasm, immediately in contact with — 
which are several small fusiform corpuscles (7, 2). These lie flattened against 
the ovum round its yelk, and are exactly similar to fusiform corpuscles, of 
which the stroma (7) is composed. Around an ovum slightly farther advanced 
in growth we find one or two of the fusiform corpuscles (”, 2) have assumed 
a swollen condition, and in some instances individual corpuscles are im 
the act of dividing. In the case of an ovum still farther advanced in develop- 
i 

