THE OVARY OF THE SPERMOPHILE 133 
Experiment 275-16 (spermophile 310). Captured May 1, 1916. 
One ovary was removed and the uterus ligated May 4, 1916. - 
Gross observations. There are no recognizable signs of pregnancy 
in the uterus, but the ovaries contain what resemble young corpora 
lutea. 
Microscopic observations of thé ovary removed. Fixative, formalin 
zenker. Stain, hematoxylin and eosin (fig. 13). 
The nuclei of these early luteal cells are strikingly like those of 
the follicle cells. The nuclei of the latter have several small nucleoli 
with quite conspicuous chromatin strands. The nuclei of most of 
these early luteal cells also have several small nucleoli with numerous 
chromatin strands. But in some cells, the nucleus is much larger and 
contains only one or two larger and darker nucleoli, while the chro- 
matin strands are finer and fewer. 
A very few of the luteal cells in the early luteal structures show 
mitotic figures. There were none at all in those of spermophile 303. 
Of all the early corpora lutea studied, mitotic figures were found in 
these structures in the ovaries of only three spermophiles. These 
were apparently the earliest luteal bodies found. If mitosis occurs, as 
a rule it occurs just after the bursting of the follicle. It may be that 
the luteal cells which show mitotic figures are the transformed follicle 
cells undergoing mitosis as the bursting occurred. 
There is one abnormal early luteal structure in the ovary (spermo- 
phile 310) which deserves mention, as it seems quite common and 
furnishes further proof that the luteal cells are simply transformed 
granulosa cells (fig. 24). The structure with this staining appears at 
first glance like a mature follicle. The liquor folliculi is present and 
the ovum lies over at one side of the central cavity against the sur- 
rounding cells, which resemble the granulosa cells of the follicle. 
On closer observation, however, it will be seen that the cells which 
were thought to be the epithelial cells of the follicle are larger, richer 
in protoplasm, and more irregular in shape and size. Scattered through 
them are numerous fibroblasts and endothelial cells. These fibroblasts 
are quite numerous about the ovum, as if they were attempting to wall 
it off. The ovum has been stripped of its own rim of granulosa cells 
and appears to be undergoing degeneration. The internal theca is 
missing. In fact, what we have here is a corpus luteum formed in a 
follicle which, if it burst, did not throw out enough of its contents to 
get rid of the ovum. Practically all-of the epithelial cells must then 
have been retained. Where are they if they are not the luteal cells? 
The only missing cells are those of the internal theca and the only 
new cells are the fibroblasts and endothelial cells. Does it not appear 
reasonable that the internal theca cells which are of the same origin 
as the connective-tissue cells expend themselves in the formation of 
the new fibroblasts and endothelial cells? It is hard to account for 
these abnormal structures. Several of them showed blood in the 
central cavity, as if the normal hemorrhage had occurred into them. 
Possibly they are formed in the mature follicles that are ready to burst, 
