366 
probably heterotypic, resulting in two secon- 
dary spermatocytes (e), and the second 
homeotypic, which divides the secondary 
spermatocytes into four spermatids (/). Other 
potential primary spermatocytes fail to com- 
plete the spermatogenic process. In these, 
small vacuoles appear in their cytoplasm, then 
coalesce to form a large vacuole which sur- 
rounds and often pushes the shrunken nu- 
cleus to one side of the cytosome (b). All 
stages of cell disintegration may be observed. 
The contents of disintegrated cells probably 
serve as nutrient material both during and 
after the metamorphosis of the spermatids to 
spermatozoa. If the central lumen (Fig. 5g) 
that forms in the once compact follicle (Fig. 
4) is the result of the action of Sertoli cells, it 
is possible to assume that what appears to be 
a lumen bounded by a syncytium of Sertoli 
cells is in reality the distal portions of many 
Sertoli cells already containing spermatids. 
Scattered in between these cells is found the 
debris of disintegrating primary spermato- 
cytes. In any event, the diameter of the lumen 
increases and the ’’ring” of Sertoli cells which 
surrounds the mass moves toward the peri- 
phery of the follicle until, finally, only a 
single layer of epithelium remains. 
A longitudinal section of a collecting 
tubule (Fig. 6) reveals that the epithelium (b) 
in this region appears to contribute a mucus 
to the continuous sperm mass. Whether this 
material serves a nutritive or lubricative func- 
tion was not determined. Long fibrils (c), the 
longitudinal axes of which lie parallel to the 
flow of the sperm mass, are clearly seen. It 
should also be pointed out that, whereas the 
developing spermatids (d) clump in rather 
definite areas, the remainder of the sperm 
mass (e) is scattered indiscriminately. These 
tubules, which contain the continuous sperm 
mass, coalesce with other similar tubules until 
finally, in the mid-region of the testis (Figs. 
3c, d), sections are encountered which possess 
structures identical with those shown in 
Figure 7. 
When a comparison is made of sections 
PACIFIC SCIENCE, Vol. V, October, 195 N 
here illustrated by Figures 6 and 7, the pres- I ; 
ence or absence of a spermatophoric wall / 
(Fig. 7d) is not the only significant difference 
to be seen. The deposition of this wall (Fig. 
7d) could possibly account for the compact- ; 
ness of the sperm mass, but could scarcely 
account for the distinct, cell-like membranes 
which isolate the developing spermatids into 
distinct clumps. Whereas the longitudinal 
sections of the collecting tubule (Fig. 6) 
present the effect of streaming fibrils (r), , 
cross sections through the tube (Fig. 7) clearly 
show these to be portions of Sertoli cells (e) 
cut at right angles to their longitudinal axes. 
Whether this isolation into clumps of de- 
veloping spermatids is due to their having 
been contained within Sertoli cells that have ^ 
become liberated, or whether the developing 
spermatids are mechanically isolated by the 
pressure of the other cells, is difficult to as- 
certain. It appears very unlikely, however, , 
that the clumping of the developing sperma- 
tids is due to an increase in intercellular pres- 
sure because these clusters are first observed 
in sections of follicles where the lumen (Fig. 
3g) is just forming, and when the pressure 
would be negligible. The occurrence of 
spermatid clusters in the region of initial 
lumen formation strongly suggests that the 
spermatids in each cluster represent those 
individuals that develop within a given ^ 
Sertoli cell, and that, as the Sertoli cell is 
sloughed off, the contained developing 
spermatids remain encompassed. 
As previously noted, the wall of the sperma- 
tophore (Fig. 7d) is encountered when the 
sperm mass of the collecting tubules (Fig. 6) 
has reached the position indicated by Figure 
3c. Throughout the length of this highly 
coiled tube which traverses the testis for some 
distance both anteriorly and posteriorly , 
(Fig. 3d) the glandular epithelium of its wall 
secretes the material which surrounds and 
forms the true wall of the spermatophore. 
Although the thickness of the spermatophoric 
wall increases as this portion of the tube is 
traversed, neither the overall diameter of the 
