Fig. 1. Pole view of spermatogonial metaphase, showing the thirty-three chromosomes. It will be observed that the chromosomes are of unequal sizes, and that the large ones arrange themselves in a circle on the outside of the figure.
Fig. 2. Very young spermatocyte. The chromatin derived from the breaking down of the spermatogonial chromosomes in a diffuse condition, with no trace of a linear arrangement. The accessory chromosome x on the periphery of the nucleus, darkly staining and homogeneous.
Fig. 3. Early stage in the formation of the spireme. In the cytoplasm the remains of the spermatogonial spindle. The cell has entered upon the growth period.
Fig. 4. A later stage in the spireme formation. The accessory chromosome larger and more flattened. A surface view shows it as an apparently fenestrated plate. The remains of the two spermatogonial spindles still persisting.
Fig. 5. First appearance of definite chromosomes. One shown entire with longitudinal and cross-divisions marked. The accessory chromosome is here seen to be in a spireme condition.
Fig. 6. Condition of the chromosomes after further contraction of the early segments. As here shown, they are more granular than is usually the case.
Fig. 7. Common types of the prophase chromosomes.
Fig. 8. A cell in which one of the chromosomes has its halves widely separated along the longitudinal division, forming Paulmier’s double-V figure.
Fig. 9. In this cell may be seen the variation in form and size of the early spermatocyte chromosomes.
Fig. 10. Two cells of the late prophase, with the chromosomes at almost the extreme degree of concentration.