Quarterly Journal of Microscopical Science, Vol s2-87, 31-43, Copyright © 1946 by Company of Biologists

Memoirs: On the Origin of the Acrosome and the Behaviour of the Nebenkern in Diestrammena sp

¹ Department of Biology, National University of Chekiang, Meitan, Kweichow, China

1. In the early spermatocyte of Diestrammena the Golgi material and the chondriosomes are aggregated on one side of the nucleus. During the growth period both spread out around the nucleus and become evenly scattered through the cytoplasm.

2. During the maturation divisions the chondriosomes, in the form of threads, surround the mitotic figure as a mantle and are distributed equally to the daughter cells during telophase. During these stages Golgi bodies could not be demonstrated by any of the methods used.

3. The acrosome is of multiple origin. It is formed separately from the chromophobic material of the Golgi bodies, which never fuse together to form a single acroblast, as is frequently observed in other forms. After the acrosome is complete the Golgi remnants migrate posteriorly and slough off along the tail with the cytoplasmic remnant.

4. The acrosome sphere migrates to the anterior pole and presses on the nuclear membrane. Within this sphere two portions of chromatic substance are formed; these fuse and elongate to form the front piece of the sperm.

5. As spermiogenesis goes on, the chromatin within the nucleus forms a peripheral layer inside the nuclear membrane. Finally the nucleus elongates to form the head of the sperm.

6. The chondriosomes condense to form the Nebenkern. This then differentiates into chromophilic and chromophobic substance. The former appears as a plate embedded in the latter and gradually decreases in amount. At the same time the central substance appears within the chromophobic substance. When the chromophilic substance has completely disappeared, the Nebenkern divides into two equal parts. It then spins out as two series of blebs. Eventually the blebs disappear and the materials thus left twist around each other to form the sheath of the tail.

7. On the anterior side of the nucleus there exist some granules. Their origin and nature are doubtful. They resemble the fat droplets in the spermatid of Hemiptera. Ultimately they are sloughed off along the tail together with the cytoplasmic remnant.

The writer wishes to express his thanks to Professor S. Hsü, under whose supervision this work has been carried out. He is also indebted to Professor S. Pai for his valuable suggestions and criticisms in reading over the manuscript.