Quarterly Journal of Microscopical Science, Vol s2-63, 445-491, Copyright © 1919 by Company of Biologists

Memoirs: The Cytoplasmic Inclusions of the Germ-Cells. Part V. The Gametogenesis and early Development of Limnæa Stagnalis (L.), with Special Reference to the Golgi Apparatus and the Mitochondria

¹ Senior Demy, Magdalen College, Oxford; Senior Assistant in Zoology, Lecturer in Cytology, University College, London

(1) In the germinal epithelial cell of Limnæa stagnalis a Golgi apparatus is present. It is excentric and lies around the archoplasm, consisting of a number of rods (chondrioplasts or dictyosomes, dittosomi).

(2) In the progerminative oöcyte mitochondria appear at a very early stage, but it is not known whether they exist in the indifferent germinal epithelial cell. The mitochondria lie at first in the zone of the Golgi apparatus.

(3) The rods of the Golgi apparatus divide by binary fission and keep growing in number. The archoplasm upon which they repose gradually becomes divided into regions; these regions again subdivide till each Golgi rod is discrete and provided with a small part of the archoplasm, which it partly embraces. As each Golgi rod divides transversely the urchoplasm does not divide. The latter only divides by binary fission after it has become studded with a number of rodlets.

(4) The Golgi apparatus gradually, from its excentric position, spreads completely throughout the egg cytoplasm, and in the full-grown oocyte is evenly distributed here and there in all parts of the egg cytoplasm. No segregation into special regions was noticed.

(5) The mitochondria, from their excentric position near the Golgi apparatus, grow, divide, and spread evenly throughout the cytoplasm. The mitochondria are not all the same size; this is apparently due to the fact that some granules grow larger and more quickly than others.

(6) While the egg mitochondria grow much larger than the spermatid mitochondria, it has been shown that the individual Golgi batonette or rodlet never grows beyond a certain size. The difference between the Golgi apparatus of a young oöcyte and a full-grown ovum lies, not iu the fact that the Golgi rods of the latter are individually very much larger (if at all) than those of the former, but mainly in the fact that the rods have increased enormously in number by binary fission. The individual Golgi rodlet of spermatid, young and old oöcyte are approximately subequal in size.

(7) Deutoplasmagenesis, or the formation, of yolk, does not begin very early; the first yolk-discs make their appearance after the Golgi elements and mitochondria have progressed far in the process of spreading throughout the growing oöcyte. The yolk-discs do not appear in any special region of the cytoplasm, but eventually become evenly spread out. The discs at first are very small, and later grow some two or three times larger than the largest mitochondria. In Flemming-without-acetic (overnight) + iron-alum hæmatoxylin, yolk goes dark brownish-green, mitochondria black.

(8) Towards the end of oögenesis the cytoplasm gradually becomes filled with vacuoles of a fluid nature. These leave a coagulum on fixation, but most of the vacuole is empty. The granules in the cytoplasm only abnormally lie in these vacuoles; yolk, Golgi elements and mitochondria lie in the trabeculas between the vacuoles.