Yolk-Formation in Periplaneta Orientalis

Abstract

1. The Golgi vacuoles and fatty yolk-formation in Peri-planeta orientalis were studied by means of Mann-Kopsch, Kolatschev, 2 per cent, osmic acid and neutral red preparations. 2. The Golgi vacuoles of the young oocytes are situated in the vicinity of the nucleus; later they pass to the periphery of the cell. In the older oocytes, towards the posterior end of the ovarioles, they become evenly distributed in the ooplasm, store up fat, increase greatly in size, and give rise to the fatty yolkspheres. In the older oocytes they darken much more rapidly in 2 per cent, osmic acid. 3. In neutral red preparations clear non-stained vacuoles are seen to occupy similar positions to those of the dark bodies of the osmic preparations; on introducing a few drops of 2 per cent, osmic acid under the cover slip the vacuoles develop an osmophilic rim. These Golgi vacuoles are not stained by neutral red. 4. In 2 per cent, osmic acid preparations the Golgi vacuoles are seen to consist of an osmophilic rim and a central clear substance. 5. The Golgi vacuoles of the follicle-cells are similar to those of the egg, except that they do not increase greatly in size and are not so rapidly darkened in 2 per cent, osmic acid. 6. The nucleoli of the early oocytes are spherical in shape and are amphiphil or slightly basophil in staining reaction; they may contain small vacuoles. In slightly older oocytes the nucleoli are non-vacuolated; they become strongly basophil, irregular in outline, and, at the same time, give rise to emissions which pass through the nuclear membrane to the ooplasm, where they ultimately disappear. In a certain few oocytes the nucleolus was seen to have broken up into several masses, some of the latter, in all probability, fragmenting to form nucleolar extrusions. In a certain oocyte one of the masses was observed to be vacuolated before the first type of extrusion had ceased. 7. In the more highly developed oocytes the first type of nucleolar emission ceases, and the nucleolus becomes more spherical in outline. Numerous vacuoles appear which give origin to nucleolar extrusions. The latter become vacuolated, either before extrusion through the nuclear membrane, or later in the ooplasm. 8. The second type of nucleolar extrusions pass to the periphery of the egg. Later they become evenly distributed in the ooplasm, where they fragment to forin homogeneous granules. The latter form clear spheres (Kolatschev material) which rapidly increase in size to form the albuminous yolk-globules. 9. Chromatin was not observed in the oocyte nuclei, nucleoli, or nucleolar extrusions (Feulgen's technique). The chromatin of the follicle-cells is in the form of granules connected by threads (which give the chromatin reaction). The chromatin of the follicular epithelial-cells was observed as granules scattered through the nuclei. 10. Bacteroid forms were observed in the ooplasm at the periphery of the older oocytes. 11. The method of yolk-formation is similar to that of Peri-planeta americanaas described by Nath and Piare Mohan. 12. The writer's conclusions regarding the shape and character of the Golgi vacuoles agree with tne findings of Nath and his co-workers and with the former conclusions of the present writer for oocyte Golgi vacuoles.