There was little variation in their gonad and oocyte development. The egg diameter of oocyte at the 5-phase was 700-870 μm with one oil globule at 260-400 μm diameter,and the thickness of primary egg membrane was 12-19 μm.
From June to September, 1988 and from October, 2001 to May, 2002, gonadal sex differentiation, changes on the structure of oocytes, formation of yolk granules, development of follicle cells as well as formation of the micropylar cell and the egg membrane in Mystus macroptems were studied by means of histological and histochemical methods.
sinensis consisted of three layers,E1,E2 and E3,whereas the embryo attachment system is composed of only the outermost singular layer E1. The oolemma of mature oocyte consisted only of layer E1,and E1 could be divided into sub-layers E1a′ and E1b′.
Structure of the floss-like oolemma is appeared to inner of oocyte in the stage III, and the besides is appeared to the radiation zone. At the stage, the structure of spherical lysosomes(SLY) is disappeared, and at some of NLY are appeared between the floss-like oolemma and the radial zone.
About 80s after fertilization, the angle of sub-elasticityenvelope expands. 110s, sub-elasticity envelope in zona radiatal becomes parallel with plasma membrane, later, the same phenomenon happen in zona radiata2 and zona radiata3, which result in the fertilization envelopes (egg envelopes) outspreading; 140min after fertilization, the fertilization envelopes come into being.
A correlation between the structure of the sperm acrosome and that of the egg envelope is discussed.
Egg envelope development does not appear to commence until after the onset of vitellogenesis.
During the vitellogenic phase, biosynthesis of four types of organelles occurs, including lipid droplets, yolk granules, cortical granules, and unknown inclusions, which are exocytosed as part of egg envelope biogenesis.
Egg envelope organisation in the icefish Chionodraco hamatus
Identification and spatial distribution of the mRNA encoding an egg envelope component of the Cyprinid zebrafish, Danio rerio, h
The micropyle was observed on the oolemma of follicular cells.
The process of elaboration of the oolemma is reported in detail.
In the vitellogenic oocytes of both species, numerous invaginations of the oolemma result in the formation of intraooplasmic channels throughout the ooplasm.
schayeri are firmly anchored to the germinal epithelium by an attachment complex consisting of specialised attachment cells and basophilic strands that radiate between the oolemma and the nucleus.
During the final stages of oogenesis, after having migrated to the extreme periphery of the oocyte and having firmly adhered to the oolemma, the nucleus became indented, assuming a sickle or dome shape.