CYTOLOGICAL STUDY ON FERTILIZATION IN OF HEMIBARBUS LABEO

The fertilized eggs ofHemibarbus labeo have been observed by TEMand OM, and mostly events of fertilization cytology have been studied, too. The result suggest:The micropylar apparatus comprising of vestibule and micropylar tube is deeply sunken with a short tunnel, the diameter of the micropylar tube is about 2.143μm, and the diameter of the spermis about 1.445μm. Before spermpenetrates, the chromosomes are at metaphase in the ovum, following prophase and preceding anaphase, during which the chromosomes are aligned along the metaphase plate. About 2s after fertilization in 17 ℃, sperms arrive at micropylar tube; 3s, a sperm is penetrating into micropylar tube, 5s, sperms enter into cytoplasmof ovumwhere the cytoplasm is sunken; 30s, some yolk granules begin to decompose; 35s, the spermaster comes into being; 5min, we find the phenomena of polyspermy in a fewof the ovum, which is rare in teleost; but the sperms can＇t come into being spermaster; 8-15min, the chromosome are at anaphase, and 20min, at telophase of meiosis, later, the second polar body expels, and the blastodermforms in animal hemisphere; 25min, both the male pronucleus and the female pronucleus can be seen; 30-35min, the female pronucleus move towards the male pronucleus, at the same time, both the pronucleuses move to the pivot of blastoderm; 40min, both the pronucleuses press close, and 50min, conjugate into zygote, and then, the zygotic nucleus expands; 70min, chromosomes are situated at metaphase of the first karyokinesis,80min, at anaphase, and 120min, at telophase, the oosperm is segmentalized in daughter cells. 140min, chromosomes of the daughter cells are situated at metaphase of the second karyokinesis, while the daughter cells don＇t separate. There have two hypothesizes to explain the mechanism how the male pronucleus and the female pronucleus conjugate. One is the Cytoplasm Flowage, which thinks the cytoplasmpflowage in ovum result in the conjugation. The other is the Spermaster Traction, which thinks the conjugation result from the spermasterptraction. We think the both hypothesizes are unilateral, which reason is the difference of the experimental specimen that the researchers use. We infer, there have some sites which the spermaster can identify in the female pronucleus. With the spermasterpelongate, the spermaster will capture and tract the female pronucleus, which make the male pronucleus and the female pronucleus conjugate. The site of conjugation isnpt at the pivot of blastoderm, however, cytoplasmps flowage can solve it. This is the Hypothesis on Spermasterps Elongate, Traction and Cytoplasmps Flowage in the paper.