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Premium Light and Electron Microscopic Studies on Fertilization of Pelmatohydra Robusta I. Sperm Entry to a Specialized Region of the Egg
Publication year1981
Publication title
development, growth and differentiation
Resource typeJournals
PublisherBlackwell Publishing Ltd
Fertilization of a fresh water polyp, Pelmatohydra robusta , was studied by light and electron microscopy. A small depression was observed in the animal pole of the unfertilized egg. The egg pronucleus was always situated in close contact with the bottom of the depression. Microvilli which were covered with an egg coat consisting of filamentous components were observed on the egg surface. Microvilli and the egg coat were not detected on the surface of the depression. Sperm were associated with the egg plasma membrane and entered the egg only at the bottom of the depression. Excess sperm aggregated around the depression of inseminated eggs. After fertilization, the egg made a protrusion in the region where the egg pronucleus and sperm were in close contact with each other. A new egg coat was formed on the entire surface of the fertilized egg. The restriction of sperm‐egg interactions to a specialized region of the hydra egg is discussed in connection with the micropyle of Pisces eggs and the animal dimple of Discoglossus (Anura) eggs.
Subject(s)anatomy , biology , botany , coat , ecology , embryo , embryogenesis , human fertilization , microbiology and biotechnology , oocyte activation , pronucleus , sperm , zoology , zygote
SCImago Journal Rank0.864

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