title: The use of poly-L-lysine to facilitate examination of sperm entry into pelagic, non-adhesive fish eggs.
abstract: The fish egg is surrounded by a thick envelope called the chorion. The fertilizing spermatozoon enters the egg through a canal-like structure in the chorion, the micropyle. Examination of micropyle at fertilization is difficult if eggs are large and have no distinct landmarks surrounding the micropyle, or if they are positively buoyant in water. Eggs of many commercially important fishes (e.g., flounder, sea bream and eel) are buoyant in water or only slightly adhere to solid objects (e.g., sands, rock and water plants), which makes observation of spermatozoa at fertilization difficult. Here, we report that such eggs can be firmly attached to plastic and glass dishes that have been previously coated with poly-L-lysine. These adhering eggs can be fertilized and develop normally on the dishes. Observations of micropyles of three fish species, before and after sperm entry are presented.
authors.affiliation: Hokkaido National Fisheries Research Institute, Fisheries Research Agency, Kushiro, Hokkaido, Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Andoh
authors.forename: Takahiro
authors.initials: T
authors.lastname: Matsubara
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Harumi
authors.forename: Ryuzo
authors.initials: R
authors.lastname: Yanagimachi
mesh_terms: D000818:Animals; D015509:Developmental Biology / Q000295:instrumentation / Q000379:methods; D005260:Female; D005306:Fertilization; D005399:Fishes; D008297:Male; D008954:Models, Biological; D008970:Molecular Weight; D009865:Oocytes / Q000378:metabolism; D011107:Polylysine / Q000494:pharmacology*; D013075:Sperm Capacitation; D013081:Sperm Motility; D013084:Sperm-Ovum Interactions / Q000187:drug effects*; D013094:Spermatozoa / Q000502:physiology*; D014817:Vitelline Membrane / Q000378:metabolism*
chemical_list: D011107:Polylysine