title: Ultrastructure of the spermatozoa and eggs of the ocean pout (Macrozoarces americanus L.), an internally fertilizing marine fish.
abstract: Ultrastructure of sperm and eggs of the ocean pout (Macrozoarces americanus L.), an internally fertilizing marine teleost, was examined by scanning and transmission electron microscopy. The results showed that the sperm do not have an acrosome but have a very long mid-piece (one to two times the sperm head length) containing numerous well-developed elongated mitochondria. The sperm also have two tails (is biflagellate) each consisting of nine peripheral and one central pair (9 +/- 2) of microtubules. This long mid-piece and the biflagellate nature of the sperm appear to be associated with the long life-span of the sperm and with sperm dispersal in the ovary to fertilize the eggs internally. The ocean pout eggs are enveloped by a porous chorionic membrane similar to that found in other teleosts but have two micropyles, a condition likely related to a mechanism of egg fertilization which increases the egg fertility in the presence of low sperm numbers. Following insemination, some biochemically undefined excretions appeared on the surface of fertilized eggs and led to the acquisition of adherent capability of the eggs which formed a tightly associated egg mass in sea water.
authors.affiliation: Ocean Science Centre, Memorial University of Newfoundland, St. John's, Newfoundland, Canada.
authors.forename: Z
authors.initials: Z
authors.lastname: Yao
authors.forename: C J
authors.initials: CJ
authors.lastname: Emerson
authors.forename: L W
authors.initials: LW
authors.lastname: Crim
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000648:ultrastructure; D005260:Female; D005306:Fertilization; D005399:Fishes / Q000033:anatomy & histology*; D007315:Insemination, Artificial; D008297:Male; D008854:Microscopy, Electron; D008855:Microscopy, Electron, Scanning; D009865:Oocytes / Q000648:ultrastructure*; D013094:Spermatozoa / Q000648:ultrastructure*