Ultrastructure of the fertilized egg envelope from Poropanchax normani, Poeciliidae, Teleostei

Abstract We examined the morphology of fertilized egg and fine structure of fertilized egg envelopes of Norman’s lampeye, Poropanchax normani belongs to Poeciliidae using light and electron microscopes. The fertilized eggs with narrow perivitelline space were spherical, demersal, and have small oil droplets in the vitelline membrane. And a bundle of adhesive filaments was on one side of fertilized egg. The size of fertilized egg was about 1.49 ± 0.07 mm (n = 30) and length of a bundle of adhesive filaments with very high elasticity was about 1–3 mm. The outer surface was smooth. The adhesive filaments are distributed around the egg envelope and each adhesive filaments are joined together to form a long bundle. The around the micropyle was a peak shape with several straight wrinkles. But accurate structure of micropyle could not be observed because it is in too deep. Also the total thickness of the egg envelope was approximately12.5-14.5 µm and the egg envelope consisted two layered, an outer electron dense layer and an inner lamellar layer consisting of 10 layers of differing thickness. Collectively these morphological characteristics of fertilized egg and fine structures of around micropyle, outer surface, adhesive structure consisting adhesive filaments and section of fertilized egg envelope are showed species specificity.