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Ultrastructural observations of euspermatozoa and paraspermatozoa in a copulatory cottoid fish Blepsias cirrhosus
Author(s) -
Hayakawa Y.,
Munehara H.
Publication year - 2004
Publication title -
journal of fish biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.672
H-Index - 115
eISSN - 1095-8649
pISSN - 0022-1112
DOI - 10.1111/j.0022-1112.2004.00407.x
Subject(s) - biology , spermiogenesis , ultrastructure , sperm , acrosome , spermatogenesis , anatomy , zoology , botany , endocrinology
Euspermatozoa and paraspermatozoa of a copulatory (internal insemination with external sperm transfer) cottoid fish Blepsias cirrhosus were observed ultrastructurally. Euspermatozoa of B. cirrhosus consisted of an acrosome‐less, thin, disk‐like sperm head (1·6‐2·0 μm in length and 1·3‐1·6 μm in width), a long middle piece, and a long flagellum ( c . 30 μm). Aberrant spermatids, which were rich in cytoplasm and possessed two nuclei, occurred in testicular lobules. They were also observed in semen and were round (5·0‐5·3 μm in diameter) and biflagellate, suggesting that they are released along with euspermatozoa at ejaculation. The nuclei of aberrant spermatids developed into masses of highly electron‐dense globules. Judging from their form, nuclear condition, and connection with normal spermatids by intercellular bridges during spermiogenesis, aberrant spermatids of B. cirrhosus are considered hyperpyrenic paraspermatozoa formed by incomplete cytokinesis at the second meiotic division.