Spermatozoal ultrastructure in Branchiostoma moretonensis Kelly, a comparison with B. lanceolatum (Cephalochordata) and with other deuterostomes

Jamieson B.G.M. (1984) Spermatozoal ultrastructure in Branchiostoma moretonensis Kelly, a comparison with B. lanceolatum (Cephalochordata) and with other deuterostomes. Zoologica Scripta, 13 3: 223-229. doi:10.1111/j.1463-6409.1984.tb00039.x


Author Jamieson B.G.M.
Title Spermatozoal ultrastructure in Branchiostoma moretonensis Kelly, a comparison with B. lanceolatum (Cephalochordata) and with other deuterostomes
Journal name Zoologica Scripta   Check publisher's open access policy
ISSN 0300-3256
Publication date 1984
Sub-type Article (original research)
DOI 10.1111/j.1463-6409.1984.tb00039.x
Volume 13
Issue 3
Start page 223
End page 229
Total pages 7
Subject 1103 Clinical Sciences
Abstract The spermatozoon of Branchiostoma moretonensis closely resembles that of B. lanceolatum and, though near the primitive sperm, allows recognition of a cephalochordate sperm type. This has: a bell-shaped acrosome; diffuse subacrosomal material not structured as an acrosome rod; subovoidal nucleus with shallow anterior concavity, deep tubular posterior fossa (endonuclear canal) and condensed but lacunate chromatin; single asymmetrical, postnuclear mitochondrion almost completely or completely encircling the centrioles; mutually perpendicular proximal and distal centrioles of the triplet type, with the distal forming the basal body of the flagellum and the proximal (always?), as in B. moretonensis, with a spur-like extension (striated rootlet) into the nuclear fossa; flagellum tilted relative to the longitudinal axis (and endonuclear canal) of the nucleus; a 9 + 2 axoneme with hollow tubules and both dynein arms present on the doublets; and scattered glycogen granules, numerous around the distal centriole. The mitochondrion of B. moretonensis is C-shaped in transverse section, as in urochordates, but cephalochordate sperm resemble those of echinoderms, and specifically holothuroids, more closely. The occurrence of flagellar rootlets and composite mitochondria in various animal groups is discussed. The term paramorphy is proposed for parallel and convergent acquisition of an identical character: symparamorphy where acquisition is by parallelism and alloparamorphy where it is by convergence; the two terms represent, however, extremes of a continuum. Superficially similar but structurally different characters acquired by convergence are termed analogomorphies.
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article (original research)
Collection: Scopus Import
 
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