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Spermiogenesis in the Moss Aulacomnium palustre

Douglas L. Bernhard and Karen Sue Renzaglia
The Bryologist
Vol. 98, No. 1 (Spring, 1995), pp. 52-70
DOI: 10.2307/3243642
Stable URL: http://www.jstor.org/stable/3243642
Page Count: 19
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Spermiogenesis in the Moss Aulacomnium palustre
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Abstract

The complete development of sperm from spermatid is described at the ultrastructural level in the bryalean moss Aulacomnium palustre. Blepharoplast ontogeny is characterized by the positioning and growth of basal bodies in synchrony with development of an underlying four-layered multilayered structure (MLS). Fully-developed basal bodies are dimorphic and staggered in position. The anterior basal body (ABB) is located over an aperture in the spline, the microtubular backbone of the cell. The posterior basal body is unlike any examined heretofore in that it extends anterior to the ABB and MLS. The two mitochondria in the mature cell are formed by fusion of numerous small mitochondria in the young spermatid and subsequent division of the single organelle into an anterior mitochondrion (AM) and a posterior mitochondrion (PM). The AM is associated with numerous oil droplets and microbodies (presumably glyoxisomes) and is located subjacent to the blepharoplast. The PM and single plastid form the Nebenkern in the posterior region of the cell Nuclear shaping and condensation occur in register with growth of the spline microtubules. In the final stages of differentiation, the AM elongates alongside the condensed nucleus and the PM recedes from around the plastid. These events, accompanied by elimination of extraneous cytoplasm, lead to a narrow elongated mature sperm.

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