ISSN:
0002-9106
Keywords:
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Medicine
Notes:
The ultrastructure of the normal bovine sperm head has been studied and particular attention has been given to the morphology and coverings of the nucleus and the formation of the equatorial segment.The bovine sperm head consists of a homogeneous, flattened nucleus which is covered anteriorly by a three-layered head cap and posteriorly by a loose, thin, dense, post-nuclear cap. The nucleus measures approximately 0.2 to 0.3 μ in thickness. It tapers anteriorly to a sharp point along the frontal portion of the head and thickens posteriorly to accommodate an implantation socket for the tail. The nuclear membrane is double and porous. Vacuoles or openings of variable size and shape are present in the nucleoplasm, predominantly in the posterior portion of the nucleus. The head cap measures approximately 350 to 500 Å in thickness. It consists of dense inner and outer membranes which envelop a moderately electron dense middle layer. The head cap thickens across the frontal part of the head forming a ridge on one side of the nucleus.A sequence of structural alterations in the head cap provide evidence for the appearance of the equatorial segment. The anterior portion of the head cap swells and deteriorates leaving the posterior portion intact as a band about the center of the nucleus. This band represents the equatorial segment.
Additional Material:
2 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/aja.1001150109
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