ZIB

Hits per page

hits 1 - 2 | 2 hits

Sorting

Electronic Resource

Locomotion of the filiform sperm of Littorina (Gastropoda, Prosobranchia) (1981)

Buckland-Nicks, John A. ; Chia, Fu-Shiang

Springer

Cell & tissue research 219 (1981), S. 27-39

add to mindlist on the mindlist

Details

ISSN: 1432-0878

Keywords: Sperm motility ; annulus ; mollusca ; Littorina

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Medicine

Notes: Summary The filiform sperm of Littorina sitkana swims effectively in sea water and more viscous fluids, overcoming the problems of a non-uniform flagellar beat with an unusual mechanism, which involves three main events: (1) the sperm rotates anti-clockwise (looking from tail to head); then (2) stops rotating and stiffens itself to form a screw-shape, with the tail being held perpendicular to the middle piece, and finally; (3) reverses its rotation and propels itself forward in a clockwise spiral. The average velocity of sperm is approximately 185 μms with a rotational frequency of 24 revs. The mechanism of propulsion may involve two kinetic centers at opposite ends of the sperm, which coordinate their movements to produce anti-clockwise rotation, stationary twisting, or clockwise rotation, in a manner reminiscent of spirochaetes. Littorina sperm also exhibit slower methods of propulsion including swimming backwards (tail first) at 18 μm, and “gliding” at about 30 μm. The adaptive significance of the rapid propulsion is not obvious, because Littorina copulate and fertilize internally and at each stage in the transfer there are external aids to sperm transport, such as ciliary action (oviduct) and muscular expulsion (bursa and seminal receptacle). The filiform shape, however, is well-adapted for long-term storage in the female body. These points are discussed.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00210016

Permalink

Library	Location	Call Number	Volume/Issue/Year	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

Electronic Resource

Fertilization in a chiton: Acrosome-mediated sperm-egg fusion (1988)

Buckland-Nicks, John ; Koss, Ron ; Chia, Fu-Shiang

New York, NY : Wiley-Blackwell

Gamete Research 21 (1988), S. 199-212

add to mindlist on the mindlist

Details

ISSN: 0148-7280

Keywords: egg envelopes ; polyspermy ; mollusca ; polyplacophora ; Life and Medical Sciences ; Cell & Developmental Biology

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Biology

Notes: Contrary to the widely accepted view that chiton sperm lack acrosomes and that fertilization in this group occurs via a micropyle, we demonstrate here that fertilization in Tonicella lineata occurs by acrosome-mediated sperm-egg fusion. The acrosome is a small vesicle containing two granules located at the tip of the sperm. The eggs have an elaborate hull (=chorion), which is formed into cupules that remain covered by follicle cells until maturity. When dissected ripe eggs were exposed to sperm in vitro, the sperm were attracted only to open cupules, inside which they swam through one of seven channels to the base where they penetrated the hull. The acrosome fired on contact with, or in, the hull, and during passage through it the apical granule was exhausted while the basal granule was exposed. If sperm contacted follicle cells between the cupules the acrosome did not react. The vitelline layer beneath the hull contains pores arranged in a regular pattern. Embedded in the base of each pore is an egg microvillus. Having penetrated the hull the sperm anterior filament located a pore and fused with the tip of the egg microvillus projecting into it. This created a membranous tube, through which the sperm nucleus was injected into the egg. The egg membrane appeared to be raised up into a small fertilization cone around the penetrating sperm, the vitelline layer became slightly elevated, and some cortical granules were released by exocytosis.

Additional Material: 13 Ill.