Sperm-induced protrusions in sea urchin oocytes: A study of phase separation and mixing in living cytoplasm

Runnström, John

doi:10.1016/0012-1606(63)90105-2

Cited by 29 publications

(18 citation statements)

References 5 publications

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“…There have been many studies on the ultrastructure of sea-urchin eggs and oocytes (Runnstrom, 1963;Lonning, 1965;Franklin, 1965;Kidd, 1978;Longo, 1978;Tilney & Jaffe, 1980); however, we wish to point out several aspects of particular relevance to our present study. First, germinal vesicle stage oocytes have an extensive surface area due to the presence of long and numerous microvilli ( Fig.…”

Section: Morphological Eventsmentioning

confidence: 48%

“…Bleb formation in oocytes appears to be analogous to the formation of the fertilization cone in the mature egg (Franklin, 1965). As reported previously, oocyte blebs are usually retracted 10-20min after insemination (Hagstrom & Lonning, 1961;Runnstrom, 1963).…”

Section: Morphological Eventsmentioning

confidence: 55%

“…First, in order to grow pressure must be generated within the cytoplasmic protrusion. It has been suggested that ground cytoplasm flows from the cell interior to the area of sperm entry (Runnstrom, 1963;Lonning, 1965). Alternatively, we raise the possibility that the total volume of the cell may increase following sperm penetration and this implies an influx of water from the environment.…”

Section: Discussionmentioning

confidence: 93%

“…3B). The plasma membrane of the cone lacks microvilli and the cytoplasm lacks organelles, as shown also by Runnstrom (1963). The cortical granules (arrows) present in the deeper layer of cytoplasm remain intact.…”

Section: Morphological Eventsmentioning

confidence: 91%

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Sperm–oocyte interaction

Elder¹,

Dale²

2000

In Vitro Fertilization

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SUMMARYA study was made of the electrical and morphological changes in the sea-urchin oocyte during interaction with spermatozoa. The first event, a small step depolarization accompanied by a 20-40 % decay in input resistance occurs within seconds of attachment. The evidence suggests that this electrical event is the result of sperm-oocyte fusion, and that the ion channels that lower the resistance across the oocyte-sperm complex are located in the sperm plasma membrane. This primary electrical event does not necessarily lead to sperm incorporation. A second, determinative, event occurs at SO s, which leads to sperm entry and the formation of a cytoplasmic protrusion at the site of sperm entry. This second event probably results from the transfer of a soluble component from the spermatozoon into the oocyte cytoplasm, which leads to sperm incorporation and formation of the protrusion. The changes in the oocyte following insemination are compared with the events of egg activation.

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Section: Morphological Eventsmentioning

confidence: 48%

Section: Morphological Eventsmentioning

confidence: 55%

Section: Discussionmentioning

confidence: 93%

Section: Morphological Eventsmentioning

confidence: 91%

See 2 more Smart Citations

Sperm–oocyte interaction

Elder¹,

Dale²

2000

In Vitro Fertilization

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“…Consequently, there is no reason to believe that activation events would prevent their further progression. The length and density of microvilli, location of cortical granules, 21,27,111 and the priming of the intracellular Ca 2+ release mechanism 112 are events in oocytes that are tightly controlled by the actin cortical cytoskeleton. 113 In the 1970s, it was already suggested that G-actin, sequestered on the membrane, polymerizes during the first few seconds of sperm-oocyte interaction.…”

mentioning

confidence: 99%

Achieving monospermy or preventing polyspermy?

Dale¹

2016

RRB

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Images of sea urchin oocytes with hundreds of spermatozoa attached to their surface have fascinated scientists for over a century and led to the idea that oocytes have evolved mechanisms to allow the penetration of one spermatozoon while repelling supernumerary spermatozoa. Popular texts have extrapolated this concept, to the mammals and amphibians, and in many cases to include all the Phyla. Here, it is argued that laboratory experiments, using sea urchin oocytes deprived of their extracellular coats and inseminated at high densities, are artifactual and that the experiments leading to the idea of a fast block to polyspermy are flawed. Under natural conditions, the number of spermatozoa at the site of fertilization is extremely low, compared with the numbers generated. The sperm:oocyte ratio is regulated first by dilution in externally fertilizing species and the female reproductive tract in those with internal fertilization, followed by a bottleneck created by the oocytes extracellular coats. In order to progress to the oocyte plasma membrane, the fertilizing spermatozoon must encounter and respond to a correct sequence of signals from the oocytes extracellular coats. Those that do not, are halted in their progression by defective signaling and fall to the wayside. Final success and entry is finely tuned by the spermatozoon anchoring to an actin-rich predetermined site on the plasma membrane. In this review, the variation in the form, function, and number of gametes produced across the animal kingdom and the many ways in which sperm-oocyte interactions are regulated to reduce numbers are discussed. Since in nature, final sperm:oocyte ratios approach unity it would appear that selective pressures have favored the achievement of monospermy, rather than the evolution of polyspermy preventing mechanisms.

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Fertilization in Aquatic Animals

Dale

1990

Experimental Embryology in Aquatic Plants and Animals

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Sperm-induced protrusions in sea urchin oocytes: A study of phase separation and mixing in living cytoplasm

Cited by 29 publications

References 5 publications

Sperm–oocyte interaction

Sperm–oocyte interaction

Achieving monospermy or preventing polyspermy?

Fertilization in Aquatic Animals

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