Researchers at Karolinska Institutet in Sweden have obtained the first 3D snapshots of a sperm protein attached to a complementary egg coat protein at the beginning of fertilisation. The study, which reveals a common egg protein architecture that is involved in the interaction with sperm in both mollusc and mammal, is published in the respected scientific journal Cell. By transmitting the genetic information to the next generation and marking the beginning of a new life, the encounter between female and male gametes at fertilisation is one of the most fundamental processes in biology. Although egg and sperm were first observed centuries ago, how sperm recognises the coat of the egg and penetrates it has remained unknown. Using X-ray crystallographic data collected at the European Synchrotron Radiation Facility ESRF , Luca Jovine's research team at Karolinska Institutet first visualised the sperm-interacting regions of two egg coat proteins, ZP2 in mammals including humans and VERL in the marine mollusc abalone a classic model system of invertebrate fertilisation. Both of these molecules contain repeated sequences that play a key role in gamete recognition.
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This gallery of images and movies illustrates the anatomy of spermatozoa from the nematode C. All images are the work of Sam Ward U. Arizona, retired , Paul Muhlrad U. Gallery of Sperm Images and Videos: This gallery of images and movies illustrates the anatomy of spermatozoa from the nematode C. Click pictures for a new window with image or video and detailed legend Spermatozoon SEM This is a mature sperm cell, or spermatozoon, from C. At the right is the pseudopod, which the cell uses for crawling.
Image of sperm and egg (jpg)
Plate A is a light photomicrograph of sperm smear and green sperm heads in plate B show damage to sperm DNA under fluoroscent microscopy. Nuclear transfer in Mouse Oocytes: A - lancing of zona pellucida, B and C - removal of germinal vesicle, D - an isolated germinal vesicle. This photo shows a human blastocyst - an embryo days old. This embryo is hatching out of its "shell" to the right. The shell, known as the zona pellucida, is visible as an almost transparent structure surrounding part of the embryo on the left.
All rights reserved. Once inside a female, sperm cells can discern and—via structures on their heads—literally hook up with their brethren amid the crush of sperm from other males. The cells can then draft, Lance Armstrong-style, moving faster than they could alone thanks to more "engine" power from the cluster, said study co-author Heidi Fisher, an evolutionary geneticist at Harvard University's Hoekstra Laboratory.