Metastasis is when tumor cells move from the primary tumor to distant tissues - it is metastasis of the primary tumor that kills most cancer patients. One of the least studied routes of metastasis is the lymphatic system, though many tumors produce factors that promote the formation of new lymphatic vessels (lymphangiogenesis). The newly formed lymphatic vessels enable tumor cells to travel from the primary tumor to the regional lymph nodes from whence they can spread throughout the body.

Current treatment practice is to surgically remove the primary tumor as well as the metastatic lymph nodes, but tumor cells in metastatic transit inside the lymphatic vessels have not been given much attention. 

A milestone in the international Avogadro project coordinated by the Physikalisch-Technische Bundesanstalt (PTB) has been reached - with the aid of a single crystal of highly enriched ²⁸Si, the Avogadro constant has now been measured more precisely than ever before, with a relative overall uncertainty of 3 · 10^-8.

Within the scope of the redefinition of the kilogram, the value N_A = 6.02214078(18) · 10²³ mol^-1 allows a more exact realization of this unit. 

Bacteria attack with toxins designed to hijack or kill host cells but they have ways of protecting themselves from their own toxins.   Researchers have described one of these protective mechanisms, potentially paving the way for new classes of antibiotics that cause the bacteria's toxins to turn on themselves.

Scientists determined the structures of a toxin and its antitoxin in Streptococcus pyogenes, common bacteria that cause infections ranging from strep throat to life-threatening conditions like rheumatic fever. In Strep, the antitoxin is bound to the toxin in a way that keeps the toxin inactive.

Two STEREO spacecraft are now 180 degrees apart from each other and providing scientists with a 360-degree view of the Sun. NASA's STEREO (Solar Terrestrial Relations Observatory) spacecraft were launched on October 25, 2006, and have been gathering images of solar activity, especially solar storms, since the mission began.

As the 21st century unfolds, if even one woman does not get a job, there will be claims of discrimination.   And some will believe discrimination occurs institutionally despite the evidence, and insist any action by individuals is proof of sexism.   That's the nature of humans being humans.

X-ray imaging technology is helping scientists better understand how snakes lost their legs during evolution and perhaps help help resolve the debate about whether they evolved from a terrestrial lizard or from one that lived in the oceans.

New 3-D images in the Journal of Vertebrate Paleontology reveal that the internal architecture of an ancient snake's leg bones strongly resembles that of modern terrestrial lizard legs.