The hedgehog signaling pathway is a mechanism that directs the development of embryonic cells in animals, from invertebrates to vertebrates. The hedgehog signaling pathway is a system of genes and gene products, mostly ...

Dinosaur egg parataxonomy is a classification system that organizes dinosaur eggs by descriptive features such as shape, size, and shell thickness. Though egg parataxonomy originated in the nineteenth century, Zi-Kui Zhao ...

When scientists discovered a 3.3 million-year-old skeleton of a child of the human lineage (hominin) in 2000, in the village of Hadar, Ethiopia, they were able to study growth and development of Australopithecus afarensis, ...

Diethylstilbestrol (DES) is an artificially created hormone first synthesized in the late 1930s. Doctors widely prescribed DES first to pregnant women to prevent miscarriages, and later as an emergency contraceptive pill ...

Telomerase is an enzyme that regulates the lengths of telomeres in the cells of many organisms, and in humans it begins to function int the early stages of embryonic development. Telomeres are repetitive sequences of DNA ...

The Y-chromosome is one of a pair of chromosomes that determine the genetic sex of individuals in mammals, some insects, and some plants. In the nineteenth and twentieth centuries, the development of new microscopic and ...

Telomeres are sequences of DNA on the ends of chromosomes that protect chromosomes from sticking to each other or tangling, which could cause irregularities in normal DNA functions. As cells replicate, telomeres shorten ...