Mother and Child

A ground-breaking study into the changes that occur in a woman’s breast, from growing into one that provides milk for a new-born, and then back to its normal state, has discovered that milk-producing cells are, in effect, cannibalized by other cells following the period of breastfeeding. The human body can usually cope with the limited amount of detritus created from normal cellular lifecycles through the deployment of immune cells to remove the material. But just how it manages to eradicate the large amounts of dead or redundant mammary cells, and left over milk, following breastfeeding without triggering inflammation due to the quantities of immune cells which would be needed, wasn't fully known. During the lactation process, women produce vast quantities of milk for their babies -- up to nearly a litre per day. To do this breasts change dramatically during pregnancy, developing the tissue so that cells can make lots of milk. But when weaning finishes, the breasts ne...

Key sex-determining genes continue to operate in a mammalian species that lacks the Y chromosome, taking us a step further toward understanding sex differentiation. In most placental mammals, the Y chromosome induces male differentiation during development, whereas embryos without it become female.  The sex-determining gene SRY is present on the Y chromosome and induces other regulatory genes that suppress female differentiation. The Amami spiny rat (Tokudaia osimensis) is exceptional as it lacks a Y chromosome and thus the SRY gene, raising the question of why male differentiation can still occur. Tomofumi Otake and Asako Kuroiwa of Hokkaido University in Japan performed gene mapping to determine the chromosomal locations of sex-related genes in the T. osimensis genome.  They then compared its nucleotide and amino acid sequences with those of the mouse and rat. Furthermore, using cultured cells, they examined how the sex-related genes were regulated. SR...