Cross, J., Z. Werb, and S. Fisher: "Implantation and the Placenta: Key Pieces of the Development Puzzle," Science, vol. 266, pages 1508–18, December 2, 1994. What kinds of lethal mutations will affect implantation of a mammalian embryo in the placenta?

DeRobertis, E.: "Dismantling the Organizer," Nature, vol. 374, pages 407–8, March 30, 1995. A discussion of mutation and organogenesis of the head in mammals, the "organizer" being, of course, the homeobox.

Holden C.: "Perils of Freezing Embryos," Science, vol. 267, pages 618–19, February 3, 1995. How do we save fertilized embryos in vitro for later implantation? Are the processes currently available good enough?

Holmes, B.: "Genetic Engineering in the Womb," New Scientist, vol. 145, page 16, March 4, 1995. Why wait until a baby is born to try to correct genetic defects? Scientists have already met with some success in in utero gene transfer.

Munson, P., D. Counts, and G. Cutler: "Patterns of Human Growth," Science, vol. 268, pages 442–47, April 21, 1995. Human infant development is explored in detail.

Nilsson, L. and J. Lindberg: Behold Man, Little, Brown & Co., Boston, 1974. A wonderful collection of color photographs of the developing human fetus.

Science: "Special Issue: Frontiers in Biology: Development," vol. 266, October 28, 1994. An entire issue dedicated to current issues and topics of research in developmental biology.

Tickle, C.: "Vertebrate Development: A Tool for Transgenesis," Nature, vol. 358, pages 188–89, July 16, 1992. A discussion of homeobox genes and the development of vertebrate extremities.