1 • EMBRYOLOGY: PROBLEMS AND 

 SCOPE 



I his 



his book is addressed to all students of biology. No distinction is made 

 among the premedical student, the college student, and the experimental- 

 embryology student. Indeed, I think there is only one embryology, and that 

 is the study of the processes and principles of development. 



The premedical student should remember that as a physician he will 

 always be dealing with the process of development, whether in the embryo or 

 the adult. The replacement of red blood cells, the formation of spermatozoa, 

 the healing of wounds are all developmental processes. Cancer, too, is funda- 

 mentally an embryological problem. Why do certain cells become different 

 from their neighbors and multiply as such? In the practice of surgery we 

 must recognize the application of the principles of development. Trans- 

 plantation of tissues from one embryo to another is one of the most common 

 of embryological methods. Extirpation of tissues and the repair and healing 

 of the wound are everyday phenomena in developmental studies. Regenera- 

 tion and growth of nerve fibers constitute one aspect of the science of 

 development, and the basic principles of the development of the nerve fiber 

 have been put to practical application. The discovery and isolation of many 

 important hormones, such as testosterone, estrone, progesterone, and certain 

 pituitary hormones, such as the follicle-stimulating hormone were aided by 

 researches in embryology. 



