. Animal growth and development. Embryology; Growth; Biology; Growth; Embryology; Animals -- growth & development. Cellurar Differentiation rofessor Curt Stern, one of the fathers of mod- ern genetics, in his article ^ entitled "Two or Three Bristles," has a superb discus- sion of cellular differentiation that is de- signed to be read by scientists who are not biologists; it can easily be understood and will be greatly appreciated by seri- ous beginning students of biology. To illustrate the problems inherent in cellular differentiation, Dr. Stern de- scribes the formation of bri
. Animal growth and development. Embryology; Growth; Biology; Growth; Embryology; Animals -- growth & development. Cellurar Differentiation rofessor Curt Stern, one of the fathers of mod- ern genetics, in his article ^ entitled "Two or Three Bristles," has a superb discus- sion of cellular differentiation that is de- signed to be read by scientists who are not biologists; it can easily be understood and will be greatly appreciated by seri- ous beginning students of biology. To illustrate the problems inherent in cellular differentiation, Dr. Stern de- scribes the formation of bristles upon the abdomen of the fruit fly: In some regions there arise short or long outgrowths—the bristles—strong and wide at the base and gently tapering to a fine point. Narrow grooves, as in fluted columns with a slightly baroque twist, extend along their lengths. A short stalk fits each bristle into a round socket within the body armor so that the bristle can be moved within this articulation . . The bristles are tiny sense organs, perhaps sensitive to the fluctuations of air pressure when the fly is in flight. Dr. Stern goes on to describe the cellular structure of the bristle organ. It consists of three cells: the bristle cell it- self, which secretes the tapered out- growth; the socket cell that secretes a socket-like ring of hard chitin into which the base of the bristle fits; and, below these two, a sensory nerve cell that is linked to the bristle by a short nerve fiber and whose other long nerve fiber connects up with the central nervous sys- tem, thereby communicating to it stimuli felt by the bristle. 1 Published in American Scientist, April 1, 1954. 69. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Sussman, Maurice. Englewood Cliffs, N. J. , Prentice-Hall
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