EMBRYONIC DEVELOPMENT OF THE BRAIN ©David B. Fankhauser, Ph.D., Professor of Biology and Chemistry University of Cincinnati Clermont College, Batavia OH 45103
60 hour chick 15x	This page has been accessed  times since 23 December 2002.  26 December 1993, rvsd 6 Jan 1994, 30 Dec 1994, 8 Jan. '97, 7 Jan '98, 7 Jan 00, 4 Jan 01	60 hour chick, 80x

Studying the early development of the brain reveals structural and functional relationships between the portions of the adult brain. Since the early development of most vertebrates is similar, the 60 hour chick embryo can serve as a study organism roughly equivalent to the 5 week human embryo.  See Martini, 5^th Ed, pp 438-439,  & handout from Balinsky (next page in packet).

Note: This prepared slide is unusually thick, so it is especially important to follow correct microscope protocol. (Do not ram the slide with the objective). Also, since the specimen mounting medium softens as it warms, remove the slide as soon as you are done, and allow it to cool flat on the surface of the desk before you return it to the slide case. Use the 4x objective to locate, illustrate, label and describe the bolded features of the chick embryo in the following table.   As a study aid, here are two views of the 60 hour chick unlabeled and labeled.

Slide 7. Chick, 60-70hour , whole mount, chicken (H 2195)    Unlabeled:       Labeled: 
 

primitive vesicles	intermediate vesicles	mature brain components	functions
prosencephalon	telencephalon	cerebrum lateral ventricles [ rudimentary nose]	control skeletal muscles sensory perception language intelligence , consciousness
	diencephalon	thalamus	sensory relay
		hypothalamus	regulation of autonomic activities
		epithalamus (pineal)	biological clock
		[ optic cup]	will become eye, vision
mesencephalon	mesencephalon	midbrain * corpora quadrigemina cerebral peduncles	visual reflexes auditory reflexes connection to cerebrum
rhombencephalon	metencephalon	cerebellum	plan & coordinate voluntary movement, maintain balance
		pons *	commisural nerve tracts
	myelencephalon	medulla oblongata*	regulates vital functions
		[ otic vesicle]	hearing
* These constitute the brain stem, which regulates consciousness and some autonomic reflexes: respiration, coughing, swallowing, cardiovascular control.

When finished illustrating the embryonic brain, a brief, student-graded 10 question quiz will be given to see how well these features were learned.