Two significant benefits derived from reading and discussing classic scientific papers in undergraduate biology courses are 1) providing students with the realistic perspective that science is an ongoing process (rather than a set of inarguable facts) and 2) deepening the students' understanding of physiological processes. A classic paper that is useful in both of these regards is by I. E. Lawton and N. B. Schwartz (A circadian rhythm of luteinizing hormone secretion in ovariectomized rats. Am J Physiol 214: 213–217, 1968). The primary objective of the study is to determine whether tonic (pulsatile) secretion of luteinizing hormone (LH) from the pituitary gland exhibits a circadian rhythm. While this hypothesis seems relatively straightforward, its in vivo investigation necessitates an awareness of the multitude of factors, in addition to the circadian clock, that can influence plasma LH levels (and a consideration of how to control for these factors in the experimental design). Furthermore, discussion of the historical context in which the study was conducted (i.e., before the pulsatile nature of LH secretion had been discovered) provides students with the realistic perspective that science is not a set of facts but rather a systematic series of attempts by scientists to understand reality (a perspective that is difficult to convey using a traditional textbook alone). A review of the historical context in which the study was conducted, and a series of discovery learning questions are included to facilitate classroom discussions and to help deepen students' understanding of the complex nature of pituitary hormone regulation.
