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. Author manuscript; available in PMC: 2009 Nov 1.
Published in final edited form as: Bull Math Biol. 2008 Aug 9;70(8):2211–2228. doi: 10.1007/s11538-008-9341-2

Figure 1.

Figure 1

Illustration of the variables in the mathematical model, and their interactions. The circle represents a gonadotroph. A solid arrow represents secretion, regulated by the GnRH frequency G. A dashed arrow represents effects on gene transcription. A closed arrowhead represents a positive action, while a short terminating line segment represents a negative action. An open arrowhead represents both the effects of G on secretion and the irreversible binding of activin and follistatin. FSH=follicle stimulating hormone, LH=luteinizing hormone, FS=follistatin, I=inhibin, A=activin, FSA=follistatin-activin complex, subscript b=plasma level, subscript p=intracellular protein level.