GONADOTROPIC SUBSTANCES 



thyroidism, in which the concentration of iodine in the 

 thyroid may be low, is an analogous case of hypersecretion in 

 which the gland concerned contains an abnormally small 

 amount of its characteristic hormone. The analogy, however, 

 is by no means a satisfactory one. Moreover, the richest 

 source of hormone in all normal glands of internal secretion 

 is the gland secreting the hormone. Zondek's latest view 

 (1935) is that prolan is a secretion of the anterior pituitary 

 lacking a "synergic factor" (see the later section on the po- 

 tentiation of prolan effects). The complete anterior pituitary 

 gonadotropic secretion(s) he describes as "prosylan," the 

 "synergic factor" as "synprolan"; prolan, therefore, would be 

 "prosylan" without "synprolan." 



Analogous or different effects Jollovoing the administration 

 oj prolan to normal animals. — Although at first it appeared 

 that prolan and anterior pituitary implants or extracts pro- 

 duced about the same gonadotropic effects after administra- 

 tion to immature rodents, much of the later work has dis- 

 closed important differences. If prolan is administered to im- 

 mature female rats for 4 or 5 days^ the ovarian hypertrophy 

 is not much increased by markedly increasing the dose; 

 whereas a potent anterior pituitary extract produces hyper- 

 trophy more nearly proportional to the dose. For ex- 

 ample, Evans and Simpson (1929) reported that the ovarian 

 weights of immature animals receiving prolan were trebled 

 by increasing the dose one hundred and sixty fold; on the 

 other hand, a fourfold increase of the dose of anterior pitui- 

 tary extract, similarly injected into other animals, approxi- 

 mately quadrupled the ovarian weights. A similar "quanti- 

 tative" difference has been reported by others (Evans, 

 Meyer, and Simpson, 1931, 1932; Fluhmann, 1933-34; Leon- 

 ard, 1933; and Hamburger, 1934). According to Fluhmann, 

 the greater uterine hypertrophy may be caused by prolan. 

 Both Evans and Simpson, and Hamburger believed that pro- 

 lan brought about less follicular growth and maturation than 



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