254 



HYPOPHYSIS AND GONADOTROPHIC HORMONES 



would have tlie sustaining action they could 

 be presumed to have in this situation, has 

 apparently not been investigated. 



Inasmuch as the pituitary-gonad inter- 

 relationshii)s are complex and little under- 

 stood, it is not to be expected that the 

 administration of either isogeneric or heter- 

 ozoic gonadotrophic complexes would elicit 

 the normal pattern of sexual functions. As 

 a demonstration in point, Witschi (1955) 

 injected sparrows with the suspended pow- 

 ders of human, beef, or turkey hypophyses 

 and found that human hypophyses produced 

 good follicle growth but the oviducts were 

 only incompletely developed; turkey and 

 beef glands, on the contrary, promoted 

 intense stimulation of the reproductive tract 

 and only minor ovarian enlargement. None 

 of these preparations produced a balanced 

 development of the gonads and accessory 

 sexual organs, nor did ovulation and egg- 

 laying occur. 



Prolactin is present in extracts of the 

 hypophyses of fish, amphibians, and reptiles 

 (Leblond and Noble, 1937) and its presence 

 in avian pituitary was amply demonstrated 

 by Riddle's group in the middle 'thirties. 

 Their classic studies showed that prolactin 

 exerts full control over the proliferative 

 development of the crop sac in pigeons, but 

 it also appeared to have a suppressive action 

 on the gonads in these as well as other birds. 

 Prolactin of mammalian origin administered 

 to laying hens resulted in regression of 

 ovaries, cessation of laying, and appearance 

 of broodiness (Breneman, 1942; Nalbandov, 

 Hochhauser and Dugas, 1945; Nalbandov, 

 1953a). Nalbandov expressed the opinion 

 that broodiness is secondary to ovarian 

 failure, with attendant reduction in estrogen 

 secretion — a view nicely supported by the 

 earlier finding of Godfrey and Jaap (1950) 

 that broodiness can be quickly terminated 

 by estrogen injections (also see chapter by 

 Lehrman). Prolactin has also been noted 

 to induce broodiness in cocks (Nalbandov 

 and Card, 1946) and atrophy of the de- 

 veloping right gonad in poulards (Kornfeld 

 and Nalbandov, 1954). The mechanism for 

 the suppressive influence of prolactin on the 

 gonads of birds is unknown, but it can be 

 presumed to involve central nervous sys- 

 tem centers concerned in some manner with 



regulation of the anterior pituitary. Prolac- 

 tin has also been noted to have a calori- 

 genic action (Riddle, Smith, Bates, Moran 

 and Lahr, 1936) , but it has not been possible 

 to correlate this with the induction of 

 broodiness. Likewise, its ability to increase 

 the body temperature of roosters 2 to 4°F. 

 is not contributory, since broody fowl have 

 subnormal temperatures. 



6. Menu ma Is 



Information on the effectiveness in mam- 

 mals of pituitary gonadotrophins from 

 lower orders is scanty. As would be antici- 

 pated, avian gonadotrophins are by far the 

 most potent. Unfractionated gonadotrophic 

 extracts of avian pituitaries exhibited both 

 follicle-stimulating and luteinizing activity 

 (Leonard, 1937; Witschi, 1937; Gorbman, 

 1941; Traps, Fevold and Neher, 1947; Nal- 

 bandov, Meyer and McShan, 1951). The 

 nature of the gonadal reactions induced in 

 mammals by avian gonadotrojjhins are 

 ciualitatively similar to those produced by 

 mammalian gonadotrophins (Riley and 

 Fraps, 1942a, b; Breneman, 1945; Nalban- 

 dov and Card, 1946; Breneman and Mason, 

 1951). 



Moderate folheuhir development and lu- 

 teinization in rats and mice has been in- 

 duced by chicken and turkey pituitaries, but 

 full estrous development of the reproductive 

 tracts is generally not attained. Riley and 

 Fraps (1942a, b), using the mouse ovary 

 assay, estimated the ratio of FSH to LH 

 potency in bird hypophyses, and they along 

 with Chance, Rowlands and Young (1939), 

 Witschi (1940), and others, in fact, at- 

 tempted quantitative estimations of the 

 F8H-LH ratio in hypophyses of a variety 

 of birds and mammals. Such precise numeri- 

 cal values are unfortunately of little signifi- 

 cance, owing to the limitations of the bio- 

 assays. Nonetheless, two indications seem to 

 emerge from these studies: the FSH-LH 

 ratio varies greatly from one species to 

 another, and within a given species rhythmic 

 fluctuations have been noted. Pituitaries 

 from such cold-blooded forms as fish, frogs, 

 and tui'tles have at l)cst shown liarely posi- 

 ti\-e ti'aces of gonadotrophic activity in rats 

 and mice (for litei'aturc, see Witschi, 1955). 

 In tact, A(hinis and Granger (1941) had to 



