54 Discussions 



development of the cords. Genetic males could be transformed into females with 

 estrone. Unfortunately, this result does not follow in all amphibia as Witschi demon- 

 strated in frogs. 



The experiments of Burns provide evidence for the direct effect of sex hormones on 

 the development of the primary and secondary cords of the developing gonad. 



Changes in the nature of the follicular contents have been referred to in the discussion. 

 It is interesting that Van Oordt and his co-workers have observed comparable changes 

 with the seminiferous tubules. The administration of anterior pituitary hormones 

 transforms the viscous contents of the tubules to a watery consistency and there is a 

 simultaneous disappearance of mucopolysaccharide. However, 1 suppose caution 

 should be exercised in considering this to be homologous with changes in the ovarian 

 follicle. 



Finally, it may be of interest to report in connection with Dr. Simpson's results 

 some observations of Dr. R. R. Humphrey on axolotls. He tried to ovulate these 

 animals with Armour LH with which we provided him. This experiment was unsuc- 

 cessful. Armour FSH, on the other hand, did a beautiful job in ovulating the axolotls. 



Dr. M. C. Chang: I should like to comment here about Dr. Noyes' paper in connection 

 with the point raised by Dr. Pincus, whether the presence of estrogen in the follicle 

 would inhibit or facilitate maturation of the egg. In 1955 (J. Exp. Zool. 128, 379; 

 Science 121, 867) I did some work on the cultivation and transplantation of follicular 

 eggs in the rabbit. It was found that eggs recovered from follicles of the unmated 

 rabbit could mature, that is, there was disappearance of the nuclear membrane, 

 formation of the first maturation spindle, extrusion of the first polar body and formation 

 of the second maturation spindle, either in culture or in the fallopian tubes. It seems 

 to me that there is perhaps a factor in the follicle which inhibits the maturation of the 

 egg. Whether it is estrogen, I do not know. Some of these eggs can be fertilized, but 

 most of them failed to develop into normal young after fertilization. It seems to me 

 that whether an egg with second maturation spindle observed outside the follicle is 

 really matured in the follicle or matured in vitro is uncertain and whether or not they 

 are really normal is also difficult to say. By application of potassium fluoride, Nadamitsu 

 (/. Sci. Hiroshima Univ. 17, 47, 1957) observed the ovulation of rat ovaries in vitro 

 and claimed that the eggs are normal because of the presence of the second maturation 

 chromosomes. I wonder whether these eggs ovulated in vitro or in the anterior chamber 

 of eye are really normal. 



Dr. Gregory Pfncus: The experimenter has done more than that. He has actually taken 

 eggs and added gonadotropin in vitro, and decided that unless the gonadotropin is 

 present, the eggs do not go through the first maturation division. Unfortunately, I 

 don't think that he is statistically minded, so we cannot find out more details. 



All you need to do with rabbit eggs is take them out of the follicles, put them in 

 culture, and it can be a variety of types of cultures, and they will go through the first 

 maturation division. 



The second division doesn't occur, ordinarily, unless the egg is fertilized or partheno- 

 genetically activated. 



It is the first maturation division which occurs in the ovaries in practically all 

 species. 



Dr. Robert W. Noyes: These early follicular eggs cannot be fertilized because of the 

 immaturity of the cumulus, corona and probably zona pellucida. Although certain 

 features of nuclear maturation and meiosis take place in such ova removed to in vitro 

 conditions, the cumulus and corona do not mature, and spermatozoa do not penetrate 

 these coats if the cultured ova are transferred into a recipient oviduct. 



Chairman Greep: Does any one know about the hyperemia test? 



Dr. Charles A. Barraclough: Would the development beyond the secondary follicle 

 occur with a smaller amount of FSH, given to the estrogen-primed animal ? 



