reversal in the experimental lot was induced by the cortisone. Fig. 2 to 4 show how the degenerative processes in the ovarian cortex are immediateIy followed by thickening of the walls of the ovarian sacs, proliferation of numerous medullary cords, and differentiation of seminal tubules. The ovarian sacs become gradually reduced to seminal and reticular tubules of the testis.The cortisone esperiments are being continued, in order to obtain more information about the range of dosages, that will result in sex reversal: however, the fact that this substance like the other tested androstanes interferes with normal ovarian development and eventually causes sex reversal in females of R Q~Q S J~V Q~Z ' C Q , is now safely established. This result is somewhat surprising because cortisone has not, so far. been known to have androgenic functions. -4s a matter of fact, the results of our experiment should neither be considered as a demonstration of an androgenic character. This term should rather be restricted to designate the stimulation of male secondary sex characters. In our experiment cortisone evidently acts entirely by interfering with normal ovarian development. The development of the gonadal cortex becomes inhibi'ted, and later the differentiated OVOcytes are caused to degenerate. The transformations that lead to the development of the testicular structure probably are not induced directly by the cortisone. Since constitutionally the female larvae are bisexual, with the female determiners epistatic over the male factors, the inhibition or destruction of the ovarian cortex automa tically creates the possibility for a compensatory, medullary-testicular development ( 3 ) . The action of cortisone on the sex glands is, therefore, best characterized as antagonistic to the development of an ovarial cortex or, shortly, as anti-ovariogenic.Cortisone, like 3 other tested alkyl substituted androstanes, causes the transformation of ovaries of frog larvae into testes. Its action is initially anti-ovariogenic, and sex reversal follows by a compensatory development of the medullary rudiment. The dosages that produce sex reversal are high in comparison with the threshold values of testosterone and methyltestosternne.
Suiwnary.,From t k e Dopart i i w n t of Bacteriology, A r i i r y Medical Service GradfLate School, Washington, D. C. .Serologic studies of the pleuropneumonia-'like organisms (hereafter referred to as -PPLO) have been hampered by the difficulties 'encountered in isolating and maintaining strains. Cultural and morphologic characteristics of human strains have been studied, but relatively few observations employing serologic methods have been recorded. Warren and Sabin(1) compared one human strain
Listeriosis is a mildly infectious but highly fatal disease of several species of animals, including man. The disease is caused by Listeria monocytogenes, which has heretofore been isolated only from man and animals showing symptoms or
Procedures for maintaining
Mycoplasma
strains are described. Liquid nitrogen storage provided an adequate means for keeping stock cultures stable. Over 74 strains of approximately 26 species have been preserved in this way, some for as long as 9 years.
Mycoplasma
strains can also be recovered satisfactorily from the freeze-dried state when the procedure described includes the use of 12% (v/v) sucrose as an additive. Fifteen strains representing 12 or more species were subjected to a freeze-drying program with and without sucrose added to concentrated cell suspensions in growth medium. Cell counts indicate improved survival with sucrose.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.