Palade and Farquhar (1) have recently reported the presence of a unique fibril in the skin of Amphibia and, in less well developed form, in various sites in the rat. Previous to that report, Brody (2) and Younes (3) observed similar fibrils in human skin and cervix, respectively, but did not emphasize their unusual character. Recent observations in our laboratory indicate that a similar fibril ...

The differentiation of the male germ cells into spermatozoa has long been a subject of particular interest to cytologists. In the period from 1890 through the first decade of the present century, Meves (28), McGregor (27), Ballowitz (2), and a number of other skilled observers made notable contributions to our understanding of the metamorphosis Of the germ cells in several vertebrate species. L...

The ribonucleic acid synthesis in cleaving stage embryos has been studied _??_ n some detail in amphibia and in echinoderms. In amphibia, results from autoradiographic studies (Ficq 1964) with RNA precursors agree with biochemical data that no ribosomal synthesis takes place in mature oocyte and early cleavage stages (Brown 1964). In echinoderms, Brachet, Decroly, Ficq, and Quertier (1963) repo...

Transcription start sites of chicken mitochondrial DNA have been mapped in the control region by direct sequencing of in vitro capped mitochondrial RNA species, by primer extension and by S1 nuclease protection analysis. Transcription of the heavy strand initiates predominantly at a site 156 nucleotides upstream of the tRNA(Phe) gene, i.e. about 135 nucleotides further upstream than the corresp...

Heyer, W. Ronald. Systematics of the pentadactylus Species Group of the Frog Genus Leptodactylus (Amphibia: Leptodactylidae). Smithsonian Contributions to Zoology, number 301, 43 pages, 23 figures, 12 tables, 1979.—Sixteen mensural and pattern characters are analyzed for the adult members of the Leptodactylus pentadactylus species group. Available data on tadpoles, mating calls, and karyotypes ...

Introduction The ability ofthe kidney to conserve or excrete free water independent of changes in solute excretion was a prerequisite for the successful adaptation of vertebrates to prolonged periods on land (1, 2). Renal conservation of water in amphibia, reptiles, birds, and mammals is controlled by antidiuretic hormone (ADH)."2 In these animals, body fluid osmolality is maintained within ver...

There is currently little evidence of pollution-induced endocrine dysfunction in amphibia, in spite of widespread concern over global declines in this ecologically diverse group. Data regarding the potential effects of endocrine-disrupting contaminants (EDCs) on reproductive function in amphibia are particularly lacking. We hypothesized that estrogenic EDCs may disrupt progesterone-induced oocy...

This essay looks at the historical significance of five APS classic papers that are freely available online: Wearn JT and Richards AN. Observations on the composition of glomerular urine, with particular reference to the problem of reabsorption in the renal tubules. Am J Physiol 71: 209-227, 1924 (http://ajplegacy.physiology.org/cgi/reprint/71/1/209). Richards AN and Walker AM. Methods of colle...