Hynobius Retardatus Research Articles

Reproductive Behavior of the Salamander Hynobius nigrescens: Monopoly of Egg Sacs during Scramble Competition

urans (Wells, 1977). Breeding males of Hynobius retardatus (Sasaki, 1924), H. dunni (Masiba, 1969), and H. nigrescens (Hasumi and Iwasawa, 1990) form a mating ball around a pair of egg sacs, scrambling to fertilize the eggs. A striking increase in male head width occurs during the aquatic breeding phase of these species, a phenomenon unknown in other families (Hasumi and Iwasawa, 1990). Increased head width in H. nigrescens may be related to androgens rather than prolactin (Hasumi and Iwasawa, 1992a, b; Hasumi et al., 1993), but the potential selective advantage of increased head width is unknown. If males with well-developed secondary sexual characteristics, including increased head widths, monopolize egg sacs during the formation of mating balls, male-male competition may be responsible for increased head width (Hasumi and Iwasawa, 1990). To examine this possibility, I observed breeding males engaging in scramble competition in the laboratory. I compared the secondary sexual characteristics of egg sac-monopolizing males with those of other males. Also, I present a preliminary description of the sexual behavior of H. nigrescens. Aquatic-phase males and gravid females of H. nigrescens were collected from a pond in Iwamuro-mura, Niigata Prefecture, Japan (37?44'N, 138?50'E; 180 m elevation) during the breeding season of March 1991. Males were anesthetized in 0.1% MS 222 solution and marked by Wolf and Hedrick's (1971) method, in which figure-type clippings from filter paper soaked in 10% acetic acid were placed on their backs for 1 min. Both sexes were kept separately in water at 2 C in order to maintain their sexual motivation and propensity to breed prior to observations. Eight or 10 marked males were placed in an aquarium (66 x 50 x 38 cm) filled with aged tap water at approximately 10 C at 1800 h. One female ready to oviposit (see Hasumi and Iwasawa, 1990) was added at 1900 h. A branched twig was laid across the aquarium as a substrate for egg sac deposition. I observed behavioral interactions under dim red light from 1900 h until the disassembly of the mating ball. The marks on individual males were just distinguishable under this illumination. Sexual behavior was monitored contin-

Spermatogenesis is extraordinarily accelerated in metamorphosis-arrested larvae of a salamander,Hynobius retardatus

Laboratory experiments were conducted to induce neoteny inHynobius retardatus, which had been reported to propagate in larval forms like axolotl. A large number of newly hatched larvae were reared in an aqueous solution of thiourea (TU) and sodium perchlorate (SPC) in order to arrest the metamorphosis. Gonadal development in the metamophosis-arrested larvae was compared with that in normally metamorphosing and metamorphosed controls. Metamorphosis-arrested male larvae produced morphologically mature spermatozoa approximately 4 months after hatching, when the gonads in the controls began to differentiate into testes, or to show the premeiotic proliferation of germ cells. Possible endocrine controls of these phenomena are discussed.

Melanophore dispersion in northern amphibian larva induced by exposure to cold

AbstractIsolated tails from larvae of the northern amphibians Rana chensinensis and Hynobius retardatus showed light skin color in physiological salt solution at room temperature. However, when the tails were exposed to cold, they became dark. Microscopic observation revealed that exposure to cold caused reversible dispersion of melanin granules within integumental melanophores. There was no darkening, however, in the tail of the Xenopus tadpole at low temperatures, as the dispersion effect of melanophore‐stimulation hormone (MSH) on melanophores in Xenopus was blocked. Calcium ions are required for the action of MSH, but the effect of cold on melanophore dispersion observed in R. chensinensis and H. retardatus was not dependent on calcium ions. Beta adrenergic agents dispersed the melanophores of isolated tail from these amphibian larvae and propranolol antagonized the effect. However, during exposure to cold, this beta antagonist failed to inhibit the melanophore dispersion.

The effect of temperature on the action of thyroid hormone and prolactin in larvae of the salamander Hynobius retardatus

To elucidate the environmental factors and endocrine mechanisms which are responsible for inducing neoteny in the salamander Hynobius retardatus, the effect of temperature on the growth and metamorphosis of this amphibian, as well as the actions of thyroid hormone and prolactin at low temperature, were studied. (1) The metamorphosis of larvae cultivated at 10° was significantly delayed compared with that of larvae cultivated at 22°, but the metamorphosis was eventually completed. At 4°, metamorphosis never occurred, even after 2 years. (2) Exogenously administered thyroid hormone accelerated metamorphosis at 10° or 22°, but was ineffective in larvae kept at 4°, whether administered by injection or immersion. (3) If a higher concentration of thyroid hormone was given by a single injection to larvae cultured at 4°, an appreciable acceleration of metamorphosis was observed after transferring the larvae to 22°. (4) Unlike thyroid hormone, prolactin promoted growth at 4°.

Cytological changes induced by low temperature in the thyroid glands of larvae of the salamander Hynobius retardatus

In order to study the environmental conditions and the endocrine mechanism which induce neotenous characteristics, the fine structure of the thyroid glands of larvae of the salamander Hynobius retardatus were examined. The thyroid glands of larvae exposed to a low temperature (4°) were compared with those of larvae exposed to a higher temperature (20°). At 4°, the follicular lumen was large and its contents of low electron density; the epithelial cells were flat or cuboidal. In contrast, the 20° larvae showed a small dense lumen and tall cylindrical epithelial cells, which may indicate a higher level of activity. No apical vesicles were found in the epithelial cells of the 4° larvae, although they were present in 20° larvae. On the other hand, in 4° larvae the chromatin in the nuclei was scattered, while in 20° larvae it was condensed. In addition, large dense granules occupied 2.4% of the epithelial cytoplasm in 4° larvae and as much as 7.3% in 20° larvae. The structural features observed in larvae exposed to the cold resembled those reported for thyroid glands made inactive by a lack of thyrotropin.

Prolactin induces increase in the specific gravity of salamander, Hynobius retardatus, that raises adaptability to water.

The migration of the salamander, Hynobius retardatus, from land to water, which normally occurs in the breeding season, was induced by the injection of prolactin. The migration was accompanied by certain morphological changes (wider tail or swollen body); the observed morphological changes resembled those of salamanders collected from ponds during the breeding season. The prolactin-treated salamanders sank to the bottom of the water. In contrast, the control salamanders that did not receive prolactin floated near the water surface. The specific gravity of the whole body of the prolactin-treated animals was greater than unity. Prolactin injection induced a remarkable enlargement of the tissue between the skin and muscle, in which a considerable amount of mucopolysaccharide-rich substance accumulated. Because of the hydrophilic nature of the mucopolysaccharides, and increased mucopolysaccharide may absorb more water, which, in turn, may result in an increase of the osmotic pressure of the serum. This may eventually cause the animals to migrate from land to water to quench the "thirst." The absorption of water may make the specific gravity greater, and this allows the animals to sink in water.

Nervus tenuis, a Hitherto Unknown Cranial Nerve of the Fourth Metamere

AbstractIn hynobiid urodele embryos there are three serially arranged muscles associated with the otic and occipital regions of the endocranium. These muscles are continuous posteriorly with the succession of trunk myomeres and most likely represent myotomic derivatives attributable to the third, fourth, and fifth metameres of the body. From front to back these muscles are designated: anterior basiotic, posterior basiotic, and occipital. A hitherto unknown cranial nerve is directed towards the posterior basiotic muscle in embryos of Hynobius retardatus. For this new somatic motor nerve the term nervus tenuis is proposed. Together with the glossopharyngeal nerve it constitutes the fourth cranionerval segment.

A STUDY OF THE EVOLUTION OF THE AMPHIBIAN AND DIPNOAN PRONEPHROS BY AN ANALYSIS OF ITS RELATIONSHIP WITH THE ANTERIOR SPINAL NERVES

The fact that an anterior spinal nerve and nephrostomial tubule and nephrostome are constantly associated with each other in individual specimens of urodeles, Anura and dipnoan larvae waa exploited to analyse the phylogeny of their pronephroi. Spinal nerves of numerically identical body segments but in different genera are homologous quantitatively i.e. develop from the same numbered segment as well as qualitatively; therefore it is assumed that individual but segmental pronephric units in different genera, when related to numerically identical spinal nerves, are homologous quantitatively and qualitatively also.A large number of nephrostomial units, e.g. present in the apodan Hypogeophis (Brauer, 1902) represents a primitive condition and commonly five functional units, though the fifth is reduced, are included in the pronephros of Cryptobranchus japonicus related to spinal nerves I to V (metotic segments 4 to 8; total body segments 7 to 11 inclusive). The phylogenetic development is expressed in the loss of front and rear tubules and can be traced through Hynobius retardatus, H. (Salamandrella) keyaerlingii, H. nebulosus, Necturus maculatus. Plethodon cinerevs and Ambystoma mexicanum to Triturus cristatus and Pleurodeles waltlii, which pronephroi each possess two functional nephrostomial units related to spinal nerves II and III (metotic segments 6 and 6; total body segments 8 and 9) or Salamandra maculosa and Desmognathus quadrimaculatus, where there are two units related to spinal nerves III and IV (metotic segments 6 and 7; total body segments 9 and 10).All the anuran pronephroi (except for a few which possess four units) originally are composed of three functional nephrostomid units related to spinal nerves I, II and III. If the anuran skull includes five segments (not counting the condyles) then the pronephric tubules belong to metotic segments 3, 4 and 6 or total body segments 6, 7 and 8; if the skull includes six segments the pronephric tubules would belong to metotic segments 4, 5 and 6 or total body segments 7, 8 and 9.Pronephroi of Neoceratodus and Protopterus—derived from a more numerous series of tubules (Kerr, 1919)—are each composed of two remaining funationel nephrostomial units, related to the nerves directly in front of the occipital and occipito‐spinal II arches (or their equivalent nerves in Protopterus). This arrangement probably refers the tubules to total body segments 8 and 10 and thus functional tubules of body segments 7, 9 and 11 (present in Cryptobranchus japonicus) are abaent.It is thought possible that the phylogenetic pattern described in the various specimens may provide a framework into which the pronephroi of all extant larvae of Urodela, Anura and Dipnoi can be arranged.

Effects of Testosterone Propionate on Sex Development in Female Ambystoma Larvae

Previous articleNext article No AccessEffects of Testosterone Propionate on Sex Development in Female Ambystoma LarvaeBeatrice MintzBeatrice Mintz Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by Volume 20, Number 4Oct., 1947 Article DOIhttps://doi.org/10.1086/physzool.20.4.30151968 Views: 4Total views on this site Citations: 14Citations are reported from Crossref Journal History This article was published in Physiological Zoology (1928-1998), which is continued by Physiological and Biochemical Zoology (1999-present). PDF download Crossref reports the following articles citing this article:Dustin S. Siegel, David M. Sever, Robert D. Aldridge The pelvic kidney of male Ambystoma maculatum (Amphibia, urodela, ambystomatidae) with special reference to the sexual collecting ducts, Journal of Morphology 271, no.1212 (Sep 2010): 1422–1439.https://doi.org/10.1002/jmor.10883 両生類の性決定及び性分化, Newsletter of Japan Society for Comparative Endocrinology 2003, no.109109 (Jan 2003): 109_11–109_19.https://doi.org/10.5983/nl2001jsce.2003.109_11E. Romo, M. P. De Miguel, M. I. Arenas, L. Frago, B. Fraile, R. Paniagua Histochemical and quantitative study of the cloacal glands of Triturus marmoratus marmoratus (Amphibia: Salamandridae), Journal of Zoology 239, no.11 (May 2009): 177–186.https://doi.org/10.1111/j.1469-7998.1996.tb05445.xDavid O. Norris, Harriet B. Austin, Amal S. Huazi Induction of cloacal and dermal skin glands of tiger salamander larvae, (Ambystoma tigrinum): Effects of testosterone and prolactin, General and Comparative Endocrinology 73, no.22 (Feb 1989): 194–204.https://doi.org/10.1016/0016-6480(89)90092-0David O. Norris Regulation of Male Gonaducts and Sex Accessory Structures, (Jan 1987): 327–354.https://doi.org/10.1007/978-1-4613-1869-9_11Günter Dörner Sexualhormonabhängige Differenzierungsprozesse der Sexualorgane und des Hypothalamus, (Jan 1972): 97–129.https://doi.org/10.1007/978-3-7091-5603-2_3L. Gallien Comparative activity of sexual steroids and genetic constitution in sexual differentiation of amphibian embryos, General and Comparative Endocrinology 1 (Jan 1962): 346–355.https://doi.org/10.1016/0016-6480(62)90108-9Emil Witschi EMBRYOLOGY OF THE UTERUS: NORMAL AND EXPERIMENTAL, Annals of the New York Academy of Sciences 75, no.2 The Uterus2 The Uterus (Jan 1959): 412–435.https://doi.org/10.1111/j.1749-6632.1959.tb44565.xJoyce A. Bruner, E. Witschi Pluripotentiality of the mesonephric blastema and the mechanism of feminization of male salamanders by androgenic hormones, The Anatomical Record 120, no.11 (Sep 1954): 99–117.https://doi.org/10.1002/ar.1091200108Beatrice Mintz, Louis Gallien Androgen-induced feminization of urodele larvae in the absence of the hypophysis, The Anatomical Record 119, no.44 (Aug 1954): 493–517.https://doi.org/10.1002/ar.1091190407Chih Ye Chang Parabiosis and gonad transplantation in Xenopus laevis Daudin, Journal of Experimental Zoology 123, no.11 (Jun 1953): 1–27.https://doi.org/10.1002/jez.1401230102DONALD PAUL COSTELLO Growth and Development, (Jan 1949): 115–153.https://doi.org/10.1016/B978-1-4832-0000-2.50008-1ROBERT K. BURNS Hormones and the Differentiation of Sex, (Jan 1949): 233–266.https://doi.org/10.1016/B978-1-4832-0000-2.50010-XR. R. Humphrey Reversal of sex in females of genotype WW in the axolotl (Siredon or Ambystoma mexicanum) and its bearing upon the role of the Z chromosomes in the development of the testis, Journal of Experimental Zoology 109, no.22 (Nov 1948): 171–185.https://doi.org/10.1002/jez.1401090202

Sex-modification in a Semidifferentiated Salamander, Hynobius retardatus Resulting from Implantation of Testis and Hypophysis

Sex-modification in a Semidifferentiated Salamander, Hynobius retardatus Resulting from Implantation of Testis and Hypophysis

Cytological observations on the fertilization of the egg of <i>Hynobius retardatus</i> DUNN

The fertilization phenomena in Hynobius retardatus are observed in sections of the eggs, fixed at different intervals after insemination of the spermatozoa. The results are briefly outlined as below:1) About 1 to 1 1/2 hours after insemination of the spermatozoon the the second polar division is completed, and formation of the second polocyte follows about 1 1/2 to 2 hours after insemination.2) About 2 1/2 to 3 hours after insemination there is found at the periphery of the egg the already metamorphosed female pronucleus, which moves away from the surface towards the interior of the egg.3) The spermatozoon enters the egg as early as 15 minutes after insemination and then, within 1 hour, it metamorphoses into the male pronucleus.4) The conjugation of the male and female pronuclei generally takes place between the 5th and 6th hour after fertilization. They meet at a distance of about 1/4 to 1/3 the egg diameter from the animal pole, along an egg-axis joining the second polocyte with the center of the egg.5) At the time of the conjugation, both pronuclei are quite similar in their structure, size and staining condition; they are nearly spherical with a smooth nuclear membrane and are filled with colourless nuclear sap. Generally they measure 0.038-0.042mm in diameter.6) After the two pronuclei meet together, they do not actually fuse, but lie side by side in close contact with the nuclear membrane intact. The maternal and paternal nuclear elements are separated in distinct groups during the stages preparatory to the first cleavage division and the chromosomes are formed independently in each respective nuclear vesicle.7) In the egg about 7 hours after insemination, the first cleavage spindle is usually found in the process of division.