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The zone of mature spermatozoa in the testis of the european fire salamander, Salamandra salamandra, consists of numerous lobules embedded in a vascularized connective tissue. Most of the lobule boundary cells show features of SH-secreting cells (an increased amount of smooth ER, globular mitochondria with tubular cristae), whereas other retain a fibrocytic appearance. The mature spermatozoa within the lobules seem to be at least partly phagocytized and digested by the often highly vacuolized Sertoli cells. Lobules open into efferent ductules lined by a monolayered epithelium, whose cells are highly interdigitated. The capillaries of the interlobular connective tissue possess enlarged luminal and basal surfaces.
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In the adrenal gland of Discoglossus pictus, various types of chromaffin cells are described: noradrenaline cells, adrenaline cells and small granule-containing cells (on the basis of electron density and shape of the granules). The chromaffin cells occur in small groups, and have cytoplasmic processes which may surround them in the form of parallel layers. Their nerve supply is sparse. The possible function of SGC-cells, in relation to those described in other vertebrates, is discussed.
Cutaneous glandular Anlagen in Salamandrina terdigitata appear in the early larval stages as sphere-shaped intraepidermal cell nests. A stromal screen rises into the epidermis from the primordial dermis surrounding the Anlagen and isolates them from future keratinous elements. At this stage the only contact between the stroma and the gland blastocytes is through their cell coat, whilst the adjacent keratinocytes show a complex dermo-epidermal type junction. This structural asymmetry, confirmed by cytochemical findings, plays a direct role in guiding processes governing glandular bud differentiation. Interactions are in fact established between the stroma and the ample portion of the Anlage which it surrounds, which coordinate development, initiating differentiation of the contractile and secretory elements. Only a few bud cells, grouped below the epidermal basal layer, avoid such contact with the dermis, and constitute the regenerative matrix of the gland by maintaining their indifferentiated state. Above these, several keratinocytes form the excretory duct.
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The epidermis and the gill epithelium of larval intrauterine Salamandra salamandra were studied by the electron microscope. Both epithelia are bilayered. In the epidermis of the skin three cell types occur: pavement cells containing apical mucous granules, basal cells, Leydig cells and sporadically pea-shaped cells which obviously correspond to the Langerhans cells described by previous authors. The epithelium of the gills is composed of pavement-, basal-, pea-shaped, and ciliated cells. In the primary gill bar there are additional mitochondria-rich cells and single Leydig cells. In the secondary gill filament the thickness of the epithelium is reduced. There is no morphological evidence for the uptake of material by endocytosis in the apical plasmalemm of the pavement cells.
Siphonops annulatus possesses a single line ("Zahnzeile") of teeth in the upper jaw as well as in the palate paralleling the curvature of the jaws. An undivided continuous dental lamina provides the 2 nasopremaxillas and both maxillaries of the maxillopalatines with teeth, whereas each vomer and each (maxillo)-palatine is toothed by a separate dental lamina. The teeth are monocuspid, pedicellate and ancylosed to the bones in an extremely pleural condition. The results are compared to the conditions observed in the palate and upper jaw of urodeles.
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The study concerns the effects obtained at the medulla by electrical stimulation of mechanoreceptive afferences associated to the hyomandibularis nerve and branches of V and VII cranial nerves of the frog. Each of the afferences examined activates both nuclei of XI and XII in spite of the different medullary input; this action is very similar to that carried out by the mechanoreceptor afferences coming from papillae fungiformes. These result show very well the common ability of all the afferences coming from the mouth to obtain a similar action at the medulla. These properties suggest a convergence of the oral mechanoreceptor information on a mechanism of integration in order to obtain a coordination of the tongue and oesophagus motor reflex.
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A hierarchical system, consisting of several levels of genetic divergence, is formed by distribution of genetic distances between diploid taxa of the green toad species complex (subspecies Bufo viridis viridis--B. v. turanensis and species B. viridis--B. sp.) and taxa representing western (B. viridis s.l.) and eastern (B. raddei) Pale-arctic regions. Formally, genetic differentiation of the tetraploid toad B. danatensis from the parapatric diploid species reaches the species level. Genetic diversity of the tetraploid species is more than twofold higher than the total diversity of two modern diploid species. This suggests that B. danatensis was formed with the participation of other unknown species in the past. The polyploid species B. danatensis is assumed to have originated by hybridization of two species groups that arose approximately 2.6 million years ago in Mediterranean and Central Asian regions of the western Palearctic. The genetic heterogeneity of geographical populations of the polyploid species indicates its polyphiletic origin. The heterogeneity range suggests that formation of the tetraploid species continued for a very long period (about 1 million years).
Parapolystoma johnstoni n. sp. is described from Litoria nyakalensis from northern Queensland. Parapolystoma bulliense is recorded from a new host, Litoria pearsoniana. The pattern of the ciliated cell on the oncomiracidium of P. bulliense is described. The subfamily diagnosis of the Diplorchiinae is amended to include the species of Diplorchis, Neodiplorchis, Parapolystoma, and Pseudodiplorchis.
We investigated phylogenetic relationships among five species of Japanese brown frogs by the analysis of nucleotide sequences in the cytochrome b gene of mitochondrial DNA (mtDNA). The sequence of the 251-base pairs, which cover approximately 22% of the cytochrome b gene, was determined by PCR-Direct sequencing method. Phylogenetic relationships were analyzed by UPGMA, neighbor-joining, maximum-likelihood, and maximum parsimony analyses. The sequences only slightly varied within one population of Rana japonica. Intraspecific variation in sequences varied among species, and R. tagoi showed more pronounced variation than did R. ornativentris. Rana japonica and R. tagoi share 2n = 26 chromosomes with each other, but the former was closer to R. pirica and R. ornativentris, both with 2n = 24, than to the latter. Phylogenetic relationships estimated from the nucleotide sequence of the cytochrome b gene generally conformed to the idea hitherto proposed chiefly on the bases of morphological and ecological evidences.
The directed ingression of Lhd-B gene from R. lessonae to R. ridibunda observed during hybridization between these species was confirmed in the present study. The ingression was accompanied by decreased of the initial allele activity, segregative disturbances in heterozygotes and changes in electrophoretic mobility. The population genetic analysis has shown stable preservation of abnormal alleles in hybrid populations. The results are discussed with reference to the concept of genetic instability, its application to speciation models, and the neutralist vs. adaptationist controversy. Our data supports the neutral concept of allozyme variation.