Temperature dependent changes in the thyroid gland of Mertensiella caucasica (Urodela,Amphibia)

Summary The influence of temperature on the thyroid gland of the Caucasian salamander, Mertensiella caucasica has been studied (1) with the light- and electron microscopes, (2) with enzyme histochemical and quantitative methods. Animals which had been kept for years at 16° C were exposed for 48 hrs to 4° C or 27° C.At 4° C the follicular epithelium consisted of cuboidal cells with well-developed rough ER, occasional distended cisternae of the rough endoplasmic reticulum (ER) filling most of the cytoplasm, a relatively small Golgi apparatus and numerous round or oval shaped lysosomes. In animals kept at 27° C the follicular wall was composed of markedly taller epithelial cells, the apices of which bulged into the follicular lumen. Compared to the animals at 4° C, there appeared to be a decrease in the rough ER. The Golgi apparatus did not exhibit clear differences. The lysosomes increased in number and showed various shapes among which elongated ones with pointed ends were particularly striking. In the apical cytoplasm colloid droplets appeared indicating hormone release. The apical microvilli increased in number.The measurements of total T₄ have shown that the hormone level in animals kept at 27° C was about twice as high as in animals kept at 4° C.Dedicated in gratitude to Professor Dr. Drs. h.c. W. Bargmann on the occasion of his 70th birthday.Supported by the Deutsche Forschungsgemeinschaft (We 380/5).     

The dorsal tail tubercle of Mertensiella caucasica and M. luschani (Amphibia: Salamandridae)

Males of the two species of Mertensiella (M. caucasica and M. luschani) possess a tubercle projecting from the skin of the dorsal tail base, the single morphological character that defines the genus. The dorsal tail tubercle functions during courtship, and its role is similar in both species. The tubercle is inserted into the cloaca of the female during ventral amplexus, shortly before the male deposits a spermatophore. Histological examination, however, revealed that the dorsal tubercles differ structurally between the two species. In M. caucasica, the tubercle consists primarily of elongate mucous glands, with granular glands occurring only at the base. Both mucous and granular glands of the tubercle are larger than those in typical skin. Unlike typical skin, however, mucous glands are larger than granular glands. In M. luschani, mucous glands and granular glands occur throughout the tubercle, and the granular glands are larger than the mucous glands, although both types are larger than those in typical skin. The dorsal tubercles of M. caucasica and M. luschani may not be homologous structures and may have resulted from convergent evolution. J Morphol 232:93–105, 1997. © 1997 Wiley-Liss, Inc.     

Histochemical, enzyme histochemical and ultrastructural investigation on the sperm-duct glands of Padogobius martensi (Pisces, Gobiidae)

The functions of the sperm-duct glands of Padogobius martensi were investigated by histochemical, enzyme histochemical and fine structural methods during the prereproductive and reproductive periods, i.e. during their maximum activity. The epithelium lining the spermduct gland tubules produces strongly acidic sulphomucins, probably conjugated with proteins and the variety of sulphomucins increases during the reproductive period when the exocrine epithelium is also involved in the phagocytosis of degenerating sperm cells. A contractile network of myoid cells surround the tubules. The gland interstitium contains cells similar in enzyme histochemical and ultrastructural features to the testicular interstitial cells (Leydig cell homologues). Unlike the latter, however, the interstitial cells of the sperm-duct gland are able to produce steroid glucuronides, which act possibly as pheromones.     

Histological,immuno- and enzyme-histochemical investigations on the adenohypophysis of the urodeles,Mertensiella caucasica and Triturus cristatus and the caecilian,Chthonerpeton indistinctum

Summary The pituitary glands of two urodelan species (Mertensiella caucasica, Triturus cristatus) and one caecilian species (Chthonerpeton indistinetum) were examined with histological (Alcian blue, Brookes' trichrome stain), enzyme histochemical (acid phosphatase, -naphthylacetate-esterase, acetylcholinesterase) and immunofluorescence techniques (anti-carp GTH, anti-ovine prolactin, anti-synthetic -MSH). In the pituitary gland of Mertensiella and Triturus six chromophilic cell types could be distinguished. A strong fluorescence was observed in the MSH-, GTH- and TSH-cells.In the pituitary gland of Chthonerpeton only five chromophilic cell types could be distinguished: in the rostral part of the pituitary gland the B₃-cell; in the basal region of the central area the B₂-cell; dorsocaudally the B₁-cell. The acidophilic cells were found in the central and caudal part of the pars distalis. The basophils of the pars intermedia could be observed in the dorsocaudal part of the pituitary gland surrounding the neurohypophysis. All acidophilic cells showed a strong immunofluorescence with anti-ovine prolactin (LTH).     

Complex secretory products in the oviduct of the plethodontid salamander Bolitoglossa dofleini (Amphibia, Urodela)

The ultrastructure of the secretory granules in the cells of the subdivisions of the oviduct in the neotropical plethodontid salamander Bolitoglossa dofleini was studied by transmission electron microscopy. In addition, we applied the cationic dye Cuprolinic Blue (CB) at different electrolyte concentrations to demonstrate proteoglycans, and the pyrogallol red-copper (PR-C) method to stain proteins at the ultrastructural level. The entire oviduct is lined by a simple epithelium that contains ciliated and microvillous cells in the first subdivision, the aglandular pars recta; microvillous cells show a moderate secretory activity. The following pars convoluta is differentiated into five glandular subdivisions and the aglandular “uterine portion”. Especially in the glandular parts, the epithelium is arranged in longitudinal folds. At their crests ciliated and microvillous cells similar to those in the pars recta occur. Gland cells are crowded with secretory granules that differ in their structural complexity (with and without electron-dense spheres or masses; elaborated, homogeneous or granular matrix; spherical; distorted) along the various subdivisions. Further, as suggested by the CB-technique, the cranial subdivisions contain large amounts of sulphated proteoglycans that decrease in the caudal direction. Carboxylated proteglycans appear to be present in all subdivisions examined. Electron-dense spheres of secretory granules are largely free of CB-precipitates, but stain more or less intensely with PR-C. The ultrastructure of the pars recta, and especially the “uterine portion” indicates transporting capability. The epithelial cells of the “uterus” have coated pits and a considerable amount of lysosome-like bodies.     

Morphological studies on the mouth cavity of Urodela IX. Teeth of the palate and the splenials in Siren and Pseudobranchus (Sirenidae: Amphibia)

1. Dentition, tooth structure and course of dental laminae of adult and subadult Sirenidae (Siren intermedia, S. lacertina, Pseudobranchus striatus) have been studied by light microscopy and scanning electron microscopy. 2. Splenials, vomers und palatines bear monocuspid unbladed teeth, arranged in a polystichous pattern, whereas praemaxillaries and maxillaries (so far as present) are edentate. Teeth in S. intermedia show a rough basis, which is more prominent in S. lacertina and which has break-throughs in P. striatus. This zone perhaps is homologous to a developing dividing zone typical for teeth in many “Lissamphibia”. 3. With respect to structure and organisation of dentigerous bones and teeth Sirenidae obviously possess a mosaicism of differently developed larval characters in their mouth cavity. 4. The dentition in the recent forms investigated is compared to that of other paedomorphic Urodela und the ancient Habrosaurus dilatus (Sirenidae).     

Fine structural and enzymehistochemical observations on the notochord of Ichthyophis glutinosus and Ichthyophis kohtaoensis (Gymnophiona,Amphibia)

Summary The notochord of Ichthyophis glutinosus and I. kohtaoensis consists of peripheral flattened cells characterized by a well-developed system of rough endoplasmic reticulum, bundles of tonofilaments, and abundant glycogen particles. These cells contain furthermore fairly high activities of -naphtyl-acetate esterase and 4-chloro-5-bromoindoxyl acetate esterase as well as acid phosphatase which was found in lysosomal localization. The huge intracellular vacuoles of the centrally situated cells possibly originate from electron translucent spaces within the glycogen fields of the peripheral cells.The notochord sheath consists of variously differentiated layers of collagen fibers and of an elastica externa. The diameters of the collagen fibers increase from the inner towards the outer region of the sheath. A peculiar feature of the Ichthyophis notochord sheath is a ring of mineralized collagen. The notochord of the caecilians investigated is compared with that of anurans, urodeles, and several groups of fish.Supported by the Deutsche Forschungsgemeinschaft.     

Anatomy and ultrastructure of the salivary (prosomal) glands in unfed water mite larvae Piona carnea (C.L. Koch, 1836) (Acariformes: Pionidae)

Anatomy and ultrastructure of prosomal salivary glands in the unfed water mite larvae Piona carnea (C.L. Koch, 1836) were examined using serial semi-thin sections and transmission electron microscopy. Three pairs of alveolar salivary glands shown are termed lateral, ventro-lateral and medial in accordance with their spatial position. These glands belong to the podocephalic system and are situated on the common salivary duct from back to forth in the above mentioned sequence. The arrangement of the medial glands is unusual because they are situated one after another on the medial (axial) body line, therefore they are termed anterior and posterior medial glands. The secretory duct of the anterior medial gland mostly turns right, and the duct of the posterior gland turns left. The salivary glands are located in the body cavity partly inside the gnathosoma and in the idiosoma in front of the brain (synganglion). Each gland is represented by a single acinus (alveolus) and is composed of several cone shaped secretory cells arranged around the large central (intra-acinar) cavity with the secretory duct base. The cells of all glands are filled with secretory vesicles of different electron density. The remaining cell volume is occupied by elements of rough endoplasmic reticulum, and the membrane enveloping vesicles may have ribosomes on its external surface. Large nuclei provided with large nucleoli occupy the basal cell zones. The pronounced development of the prosomal salivary glands indicates their important role in extra-oral digestion of water mite larvae.     

Immune- and enzyme histochemical characterisation of leukocyte populations within lymphoid and mucosal tissues of Atlantic halibut (Hippoglossus hippoglossus)

Leukocyte populations within the kidney, spleen, posterior intestine and gills of Atlantic halibut were investigated using a panel of histological, enzyme- and immunohistochemical methods. In the kidney and spleen, a diverse population of leukocytes was associated with the extensive network of sinusoids and larger blood vessels present in these tissues. IgM+ cells (B-cells, plasma cells and IgM-bearing macrophages) and large mononuclear cells showing reactivity for non-specific esterase (NSE) and acid phosphatase (ACP), representing macrophage populations, were often associated with vessel walls that were also the site of trapping of fluorescent microspheres. In the kidney, trapping of 0.1 and 0.5 microm diameter microspheres occurred at these sites but in the spleen, the 0.1 microm diameter microspheres were retained in ellipsoids. The lymphoid tissues of the kidney and spleen possessed a spread population of 5'-nucleotidase+ (5'N+) cells but compartmentalisation of the splenic white pulp was suggested by an absence of these 5'N+ reticular cells in areas associated with melanomacrophage accumulations and in areas rich in IgM+ cells. A striking feature of the mucosal tissues was the diversity of leukocyte populations within the epithelium particularly of the posterior intestine, including IgM+ cells and NSE+, ACP+ and 5'N+ mononuclear cells. Although limited in numbers in the posterior intestine, IgM+ cells were more common in the epithelium than in the lamina propria. In the gills, leukocytes as detected by enzymatic reactivity were scarce, but IgM+ cells were very abundant in the stratified epithelium of the gill arch and filaments. The difference in distribution of these leukocyte populations between the intestines and gills suggested a compartmentalisation of the mucosal immune system and the need to assess the immunological competence of mucosal tissues in Atlantic halibut.     

A histochemical study of the secretions of reproductive glands and of the egg envelopes of Achatina fulica (Pulmonata: Stylommatophora)

Histochemical investigations of the secretions of reproductive glands—albumen gland, apical uterus, basal uterus and prostate gland—indicate the presence of galactogen in the albumen gland, acid mucopolysaccharide in the apical uterus, and lipoprotein in the basal uterus and prostate gland of A. fulica. The proteinaceous secretions produced by the glands do differ in their terminal reactive sites. Intense alkaline phosphatase reaction is found in albumen gland and apical uterus; carbonic anhydrase activity could be detected mainly in the uterine glands. The cyclical secretory activity of the reproductive glands has been studied preparatory to egg-laying and in the spent phase. Histochemical characteristics of the egg envelopes—albumen, shell membrane and egg-shell—suggest a possible sequential deposition of glandular products during the descent of eggs through the repv. ductive tract. The factors contributing to the stability and resistant nature of the egg envelopes, and the possible role of nutritive materials contained in reproductive gland secretions in the development of the embryo (even while the eggs are inside the uterus), are discussed.     

Histological and histochemical observations on the neurosecretory cells in the diencephalon of Chthonerpeton indistinctum and Ichthyophis paucisulcus (Gymnophiona,Amphibia)

Summary In the diencephalon of two species of Gymnophiona (Amphibia) two neurosecretory nuclei were examined with histological (Alcian Blue, Aldehyde Fuchsin, Brookes Trichrome stain) and enzyme histochemical techniques (acid phosphatase, -naphthyl acetate esterase, acetylcholinesterase (AChE)). In the preoptic nucleus two categories of secretory neurons were distinguished: large and medium sized neurons. The perikarya of both cell types contain very little neurosecretory material. The Alcian Blue method stained the medium sized neurons faintly but selectively. The tractus praeopticohypophyseus is marked by the presence of Herring bodies, which, however, are relatively scarce. The neurohypophysis, in contrast, contains large amounts of neurosecretory material. Both cell types of the preoptic nucleus are characterized by their very strong AChE and -naphthylacetate esterase activity. The AChE also marks the tractus praeoptico-hypophyseus. In the large neurons acid phosphatase is present around the nucleus; in the medium sized neurons this enzyme is concentrated close to the origin of the axon. In the dorso-caudal hypothalamus a small group of neurons is stained with Alcian-Blue. These neurons, which also contain AChE, are located immediately under the ependyma which seems to be specialized in this region.The financial support of the Deutsche Forschungsgemeinschaft is gratefully acknowledged (We 380/5)     

SEM observations on polar body elimination and changes of the oocyte surface during egg maturation in the newt Triturus alpestris (Amphibia,Urodela)

Summary We have studied the surface of the animal half of ovulated newt eggs recovered from different portions of the oviduct. The germinative area, about 40 m diameter, is localized in the region of the whitish polar spot, about 450 m diameter. The structural changes in the germinative area are connected with the formation and extrusion of the first and second polar bodies. Of the two types of oviductal eggs observed, those covered with microvilli (type 1) were found only in the ostial portions of the oviduct, whilst those covered with microfolds (type 11) were found more distally. The structural difference between these two types may be related to the known reduction in surface area of the cell membrane during oocyte maturation. Offprint requests to: W. Kilarski     

Hygrobates salamandrarum sp. nov. (Acari, Hydrachnidia, Hygrobatidae) from China: the First Record of a Freshwater Mite Parasitizing Newts (Amphibia, Urodela)

Females of a new water mite species of the genus Hygrobates (Acari, Hydrachnidia, Hygrobatidae) were found to parasitize Pachytriton labiatus (Unterstein, 1930) (Amphibia, Salamandridae), a newt species from S China. Obviously, their particularly modified mouthparts are an adaptation for penetrating the amphibian skin. These data provide the first record of an adult water mite parasitizing a vertebrate host.     

Histological and enzyme histochemical changes in the kidney of male bullhead (Cottus gobio) during the spawning period

Histological and enzyme histochemical studies were carried out on the excretory kidney of the male bullhead ( Cottus gobio ). During the spawning season striking morphofunctional changes were observed in the second proximal segment of the kidney tubule. The tubular epithelium was greatly hypertrophied, strongly basophilic and produced a PAS-positive secretion. The enzyme histochemical pattern also changed conspicuously during this time: the alkaline phosphatase activity in the brush border was greatly reduced; the acid phosphatase and non-specific esterase activity in the cytoplasm was distinctly elevated.     

Morphological and functional aspects of the arrangement of connective tissue and muscle fibres in the tail of the Mexican axolotl, Siredon mexicanum (Shaw) (Amphibia, Urodela).

In the lateral musculature of the axolotl tail a multipennate arrangement of muscle fibres is found in the 3rd postanal myomere and all following myomeres. This arrangement appears in larval stages as soon as the myomeres concerned are fully differentiated. Within a myomere a uniform degree of contraction of the muscle fibres may be achieved either by helical arrangement as seen in Teleosts, by diminishing fibre length in medial direction or by a combination of both phenomena. The relation between muscle fibre length and angle of insertion in the myomeres showing pennate arrangement is approximated by the Benninghoff and Roll-h?user equation but the values recorded deviated systematically from the values calculated. In the rather slender tail of the axolotl the transition from the helical or parallel fibre system into the pennate arrangement will be in favour of the development of relatively strong bending moments in the region concerned while a reasonable uniformity of the rate of contraction is maintained.     

Ultrastructural and histochemical observations on the tegument of Gastrodiscoides hominis (Paramphistoma: Digenea)

The tegument of the paramphistome, Gastrodiscoides hominis, is basically similar to that of other digeneans. It is folded into concentrically arranged furrows and ridges bearing numerous tightly packed tubercules, and extends into the oral cavity. An area of specialized tegument is present on the ventral surface, anterior to the disc region. Mitochondria are absent from the tegumental syncytium and underlying tegumental cells, suggesting that the tegument may serve principally as a protective layer rather than in active uptake phenomena. However, extensions of the lymph and parenchyma systems are closely associated with the base of the tegumental syncytium and may provide ATP for active processes. Ciliated and non-ciliated sensory papillae are present, particularly around the oral opening. Numerous lymph channels are present in the sub-tegument and may be involved in osmoregulation.     

Distribution of catecholaminergic and serotoninergic systems in forebrain and midbrain of the newt,Triturus alpestris (Urodela)

Summary Mapping of monoaminergic systems in the brain of the newt Triturus alpestris was achieved with antisera against (1) thyrosine hydroxylase (TH), (2) formaldehyde-conjugated dopamine (DA), and (3) formaldehyde-conjugated serotonin (5-HT). In the telencephalon, the striatum was densely innervated by a large number of 5-HT-, DA-and TH-immunoreactive (IR) fibers; IR fibers were more scattered in the amygdala, the medial and lateral forebrain bundles, and the anterior commissure. In the anterior and medial diencephalon, TH-IR perikarya contacting the cerebrospinal fluid (CSF-C perikarya) were located in the preoptic recess organ (PRO), the organum vasculosum laminae terminalis and the suprachiasmatic nucleus. Numerous TH-IR perikarya, not contacting the CSF, were present in the posterior preoptic nucleus and the ventral thalamus. At this level, DA-IR CSF-C neurons were only located in the PRO. In the posterior diencephalon, large populations of 5-HT-IR and DA-IR CSF-C perikarya were found in the paraventricular organ (PVO) and the nucleus infundibularis dorsalis (NID); the dorsal part of the NID additionally presented TH-IR CSF-C perikarya. Most regions of the diencephalon showed an intense monoaminergic innervation. In addition, numerous TH-IR, DA-IR and 5-HT-IR fibers, orginating from the anterior and posterior hypothalamic nuclei, extended ventrally and reached the median eminence and the pars intermedia of the pituitary gland. In the midbrain, TH-IR perikarya were located dorsally in the pretectal area. Ventrally, a large group of TH-IR cell bodies and some weakly stained DA-IR and 5-HT-IR neurons were observed in the posterior tuberculum. No dopaminergic system equivalent to the substantia nigra was revealed. The possible significance of the differences in the distribution of TH-IR and DA-IR neurons is discussed, with special reference to the CSF-C neurons.Abbreviations AM amygdala - CAnt commissura anterior - CH commissura hippocampi - CP commissura posterior - Ctm commissura tecti mesencephali - DH dorsal hypothalamus - DTh dorsal thalamus - FLM fasciculus longitudinalis medialis - Fsol fasciculus solitarius - H habenula - LFB lateral forebrain bundle - ME median eminence - MFB medial forebrain bundle - NID nucleus infundibularis dorsalis - nIP neuropil of nucleus interpeduncularis - NPOP nucleus preopticus posterior - NS nucleus septi - OVLT organum vasculosum laminae terminalis - PD pars distalis - Pdo dorsal pallium - PHi primordium hippocampi - PI pars intermedia - Pl lateral pallium - PN pars nervosa - PRO preoptic recess organ - Ptec pretectal area - PVO paraventricular organ - Ra nucleus raphe - Rm nucleus reticularis medius - SCO subcommisural organ - ST striatum; strm stria medullaris thalami - strt stria terminalis thalami - TM tegmentum mesencephali - TO tectum opticum - TP tuberculum posterius - trch tractus cortico-habenularis - trmp tractus mamillopeduncularis - VH ventral hypothalamus - Vm nucleus motorius nervi trigemini - VTh ventral thalamus - II optic nerve     

Ultrastructural and histochemical observations on the tegument of Gastrodiscoides hominis (Paramphistoma: Digenea).

The tegument of the paramphistome, Gastrodiscoides hominis, is basically similar to that of other digeneans. It is folded into concentrically arranged furrows and ridges bearing numerous tightly packed tubercules, and extends into the oral cavity. An area of specialized tegument is present on the ventral surface, anterior to the disc region. Mitochondria are absent from the tegumental syncytium and underlying tegumental cells, suggesting that the tegument may serve principally as a protective layer rather than in active uptake phenomena. However, extensions of the lymph and parenchyma systems are closely associated with the base of the tegumental syncytium and may provide ATP for active processes. Ciliated and non-ciliated sensory papillae are present, particularly around the oral opening. Numerous lymph channels are present in the sub-tegument and may be involved in osmoregulation.     

Observations on morphology and hydrolytic enzyme histochemistry of excysted metacercariae of Himasthla rhigedana (Trematoda: Echinostomatidae)

The morphology of in vitro excysted metacercariae of Himasthia rhigedana was studied by light microscopy, enzyme histochemistry, and scanning electron microscopy (SEM). The body surface is covered with longitudinal rows of pointed spines which extend from the anterior end to just below the acetabulum. Histochemical methods for acid and alkaline phosphatases, β-glucoronidasc, leucine aminopeplidase, nonspecific esterase, acetylcholinesterase, butyrylcholincsterase, chymotrypsin-like protease, α-galactosidase and β-galactosidase were applied to the excysted metacercariae. Certain systems of the metacercaria containing these enzymes showed positive reactions to the appropriate methods and were selectively visualized. Reactions for alkaline phosphatase occur throughout most of the excretory system while acid phosphatase occurs in the gut, oral, and ventral suckers. Reactions for nonspecific esterases and cholinesterascs are found throughout the nervous system, in the gut, and in the oral and ventral suckers. The results of including specific inhibitors or activators in the incubation medium after preineubation m 10^?5m diethyl p-nitrophenyl phosphate (E-600) suggested that A-and C-typc esterases are present in the gut. Inclusion of 10^?4m eserine in the incubation medium abolished cholinesterase activity in the nervous system.     

Further freeze-fracture studies on the uterine epithelium of Salamandra salamandra (L.) (Amphibia,Urodela) using the antibiotic filipin

Summary The apical portion of the uterine lining of the ovoviviparous fire salamander, Salamandra salamandra, was studied by the freeze-fracture technique in conjunction with the polyene antibiotic filipin. Filipin-sterol complexes were found in the luminal plasmalemma and in the membranes limiting the mucous secretory granules typical of this epithelium. In all females, but particularly in non-pregnant females, more or less discrete clusters of filipinsterol complexes were occasionally found overlying heavily affected secretory granules. The findings are discussed with regard to comparable results (Orci et al. 1980) based on the examination of collapsed and stretched urinary bladders of toads.We are indebted to Mrs. K. Ott for excellent technical assistance, to Miss E.S. MacLure for linguistic corrections and to Dr. J.E. Grady of the Upjohn Co., Kalamazoo, Michigan USA, for kindly providing the filipin