Gonadal Ducts Research Articles

Histopathologic survey of free-living populations of 2 species of freshwater mussels in Indiana.

Freshwater mussels are one of the most endangered groups of animals in Indiana, with nearly half of the native species either extirpated or listed as "state endangered" or of "special concern." Nationally, numerous freshwater mussel species are considered threatened. Freshwater mussel diseases are not well understood and few published accounts of freshwater mussel diseases with detailed histological descriptions exist. Mass mortality events within mussel populations are increasingly recognized, often with undetermined etiology. Our objective was to determine baseline histopathology in free-living populations of freshwater mussels. One-hundred twenty individual mussels representing 2 species-plain pocketbook (Lampsilis cardium) and fatmucket (Lampsilis siliquoidea)-were collected from 3 different locations within the Wildcat Creek watershed in central Indiana during June and July 2019. A cross-section through the visceral mass was obtained and immersed in 10% neutral-buffered formalin, with routine processing and hematoxylin and eosin staining. Branchial acariasis occurred in 43/60 fatmuckets and 22/60 plain pocketbooks. Infection with a bucephalid trematode was recognized in 18/60 fatmuckets, while infection of the gonadal duct with an unidentified trematode species was identified in 4/60 fatmuckets and 18/59 plain pocketbooks. Additional changes associated with unidentified trematodes, bacteria, fungi or oomycetes, and ciliates were observed. Other miscellaneous changes included mineralization, neuronal lipofuscinosis, and gonadal atrophy/atresia. A range of histological changes were observed. These changes likely represented background lesions: incidental findings, spontaneous infectious or endosymbiotic conditions, or normal physiological changes that routinely occur in free-living wild populations. Awareness of baseline lesions should inform future diagnostic investigations of mussel mortality events.

First subcellular localization of the amnesic shellfish toxin, domoic acid, in bivalve tissues: Deciphering the physiological mechanisms involved in its long-retention in the king scallop Pecten maximus

Domoic acid (DA), the phycotoxin responsible for amnesic shellfish poisoning (ASP), is an excitatory amino acid naturally produced by at least twenty-eight species of the bloom-forming marine diatoms Pseudo-nitzschia spp. Suspension feeders, such as bivalve mollusks, can accumulate and lengthy retain high amounts of DA in their tissues, threatening human health and leading to extensive-prolonged fishery closures, and severe economic losses. This is particularly problematic for the king scallop Pecten maximus, which retains high burdens of DA from months to years compared to other fast-depurator bivalves. Nonetheless, the physiological and cellular processes responsible for this retention are still unknown. In this work, for the first time, a novel immunohistochemical techniques based on the use of an anti-DA antibody was successfully developed and applied for DA-detection in bivalve tissues at a subcellular level. Our results show that in naturally contaminated P. maximus following a Pseudo-nitzschia australis outbreak, DA is visualized mainly within small membrane-bounded vesicles (1 – 2.5 µm) within the digestive gland cells, identified as autophagosomic structures by means of immune-electron microscopy, as well as in the mucus-producing cells, particularly those from gonad ducts and digestive tract. Trapping of DA in autophagososomes may be a key mechanism in the long retention of DA in scallops. These results and the development of DA-immunodetection are essential to provide a better understanding of the fate of DA, and further characterize DA contamination-decontamination kinetics in marine bivalves, as well as the main mechanisms involved in the long retention of this toxin in P. maximus.

Pathological changes by Eosinophilic Rickettsia-like organism in Japanese oyster, Crassostrea gigas

Rickettsia infection in adult Japanese oysters (Crassostrea gigas) was observed in 2015 at San Ignacio Lagoon, Baja California Sur, Mexico and characterized using molecular tools. In the present study, the degree of infection by Eosinophilic Rickettsia-Like Organism (E-RLO), characterized by intracellular inclusions in gill, mantle, labial palps, digestive tract and gonadal ducts, was evaluated using histological methods and was associated with visible injuries on body surface, such as blisters, shell damage and necrosis. Most of the oysters (92.2%) had some type of observable symptoms; 90.2% of all oysters had blisters in the mantle, and all oysters presented with E-RLO in the epithelia of at least one of the analyzed tissues (gills, labial palps, mantle, gonadal ducts and digestive tract). The highest intensity of infection (percent of E-RLO coverage) was observed in the labial palps (18.6%) and the lowest in digestive tract (2.6% of the examined tissue). Oysters with external injuries had higher infection intensities than the oysters without external injuries. Considering the clinical signs (observable symptoms and histological findings), we propose three infective stages of E-RLO disease development, a scale that could be used for early detection.

Effect of triclosan on anuran development and growth in a larval amphibian growth and development assay.

A larval amphibian growth and development assay was performed to evaluate the potential effects of environmentally-relevant concentrations of triclosan (TCS) on amphibian development and growth. Xenopus laevis were exposed to TCS 0.0 (control), 6.3, 12.5 and 25.0 μg l-1 (estimated maximum tolerable concentration) until 10 weeks post-metamorphosis. At median metamorphosis time (Nieuwkoop and Faber stage 62), five larvae per replicate were collected for snout-vent length, hind limb length and body weight measurements, and histopathological examination of thyroid glands. Endpoints evaluated at test termination were based on draft guidance (USEPA, ) and included: survival; snout-vent length; body weight; gender; nuptial pad development (males); and liver, kidney, gonad and gonadal ducts histopathology. Exposure to TCS did not decrease survival, induce general signs of toxicity, affect median metamorphosis time or alter sex ratios. Exposure to TCS 12.5 and 25 μg l-1 increased growth during the metamorphic stages relative to the control, but did not influence growth during the post-metamorphic phase. Overall, several statistically significant findings were found in larvae exposed to TCS, such as a decrease in the prevalence of stage 3 Müllerian ducts in the anterior trunk sections of TCS 25.0 μg l-1 dose group females as compared to controls; most were not considered toxicologically relevant. Copyright © 2017 John Wiley & Sons, Ltd.

Early gametogenesis in the Pacific oyster: new insights using stem cell and mitotic markers.

While our knowledge of bivalve gametogenesis has progressed in recent times, more molecular markers are needed in order to develop tissue imaging. Here, we identified stem cell and mitotic markers to further characterize oyster early gametogenesis, mainly through immunofluorescence microscopy. Intense alkaline phosphatase activity, a non-specific marker for stem cells, was detected on the outer edge of the gonad ducts at the post-spawning stage, suggesting an abundance of undifferentiated cells very early during the sexual cycle. This observation was confirmed using an antibody against Sox2, a transcription factor specific for stem or germline cells, which labeled cells in the gonad duct inner mass and ciliated epithelium early during the initial oyster sexual cycle. Moreover, Vasa, a cytoplasmic marker for germline cells, was also detected in the gonad acini and duct cells, thus confirming that germline cells were abundant early on. In addition, the binding of the minichromosome maintenance MCM6 protein to chromatin indicated the gonad acini and duct cells were engaged in the cell cycle. DNA replication was indeed confirmed by an abundant in vivo incorporation of BrdU into the duct cell chromatin. Finally, proliferation of acini and duct cells was demonstrated by the chromatin-bound Ser10-phosphorylated histone H3, a mitotic marker. The markers for the cell cycle and mitosis used here thus indicate that acini and duct cells were already actively dividing early during the oyster sexual cycle. In addition, together with the stem cell markers, these data reveal that the epithelium delimiting the duct outer edge contains a dynamic population of undifferentiated cells.

Androgen receptors in the bonnethead, Sphyrna tiburo: cDNA cloning and tissue-specific expression in the male reproductive tract

As demonstrated in past studies, androgens appear to play critical roles in regulating reproduction in male sharks. However, little is known about the cell-specific actions of androgens in these fishes. To address this, this study examined androgen targets in reproductive organs of a seasonally reproducing shark, the bonnethead (Sphyrna tiburo). A partial bonnethead AR cDNA clone was isolated and found to exhibit strong homology with known vertebrate ARs. Using RT-PCR and in situ hybridization, AR was found to be expressed in multiple cell types in the male bonnethead testis (premeiotic germ cells, Leydig-like interstitial cells, Sertoli cells, peritubular myoid cells, and mature spermatozoa) and gonadal ducts (stromal cells, luminal epithelial cells, mature spermatozoa). Furthermore, AR expression in these organs was found to vary temporally in relation to the seasonal reproductive cycle. Based on immunocytochemistry, the presence of AR protein in male bonnethead reproductive organs was largely consistent with patterns of AR gene expression with the single exception of mature spermatozoa, which exhibited consistently strong mRNA expression but only inconsistent and weak AR protein immunoreactivity. These results suggest important roles for androgens in regulating germ cell proliferation, hormone production, spermatid elongation, spermiation, and gonadal duct function in male bonnetheads. In addition, high abundance of AR mRNA in bonnethead spermatozoa suggest the potential for de novo protein synthesis following spermiation/copulation and/or a role for AR mRNA in early embryonic development, both of which have been proposed to explain the occurrence of mRNA transcripts in spermatozoa from various vertebrates.

Insights into Molecular Features of Venerupis decussata Oocytes: A Microarray-Based Study

The production of Venerupis decussata relies on wild seed collection, which has been recently compromised due to recruitment failure and severe mortalities. To address this issue and provide an alternative source of seed, artificial spawning and larval rearing programs were developed. However, hatchery-based seed production is a relatively new industry and it is still underdeveloped. A major hurdle in the European clam seed production is the control of spawning and reproduction, which is further hindered by the impossibility of obtaining fertile gametes by gonadal “stripping”, as meiosis re-initiation is constrained to a maturation process along the genital ducts. In the present study, oocytes were collected from 15 females and microarray analyses was performed to investigate gene expression profiles characterizing released and stripped ovarian oocytes. A total of 198 differentially expressed transcripts between stripped and spawned oocytes were detected. Functional analysis carried out on these transcripts highlighted the importance of a few biological processes, which are most probably implicated in the control of oocyte competence. Significant differences were observed for transcripts encoding proteins involved in meiosis progression (e.g. dual specificity phosphatase CDC25), WNT signalling (e.g. frizzled class receptor 8, wingless-type MMTV integration site family member 4), steroid synthesis (e.g. progestin and adipoQ receptor family member 3, cytochrome P450-C17), mRNA processing (e.g. zinc finger protein XlCOF28), calcium regulation (e.g. regucalcin, calmodulin) and ceramide metabolism (ceramidase B, sphingomyelinase). This study provides new information on transcriptional profiles putatively associated with ovarian egg infertility, and suggests potential mechanisms regulating early oocyte development in clams. Genes which were differentially expressed between stripped and spawned oocytes might have a pivotal role during maturation process in the gonadal duct and could be interesting targets for further functional studies aiming to make ovarian oocytes fertilizable.

Retrograde positive contrast urethrocystography of the fish urogenital system.

The radiological differences between the urinary tract of Dicentrarchus labrax, Sparus aurata, Tinca tinca, and Cyprinus carpio are shown. In fresh water teleosts the urinary bladder is sigmoid and a short urethra leads to the urinary pore. Genital and anal pores are present. In Sparus aurata the urinary bladder has a globoid shape. In Dicentrarchus labrax the urinary bladder is smaller and elongate. In both marine teleosts a single urogenital pore is visible. Positive contrast was used to survey the urogenital system and evaluate shape and size of the bladder, urethra, ureter, and gonadal ducts. Results demonstrate the morphological variability of the urinary bladder and the craniodorsal entry of the ureters into the bladder. It is envisaged that this work will provide baseline information for further imaging studies for investigating the urogenital morphology and can be applied to identify disorders in fishes. Furthermore, the main interest of this study is that it demonstrates the morphological variability of the lower urinary system that exists between different species of fishes.

High Prevalence of Proposed Müllerian Duct Remnant Cysts on the Spermatic Duct in Wild Eurasian Otters (Lutra lutra) from Sweden

The spermatic ducts (vasa deferentia) of 235 otters (Lutra lutra) found dead between 1999 and 2012 in Sweden were examined for presence of paraductular cysts. Single or multiple elongated uni- or bilateral cysts parallel to the spermatic duct were noted in 72% of the examined males. The cysts were adjacent to, but did not communicate with the lumen of the spermatic duct, and were usually located within a few centimeters of the testis and epididymis. The cysts are proposed to be congenital Müllerian duct remnants. Other morphologic abnormalities in the reproductive organs were not noted within this study. Possible causes of the incomplete regression of the embryonic female gonadal duct are exposure to environmental contaminants such as elevated concentrations of estrogen-like compounds (endocrine disrupting chemicals), inbreeding, or a naturally occurring anatomic defect. No obvious geographical pattern was observed for otters with or without cysts. This is the first study and description of cysts on the spermatic duct in otters.

A new species of Hemiphyllodactylus (Reptilia: Gekkonidae) from northern Vietnam.

We describe a new species of the genus Hemiphyllodactylus on the basis of four specimens from Cao Bang Province, northern Vietnam. Hemiphyllodactylus zugi sp. nov. is distinguished from the remaining congeners by a combination of the following characters: a bisexual taxon; average SVL of adult males 41 mm, of adult female 46.6 mm; chin scales bordering mental and first infralabial distinctly enlarged; digital lamellae formulae 3-4-4-4 (forefoot) and 4-5-5-5 (hindfoot); femoral and precloacal pore series continuous, 18-21 in total in males, absent in female; cloacal spur single in males; dorsal trunk pattern of dark brown irregular transverse bands; dark lateral head stripe indistinct; upper zone of flank with a series of large light spots, edged above and below in dark grey; caecum and gonadal ducts unpigmented.

Selfing in a malacostracan crustacean: why a tanaidacean but not decapods

The crustacean class Malacostraca, with over 22,000 species, includes commercially important members, such as crabs, shrimps, and lobsters. A few simultaneous hermaphrodites are known in this group, but self-fertilization was unknown. Here we show, through microscopy and breeding experiments, that the simultaneously hermaphroditic malacostracan Apseudes sp. (order Tanaidacea) can self-fertilize; individuals reared in isolation become hermaphroditic via a male-like phase and produce eggs that develop into fertile adults. Although selfing occurs in crustaceans like the Branchiopoda, in which simultaneous hermaphrodites have the sex ducts united, in decapods the separation of gonadal ducts and gonopores, specialized mating organs, and complex mating behavior appear to have constrained the evolution of selfing. In contrast, in most tanaidaceans, sperm is released externally by a male and reaches the eggs in the female brood pouch, where fertilization occurs. This mode of fertilization permitted Apseudes sp. to achieve selfing without large modifications in morphology or behavior.

A re-evaluation of morphological characters of the invasive ascidian Corella eumyota reveals two different species at the tip of South America and in the South Shetland Islands, Antarctica

The native solitary ascidian Corella eumyota Traustedt, 1882) is commonly found in the Southern Hemisphere in the cold-temperate waters of the Subantarctic and Antarctic regions. Its recent spread into the Northern Hemisphere throughout the NE Atlantic gave the species the status of invasive. Together with its widespread distribution, reports on its wide variability (several distinct morphological characters, genetic discontinuities and also possible misidentifications) cast doubt on the taxonomic status of different populations of this species. This work, based on the observation, quantification and analysis of specific morphological characters in specimens collected at five different localities of South America and Antarctica, strongly indicates that there are two different species: C. eumyota from South America and Corella antarctica Sluiter, 1905) from Antarctica, which has been till now considered a junior synonym of the former. The species clearly differ in the arrangement of the gonadal ducts, the size of the larvae and the shape of the anus, among other characters. Morphological variation displays a defined, discrete grouping supporting a clear differentiation into two species. This result shows the need for careful inspection of specimens to avoid wrong interpretations in a context of changes of marine biota due to biological invasions.

Checklist for the Structural Description of the Deep Phenotype in Disorders of Sexual Development

This paper addresses the question, how the variations of the deep phenotype in disorders of sex development (DSD) are appropriately described. This is a relevant question, because extensive phenotypic variability occurs in gonads and sex ducts. With the advance of video endoscopy and laparoscopy, fresh insight in gonadal and sex duct anatomy is emerging. So far, an attempt to standardize the diagnostic approach and, in particular, how to document these findings has not been published. We propose a standardized examination schedule for these procedures. It consists of 5 pictures of relevant anatomic features. For laparoscopy, it includes two pictures each of gonads and sex ducts on either side and an image of the retrovesical space. For endoscopy, the examination of the ureteric orifices, the posterior urethra, and the urogenital sinus derivates is recommended. Adherence of a standardized schedule and image storing enhances patient autonomy, because they can carry their examination for a second opinion without need for repeated examination. Physicians and scientists create a structured image library that facilitates the comparison of clinical outcomes, research on genotype phenotype associations and may lead to better classifications.

Autonomic control of the urogenital tract

The urogenital tract houses many of the organs that play a major role in homeostasis, in particular those that control water and salt balance, and reproductive function. This review focuses on the anatomical and functional innervation of the kidneys, urinary ducts and bladders of the urinary system, and the gonads, gonadal ducts, and intromittent organs of the reproductive tract. The literature, especially in recent years, is overwhelmingly skewed toward the situation in mammals. Nevertheless, where specific neurochemical markers have been investigated, common patterns of innervation can be found in representatives from most vertebrate classes. Not surprisingly the vasculature, epithelia and smooth muscle of all urogenital organs receives adrenergic innervation. These nerves may contain non-adrenergic non-cholinergic (NANC) neurotransmitters such as ATP and NPY. Cholinergic nerves increase motility in most urogenital organs with the exception of the kidney. The major NANC nerves found to influence urogenital organs include those containing VIP/PACAP, galanin and neuronal nitric oxide synthase. These can be found associated with both smooth muscle and epithelia. The role these nerves play, and the circumstances where they are activated are for the most part unknown.

Sexual reproduction in Chondrilla australiensis (Porifera:Demospongiae)

Increasingly, sponges are being used as models for a wide range of biological systems. However, little is known about the reproductive biology of a group that has been shown to lack gonads or gonadal ducts. The development of gametes in the oviparous demosponge Chondrilla australiensis at Fremantle, Western Australia, was investigated using light microscopy and transmission electron microscopy over 5 years. Results indicate that C. australiensis is gonochoric and oviparous. Egg and sperm development were first apparent inside choanocyte chambers, with both types of gamete apparently developing from choanocytes. During egg development, large numbers of nurse cells appeared attached to eggs, with which they fused at the time of spawning. The origin of the nurse cells remains unclear, but they may also have a choanocyte origin. Eggs took 4 weeks to develop and sperm took approximately 2 weeks, during which time the nucleus condensed and the cytoplasm reduced. Mature sperm could occupy almost the entire matrix of fecund males and were not contained in cysts. Spawning occurred in late summer and autumn over a period of 4–5 days, when the tides were at the maximum height for the month.

Histological characterization of the spawning process in the catarina scallop, Argopecten ventricosus (Sowerby II, 1842) induced by thermal shock and serotonin injection

Summary The histology of the spawning catarina scallop Argopecten ventricosus was studied to characterize cellular and anatomical changes occurring along the gonad-kidney pathway. Broodstock were conditioned for 25–30 days and induced to spawn with two methods: thermal shock and serotonin by intracardiac injection. Samples of the kidney-gonad-digestive gland complex were fixed at the sperm and oocyte stages of gamete emission and at the end of spawning. Both induction methods elicited gametes, and no particular difference in the microscopic anatomy of the acini-kidney pathway was detected. However, serotonin injection, apart from producing a rough valve opening, sporadic movement (opening and closure of valve), and pronounced foot extension, induced gamete emission in less time than thermal shock. Primary gonad ducts opened to acini to permit sperm emission; at the same time, germinal vesicles broke down in female acini and meiosis restarted. Shortly afterward, oocytes gradually changed form from typically poly-hedral to a more malleable form. This probably contributed to oocyte transport through ciliary activity along the gonad and kidney ducts. Nucleoli disintegration, chromosome condensation, and appearance of meiotic figures were observed along the acini-kidney pathway. Although sperm and oocytes were sometimes observed in gonad or kidney ducts, self-fertilization was rarely observed.

Exposure of juvenile roach (Rutilus rutilus) to treated sewage effluent induces dose-dependent and persistent disruption in gonadal duct development.

Wild roach (Rutilus rutilus) have been found with intersex gonads in rivers throughout the United Kingdom. The incidence of intersexuality is strongly correlated with discharges of estrogenic treated sewage effluent into those rivers, and this has led to the hypothesis that estrogenic chemicals in effluents are feminizing wild male fish. In this study, early-life stage roach (50 days post hatch, dph) were exposed for 150 days to a graded concentration (0%, 12.5%, 25%, 50%, and 100%) of treated sewage (primarily domestic) effluent to examine the effects of exposure on sexual differentiation and development. Measurement of steroid estrogens and alkylphenolic chemicals in the effluent and a resulting dose-dependent induction of vitellogenin (VTG; a female-specific, estrogen-dependent plasma protein) confirmed that the fish had been exposed and responded to "estrogen" in the effluent. Exposure to treated sewage effluent induced feminization of the reproductive ducts in "male" roach in a dose-dependent manner (in full-strength effluent, 100% of the fish had feminized ducts), indicating that the disruption of the gonad ducts seen in wild roach is the result of exposure to treated sewage effluents during early-life stages. There were no effects of treated sewage effluent exposure on germ cell development; therefore, no oocytes occurred in the testes of the feminized male roach. Subsequent, depuration of the effluent exposed fish in "clean" water for 150 days resulted in a reduction in plasma VTG but no alteration of the feminized ducts, indicating that the effect of the treated sewage effluent on reproductive duct development was permanent. The causality of oocytes in the testes of wild male roach therefore remains to be elucidated.

Gonadal cysts in spotted gar ( Lepisosteus oculatus) from Bayou Trepagnier, Louisiana, USA

Gonadal cysts of spotted gar ( Lepisosteus oculatus), an air-breathing teleost commonly found in Louisiana waters, are described. Fish were collected from two sites: Bayou Trepagnier, a petroleum-contaminated site (30 males and 42 females), and Bayou Traverse, a control site (17 males and 15 females). After fish were evaluated for gross abnormalities, they were necropsied and the gonads, gonadal ducts, and gonadal cysts were evaluated histologically. Multilocular fluid-filled cysts were noted in the testes, or spermatic ducts of four spotted gars from the Bayou Trepagnier. Unilateral ovarian cystadenomas were present in one female from Bayou Trepagnier. No cysts were observed in the gonads of spotted gar from the control site.

Origin and formation of eggshell in Limnadia lenticularis (Linnaeus, 1761), Crustacea, Branchiopoda, Conchostraca

Summary We studied the structure of the walls of the central gonadal duct in Limnadia lenticularis, the structures responsible for eggshell formation. The longitudinal duct wall is made of a single layer of somatic glandular cells, mixed with female germ cells. The material forming up the shell was produced within a system of vesicles derived from the nuclear membrane and then transported to the lumen's surface and released in the form of drop-like secretions that came together gradually in a mass that would eventually fill the gonad. We then studied eggshell maturation in newly spawned and mature eggs and observed it through its various transformations until they reached their definitive shape, that of so-called “twisted” eggs. We compared data on ultrastructure, obtained from comparison of the eggshell in Limnadia with those from other Branchiopods as Triops and the Leptestheriidae, and from the results we concluded that eggshell resistance in the Branchiopods we observed is correlated to the species reproductive strategies.

Anatomical Description of Anctus angiostomus (Wagner, 1827) from Northeastern Bahia, Brazil (Gastropoda, Pulmonata, Bulimulidae)

Anctus angiostomus (Wagner, 1827) is herein described anatomically, based on material collected at Queimadas, BA, caatinga habitat. This species is characterized by closed primary and secondary ureters; salivary glands distant from the buccal bulb; a poorly developed stomac h; a characteristic mode of emergence of the gonad duct from the annexe glandular sac; very long spermoviduct; a short oviduct and vagina; very long and slender penis and epiphallus and a long flagellum with retractor muscle in the tip.