Outer Circular Layer Research Articles

Muscle system of the penial complex in three species of Hygrophila (Gastropoda: Pulmonata)

The Hygrophila, a group comprising freshwater lung-bearing gastropods, have a complex copulatory apparatus, whose musculature has recently been shown to provide a number of phylogenetically informative characters that appear to concur with the results of molecular phylogenetic analyses. The number of hygrophilan species for which the male copulatory musculature is known, however, is still relatively small. We examined the muscle arrangement in the penial complex (penis and penis sheath) of three species of Hygrophila: Aplexa hypnorum (Linnaeus, 1758) (fam. Physidae), Kolhymorbis bogatovi Zatravkin et Moskvicheva, 1985 (fam. Planorbidae, tribe Segmentinini), and Planorbarius corneus (Linnaeus, 1758) (fam. Planorbidae, tribe Helisomatini) to explore whether the organization of the male copulatory musculature in these species is consistent with the previously proposed phylogenetic hypotheses. In A. hypnorum, the primarily glandular penis sheath has a three-layered musculature with outer and inner circular and intermediate longitudinal layers. The tubular penis also has a three-layered musculature, with the same sequence of muscle fibers as in the penis sheath. In K. bogatovi, the sequence of muscle layers in the penis sheath is essentially the same as in A. hypnorum. Penial musculature is also arranged in three layers, but the intermediate layer consists of small radial, rather than longitudinal fibers and the inner and outer layers are circular. In P. corneus, the boundaries between muscle layers in both penis and penis sheath are somewhat indistinct, but the circular muscles tend to lie close to their outer and inner walls, while the longitudinal fibers are concentrated in the interior. The comparison with other hygrophilan species, in which the copulatory musculature has been previously studied, shows that the male copulatory musculature of K. bogatovi is consistent in arrangement with that of other representatives of Segmentinini and that the phylogenetic lineage leading to P. corneus has probably diverged before the clade Planorbini + Segmentinini. The musculature of the penial complex of A. hypnorum is generally similar to that of another physid, Physella acuta (Draparnaud, 1805), but the penis sheath of P. acuta lacks an outer layer of circular muscle fibers, which may be explained by reduction.

Histochemical study of proventriculus in pre-hatch and post-hatch days in northern bobwhite quail (Colinus virginianus)

The present study was designed to investigate the histochemical developmental changes of the proventriculus at pre-hatching and post-hatching in the northern bobwhite quail at periods 11- and 15-days pre-hatching in addition to 14- and 21-days post-hatching. The proventriculus composed of four tunics is tunica mucosa, tunica sub-mucosa, tunica muscularis, and tunica serosa. The tunica mucosa was lined with simple columnar epithelium and the height of epithelium increases with the age also the thickness of the mucosa, the tunica submucosa filled with proventricular glands at 14- and 21-day post-hatch and the gland was height in diameters while in 11- and 15-day pre-hatch the gland less in diameter and the sub mucosa does not fill with the gland. Tunica muscularis was thicker in post-hatch than in pre-hatch, 11- and 15- day pre-hatch composed of a thin inner circular layer and thick outer longitudinal layer but in 14- and 21-day post-hatch the tunica muscularis was composed of a thin inner and outer circular layer and thick middle longitudinal layer. The mucosa and proventriculus glands give a positive reaction for Alcian blue stain and a weak to moderate reaction for periodic acid Schiff stain at pre-hatch, while at post-hatch the mucosa gives a positive reaction for Alcian blue stain and a negative reaction for periodic acid Schiff stain and the proventricular glands give a positive reaction for Alcian blue and periodic acid Schiff stains.

Histomorphological and Histochemical Studies on Proventriculus in Guinea Fowl (Numida meleagris)

Background: The proventriculus, component of digestive system of bird secretes hydrochloric acid and pepsinogen which helps the churning of food material that takes place in ventriculus. Pepsinogen produces pepsin and it smashes the peptide bonds of amino acid of food material. Methods: The twelve proventriculus samples of Guinea fowl birds were fixed in 10% neutral buffered formalin and Bouin’s fluid for histological procedure while chilled acetone and chilled ethanol were used as the fixatives for histochemical studies. The fresh unfixed samples were used on cryostat for studies of succinic dehydrogenase enzyme.Result: Histomorphologically the proventriculus of Guinea fowl was observed as the typical tubular component with four tunics from inside to outside as tunica mucosa, tunica sub mucosa, tunica muscularis and tunica serosa. The submucosal layer comprised with proventricular submucosal gland (PVSMG) which was encapsulated by elastic fibers. Tunica muscularis was inner longitudinal and outer circular layer, while the tunica serosa was observed with surrounding adipose tissue as the connective tissue constituent to endow the access of nutritional supply in the form of blood vessels. The luminal surface of proventricular submucosal glands has shown the significant activity of glycogen while intercalated, intralobular and interlobular ducts have exhibited the weak activity towards the same. The glandular cell rod of PVSMG, serosal layer and adjoining connective tissue with blood vessels has exhibited very weak activity of alkaline phosphatase. Mucosal folds and lumen of PVSMG has shown the weak activity of acidic phosphatase but the serosal limiting membrane has shown very weak activity. The succinic dehydrogenase activity was seen in the connective tissue septa of submucosal glandular cellular rods and the intense activity was observed at tunica muscularis.

Isotopic geochemical characteristics of two types of carbonate concretions of Chang 7 member in the middle-upper Triassic Yanchang Formation, Ordos Basin, Central China

Abstract Carbonate concretion is an authigenic aggregation of minerals commonly found in sandstone and shale, especially in organic-rich shale. In the outcrop, large number of carbonate concretions developed in Chang 7 member in Tongchuan. Those concretions were studied in terms of stable isotope, clumped isotope to delineate its origin and sedimentary environment. Two types of concretions are identified. Type A concretionsmainly distribute in organic-rich shale. This concretion was divided into the inner circular layer and the outer circular layer. In the inner circular layer, the value of δ13C‰(VPDB) is 9.98‰~14.19‰, and the value of δ18O‰(VPDB) is −13.32‰~-10.07‰. On the contrary, the δ13C and δ18O value of outer circular layer are4.74‰~-0.59‰,-17.86‰~-15.59‰ respectively. The formation palaeotemperature of different parts of concretion ranged from 28.6 to 76.5 °C. This may be due to methanogenesis arising from bacterial activities in the fermentation zone, and the fractional distillation of carbon isotope of organic matter was caused by the methane bacterial activities. The calcite and dolomite spherulites in carbonate concretions may be due to the calcilization and dolomitization of cyanobacteria in the early diagenesis. The type B concretions were distributed in the fine sandstone, silty sandstone, and silty mudstone. The internal structure of concretions is uniform. The carbon isotopic values were negative, and δ13C was −5.019~-12.013‰, and the δ18O values was −17.6~-19.281‰. The value of 87Sr/86Sr was in the range of 0.710072–0.710392. The temperature was established at 60.4 °C through clumped isotopes analysis. Based on isotopic analysis, the formation palaeotemperature at different parts of concretion was 55.4–65.6 °C. The origin of the concretion may be related to dehydroxylation in diagenesis, formed in the early-middle stage of diagenesis.

Morphological Descriptions of the Esophagus of the Sea Bream (Sparus aurata, Linneaus 1758)

The current work prepared to describe the microscopic morphological appearance of the esophagus of the gilthead sea bream (Sparus aurata). The esophageal wall was organized into four tunica; mucosa, submucosa, muscularis and serosa. There are many goblets cells in the esophageal epithelium. The tunica muscularis is very thick and consisting of; an outer circular thick layer and an inner longitudinal layer of striated muscle. The presences of the many goblet cells help in the esophageal lubrication and protection. By the histochemical reactions with Alcian blue and PAS staining, the esopgaster secretory epithelium devoid from any goblet cells. There are many mucous droplets of the high electron density and the low electron density between surface epithelial cells within the goblet cells. The obtained results of the current investigation may help to understanding the physiology of the esophageal digestive functions in Sparus aurata.

Diffusion tensor imaging determines three-dimensional architecture of human cervix: a cross-sectional study.

To determine the microarchitecture of the cervix using high-resolution diffusion tensor (DT) magnetic resonance imaging (MRI). Cross-sectional study. Leeds, UK. Women undergoing hysterectomy for benign pathology. Ex-vivo DT-MRI measurements were obtained using a 9.4-T Bruker nuclear magnetic resonance (NMR) spectrometer on seven fixed human cervices obtained at hysterectomy. A deterministic fibre-tracking algorithm was used to indirectly visualise underlying fibre organisation. Inter-regional differences in tissue structure were sought using quantitative measurements of diffusion. The identification of an occlusive structure in the region corresponding to the internal cervical os. Fibre tracking demonstrated two regions: an outer circular and inner longitudinal layer. The total circumferential tract volume (TV) was greatest in the proximal region of the cervix (TV: proximal, 271 ± 198 mm3 ; middle, 186 ± 119 mm3 ; distal, 38 ± 36 mm3 ). Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) measurements were significantly different between regions in all samples (P < 0.0005), indicating greater tract density and organisation towards the internal os. Fibre tracking infers a system of dense, well-defined, encircling fibres in the proximal region of the cervix, corresponding to the location of the internal os. These findings may provide evidence of specific anatomic microarchitecture within the cervix able to resist intrauterine forces associated with pregnancy. Diffusion-tensor MRI derived tractography identified well-defined encircling fibres at the internal os.

Pharmacological and morphological characteristics of the muscular system of the giant liver fluke (Fascioloides magna – Bassi 1875)

Motility is required for feeding, reproduction and maintenance of the fluke in the host's liver. According to that, the neuromuscular system can be an attractive drugable target for chemotherapy. Musculature of the Fascioloides magna is organized into three layers, an outer circular layer, beneath this layer the longitudinal layer, and third, the oblique, or diagonal layer underlies the longitudinal layer. In our study, the administration of atropine or caffeine did not cause classic muscle contractions of F. magna muscle strips. However, the Electrical Field Stimulation (EFS) induced stable and repeatable contractions, which enabled us to examine their sensitivity to the various substances. Acetylcholine (ACh) (300 μM and 1 mM), caused only a slight relaxation, without affecting the amplitude of spontaneous contractions or the amplitude of contractions induced by EFS. Contrary to that, atropine (100 μM) caused a significant increase in the basal tone and an increase of EFS-induced contractions. If acetylcholine is an inhibitory neurotransmitter in trematodes, the described effects of atropine are achieved by the blockade of inhibitory neurotransmission. On the other hand, with respect to the process of excitation-contraction coupling, the plant alkaloid ryanodine (30 μM) significantly reduced the basal tone, as well as EFS-induced contractions of F. magna muscle strips. Ryanodine inhibited the potentiating effect of atropine on the basal tone and contractions caused by EFS, which indicates that the contractile effect of atropine is dependent on Ca++ release from intracellular stores. Caffeine (500 μM) caused relaxation of fluke muscle strips and at the same time significantly enhanced the EFS-induced contractions. Both effects of caffeine can be explained by entry of extracellular Ca++ into muscle cells. The muscle contractility of F. magna depends both on the entry of extracellular calcium, and calcium release from intracellular stores, which are under the control of RyRs. Our results also suggest that antitrematodal drugs could potentially be developed from substances with selective anti-cholinergic activity.

Histological and Scanning Electron Microscopic Examination of the Digestive Tract in Whitespotted Conger, Conger Myriaster (Anguilliformes)

The morphology of the digestive tract of Whitespotted conger, Conger myriaster (Elopomorpha: Anguilliformes) was examined by light and scanning electron microscopy. The digestive tracts consist of esophagus, stomach, and intestine; no pyloric caeca were observed. The stomach was divided into cardiac, body, terminal and pyloric region. The esophagus was composed of two layers of striated muscularis; inner longitudinal layer and outer circular layer. The former was extended to the body region of the stomach. In contrast, the latter was terminated to the esophagus, and became coincident to the boundary of the outer longitudinal layer consisting of smooth muscle in the cardiac region of the stomach. The terminal region of the stomach was characterized by the thick longitudinal muscularis and subserosa, and the gastric glands were absent. Ciliated cells were distributed in the intestinal wall. The digestive tract secreted both acidic and neutral mucus throughout all regions. We found that the terminal region of the stomach is characteristic of Anguilliformes. On the other hand, the striated muscle within the body region of the stomach was unique among the Anguilliformes. These differences in stomach suggested the possible existence of morphological differences that originate from phylogenetic position among the orders in Elopomorpha.

The Distribution of Muscles Fibers and Their Types in the Female Rat Urethra: Cytoarchitecture and Three‐Dimensional Reconstruction

An attempt to explore urethral cytoarchitecture including the distribution of smooth muscles and fast and slow striated muscles of adult female Sprague Dawley rat--a popular model in studying lower urinary tract function. Histological and immunohistochemical stainings were carried out to investigate the distribution of urethral muscle fibers and motor end plates. The urethral sphincter was furthermore three-dimensionally reconstructed from serial histological sections. The mucosa at the distal urethra was significantly thicker than that of other segments. A prominent inner longitudinal and outer circular layer of smooth muscles covered the proximal end of urethra. Thick circular smooth muscles of the bladder neck region (urethral portion) decreased significantly distalward and longitudinal smooth muscles became 2- to 3-fold thicker in the rest of the urethra. An additional layer of striated muscles appeared externally after neck region (urethra) and in association with motor end plates ran throughout the remaining urethra as the striated sphincter layer. Most striated muscles were fast fibers while relatively fewer slow fibers often concentrated at the periphery. A pair of extraneous striated muscles, resembling the human urethrovaginal sphincter muscles, connected both sides of mainly the distal vagina to the dorsal striated muscles in the wall of the middle urethra. The tension provided by this pair of muscles, and in conjunction with the striated sphincter of the urethral wall, was likely to function to suspend the middle urethra and facilitates its closure. Comprehensive morphological data of urethral sphincter offers solid basis for researchers conducting studies on dysfunction of bladder outlet.

Myoanatomy of Myzostoma cirriferum (Annelida, Myzostomida): Implications for the evolution of the myzostomid body plan

Studies of rare genomic marker systems suggest that Myzostomida are a subgroup of Annelida and phylogenomic analyses indicate an early divergence of this taxon within annelids. However, adult myzostomids show a highly specialized body plan, which lacks typical annelid features, such as external body annulation, coelomic cavities with metanephridia, and segmental ganglia of the nervous system. The putative loss of these features might be due to the parasitic/symbiotic lifestyle of myzostomids associated with echinoderms. In contrast, the larval anatomy and adult locomotory system resemble those of annelids. To clarify whether the myoanatomy of myzostomids reflects their relationship to annelids, we analyzed the distribution of f-actin, a common component of muscle fibers, in specimens of Myzostoma cirriferum using phalloidin-rhodamine labeling in conjunction with confocal laser-scanning microscopy. Our data reveal that the musculature of the myzostomid body comprises an outer circular layer, an inner longitudinal layer, numerous dorsoventral muscles, and prominent muscles of the parapodial complex. These features correspond well with the common organization of the muscular system in Annelida. In contrast to other annelids, however, several elements of the muscular system in M. cirriferum, including the musculature of the body wall, and the parapodial flexor muscles, exhibit radial symmetry overlaying a bilateral body plan. These findings are in line with the annelid affinity of myzostomids and suggest that the apparent partial radial symmetry of M. cirriferum arose secondarily in this species. Based on our data, we provide a scenario on the rearrangements of muscle fibers that might have taken place in the lineage leading to this species.

Histological organization of the intestine in the crayfish Procambarus clarkii

AbstractSix longitudinal ridges span the length of the intestine in the crayfish Procambarus clarkii. A simple columnar epithelium with tetralaminar cuticle lines the lumen. Folds of the epithelium overlie a dense irregular connective tissue packed with mixed acinar (alveolar) glands. Mucous secretions are probably involved with formation and lubrication of faecal strings; neither the nature nor the role of the serous secretions is immediately apparent. Aggregations of cells with large cytoplasmic vacuoles, called bladder cells, appear in the subepithelial connective tissue near the tops of the intestinal ridges. The bladder cells are suitably positioned to bolster the integrity of the ridges. Striated muscle of the intestine occurs in inner longitudinal and outer circular layers. The inner longitudinal layer consists of six strips, with one strip associated with the base of each intestinal ridge. The outer circular layer is essentially complete, but there are periodic apertures in this layer on the left and right sides of the intestine, providing nerves and haemolymph vessels with access to the interior of the gut. Based on histological features, and consistent with reports on other crayfish, we conclude that the intestine of P. clarkii has a proctodeal (ectodermal) origin.

Comments on the taxonomic status of Ikeda taenioides (Ikeda, 1904) with some amendments in the classification of the phylum Echiura.

Examination of thin sections of trunk wall in an old specimen of Ikeda taneioides from Misaki, Sagami Bay revised previous false information about the wall musculature, actually consisting of outer circular, middle longitudinal, and inner-most oblique layers, like all other echiurans. This finding, together with the reexamination of relevant museum specimens, led to some taxonomic changes. These include that the definition of the genus Ikeda was amended to be a senior synonym of Prashadus; the family Ikedidae was regarded as a junior synonym of the family Echiuridae; and the order Heteromyota, erected virtually for I. taenioides, was abolished. Non-discovery of males and some other features in the amended genus Ikeda were noted with reference to its possible relationship with the family Bonelliidae.

Pivotal role of the interstitial cells of Cajal in the nitric oxide signaling pathway of rat small intestine. Morphological evidence.

The nitric oxide (NO) signaling pathway is a major nonadrenergic-noncholinergic transmitter mechanism in the enteric nervous system. Our aim was to localize the enzymes in question, i.e., neuronal nitric oxide synthase (nNOS), soluble guanylate cyclase (sGC), and cGMP-dependent kinase type I (cGK-I) in rat small intestine by indirect immunofluorescence. nNOS staining was found in neurons of the myenteric plexus and in varicose nerve fibers mainly in the circular muscle layer. The cells positive for neurokinin-1 (NK-1) receptor and c-kit (interstitial cells of Cajal, ICC) in the deep muscular plexus (DMP) did not show nNOS reactivity, but nNOS-positive nerve fibers were directly adjacent to them. sGC was found in flattened cells surrounding myenteric ganglia (periganglionic cells, PGC), in ICC of the DMP, faintly in smooth muscle cells (SMC), and in cells perivascularly scattered throughout the circular muscle layer. cGK-I immunoreactivity was found abundantly in PGC (which presumably are ICC), in ICC of DMP, in SMC of the innermost circular and longitudinal muscle layers, but less intensively in the outer circular layer. Weak cGK-I staining occurred in nerve cells within the myenteric and submucosal plexus. Conclusively the key enzymes of the NO signaling pathway are differentially distributed: Occurrence of nNOS exclusively in neurons and the presence of sGC and cGK-I predominantly in ICC suggest a sequence of neuronal NO release, activation of ICC, and consecutive smooth muscle relaxation. ICC of the DMP seem to be the primary targets for neurally released NO.

The deep muscular plexus of the pig duodenum: A histochemical and ultrastructural study with special reference to the interstitial cells

The aim of the present study was to describe the deep muscular plexus of the pig duodenum and to characterize its cellular components. Numerous nerve varicosities have been detected in the deep muscular plexus using anti-synaptophysin antibodies. Nerve fibres were also detected here in the outer circular muscle layer, whereas no nerve fibres were observed in the inner circular muscle layer. In the deep muscular plexus, nerve fibres projected to interstitial cells which were characterized at the ultrastructural level. The interstitial cells were of two kinds: the interstitial fibroblastic-like cells (FLC) and the interstitial dense cells (IDC), both of which were interposed between nerve fibres and smooth muscle cells. The FLC were characterized by their elongated bipolar shape, the lack of basal lamina, a well-developed endoplasmic reticulum, a Golgi apparatus, and intermediate filaments. They were closely apposed to axon terminals containing small clear synaptic vesicles and/or dense-cored vesicles. They were frequently connected to each other and to smooth muscle cells of the inner and outer circular layer by desmosomes and more rarely by gap junctions. The IDC are myoid-like cells. They had a stellate appearance and were characterized by a dense cell body, numerous caveolae, and a discontinuous basal lamina. The IDC were always closely apposed to nerve fibres and were connected to smooth muscle cells by desmosomes and small gap junctions. The present results show the unique pattern of cellular organization of the deep muscular plexus of the pig small intestine. They suggest that the interstitial cells in the deep muscular plexus are involved in the integration and transmission of nervous inputs from myenteric neurons to the inner and outer circular muscle layers. The clear-cut distinction observed here between the two types of interstitial cells (fibroblastic- and myoid-like) suggests that the interstitial cells of each type may also be involved in some other specific activity, which still remains to be determined.

Specific localization of gap junction protein, connexin45, in the deep muscular plexus of dog and rat small intestine

Cellular networks of pacemaker activity in intestinal movements are still a matter of debate. Because gap-junctional intercellular communication in the intestinal wall may provide important clues for understanding regulatory mechanisms of intestinal movements, we have attempted to clarify the distribution patterns of three types of gap junction proteins. Using antibodies for connexin40, connexin43, connexin45, smooth muscle actin, and vimentin, immunocytochemical observations were made with the confocal laser scanning microscope on cryosections of fresh-frozen small intestine and colon of the dog and rat. Connexin 45 was localized along the deep muscular plexus of the small intestine in both dog and rat. Double labeling studies revealed that connexin45 overlapped with vimentin -, but not actin-positive areas, indicating the fibroblast-like nature of the cells, rather than their being smooth muscle-like. Connexin43 immunoreactivity appeared along the smooth muscle cell surface in the outer circular layer of the small intestine of both animals. Connexin 40 immunoreactivity was not observed in the muscle layer other than in the wall of large blood vessels. It is suggested that connexin45-expressing cells along the deep muscular plexus of dog and rat small intestine are likely to act as a constituent of a pacemaker system, which may include a conductive system, by forming a cellular network operating via specific types of gap junctions.

Gene expressions of transforming growth factor-ß1 and extracellular matrix components during gastric ulcer healing in rats

This chapter describes ganglia within the mammalian gut, heart, urinary bladder, and airways. Autonomic ganglia are present in almost all organs of the body and exhibit considerable differences in their structures and properties. The most well-studied intrinsic autonomic ganglia, both in culture and in situ, are those of the enteric nervous system (ENS). The ganglia of the ENS are grouped into two major plexuses: (1) the myenteric (or Auerbach's), which lies between the outer longitudinal and circular smooth-muscle layers and (2) the submucous (or Meissner's), which lies in the connective tissue of the submucosa. The two plexuses are connected by nerves that pass through the circular muscle layer. The enteric neurons are a highly diverse population functionally, morphologically, and with respect to their neurotransmitter phenotypes. The unique advantages of culture preparations, including the increased accessibility of the cultured cells, the ability to observe cells over extended periods of time, and the ability to control their physical and chemical environment, are pertinent in the study of the regulation of phenotypic differentiation.

The cellular network of interstitial cells associated with the deep muscular plexus of the guinea pig small intestine.

Systematic examination using electron microscopic montages and serial sections has demonstrated that three types of interstitial cell, namely gap junction-rich cells, glycogen-rich cells and fibroblast-like cells, are densely located along the whole extent of the deep muscular plexus of the guinea pig small intestine. They tend to be distributed in an alternating fashion in the cellular network, connected with muscle cells of the outer, circular layer by means of gap junctions. These three types of interstitial cell show close relations to two types of nerve varicosity: one type is characterized by clear round vesicles with diameters of about 50 nm, and the other by flattened vesicles measuring about 35 nm by 70 nm. Electron-dense patches have been observed at the cytoplasmic side of the axonal membranes. Muscle cells of both inner and outer circular layers also show close relations to these two types of nerve varicosity. These morphological features are discussed with the implication that they may have some regulatory role in intestinal movement.

Interstitial cells associated with the deep muscular plexus of the guinea-pig small intestine, with special reference to the interstitial cells of Cajal.

Interstitial cells associated with the deep muscular plexus of the guinea-pig small intestine were studied by electron microscopy, and three-dimensional cell models were reconstructed from serial ultrathin sections with a computer graphic system. Three types of cells were recognized. The first type was similar in shape to smooth muscle cells, but did not contain an organized contractile apparatus. Many large gap junctions comprising about 4% of the cell surface were present; they connected cells of the first type to each other, to the second type of cell and to smooth muscle cells of the outer circular layer. The second type of cell had a well-demarcated cell body with long slender processes and was characterized by a large amount of glycogen comprising about 9% of the cell volume. The third type of cell was similar to fibroblasts, and contained well-developed Golgi apparatus and rough endoplasmic reticulum. Some of these fibroblast-like cells (a possible subtype) formed small gap junctions. All three types of cells showed close relationships with nerve varicosities. This cellular network consisting of gap-junction-rich cells, glycogen-rich cells and smooth muscle cells may be involved in the pacemaking activity of intestinal movement.

Ganglia within the Gut, Heart, Urinary Bladder, and Airways: Studies in Tissue Culture

Publisher Summary This chapter describes ganglia within the mammalian gut, heart, urinary bladder, and airways. Autonomic ganglia are present in almost all organs of the body and exhibit considerable differences in their structures and properties. The most well-studied intrinsic autonomic ganglia, both in culture and in situ, are those of the enteric nervous system (ENS). The ganglia of the ENS are grouped into two major plexuses: (1) the myenteric (or Auerbach's), which lies between the outer longitudinal and circular smooth-muscle layers and (2) the submucous (or Meissner's), which lies in the connective tissue of the submucosa. The two plexuses are connected by nerves that pass through the circular muscle layer. The enteric neurons are a highly diverse population functionally, morphologically, and with respect to their neurotransmitter phenotypes. The unique advantages of culture preparations, including the increased accessibility of the cultured cells, the ability to observe cells over extended periods of time, and the ability to control their physical and chemical environment, are pertinent in the study of the regulation of phenotypic differentiation.

Biomphalaria obstructa (Morelet, 1849): a study of topotypic specimens (Mollusca: pulmonata: planorbidae)

A description of Biomphalaria obstructa (Morelet, 1849), based on specimens collected at its type locality - isla del carmen, state of Campeche, Mexico - is presented. The Shell is small, 13 mm in diameter, 3.5 mm in width and with 5.75 whorls in the largest specimen, thin, moderately lustrous and translucent, horn-colored. Whorls increasing regularly (neither slowly nor rapidly) in diameter, rounded on the periphery side, bluntly angular on the left. Suture well-marked, deeper on the left. Right side widely concave, with first whorl deeply situated and partly hidden by the next. Left side shallower than right one, largely flattened, with first whorl plaintly visible. Aperture roundly heart-shaped, usually in the same plane as the body whorl but somewhat deflected to the left (less frequently to the right) in some specimens. Peristome sharp, seldom blunt; a distinct callus on the parietal wall. A number of young shells develop one set (seldom more) of apertural lamellae which tend to be resorbed as the shell grows. Absence of renal ridge. Ovotestis with about 70 mostly unbrached diverticula. Seminal vesicle beset with well-developed knoblike to fingerlike diverticula. Vaginal pouch more or less developed. Spermatheca club-shaped when empty, egg-shaped when full, and with intermediate forms between those extremes. Spermathecal body usually somewhat longer than the duct. Prostate with 7 to 20 (mean 12.06 ± 2.51) usually short diverticula which give off plumpish branches spreading out in a fan shape and overlapping to some extent their immediate neighbors. Foremost prostatic diverticulum nearly always partially or completely inserted between the spermathecal body and the uterine wall. Penial sheath consistently narrower and shorter than the prepuce. Muscular coat of the penis consisting of an inner longitudinal and an outer circular layers. Ratios between organ lengths: caudal to cephalic parts of female duct = 0.55 to 1.37 (mean 0.85 +- 0.17); cephalic parte of female duct to penial complex = 1.36 to 2.81 ((mean 1.90 +- 0.33); penial sheath to prepuce = 042 to 0.96 (mean 0.67 +- 0.13). Comparison with Morelet’s type specimens of Planorbis orbiculus and P. retusus points to the identity of those nominal species with B. obstructa.