bluuebunny/crossref_metadata_2025 huggingface dataset:
Differential distribution of lymphocytes and accessory cells in mouse Peyer's patches
Authors: Ermak Thomas H. , Owen Robert L.
Published: February 2005

The aim of this immunohistologic study was to determine how lymphocytes and accessory cells associated with antigen processing are distributed in the domes of Peyer's patches. Monoclonal antibodies against mouse B cells (anti‐B220), T cells (anti‐Thy‐1.2), T helper cells (anti‐L3T4), T cytotoxic/suppressor cells (anti‐Lyt‐2), macrophages (anti‐Mac‐1), and Ia+ cells (anti‐I‐Ad) were applied to cryostat sections of mouse Peyer's patches and visualized with peroxidase‐conjugated avidin‐biotin complexes (ABC). The subepithelial dome, the dome epithelium, and the follicle crypt epithelium were each surveyed for cells labeled with these antibodies. Each region had a characteristic and nonrandom distribution of labeled cells. In the subepithelial dome, B cells, T helper cells, macrophages, and Ia + accessory cells formed a cellular meshwork between follicle and the dome epithelium. T cytotoxic/suppressor cells were sparse beneath the epithelium. In the dome epithelium, solitary and paired lymphocytes occurred both above and below the level of epithelial cell nuclei. B cells predominated, and both T helper cells and T cytotoxic/suppressor cells were present. B cells sometimes aggregated in small clusters. Macrophages were rarely observed in the epithelium. The distribution of cells in the dome epithelium was distinctly different from non–Peyer's patch intestine where T cytotoxic/suppressor cells predominated and B cells were few in number. Although lymphocytes were usually absent in crypts outside Peyer's patches, in follicle crypts B cells and T cells were seen but not Ia + accessory cells or macrophages. Most of the T cells in the crypt epithelium were T cytotoxic/suppressor cells. These characteristic distributions in Peyer's patch domes and crypts are consistent with current hypotheses that antigen processing takes place in follicle domes and that specific lymphocytes may participate in fine regulation of stem cell differentiation in follicle crypts.
Structure of the satellite cell sheath around the cell body, axon hillock, and initial segment of frog dorsal root ganglion cells
Authors: Matsumoto Emiko , Rosenbluth Jack
Published: February 2005

The structure of the satellite cell sheath of frog dorsal root ganglion cells was studied in thin sections and freeze‐fracture replicas. The sheath around the cell body is composed of thin satellite cell lamellae closely applied to the neuronal plasma membrane. At the axon hillock the sheath divides into outer and inner components separated by a broad space containing a distinctive extracellular matrix and occasional flattened satellite cell processes. The sheath around the initial segment is usually multilayered but less compact than that around the cell body, and in some places it exhibits node‐like interruptions. Apart from occasional particle groupings characteristic of tight junctions and gap junctions, the satellite cells display homogeneously distributed intramembranous particles in both fracture faces in all regions of the sheath.
Blood flows in the maxillocarotid anastomoses and internal carotid artery of conscious dogs
Authors: Lee Maw‐Chang , Reid Ian A. , Ramsay David J.
Published: February 2005

Although the external carotid artery is known to contribute to the cerebral blood flow in anesthetized dogs, quantitative information on the anastomoses and their role in conscious dogs is lacking. This study was carried out to determine blood flows in these anastomoses and the internal carotid artery, and also to examine the functional significance of the anastomoses in conscious dogs. Fifteenmicron radioactive microspheres were injected into common and external carotid arteries of four conscious dogs through chronically implanted catheters. Blood flows were determined by the reference sample method and by comparing microsphere distributions in the brain and the masseter muscle. Blood flows were estimated to be 140 ± 32, 7.7 ± 1.4, and 3.3 ± 1.1 ml/minute (mean ± SD) in the common carotid artery, internal carotid artery, and anastomoses on each side, respectively. Additional evidence indicated that the anastomotic flow so determined was primarily the flow in the anastomotic artery. Humoral responses to angiotensin II infusions were also studied in conscious dogs. External carotid angiotensin increased plasma 11‐hydroxycorticosteroid concentration (used as an index of ACTH secretion) but did not increase plasma vasopressin concentration to the same extent as common carotid infusion. Therefore, the external carotid artery is functionally important in perfusing the brain in conscious dogs.
Scanning electron microscopical studies of the arterial terminals in the red pulp of the rat spleen
Authors: Satodate R. , Tanaka H. , Sasou S. , Sakuma T. , Kaizuka H.
Published: February 2005

The arterial terminals in the red pulp of the perfused rat spleen were studied by scanning electron microscopy. The arterial terminals were tubular or funnel‐shaped and ended openly in the splenic cord. No continuity was observed between the arteries and the sinuses. The endothelial cells of the arterial terminals extended their processes at the fringe of the terminal ends, and these endothelial processes were connected to the processes of the reticular cells of the splenic cord. In addition, large pores, measuring 0.5–8 μm in size, were found in the wall of the terminals adjacent to their end.
Lectin binding sites on human endocervix: A comparison with secretory and proliferative endometrium
Authors: Yen Yun , Lee Mao‐Chi , Salzmann Martina , Damjanov Ivan
Published: February 2005

Endocervix and corresponding endometrium of women of reproductive age were studied histochemically with 13 fluorescein isothiocyanate‐labeled lectins to delineate the differences between the epithelial cells in two anatomical sites. Lectin from Maclura pomifera (MPA), Ulex europaeus (UEA‐I), Glycine max (SBA), and Vicia villosa (VVA) bound only to endocervical epithelium and were the only four lectins that distinguished endocervical from endometrial epithelium. These differences were independent of menstrual cyclic changes and blood group antigen secretion. These data show that lectins can be used to histochemically distinguish endocervical from endometrial glands.
Ultrastructural immunocytochemistry of somatotrophs and mammotrophs in embryos of the dwarf mutant mouse
Authors: Wilson Doris B. , Wyatt Darlene P.
Published: February 2005

The embryonic development of somatotrophs and mammotrophs in the adenohypophysis in dwarf (dw) mutant mice was studied by means of ultrastructural immunocytochemistry. Embryos at 16–18 days of gestation were removed from litters consisting entirely of dwarf homozygotes obtained from homozygous matings of adult dwarfs in which reproductivity was induced by means of hormone supplementation and renal capsule implants of normal pituitaries. Litters from normal (−/+) matings served as controls. Pituitaries from adult normal and dwarf mice also were removed and processed with the embryonic material. Thin sections were exposed to anti‐growth‐hormone serum (anti‐GH) or to antiprolactin serum (anti‐PRL) and processed immunocytochemically with the colloidal gold procedure. In the normal pituitaries, a strong positive reaction to anti‐GH occurred in the adult and in embryos as early as 16 days, whereas the reaction to anti‐PRL was strong in the adults but relatively weak in the embryos. In dwarf embryonic and adult pituitaries, ambiguous cells showing combinations of features characteristic of somatotrophs and mammotrophs were present. However, neither these cells nor other granulated cells reacted to anti‐GH or to anti‐PRL, except for a questionable reaction to the latter at 18 days and in the adult. Thus, the dwarf pituitary shows functional as well as morphological abnormalities as early as 16 days of gestation.
Distribution of actin in sertoli cell ectoplasmic specializations and associated spermatids in the ground squirrel testis
Authors: Vogl A. W. , Grove B. D. , Lew G. J.
Published: February 2005

We have investigated the possibility that the complex patterns of fluorescence associated with spermatids of the ground squirrel labeled with 7‐nitro‐benz‐2‐oxa‐1,3‐diazole‐phallacidin (NBD‐phallacidin) are due to the presence of filamentous actin within the spermatids themselves rather than to actin in attached Sertoli cell ectoplasmic specializations, as previously reported (J. Cell Biol., 100:814–825). Enzymatic treatments (trypsin, DNAase 1) freed Sertoli cell ectoplasmic specializations from spermatids and resulted in a loss, from the spermatids, of the complex fluorescence patterns, suggesting that the latter were generated by labeled actin in ectoplasmic specializations. Moreover, ectoplasmic specializations that were detached enzymatically from spermatids demonstrated the same fluorescence patterns as those emitted from spermatids in the intact or mechanically fragmented seminiferous epithelium. Most spermatids, however, do display a weak and diffuse pattern of fluorescence that changes during spermatogenesis and that is localized between the acrosomal cap and nucleus. S‐1 decoration confirmed this subacrosomal localization and further demonstrated that the actin in adjacent Sertoli cell ectoplasmic specializations is arranged in a unipolar fashion. We conclude that the complex patterns of actin fluorescence associated with mechanically isolated spermatids are a superimposition of both Sertoli cell and germ cell actin; however, the latter is either poorly detected or not detected at all when Sertoli cell ectoplasmic specializations overlie the germ cells.
Developmental changes in the astrocytic response to lateral olfactory tract section
Authors: Sijbesma Hans , Leonard Christiana M.
Published: February 2005

When the lateral olfactory tract (LOT) of the golden hamster, Meso cricetus auratus, is transected in the first week of postnatal life, axons can grow back past the lesion and achieve functional reinnervation of caudal projection regions. In contrast, when the tract is sectioned after postnatal day 7 (P7), axons do not reinnervate regions caudal to the cut. The experiments reported here investigated whether regenerative failure after tract section in pups older than P7 is accompanied by developmental changes in the astrocytic response. LOT transections were performed at P3 and P9 and the glial reaction was observed at survival times ranging from 12 hr to 2 weeks. Immunocytochemistry with glial fibrillary acidic protein (GFAP) was employed for histological visualization of astrocytic reactivity.

Staining for GFAP immunoreactivity showed an appreciable glial reaction after tract section at both P3 and P9, but the extent of astrocytic hypertrophy and proliferation of glial processes was considerably greater and more extensive after tract section at P9. Radial glial cells were observed 2 weeks after LOT transection at P3 but were absent after lesions made at P9.

The results from this study suggest that the developmental loss of regenerative capacity after LOT transection may be related to maturational changes in the glial response. In particular, the presence of radial glial elements after P3 lesions could serve to establish a more favorable microenvironment for axonal elongation.
Dexamethasone induces proliferation and terminal differentiation of osteogenic cells in tissue culture
Authors: McCulloch C. A. G. , Tenenbaum H. C.
Published: February 2005

Dexamethasone is an important regulator of cellular proliferation and differentiation, but paradoxical effects have been noted in a variety of culture systems. The purpose of this study was to determine whether dexamethasone induces proliferation and differentiation of osteogenic precursor cells. Periosteal explants from embryonic chicks were grown in culture for 3 or 4 days, treated continuously with dexamethasone or ethanol vehicle, and then either pulse‐labeled with 3H‐thymidine at 3 days or labeled for 24 hr between day 3 and day 4. Histochemical and autoradiographic procedures were used to assess the proliferation and differentiation of osteogenic cells. At 3 days, the area of bone, the percentage of alkaline phosphatase‐positive cells, the percentage of 3H‐thymidine‐labeled cells, and the percentage of cells labeled with both markers were significantly higher in dexamethasone‐treated cultures. Between day 3 and day 4 no significant changes in these parameters were observed in the dexamethasone‐treated cultures. In comparison, control cultures exhibited significant increases in the percentage of 3H‐thymi‐dine‐labeled cells after 24 hr of continuous labeling. The data show that dexamethasone induces a burst of proliferation in a cohort of cells that undergo differentiation. Once these cells have divided, further proliferation within the culture is limited. Finally, it is apparent that the timing of experiments may be critical in determining whether dexamethasone will inhibit or stimulate proliferation.
Attraction of chick primordial germ cells by gonadal anlage in vitro
Authors: Kuwana Takashi , Maeda‐Suga Hitomi , Fujimoto Toyoaki
Published: February 2005

The attraction of primordial germ cells (PGCs) by the gonadal anlage (germinal ridge; GR) in vitro has been demonstrated in the chick. PGCs were isolated from circulating blood of stage 13 embryos (Hamburger and Hamilton, 1951), placed between the GR and other embryonic tissues (neural tube, heart, allantois, liver) as controls separated by a distance of 170 μm on collagen‐coated substrate, and cultured with modified medium 199 (Kuwana and Fujimoto, Anat. Rec., 209:337–343, 1984) containing 10% fetal calf serum (pH 7.3). The behavior of PGCs was observed for 3 hr by 16‐mm time‐lapse microcinematography.

PGCs showed directional movement toward GR. Also, there was a stronger attractive effect on the PGCs by GR from stage 13 embryos than by GR from later stage embryos. These results suggest that PGCs are attracted by some factor emitted from GR.
Axoglial contacts in the area postrema of the cat: An ultrastructural study
Authors: D'Amelio Fernando E. , Gibbs Michael A. , Mehler William R. , Philpott Delbert E. , Savage Wayne
Published: February 2005

Axoglial contacts were observed in an ultrastructural study of the area postrema of the cat. According to the disposition of the electron‐dense projections attached to the adjoining membranes these contacts were classified as symmetrical or asymmetrical. The axon profiles contained aggregations of clear vesicles randomly distributed or grouped in clusters adjacent to the electron‐dense projections. Dense core vesicles were occasionally seen. The neuroglial profiles were either astrocytic or ependymoglial in nature. The astrocytes showed a clear cytoplasm, polymorphous vesicles, mitochondria, glycogen granules, and bundles of filaments. The ependymal cells, in contrast, had a more electron‐dense and granular appearance, tubular structures, irregular vesicular formations, profiles of smooth reticuloendoplasm, and filaments grouped in bundles or isolated in the cytoplasm. The possibility that these contacts might play a role in the chemical transfer from neurons to glial cells is discussed on the basis of existing biochemical data.
Ultracytochemistry of ouabain‐sensitive K+‐dependent p‐nitrophenyl phosphatase in rat incisor enamel organ
Authors: Garant Philias R. , Sasaki Takahisa
Published: February 2005

Sprague‐Dawley strain rats of 4–5 weeks old were perfusion‐fixed with either a mixture containing 0.1 or 0.25% glutaraldehyde and 2% formaldehyde, or a 2% formaldehyde in 0.1 M sodium cacodylate buffer for 10 minutes. Non‐decalcified 30–50‐μm sections of the enamel organ taken from lower incisors were then processed for ultracytochemical demonstration of ouabain‐sensitive, K+‐dependent, p‐nitrophenyl phosphatase, by use of the one‐step lead method, representing the second dephosphorylative step of Na+‐K+‐ATPase. Throughout the secretory, transition, and maturation stages of amelogenesis, the enzymatic activity was demonstrated along the cytoplasmic side of the plasma membranes of the stratum intermedium and the papillary layer cells, especially along their numerous micro‐villi. The plasma membranes forming gap junctions and desmosomes were free of reaction or showed slight focal precipitates of reaction products. The stellate reticulum and the outer enamel epithelium exhibited either a weak reaction or were reaction negative. Secretory ameloblasts showed a weak trace‐like reaction along the basal and lateral cell surfaces; however, the latter surfaces were sometimes completely free of reaction. Tomes' processes were usually reaction negative. Ameloblasts in the transition and maturation stages were devoid of enzymatic activity, except for a slight reaction along the plasma membranes of the basal cell surfaces of transition ameloblasts facing the papillary layer. The enzymatic activity described above was completely dependent on the presence of potassium and substrate in the incubation media and was almost completely inhibited by an addition of 10 mM ouabain to the incubation media.
Differential distribution of brush cells in the rat lung
Authors: Chang Ling‐Yi , Mercer Robert R. , Crapo James D.
Published: February 2005

The distribution of brush cells in the rat lung was studied using electron microscopic morphometry. Samples were taken from six distinctive anatomical regions. Tissue from the trachea, lobar bronchi, terminal bronchioles, first alveolar duct bifurcations, proximal alveolar regions, and the distal alveolar region were isolated and embedded in Epox 812. Aside from the trachea and the lobar bronchi, the other four regions were isolated from embedded tissue using microdis‐section techniques. Electron micrographs taken from thin sections of these samples were analyzed. It was found that brush cells made up 10% of the volume of epithelium covering the first alveolar duct bifurcation. Approximately 2% of the proximal alveolar epithelium, 1.4% of the terminal bronchiolar epithelium, and 3% of the tracheal epithelium were made up of brush cells. No brush‐bordered epithelium was found in the lobar bronchi or in the distal alveolar walls. We conclude that brush cells have a distinct spatial location in the lung, being in high concentration in the trachea and in areas where first generation alveolar duets bifurcate. The highest density was on the bifurcation of the first alveolar ducts, and their density decreased radially from this region.
An HRP study of the motoneurons supplying the rat hypobranchial muscles: Central localization, peripheral axon course and soma size
Authors: Kitamura Seiichiro , Nishiguchi Takahiko , Okubo Johji , Chen Kai‐Li , Sakai Akira
Published: February 2005

The locations of motoneurons (MNs) supplying the rat hypobranchial muscles (lingual, geniohyoid, and infrahyoid) and the peripheral courses of axons of these MNs were investigated by using a method of HRP injection into the hypoglossal nerve or these muscles in combination with severing of the hypoglossal and/or cervical components of the plexus hypoglossocervicalis. Moreover, soma sizes of the MNs were investigated in both transverse and horizontal sections. The hypobranchial MNs formed a sequence of cell columns extending caudally from the hypoglossal nucleus, via the supraspinal nucleus, to the medial and then the ventrolateral subnuclei of the ventral horn of C1 to C3. The lingual and geniohyoid MNs were located in the hypoglossal nucleus. The majority of their axons passed solely through the hypoglossal nerve, whereas a small number of axons, whose somata lay in the caudal hypoglossal nucleus, passed through the first cervical nerve and then through the ansa cervicalis to reach the hypoglossal nerve. The infrahyoid MNs were located in the supraspinal nucleus and the ventral horn, and their axons passed through the first to third cervical nerves. The hypobranchial MNs were divided into three groups according to their size: the lingual, the geniohyoid and thyrohyoid, and lastly the other infrahyoid MNs, in order of smaller to larger size. The sizes of lingual, geniohyoid, and thyrohyoid MNs displayed a unimodal distribution both in transverse and horizontal sections, whereas the other infrahyoid MNs showed a bimodal distribution.
The nucleus of Darkschewitsch in the cat: A Nissl, Golgi, and electron microscope analysis
Authors: Bianchi Rossella , Gioia Magda
Published: February 2005

A light and electron microscope study was carried out to elucidate the cytoarchitectural organization of the nucleus of Darkschewitsch (ND) in the cat. From the anatomical staining methods, including Nissl and Golgi‐Cox, it appears that the ND shows a clear heterogeneity of shape and size of the neuronal population. The small or medium‐sized neurons show a high nuclear/cytoplasmic ratio and a modest basophilia. Spiny extrusions are present on many of the neurons, arranged either as varicosities giving a rosary feature or clumped in small groups over the dendritic processes; these are absent at the level of the soma. From the electron microscope analysis it appears that the neuropil is not very extensive because the neuronal bodies are numerous and compact. The synaptic complex is extensive both at the level of the nerve cell bodies and at the level of the neuropil. Since many of the synapses display the features typical of the inhibitory synapses, it is possible that they represent the anatomical basis of an inhibitory integrative function.
Preparation of flexible models of hollow gastrointestinal organs
Authors: Updike Susan J. , Holladay Steven D.
Published: February 2005

Flexible models of hollow gastrointestinal organs can be easily prepared by coating air‐dried organs with a commercially available clear plastic compound. The plastic infiltrates the full thickness of organ walls to support and protect internal as well as external structures. Models are flexible, resistant to fluids, and lightweight. This plasticizing technique is particularly useful for the preservation and study of large animal gastrointestinal tracts.
SEM studies of acellular glomerular basement membrane in human diabetic glomerulopathy
Authors: Carlson Edward C. , Surerus Kristene K.
Published: February 2005

Previous transmission electron microscopic studies have demonstrated glomerular basement membrane (GBM) thickening and mesangial matrix (MM) expansion in chronic stages of diabetes. It is difficult, however, to achieve an appreciation of GBM surface features and distribution of MM in planar views. In the current study, autopsy human renal cortical tissue from patients with end‐stage diabetic nephropathy were minced and rendered acellular with detergents prior to fixation, cryofracture, and preparation for light microscopic (LM), transmission electron microscopic (TEM), and scanning electron microscopic (SEM) observation in an effort to visualize extracellular materials in three dimensions.

Our studies demonstrated that although diabetic glomerular changes vary widely within and between individuals, most showed alterations primarily affecting peripheral (epithelial) GBM (with MM increased but diffusely distributed), or they exhibited similar GBM changes but with variable nodular MM expansion leading ultimately to capillary occlusion. Both types showed peripheral GBM thickening and demonstrated external surface irregularities that by SEM appeared as “cauliflower‐like” lobulations. In these glomeruli, GBM lamellation or reduplication was common with internal layers frequently thrown into lumenward projections.

Glomeruli with diffusely distributed MM generally showed patent capillary channels with little evidence of occlusion. By TEM, highly compact, epithelial GBMs were clearly distinguishable from the electron‐lucent MM. In these preparations the matrix was concentrated in relatively small discrete masses sometimes covered by a finely fibrillar material, which extended intermittently onto lumenal surfaces of epithelial GBMs.

In more advanced stages of MM involvement, glomeruli typically exhibited smooth‐surfaced nodules that were increased at the expense of capillary surface area. By TEM, MM nodules were comprised of a meshwork of very fine (20‐Å) fibrils surrounding a variety of detergent‐resistant structures including collagenous fibrils and non‐collagenous 30‐nm circular fibrils with 16‐nm subunits. By SEM, GBM and MM nodules were not distinguishable and merged to form substantial barriers to capillary blood flow. In those capillary channels remaining patent, inwardly projecting folds and ridges were common GBM features, and frequently thin fenestrated layers, distinctly separate from epithelial GBMs, formed sieve‐like linings for the channels. These three‐dimensional observations provide unique views of the processes leading to diabetic glomerular occlusion and suggest a potential for this technique in the study of renal BM disease.
Ultrastructural and metabolic changes associated with reproductive tract atrophy and adiposity in diabetic female mice
Authors: Garris David R. , West R. Lee , Pekala Phillip H.
Published: February 2005

The effect of progressive, diabetes‐associated adiposity on reproductive tract structure and function was examined in 4‐ to 16‐week‐old C57BL/KsJ, control (+/?) and diabetic (db/db) mice. Uterine and ovarian tissues were analyzed by transmission electron microscopy for ultrastructural changes associated with increased intracellular lipid accumulation. In addition, the same tissues were analyzed for changes in activity of tissue lipoprotein lipase, an enzyme that hydrolyzes lipoprotein‐associated triacylglycerols and supports the cellular uptake and storage of free fatty acids. Between 8 and 16 weeks of age, intracellular lipid deposits increased dramatically in the ovarian granulosa, thecal and stromal cell populations, as well as in the uterine epithelium, of diabetic mice compared to controls. By 16 weeks of age, the lipid deposits essentially occupied the entire cytoplasmic area of both the ovarian and uterine cell types in diabetics. The basal lamina underlying the uterine epithelium was expanded in the diabetics relative to controls, and the hyperglycemic condition induced an observable increase in endometrial intercellular space that was occupied by a hyaline type of ground substance of unknown composition and origin. In association with these structural changes, both ovarian and uterine lipase activities were greatly increased in the db/db mice compared with controls. These data suggest that the structural adiposity and functional decline in reproductive tract condition of the db/db mutants are related to the enhanced cellular lipid deposition observed in this species. These changes in structural and metabolic parameters are related to the reproductive incompetence characteristic of this murine model.
Microvascular smooth muscle cell quantitation from scanning electron microscopic preparations
Authors: Gattone Vincent H. , Miller Bryan G. , Evan Andrew P.
Published: February 2005

A morphometric method to analyze scanning electron micrographs (SEM) of microvascular smooth muscle cells (SMC) is validated using intestinal arterioles. Features easily obtained from these microvasculature preparations are counted (number of tapers and number of complete wraps in the central 87% of the vessel, which is one‐third of the vessel's circumference) or measured (vessel diameter and vessel segment length). These data allow the determination of wraps around the vessel per SMC, cell length, and cell width, which are not different from either the values as determined by circumferential examination and quantitation of the vascular segment or an alternative SEM quantitation method (Miller et al., 1986). The method described herein provides a relatively easy way to determine microvascular SMC parameters.
Isthmus and ligament interrelationships: A computerized analysis of the spatial relationships of the hinge structures in unionid mussels
Authors: Le Pennec M. , Petit H. , Jones D. L. , Davis W. L.
Published: February 2005

A study of the isthmus and ligament in unionid mussels was undertaken employing methods specifically designed to preserve the in vivo relationships of these interrelated structures. Serial sections of the hard and soft tissues were used for two‐dimensional analysis. From these, a tridimensional computerized reconstruction was developed. Special dissections of the undisturbed isthmus were also utilized. By using such methodologies, a new description of the ligament has been developed employing such terminology as the foliated ligament and the posterior folding laminae. Similarly, for the isthmus, an anterior lyre, a pallial crest, a pallial peduncle, and a posterior lyre are described. Such entities are both morphologically and physiologically related to the shell and ligament.
Pure population of nonmonocyte derived macrophages arising in organ cultures of embryonic rat lungs
Authors: Sorokin Sergei P. , Hoyt Richard F.
Published: February 2005

After fetal lungs are placed in organ culture, any macrophages arising in them must develop from precursors present at explantation. Whole pseudoglandular lungs from 20 litters of rats were set on an agar medium containing fetal bovine serum on the 14th prenatal day when the metamorphosing embryos do not yet have circulating monocytes. After a day in vitro, 10–30‐μm clusters of rounded cells began to appear in the pulmonary connective tissue. They increased in size, displayed mitotic figures, and were supplemented by additional clusters on succeeding days. Late in the second day, cells began to penetrate the visceral pleura and over the next week built up a large population outside. Histochemically, the intrapulmonary foci and emerging cells were reactive for naphthyl acetate esterase and acid phosphatase, and many were stainable for triglyceride. Within the lungs elevated acid phosphatase activity was first seen at 24 hours; it attained the level of activated alveolar macrophages 1–2 days later. After cells had been emerging 4–5 days, comparatively few clusters remained in the stroma, but some cells had crossed into the airway, to be swept along by ciliary currents. Some cultures were injected with submicronic iron oxide particles on the first day. The particles gradually concentrated within the stromal clusters, and a few emerging cells contained them. Emerged cells avidly ingested iron oxide and rhodamine‐coated latex microspheres. Cells adhering to the cultures were centers of rosette formation after exposure to sheep erythrocytes opsonized with rabbit antisheep IgG and complement factors. The explants evidently contained precursors of macrophages. Cultural conditions provoked them into dividing and exhibiting activation of lysosomes and capacity for directed migration; our experiments showed the transformed cells to be phagocytic and to have receptors associated with immune phagocytosis. The study indicates that macrophages directly derived from stem cells in embryonic lungs are similar in essentials to macrophages in adult lungs, and that this component of pulmonary immune defense is present in an occult form from almost the outset of development.
Rare case of the inferior mesenteric artery arising from the superior mesenteric artery
Authors: Kitamura Seiichiro , Nishiguchi Takahiko , Sakai Akira , Kumamoto Kenzo
Published: February 2005

The authors observed a variation of the inferior mesenteric artery, which arose from the superior mesenteric artery, in a 69‐year‐old Japanese male cadaver during dissection in 1984. In this case, no rudiment of the ordinary inferior mesenteric artery could be found on the abdominal aorta. There are few reports of this variation, and an extensive search of the available literature revealed only four cases, including two in Japan. Such a variation had been somewhat inadequately described as an “absence of the inferior mesenteric artery” in the previous reports, but we avoided this terminology, because all of the cases possessed an artery, which, though arising from the superior mesenteric artery instead of the abdominal aorta, had the same branches as a normal inferior mesenteric artery. Consistent with findings observed in the previous cases, the unusual inferior mesenteric artery arose as the first branch of the superior mesenteric artery, with the common trunk of both mesenteric arteries originating from the abdominal aorta at a level at which an ordinary superior mesenteric artery would arise. It is for this reason that we did not adopt another acceptable name, that is, “the common mesenteric artery,” for this variation. The variation can be explained as the result of an unusual development of the embryonic artery system, which comprises a number of ventral splanchnic arteries interconnected by longitudinal anastomotic channels to supply the primitive digestive tube.
Immunocytochemical and radioautographic evidence for secretion and intracellular degradation of enamel proteins by ameloblasts during the maturation stage of amelogenesis in rat incisors
Authors: Nanci Antonio , Slavkin Harold C. , Smith Charles E.
Published: February 2005

In the continuously erupting rat incisor the ameloblasts progress through distinct stages associated with the secretion and maturation of enamel. We have examined the possibility that the so‐called “postsecretory” ameloblasts of the maturation stage of amelogenesis remain biosynthetically active and are engaged in the synthesis, secretion, and degradation of enamel gene products. The ultrastructural distribution of antigenic sites for enamel proteins was studied within enamel organ cells during the early maturation stage of amelogenesis in rat incisors by using the protein A‐gold immunocytochemical technique and rabbit polyclonal antibodies developed against mouse amelogenins. All regions of amelogenesis from late secretion through the first complete modulation from ruffle‐ended to smooth‐ended ameloblasts were examined. Specific immunolabelling was found within the rough endoplasmic reticulum, Golgi saccules, secretory granules, and lysosomes of ameloblasts throughout these regions. The heaviest intracellular immunolabelling was found within secretory granules and lysosomes (multivesicular type). Quantitative analyses showed that the Golgi saccules and the multivesicular lysosomes of modulating ameloblasts were generally less immunoreactive compared to similar organelles in ameloblasts secreting the inner enamel layer. Radioautographic studies confirmed that ameloblasts of the maturation stage incorporated 3H‐leucine and 3H‐methionine and secreted labelled proteins into the enamel layer. Grain counts indicated that ameloblasts from the first ruffle‐ended band incorporated about twofold less 3H‐methionine and secreted about tenfold less labelled proteins into the enamel compared to ameloblasts secreting the inner enamel layer. The results of this study confirm that ameloblasts do not terminate biosynthesis and secretion of enamel proteins once the final layer has been deposited on the surface of the developing enamel. They continue to form and release new proteins during the maturation stage which intermix with older proteins laid down initially during the secretory stage of amelogenesis. Secretory activity for enamel proteins has been detected in ameloblasts up to at least the second ruffle‐ended phase of maturation, at which point the enamel matrix is partially soluble in EDTA.
Immunohistochemical localization of the secretory products of rat Clara cells
Authors: Manabe Toshiaki , Ikeda Hiromi , Moriya Takuya , Yamashita Koshi
Published: February 2005

We used proteins in rat lung lavage fluid to successfully produce an antiserum against Clara cell secretory products. When used with the immunoperoxidase method, the antiserum specifically stained cells of the bronchiolar lining, which are morphologically consistent with Clara cells, as well as a few columnar cells in the bronchial and tracheal mucosa. B‐5‐fixed lung tissue furthermore demonstrated the immunoreactive layer over the bronchiolar epithelium. The alveolar and bronchial lining layers, on the other hand, were not immunoreactive, although a trace of granular immunoreactivity was seen in the latter. It was suggested that Clara cells produce and secrete some proteinaceous materials, which are mainly localized in the bronchiolar area after secretion and are seldom transferred into the alveolar lining layer. Our antibody cross‐reacted with the Clara cells of mice, but not with those of hamsters, guinea pigs, rabbits, dogs, cats, monkeys, and man. The high degree of specificity of this antisera to Clara cells in formalin‐fixed materials should make it a valuable tool for identifying Clara cell change in non‐neoplastic lung pathology and in obtaining some insights into cell origin in neoplastic diseases.
Distribution of cell types of the islets of langerhans throughout the pancreas of the Chacma baboon
Authors: Wolfe‐Coote Sonia A. , Du Toit D. F.
Published: February 2005

Biopsies of the pancreas head, tail, and uncinate regions of four baboons were processed for immunocytochemical (ICC) studies by using avidinbiotin‐peroxidase label for light microscopy (LM). Toluidine‐blue‐ or methylene‐blue‐stained 0.5‐μm sections of nonosmicated resin‐embedded tissue were viewed to locate areas of suitable islets. For ICC investigations, batches 10 μm apart of ten consecutive 1‐μm sections throughout ten islets from each of the three regions were immunolabelled for LM. Four slides in each batch were immunolabelled consecutively for insulin, glucagon, somatostatin, and pancreatic polypeptide, the fifth acting as one of the range of controls in each batch.

The number of each of the four cell types was counted in at least ten immunolabelled islets from each of the pancreas heads, uncinate portions, and tails. The uncinate region and not the head, as in most mammals, was found to contain significantly higher numbers of pancreatic polypeptide (PP) cells and lower numbers of A (glucagon) and D (somatostatin) cells (P<.001). The PP cells occurred in clumps and not as described in other mammals as part of the mantle of A, D, and PP cells. PP and A cell numbers were significantly different for each region (P<.001), being lowest in the head for PP and in the uncinate process for A cells. D cell distribution was similar to that of the A cells whilst a significantly smaller number of B (insulin) cells was found in the tail compared with other regions (P<.001).
Thyroid development in the marsupial bandicoot, Isoodon macrourus
Authors: Johnston G. M. , Gemmell R. T.
Published: February 2005

The postnatal structural development of the thyroid gland of the Australian native bandicoot, Isoodon macrourus, was monitored and the onset of thyroid function (i.e., the secretion of thyroid hormones) was determined. Thyroid glands were obtained from bandicoots at days 1, 3, 11, 12, 13, 21, 25, 30, 34, 35, 39, 46, 48, 50, 59, 61, 75, 79, 83, and 163 of age and from adult animals, and the tissues were examined with the transmission electron microscope. The thyroid gland of the newborn bandicoot consisted of undifferentiated cells with no lumen. Follicles were first observed at day 12 postpartum, after which time rapid follicular growth occurred. The first signs of thyroid hormone secretion were seen at day 30 postpartum. A peak in thyroid activity seemed to occur around day 50 postpartum, and it correlated with the rapid rate of development of thermoregulatory capacity and hair development which occurred over the last 2 weeks of pouch life.
Trophoblast‐decidual cell interactions and establishment of maternal blood circulation in the parietal yolk sac placenta of the rat
Authors: Welsh Alerick O. , Enders Allen C.
Published: February 2005

Implantation sites from rats were studied on days 6, 7, and 8 of pregnancy to determine the sequence of events in the formation of blood spaces in the trophoblast that is part of the parietal wall of the yolk sac placenta and to determine how trophoblast gains access to maternal blood. The maternal blood flowing through these spaces is the source of nutrients that reach the embryo via the visceral endoderm. Tissues were prepared for light microscopy, scanning electron microscopy, and transmission electron microscopy. Trophoblast blood spaces are derived from the lateral intercellular spaces of trophoblast cells and are present in a collapsed condition until day 8, when maternal vessels are tapped by trophoblast. These spaces than contain circulating maternal blood, and trophoblast cells reflect adaptations for metabolic exchange including thinning of trophoblast covering Reichert's membrane and the appearance of numerous fenestrations, with and without diaphragms, in the areas where trophoblast is attenuated. Between days 6 and 7 decidual cells appear to form a barrier between the maternal circulation and trophoblast. On day 7, however, decidual cell processes penetrate the residual uterine luminal epithelial basal lamina, and then the decidual cells that are juxtaposed to trophoblast undergo degradative changes that resemble apoptosis. There is condensation of cytoplasmic contents, fragmentation of the cells, and phagocytosis of the fragments by trophoblast. Some decidual cells are interposed between endothelial cells in the walls of maternal vessels as early as day 7. Trophoblast may gain access to the maternal vessels by replacing decidual cells or by direct imposition of trophoblast cell processes between endothelial cells.
Hormonal regulation of epithelial cell proliferation in the fetal mouse duodenum in vitro
Authors: Beaulieu J.‐F. , Calvert R.
Published: February 2005

In adult rodents, radioautographic studies have shown that cell proliferation in the small intestinal epithelium is confined to the crypts. However, before birth DNA synthesis occurs also on villi. The role of extrinsic factors in the establishment of the adult pattern of enterocyte proliferation was studied in 17‐day fetal mouse duodenal explants cultured with a completely synthetic medium. The effect of dexamethasone (30 and 300 ng/ml), thyroxine (10 nM), and insulin (125 mU/ml) on labelling indices was determined after 48 hours of culture. At the onset of the culture period close to 60% of the cells located in the first five cell positions in the intervillous areas became labelled after 4 hours of culture in presence of 3H‐thymidine; 8% of the other epithelial cells found higher in the intervillous areas and on villi were also labelled. After 48 hours of culture, well differentiated crypts have developed in all the explants cultured with or without the hormones. The addition of thyroxine or insulin did not modify the labelling indices. However, after 48 hours of culture, the presence of dexamethasone (both concentrations) significantly reduced the labelling index of the cells found over cell position 5 but had no effect on the labelling index of cells located at the bottom of the crypts. When labelling index was determined for each cell position in the crypts at the end of the culture period, it appeared that dexamethasone (300 ng/ml) had no effect thereon for the first five cell positions but had a significant influence on the transitional zone from cell position 6 through 15. In controls, the labelling index fell to 5% for cell position 15, while it reached the same level in position 9 in presence of the hormone. These results indicate that during late fetal life in rodents, glucocorticoids contribute to compartmentalization of the proliferative zone at the bottom of the duodenal crypts and thus might be responsible for the acquisition of the adult proliferative pattern.
Structural organization of the vertebral artery in the giraffe (Giraffa camelopardalis)
Authors: Kimani James Kirumbi
Published: February 2005

Vertebral arteries in the giraffe were removed and their structural organization was studied with light microscopy. It has been shown that the caudal segment of the vertebral artery extending to the level of the seventh cervical vertebra has a largely elastic structure, while the cranial segment has a muscular structure. The transition of the arterial wall normally occurs between the seventh and fifth cervical vertebral levels, and involves diminution of elastic tissue in the luminal portion of the tunica media and simultaneous increase of the smooth muscle content. The smooth muscle cells in the cranial portion show a clustered arrangement consisting of several smooth muscle fibres. The individual clusters are separated by connective tissue septa from which finer strands extend to surround individual muscle fibres. It is suggested that the vertebral and carotid arteries though found in the neck have a different structural organization, which, in turn, may imply that the two blood vessels are subjected to different haemodynamic demands. The findings of this study therefore render further support to the statement that the largely muscular structure of the common carotid artery in the giraffe may be related to the unique cerebral haemodynamics of this animal, rather than being a common feature of the blood vessels situated in the neck. A corollary to this suggestion is the fact that, in the giraffe, as in most other Artiodactyls, the vertebral blood does not participate in the supply of cephalic structures because it is confined to the cervical region by the pressure barrier in the carotid‐vertebral anastomosis.
Ventricular myocardial architecture in marine fishes
Authors: Sanchez‐Quintana Damian , Hurle Juan M.
Published: February 2005

The fiber architecture of the ventricular myocardium has been studied in elasmobranch (Isurus oxyrhinchus, Galeorhinus galeus, Prionace glauca) and teleost (Xiphias gladius, Thunnus thynnus, Thunnus alalunga) fish species with hearts displaying mixed types of ventricular musculature (compact and trabecular). In all cases, the compact myocardium is organized in layers of fiber bundles with an orderly arrangement within the ventricular walls. The number of these layers appears to be dependent on the relative thickness of the compact myocardium. Differences in the pattern of myocardial fiber arrangement were observed among the different fish species. In elasmobranchs the compact myocardium at the level of the atrioventricular orifice is continuous with the trabeculated myocardium. Furthermore, in elasmobranchs the trabeculated myocardium displays a precise arrangement in arcuate trabeculae running from the auriculoventricular to the conoventricular orifices. In teleosts, the compact myocardium is independent of the trabeculated myocardium and a large number of fibers insert into the bulboventricular fibrous ring. The trabeculated myocardium in these species displays an anarchic arrangement except at the level of the bulboventricular orifice, where the fibers tend to be aligned longitudinally, also being inserted into the fibrous ring. Minor differences, consisting mainly of the presence of extra bundles of fibers, were also observed among different individuals of the same species. The possible relationship between myocardial fiber architecture and ventricular shape is discussed.