bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of esophageal epithelium in the fetal and neonatal mouse
Authors: Raymond Calvert , Anne Vézina , Millane Ghania
Published: February 2005

Development of the fetal mouse esophageal epithelium was followed using light microscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and radioautography. At 15 days of gestation in the cervical (C), mediastinal (M), and abdominal (A) segments of the esophagus, the epithelium was two or three cells thick, and only cells located in the basal (germinal) layer incorporated tritiated thymidine. Ciliated cells were sparse in all three segments. At 17 days of gestation, longitudinal mesenchymal ridges became more differentiated in the distal segment. Labeling indices were lower than at preceding stages in each segment. Ciliated cells had increased in number and appeared to be evenly distributed along the whole esophagus. In periodic acid‐Schiff (PAS)‐stained sections, an increasing proximodistal distribution of glycogen stores was observed, with greatest concentrations found in segment A. At 18 days of gestation, labeling indices were comparable in segments C and M (11.7% ± 2.9% and 12.8% ± 1.9%, respectively) but remained higher in segment A (17.9% ± 2.0%). Ciliated cells were still present. At this stage, transverse circular furrows and ridges started to appear. They increased in number at 4 days after birth and were very closely distributed in the adult. In longitudinal sections, these ridges corresponded to projections of stratum granulosum and of the overlying stratum corneum. After birth, ciliated cells desquamated rapidly but some patches were still present at 4 days. At 8 days, the esophageal epithelium was not yet keratinized.
Composition of myofiber types in the pectoral girdle musculature of sheep
Authors: Suzuki Atsushi
Published: February 2005

The muscles of the pectoral girdle in domestic animals attach the forelimbs to the trunk and function as the suspensory apparatus. In the present study the composition of the pectoral girdle musculature of sheep by myofiber types was examined. Myofibers showing a strong reaction for alkali‐stable myosin ATPase were classified into fast‐twitch/glycolytic (FG) myofibers with a weak activity for NADH tetrazolium reductase (NADH‐TR) and fast‐twitch/oxidative/glycolytic (FOG) myofibers with a moderate and strong NADH‐TR activity. Myofibers showing a weak reaction for alkali‐stable myosin ATPase and a strong activity for NADH‐TR were classified as slow‐twitch/oxidative (SO) myofibers. The SO myofibers that showed a granular and striped pattern of diformazan deposits in NADH‐TR activity were classified as SO‐1 myofibers, whereas the SO myofibers characterized by a reticular pattern of diformazan deposits were classified as SO‐2 myofibers. The trapezius, rhomboideus cervicis, and pectoralis descendens muscles situated superficially in the cranial regions of the back and chest had about 50% SO (SO‐1 plus SO‐2) myofibers. The deeply situated serratus ventralis cervicis and thoracis muscles had 37.5% SO myofibers. These five muscles included more SO‐2 myofibers with large diameters than did all other muscles, and had about 50% and more cross‐sectional area of SO myofibers. The other muscles had less than 32% SO myofibers and fewer SO‐2 myofibers. The FOG and FG myofibers accounted for 50% or less in the muscles examined. Many muscles of the pectoral girdle had many fast‐twitch (FOG plus FG) myofibers; they seem to meet locomotory requirements. In the pectoral girdle musculature, the SO myofibers were not necessarily distributed more in the deep regions than in the superficial regions. The distribution of SO myofibers appears to meet postural requirements for stabilizing the shoulder and brachium and for supporting the trunk.
Correlation between blood‐testis barrier development and onset of the first spermatogenic wave in normal and in busulfan‐treated rats: A lanthanum and freeze‐fracture study
Authors: Cavicchia Juan C. , Sacerdote Fabio L.
Published: February 2005

Pregnant rats (day 13) received 10 mg/kg of Busulfan i.p. The seminiferous tubules of their offspring from post‐natal age 1 day up to day 35 were examined with TEM after fixation plus intercellular tracers, and with freeze‐fracture techniques. During this period, the inter‐Sertoli tight junctions of controls increase both in number and in length. Between days 10 and 13 the seminiferous cords have numerous preleptotene and leptotene spermatocytes surrounded by tracer. The inter‐Sertoli junctions are tortuous and predominantly perpendicular to the basal lamina. Between ages 13 and 20 days the seminiferous epithelium reaches zygotene‐pachytene stages. The tracer is stopped at the inter‐Sertoli junctions at this stage, whereas it still permeates tubules displaying preleptotene and leptotene spermatocytes. Freeze‐fracture shows that the orientation of inter‐Sertoli junctions has changed to parallel, both to each other and to the basal lamina. In the Busulfan‐treated rats, the tubules continue having, up to post‐natal day 30, only Sertoli cells and scanty spermatogonia. In these, lanthanum penetration goes as far as the apical Sertoli cell region; the inter‐Sertoli junctions still show tortuous strands, and most are oriented perpendicular to the basal lamina. This indicates that formation of the first competent inter‐Sertoli junctions is temporo‐spatially simultaneous with the appearance of zygotene‐pachytene spermatocytes.
Biomechanical changes in the rabbit masticatory system during postnatal development
Authors: Langenbach Geerling E. J. , Weijs Wim A. , Koolstra Jan Harm
Published: February 2005

Using dissection, biometry, and two three‐dimensional mechanical models, the postnatal changes of the rabbit masticatory muscles were studied by analyzing their three‐dimensional orientation, their strength and fiber lengths, and certain functional consequences of these changes. The first mechanical model uses length‐tension relationships of the muscles and predicts the maximum bite force as a function of mandibular position. It shows that young rabbits are able to generate large bite forces at a wider gape than adult animals and that the forces are directed more vertically. In spite of the postnatal changes the mechanical advantage of the system remains about equal. However, the muscles are reoriented so that they exert a larger degree of parallel action, suggesting a larger bite force magnitude but a smaller range of bite force directions. The second model predicts this range. It shows that during postnatal development a relative gain occurs in the possibilities for the system to exert forces directed rostrodorsally. In all other directions the capability to exert force decreases. The results suggest that during development the possibility of the system to generate large bite forces is increased at the cost of a restriction in the range of jaw excursion and that a restriction takes place in the range of possible force directions that can be exerted at the molars.
Endocytotic activity of the free floating cells and epithelial cells in the endolymphatic sac: An electron microscopic study
Authors: Fukazawa Keijiro , Sakagami Masafumi , Matsunaga Toru , Fujita Hisao
Published: February 2005

The fine structure and its functional properties of both free floating cells and epithelial cells in the endolymphatic sac after injections of India ink particles or polystyrene latex beads, 0.24 μm in diameter, into the endolymphatic space, were studied using light and electron microscopy. Twenty‐four to 48 hours after injections, these foreign materials had accumulated in the lumen of the endolymphatic sac and a large number of them were ingested into free floating cells, most of which appear to be macrophages. Granular leucocytes taking up the foreign materials into the cytoplasm were also recognized in the sac lumen. A few of these leucocytes passed through the epithelium and migrated to the subepithelial connective tissue, while the others were degenerated and phagocytosed by the free floating cells in the lumen of the sac. In addition to the free floating cells, ink particles, latex beads, and degenerated leucocytes were endocytosed into some of the epithelial cells. As we reported previously, the epithelial cells were clearly classified into two types; type‐1 epithelial cells (cytoorganelle‐rich cells) and type‐2 epithelial cells (filament‐rich cells). The foreign materials and degenerated cells were taken up mainly into the type‐1 epithelial cells, while the type‐2 epithelial cells did not show so marked endocytotic activity in comparison with the type‐1 epithelial cells. Thus, it becomes clear that the endolymphatic sac plays an important role in the endocytotic activity for foreign materials and waste products, and both the free floating cells and the type‐1 epithelial cells of the sac have strong endocytotic activity.
Age effects on cytochrome oxidase activities during denervation and recovery of three muscle fiber types
Authors: White Ketti K. , Vaughan Deborah W.
Published: February 2005

The rat nasolabialis muscle is comprised of a mosaic of red, white, and intermediate muscle fiber types. Using computerized microdensitometry, cytochrome oxidase (COX) activity was quantitatively analyzed in each fiber type throughout the period of denervation and recovery in young adult (3‐month) and middle‐aged (15‐month) male Sprague‐Dawley rats. In animals of both age groups, the nasolabialis muscle on one side of the head was denervated by crushing the facial nerve. At specific days post crush (dpc) ranging from 2 days–2 months, animals were sacrificed and thick sections of normal and denervated muscles were incubated to demonstrate the activity of COX, a mitochondrial enzyme, which differentiates between the three fiber types. Enzyme activities in individual fibers were microdensitometrically analyzed using a digitizing image analyzer. Although a denervation‐induced decrease followed by eventual recovery occurred in all fibers of each type, age‐related differences were evident. For all types, younger fibers consistently showed decreased COX activity sooner than their older counterparts, and older fibers of all types consistently showed a greater decreased COX activity than the younger fibers. Denervation‐induced de‐differentiation of muscle fibers led to a more homogeneous population of fiber types in both age groups. Following recovery of function, the magnitude of the fiber enzyme activity change differed according to fiber type and to age, and was consistently smaller in older animals. The normal mosaic pattern of fiber type distribution and normal COX levels were restored 2 months after nerve lesion in both age groups.
Origin and distribution of perforatorial proteins during spermatogenesis of the rat: An immunocytochemical study
Authors: Oko Richard , Clermont Yves
Published: February 2005

The perforatorium is the subacrosomal portion of the perinuclear theca that encapsulates the nucleus of spermatozoa. In the rat, the perforatorium is a curved pointed structure, which in cross section is triangular in outline over the apical half and beyond the tip of the nucleus. The perforatorium, composed of several proteins, appears as a distinct structural entity only at the very end of spermiogenesis. In this study, polyclonal antibodies prepared against the entire isolated perforatorial fraction and against the major 16 and 34 kDa perforatorial polypeptides were used to determine the distribution of perforatorial proteins in germinal cells at various steps of differentiation. Immunoperoxidase staining at the LM level and quantitative immunogold labeling at the EM level were used. The labeling patterns with all three antibody preparations were identical. The immunolabeling first appeared in early pachytene spermatocytes and increased progressively, with a statistically significant upward trend, in both the nuclei and cytoplasm of spermatocytes and spermatids until step 9 of spermiogenesis. Up to this step the labeling concentration was significantly higher over the nucleus than over the cytoplasm. During nuclear condensation in steps 9 and 12 spermatids, there was a progressive loss of all the labeling over the nucleus and a corresponding increase of labeling over the cytoplasm. During steps 16–18, the early signs of condensation of perforatorial proteins occurred next to the inner acrosomal membrane. Then during step 19 there was a sudden condensation of perforatorial proteins into a definitive perforatorium. Thus proteins destined to form this cytoskeletal structure reside in both the nucleus and cytoplasm of spermatocytes and spermatids until nuclear condensation of the latter. Thereafter, they are restricted to the spermatid's cytoplasm and finally condense around the elongated nucleus at the end of spermiogenesis.
Glycoconjugate histochemistry of Xenopus laevis fundic gland with special reference to mucous neck cells during development
Authors: Oinuma Tsutomu , Kawano Jun‐Ichi , Suganuma Tatsuo
Published: February 2005

Mucous neck cells (MNCs) of the fundic gland are phylogenetically thought to have first appeared in amphibians. We studied the origin and differentiaion of MNCs in fundic glands of Xenopus laevis. By means of lectin histochemical methods using Griffonia simplicifolia agglutinin‐II (GSA‐II), MNCs were detected specifically in fundic glands of adult X. laevis. Mucous granules of MNCs were labeled by GSA‐II‐colloidal gold (CG) staining. Other cells such as surface mucous cells (SMCs), oxynticopeptic cells (OPCs), and endocrine cells did not react to GSA‐II. Ulex europaeus agglutinin‐I specifically stained OPCs, but not MNCs and SMCs. During the morphogenetic period of the stomach in metamorphosing larvae, GSA‐II reactive cells randomly appeared in various portions of the underdeveloped fundic glands and then rapidly localized in the neck portion. At this time, newly appearing mucous granules of MNC type were labeled by GSA‐II‐CG. Two types of cells intermediate to MNCs and SMCs and intermediate to MNCs and OPCs were observed in the larval gastric region. Cells intermediate to MNCs and OPCs were also found in adults. In these cells, mucous granules of MNC type were labeled by GSA‐II‐CG, but mucous granules of SMC type and zymogen‐like granules did not react to GSA‐II. These observations suggest that GSA‐II is a useful marker in studying the differentiation of MNCs and their precursors regardless of species differentiation.
Morphological analysis of the cellular interaction between thymocytes and a thymic stromal cell line (TEL‐2)
Authors: Hirata Kazuho , Mori Keiko , Nakamura Keiichiro , Kawabuchi Masaru , Watanabe Takeshi
Published: February 2005

In a previous study (Nakashima et al., Eur. J. Immunol., 20: 47–53, 1990), a cloned stromal cell line TEL‐2 was established from Balb/c mouse thymus. Incubation of thymocytes with TEL‐2 cells resulted in the selective elimination of CD4 and CD8 double‐positive thymocytes from the culture. In the present report, both phase‐contrast and scanning electron microscopes were used to examine, at various time intervals, TEL‐2 cells cocultivated with thymocytes in order to elucidate the kinetic sequence of their cellular interaction. The thymocytes attached to the TEL‐2 cell surface were more numerous at early times (30 min to 1 h), and their number decreased gradually with time. In contrast, the thymocytes that migrated into the TEL‐2 cell layers were less abundant at early times, their number increasing with time thereafter. Destruction of the regular arrangement of TEL‐2 cells was found at later than 1 h, suggesting active cellular interaction. The thymocytes adherent to the TEL‐2 cell surface were found to be of various shapes and often showed variable profiles, e.g., extending small cytoplasmic processes along the surface of TEL‐2 cells or appearing ameboidal. A remarkable feature of the TEL‐2 cells was that they formed numerous “round spaces” at the surface of the TEL‐2 cell layers. The thymocytes were often located around “round spaces,” and some were seen migrating into TEL‐2 cell layers through these round spaces. In addition, complementary examinations by transmission electron microscopy revealed that the internalization of thymocytes into TEL‐2 cells occurs inside the TEL‐2 cell layers after migration. Thus, the present study confirmed the existence of a certain type of cellular interaction between thymocytes and TEL‐2 cells. The TEL‐2 cell line may provide a model system for the study of the selection mechanism in the process of T‐cell maturation.
The kidney of tapirs: A macroscopical study
Authors: Maluf N. S. R.
Published: February 2005

The renal cortex of tapirs, water‐loving primordial ungulates, was continuous, nonlobed, and about 80% of renal mass in adult and 71% in term‐neonate. In the neonates even the peripheral glomeruli were moderately mature.Tapirus bairdihad about 4 million glomeruli per kidney andT. pinchaqueabout 3 million smaller glomeruli. Number of glomeruli per gm of cortex was 12,444 inT. bairdiand 13,400 inT. pinchaque. Cortical loops were common in the medullary rays.

The medulla was the simple crest‐type. The terminal collecting ducts (T.C.D.) opened separately at the crest and not into a tubus maximus. The “outer stripe” of the outer medulla apparently was telescoped into the deep cortex. The medullary loops turned at a thick portion and at nearly all levels of the medulla. The medullary crest was lined by urothelium which extended into the ends of the T.C.D. Otherwise the T.C.D. were made of columnar epithelium.

The pelvic urothelium was continuous with that of the medullary crest at the dorsal and ventral fornices. The fornices were well within the inner medulla. Hence only inner medulla could be exposed to pelvic urine.

The hilar arteries, unlike the other two perissodactyl families (rhinoceri and equids), passed through the cortico‐medullary (C‐M) border and some large arteries and veins passed through the outer medulla to and from the C‐M border without branches or tributaries. Unlike kidneys with a medullary crest in diverse eutherian mammals, tapirs lacked pelvic extensions along the major intrarenal blood vessels and thus lacked pelvic intervascular eminences.
Experimental analysis of blood vessel development in the avian wing bud
Authors: Feinberg Richard N. , Noden Drew M.
Published: February 2005

Shortly after its appearance, the avian limb bud becomes populated by a rich plexus of vascular channels. Formation of this plexus occurs by angiogenesis, specifically the ingrowth of branches from the dorsal aorta or cardinal veins, and by differentiation of endogenous angioblasts within limb mesoderm. However, mesenchyme located immediately beneath the surface ectoderm of the limb is devoid of patent blood vessels. The objective of this research is to ascertain whether peripheral limb mesoderm lacks angioblasts at all stages or becomes avascular secondarily during limb development.

Grafts of core or peripheral wing mesoderm, identified by the presence or absence of patent channels following systemic infusion with ink, were grafted from quail embryos at stages 16–26 into the head region of chick embryos at stage 9–10. Hosts were fixed 3–5 days later and sections treated with antibodies that recognize quail endothelial cells and their precursors.

Labeled endothelial cells were found intercalated into normal craniofacial blood vessels both nearby and distant from the site of implantation following grafting of limb core mesoderm from any stage. Identical results were obtained following grafting of limb peripheral mesoderm at stages 16–21. However, peripheral mesoderm from donors older than stage 22 did not contain endothelial precursors. Thus at the onset of appendicular development angioblasts are present throughout the mesoderm of the limb bud. During the fourth day of incubation, these cells are lost from peripheral mesoderm, either through emigration or degeneration.
Immunohistochemical localization of components of the immune barrier in the olfactory mucosae of salamanders and rats
Authors: Getchell Marilyn L. , Getchell Thomas V.
Published: February 2005

Immunohistochemical techniques were used to investigate the cellular distribution of components of the secretory immune system, including secretory immunoglobulin, secretory piece, and J chain, as well as other immunoglobulins and nonspecific defense factors in the olfactory mucosae of salamanders and rats.

In the salamander, secretory immunoglobulin M, and J chain were localized in duct and acinar cells of Bowman's glands, in B lymphocytes, and in sustentacular cells in immature regions of the olfactory mucosa. Lactoferrin and lysozyme were also present in Bowman's glands, in sustentacular cells in immature regions of the olfactory mucosa, and in blood cells in the lamina propria. Olfactory nerve section resulted in the presence of increased numbers of secretory immunoglobulin‐immunoreactive B lymphocytes and in an altered distribution of IgM, secretory piece, and lactoferrin.

In the rat, secretory immunoglobulin A and J chain were localized in duct and acinar cells of Bowman's glands and in B lymphocytes in the lamina propria. Secretory piece could be demonstrated in Bowman's glands only in rats that had a prior viral infection. Other defense factors, localized in the lamina propria, included IgG in the connective tissue stroma and in B lymphocytes, IgD‐immunore‐active B lymphocytes, and IgE‐immunoreactive cells that were identified as mucosal mast cells. Lactoferrin and lysozyme were present in serous acinar cells of Bowman's glands and in blood cells.

These results demonstrate that the olfactory mucosa is protected from pathogenic invasion by the secretory immune system as well as other immunoglobulins, lactoferrin, and lysozyme.
Reconstruction of basement membrane in recombinants of epidermis and dermis of chick embryonic skin in vitro: An electron microscopic study
Authors: Akimoto Yoshihiro , Obinata Akiko , Endo Hiroyoshi , Hirano Hiroshi
Published: February 2005

The tarsometatarsal skin from 13‐day‐old chick embryos was treated with EDTA and/or Dispase to separate it into epidermis and dermis, and the basal lamina was removed. The isolated epidermis and dermis were then recombined and cultured on Millipore filters in a chemically defined medium (BGJb). Beginning at 3–4 days after recombination, short fragments of new basal lamina and subbasal dense plaque were formed along the epidermal basal cell outer surface immediately subjacent to hemidesmosomes. After 6–8 days of culture, fragments of the basal lamina started to fuse together and the lamina became progressively continuous. At the same time, anchoring fibrils were formed to attach to the basal lamina. The hemidesmosome formation preceded the basement membrane formation. When normal embryonic epidermis was recombined with retinolpretreated dermis and cultured for 7 days in BGJb, short fragments of the basal lamina, the subbasal dense plaque, and anchoring fibrils were formed, but the basement membrane remained discontinuous with many interruptions in the interspace between hemidesmosomes. These results demonstrate that pretreatment of dermis with retinol causes the changes noted in the basement membrane.
Endothelial cell origin and migration in embryonic heart and cranial blood vessel development
Authors: Douglas J. , Poole Thomas J.
Published: February 2005

Using the QH‐1 monoclonal antibody as a marker for quail endothelium, blockage and transplant experiments were carried out to construct fate maps for the embryonic endocardium, to determine whether preendocardial angioblasts are migratory, and, if these cells are migratory, to outline the pathways that they use for directed migration in embryonic blood vessel development. Recent descriptive studies using QH‐1 to make immunofluorescent whole mounts have described a sequence of events leading to the establishment of the embryonic heart tube. These reports suggest that the pattern for the endocardium and cranial vasculature is established by migrating angioblasts that form vascular cords which mature into blood vessels. Blockage experiments showed that the ventrolateral edge of the anterior intestinal portal serves as a substrate for the directed migration of pre‐endocardial angioblasts and that the pattern of the cranioventral vasculature forms independent of the source of angioblasts. Transplant experiments showed that the origin for endocardial angioblasts lies in mesodermal tissue just anterior to Henson's node, that these cells undergo directed migration to the pericardial area, and that angioblasts are pluripotent with the ability to form different blood vessels. The transplant studies also showed that the embryonic mesoderm may contribute to extraembryonic blood vessels on the embryonic yolksac. These results support the hypothesis that embryonic blood vessels may develop by either the vasculogenesis or by the angiogenesis mechanism, and show that the endocardium of the primitive heart tube forms by vasculogenesis.
Epithelial cells of the epididymis show regional variations with respect to the secretion or endocytosis of immobilin as revealed by light and electron microscope immunocytochemistry
Authors: Hermo L. , Oko R. , Robaire B.
Published: February 2005

The localization of immobilin, a glycoprotein known to be present and to immobilize spermatozoa in the lumen of the epididymis, was investigated using light and electron microscope immunocytochemistry. In the light microscope, a distinct immunoperoxidase reaction product was observed in the lumen over the brush border of the epithelial nonciliated cells of the efferent ducts, while only a faint reaction was seen over their supranuclear region. In the proximal area of the initial segment of the epididymis no immunoperoxidase staining was observed either over epithelial cells or in the lumen. In the middle area of the initial segment, several epithelial principal cells became intensely immunostained but the majority were unstained; a weak reaction appeared in the lumen. In the distal area of the initial segment, more principal cells became immunostained, and while some were intensely reactive, others were moderately or weakly stained or unreactive. In the intermediate zone and proximal caput epididymidis, the principal cells showed the maximal immunoreactivity with all principal cells being reactive; staining in the lumen also reached its maximal reactivity in these areas. Immunostaining of principal cells gradually decreased along the epididymal duct and disappeared in the cauda epididymidis, however, an intense reaction persisted in the lumen. In the distal area of the cauda epididymidis, clear cells were reactive. In the electron microscope, immunogold labeling of reactive principal cells of the middle and distal areas of the initial segment, intermediate zone, and caput epididymidis was detected over cisternae of endoplasmic reticulum, stacks of Golgi saccules, and spherical electron lucent (200–400 nm in diameter) vesicles. The latter were present on the trans face of the Golgi stack, in the vicinity of the Golgi apparatus, and close to the apical cell surface; they are considered as secretory vesicles involved in the secretion of immobilin. In the distal area of the cauda epididymidis, epithelial clear cells showed an intense immunogold labeling over their endocytic apparatus. Immunogold labeling in the lumen of the epididymis was found over a fine flocculent material dispersed between the sperm. This material was especially abundant in the cauda epididymidis and did not appear to be bound to the surface of the sperm. The present results suggest that principal cells of the epididymis are involved in the secretion of immobilin, but that a differential secretory pattern exists between epididymal segments with maximal secretory activity occurring in the intermediate zone and proximal caput epididymidis, while no secretion takes place in the cauda epididymidis. Excess immobilin appears to be endocytosed for degradation by clear cells of the cauda epididymidis.
Female syrian hamster harderian gland: Development and effects of high environmental temperature and melatonin injections on histology and porphyrin deposits
Authors: Rodriguez‐Colunga Maria J. , Fernandez Covadonga , Rodriguez Carmen , Tolivia Delio , Menendez‐Pelaez Armando
Published: February 2005

We have investigated the development of the Harderian glands of female Syrian hamsters from birth to 8 months of age. The effects of melatonin injections on Harderian gland histology and porphyrin deposits of female hamsters exposed to two different temperatures were also studied. The morphology of the Harderian glands from 30‐day‐old female hamsters resembled those of sexually mature adult animals. The intraluminal area occupied by porphyrins increased significantly between 20 to 30 days of age. However, the relative number of mast cells per mm2 rose between 30 to 90 days. Both porphyrins and mast cell numbers appeared clearly reduced in the 8‐month‐old group. Secretory cells characterized by large lipid droplets (type II cells) were not observed.

Daily afternoon injections of 25 μg of melatonin to female hamsters exposed to 22°C for 14 weeks resulted in the discontinuity of estrous cyclicity, a marked dccrease in the intraluminal area occupied by porphyrins, a reduction of the number of mast cells per mm2, and in a marked augmentation of the number of type II cells per mm2. Although the administration of similar dosages of melatonin to hamsters exposed to an environmental temperature of 32°C did not interrupt estrous cycles, a clear reduction of the area occupied by porphyrins was observed. However, the number of mast cells and type II cells per mm2 was unaffected in these animals.

Our results suggest that hormones other than ovarian steroids are involved in the regulation of the female hamster Harderian glands. The possible role of melatonin on Harderian gland metabolism is discussed.
Sheets of embryonic epidermis can be isolated and cultured with or without the basal lamina
Authors: Reenstra Wende R. , Svoboda Kathy K. H.
Published: February 2005

In the current study, we determine the concentration of Dispase II, a neutral protease, and the incubation time necessary for isolation of embryonic avian epidermis. The epidermis can be isolated from the dermis consistently with or without the basal lamina. Because the action of Dispase II is selective and easily controlled, this study suggests that Dispase can serve as a powerful tool for studying epidermal‐extracellular matrix interactions. In further experiments we study the response of sheets of epidermis isolated with and without its basal lamina to extracellular matrix. When the epidermis is isolated without the basal lamina, the basal surface blebs and the actin in the basal cytoplasm are disrupted. Epidermis isolated without the basal lamina and cultured on extracellular matrix reorganizes the basal actin mat and retracts the blebs. However, epidermis isolated without the basal lamina and cultured in the absence of extracellular matrix continues to have blebs and a disorganized actin cortical mat. In contrast, the control epidermis isolated with the basal lamina retains a flat basal surface and organized actin cortical mat after culturing either with or without extracellular matrix. The extracellular matrix has been shown by many investigators to play an important role in cytoskeletal organization, metabolism, and differentiation. How the extracellular matrix interacts and influences these functions has not been completely elucidated. The ability to isolate tissue consistently with and without its basal lamina using Dispase II will facilitate addressing these and other epithelial cell biology questions.
Gross and microscopic anatomy of the vagal innervation of the rat heart
Authors: Burkholder T. , Chambers Mary , Hotmire Kurt , Wurster Robert D. , Moody Stephanie , Randall Walter C.
Published: February 2005

Intrinsic cardiac ganglia and their vagal innervation are described from gross and microscopic dissections and functional studies in the anesthetized, open‐chest, adult rat. Dissecting microscope sketches of the ventral and dorsal aspects of the rat heart provide gross descriptions of the anatomical course of the vagal cardiac nerves. Histological sectioning of adipose tissue packets surrounding the terminal endings of vagal branches distributed to the roots of the great cardiac vessels (aorta, pulmonary artery, precaval veins) revealed clusters of autonomic ganglia. These packets or “fat pads” were located: (1) along the dorsal surface of the right precava and extending medially toward the aortic root, (2) deep to the aortic arch, (3) in the angle between the root of the left precava and the pulmonary artery on the superior‐dorsal surface of the left atrium, and (4) in the rostro‐dorsal interatrial septum. Vagal distributions of small terminal branches were traced to each of these pads, which contained numerous autonomic ganglia. Electrical excitation of right or left cervical vagus elicited varying degrees of sinus slowing, slowing of A‐V conduction, and suppression in atrial contractile force. Very small quantities (0.5 mg in 10 μl saline) of the ganglionic blocking agent, hexamethonium (C6) were injected selectively into a single fat pad, followed by repetition of right or left vagal stimulation, with careful analysis of changes in heart rate (paced and unpaced), A‐V conduction, and contractile force.
Maintenance by androgen and thyroid hormone of androgen‐induced convoluted tubular cells in mouse submandibular glands
Authors: Oda Mariko , Yamamoto Reiko , Terada Nobuyuki , Nishizawa Yasuko , Takatsuka Daishiro , Kitamura Yukihiko , Matsumoto Keishi
Published: February 2005

Injection of 5α‐dihydrotestosterone (DHT) into castrated adult female mice stimulated the proliferation of a small proportion of the convoluted tubular cells in the submandibular glands. We investigated the effects of DHT and thyroxine (T4) on the maintenance of these proliferated convoluted tubular cells. For this, castrated adult female mice that had been treated daily with DHT for 3 days and then once with [3H]thymidine, received a first series of daily injections of DHT for various periods or T4 for 10 days, and then a second series of injections of treatment with DHT or T4, or no further treatment. The second series of treatments with DHT or T4 maintained the percentages of 3H‐labeled convoluted tubular cells at similar or slightly lower levels than those at the end of the first series of treatments. In mice that did not receive the second series of treatments, the percentages of 3H‐labeled convoluted tubular cells decreased markedly, becoming significantly lower than those at the end of the second series of treatment with DHT or T4. We also examined the effect of DHT on the proliferation of convoluted tubular cells of castrated adult female mice that had received 10 daily injections of DHT and then no treatment for 28 days. In these mice, the cells did not proliferate markedly on stimulation with DHT. These results suggest that androgen and thyroid hormone maintain convoluted tubular cells that have proliferated in response to androgen, and that the convoluted tubular cells may become unresponsive to androgen in terms of proliferation after their exposure to androgen.
Determination of relative fiber orientation in heart muscle: Methodological problems
Authors: McLean Miriam , Prothero John
Published: February 2005

Knowledge of the muscle pattern in the heart is important to understanding cardiac contraction and propagation of the electrical stimulus. Most work on this pattern has been carried out by blunt gross dissection, whereby fiber bundles are easily visible on the peeled heart wall. However, it has never been shown, to our knowledge, that the orientation of macroscopic fiber bundles seen in a peeled heart corresponds to that of the constituent myofibers (muscle cells). For this purpose, one needs to carry out a three‐dimensional microscopic reconstruction within a documented macroscopic reference frame. To draw valid conclusions in such a coordinated macroscopic and microscopic study, one must estimate the (slice) angle between the long axis of a muscle cell and the plane of section. Otherwise any alleged differences between the macroscopic and microscopic orientations may be just an artifact of sectioning. In this study we have shown that, provided the images of the myofibers meet simple criteria, one can be reasonably confident that the potential error incurred by sectioning is small. On this basis, we demonstrated that while there is a general correspondence between the macroscopic fiber and the microscopic myofiber orientations, there are significant differences in detail.
Correlation of the arrangement pattern of enamel rods and secretory ameloblasts in pig and monkey teeth: A possible role of the terminal webs in ameloblast movement during secretion
Authors: Nishikawa Sumio
Published: February 2005

Enamel rod architecture and ameloblast arrangement were examined in pig and monkey teeth using light microscopy and scanning and transmission electron microscopy. Enamel rods in the pig teeth were arranged in longitudinal straight rows in the initial enamel layer, in longitudinal wavy rows in the inner enamel layer, and in a staggered pattern in the outer enamel layer. Rod decussation was seen only in the inner layer. Cross‐sectined enamel rods in the pig were arcade‐shaped in the initial and inner layers, and mostly round in shape with circular boundaries in the outer layer. Arrangement of secretory ameloblasts at the level of the distal terminal web and Tomes' processes, and shape of Tomes' processes, corresponded to those of the enamel rod in the enamel layers. Distal terminal webs were well developed between straight rows of the ameloblasts forming the initial layer and between wavy rows of the ameloblasts forming the inner layer, and less developed within a row. The filament bundles in the distal terminal webs were also oriented along the rows. However, in the ameloblasts forming the outer layer, which lost their row pattern, distal terminal web filaments were distributed uniformly at the cell periphery. A similar arrangement of wavy rows of ameloblasts at the level of distal terminal web and Tomes' processes was also seen in monkey teeth.
Immunolocalization of laminin, heparan‐sulfate proteoglycan, entactin, and type IV collagen in the rat anterior pituitary. I. An in vivo study
Authors: Vila‐Porcile E. , Picart R. , Vigny M. , Tixier‐Vidal A. , Tougard C.
Published: February 2005

The distribution of three components of basement membranes (BM): heparan‐sulfate proteoglycan (HSPG), entactin (ENT), and type IV collagen (Coll. IV), was studied in the adult rat anterior pituitary and compared to the distribution of laminin (LAM) described in an earlier report (Vila‐Porcile et al., 1987, J. Histochem. Cytochem., 35, 287). Several immunocytochemical methods were applied at both light and electron microscope levels.

The three components were detected in all the pituitary BM and in endothelial and perivascular connective cells, as previously observed for LAM within epithelial cells, however, only a faint immunoreaction could be detected for the other components, with nonetheless a discrete signal for Coll. IV.

These findings indicate that (1) the four studied components are present in all the BM of the rat anterior pituitary; (2) pituitary endocrine cells contain LAM, and to a lesser extent Coll. IV, and thus could participate to the elaboration of the BM; and (3) the presence of the four components in non‐epithelial cells also suggests their cooperation in BM building. The questions of the turnover and intracellular pathways of each of these components were addressed but remain unanswered.
Glomerular size and volume distributions for cranial, medial, and caudal divisions of domestic fowl kidneys
Authors: Wideman Robert F. , Holt Laura , Pla Jose S.
Published: February 2005

Separate renal arteries and renal portal veins supply the three divisions of domestic fowl kidneys, leading to uncertainty concerning the structural and functional homology of the different divisdions. To assess the degree of anatomical similarity, separate glomerular size and volume distribution profiles were constructed for cranial, medial, and caudal divisions from the left and right kidneys of male and female domestic fowl. There were no significant differences between left and right divisions (intradivision comparisons) or between cranial, medial, and caudal divisions (interdivision comparisons) when the total number of glomeruli or total glomerular volumes were compared on a per gram kidney weight basis. Glomerular size distribution profiles were unimodal in shape, with the peaks for all divisions falling in the 0.15–0.22 mm circumference range in males and in the 0.19–0.26 mm circumference range in females. There were no significant differences in glomerular size distribution profiles for intradivision (left vs. right) comparisons. Interdivisional comparisons revealed that medial divisions had significantly lower values than caudal divisions in one of 11 glomerular circumference categories. For all remaining comparisons, there were no significant dífferences in glomerular size distribution profiles, nor were there any significant interdivisional differences when glomerular volume distribution profiles were compared. These data indicate that the three divisions of domestic fowl kidneys are structurally homologous on a per gram kidney weight basis, suggesting the separate divisions also are functionally homologous.
Macrophage development: I. Rationale for using Griffonia simplicifolia isolectin B4 as a marker for the line
Authors: Sorokin Sergei P. , Hoyt Richard F.
Published: February 2005

The isolectin B4 of Griffonia simplicifolia (GSA I‐B4) binds to cell membrane glycoconjugates bearing terminal alpha‐D‐galactose, which macrophages possess. We have investigated the merits of its use as a marker for cells of this lineage when examining the early origin of macrophage populations in rat embryos, the stages and time scale of transformation from precursor forms to active, matured cells, and the response of precursors and macrophages to colony‐stimulating blood factors, the last two studies conducted in organ cultures of prenatal lungs. In the present instance, GSA I‐B4 was used either coupled with fluorescein (FITC) for light microscopy of living and fixed cells, or with peroxidase for light or electron microscopy. Control incubations of lung culture‐derived macrophages proved that staining resulted from specific binding to galactosyl units on the cell membrane, since it was competitively inhibited by alpha‐D‐galactose. The lectin binds to few cells in 14‐day prenatal lung explants but to a great many macrophages that subsequently develop in the cultures, indicating that it can be relied on for quantitative studies on population growth; however, it is important to provide reagents with good access to the cells. Apart from macrophages and their precursors, virtually no cells in prenatal lung cultures bind this lectin. Granulocytes of adult blood are GSA positive, but they are not yet present in 14‐day prenatal explants and do not develop subsequent to culturing; hence they are not a source of confusion for experimental studies using this system. Precursors of granulocytes begin to appear in rat embryos around day 13 and have GSA‐positive cell membranes, but like definitive granulocytes they also have conspicuous peroxidase‐positive lysosomal granules which serve to distinguish them from early macrophages, particularly when cells are studied at an ultrastructural level. With these objections cleared away, GSA I‐B4 emerges as a valuable means to mark cells of the macrophage line, mature or immature.
Macrophage development: III. Transformation of pulmonary macrophages from precursors in fetal lungs and their later maturation in organ culture
Authors: Sorokin Sergei P. , McNelly Nancy A. , Blunt Dana G. , Hoyt Richard F.
Published: February 2005

The fate of macrophage precursors residing in 14‐day prenatal rat lungs was followed in organ cultures to obtain a detailed, ultrastructurally resolved picture of the sequence and timing of events accompanying their transformation into typical pulmonary macrophages. Cultures were examined at close intervals during the first day (1, 2, 3, 4, 6, 9, 12, 15, 18, and 24 hr) and at wider intervals thereafter (2, 4, 5, 7, 9, 12, and 13 days) to yield a developmental series of cells identified as in the macrophage line based on binding of peroxidase‐coupled isolectin B4 of Griffonia simplicifolia (GSA I‐B4) to cell membranes and on negligible content of peroxidase‐positive granules in the cytoplasm. Organ culturing stimulated virtually all precursors to develop into macrophages. GSA‐positive cells in explants occurred outside vessels in pulmonary connective tissue, and at the outset none were typical macrophages: 71% were angular cells, resembling unlabeled mesenchymal cells around them, 16% were undifferentiated leukocytes, and the remainder were irregularly shaped cells with few vacuoles intermediate between the preceding and the macrophages. During the first 12 hr in culture the proportion of angular cells and leukocytes fell to zero, and that of Intermediate cells first rose, then receded. In the same interval the proportion of macrophages rose to 87.5%, and by 24 hr all GSA‐positive cells were typical macrophages generally engorged with phagocytosed material; about 8 hr appear necessary for converting half the population. Notable ultrastructural changes during this period of transformation involved the centrioles and cytoskeleton, reflecting enhanced cell mobility and phagocytosis. A period of maturation followed, marked by disappearance of cellular debris from phagosomes and an increased prevalence of cells with elaborate lamellipodia. This accords with earlier work showing that macrophage Fc receptor density increases sharply during the first 24 hr, but elevated levels of histochemically demonstrable acid phosphatase appear only later. Mitotic activity was conspicuous in GSA‐positive cells throughout both periods. 3H‐thymidine labeling indices for precursors and macrophages, determined at six intervals between 1 hr and 24 hr, remained steady at ∼ 34%, whereas indices of other categories of lung cells (GSA‐negative strimal cells, pleural cells, and airway epithelium) began at this level but rapidly declined, indicating that the GSA‐positive cells constitute a single population distinct from others in the lungs. Macrophages found outside the lung cultures after 4–5 days qualify as a mature population, but having migrated away from direct contact with the lung stroma, they survive only a week or two and no longer divide.