bluuebunny/crossref_metadata_2025 huggingface dataset:
Immunolocalization of laminin, heparan‐sulfate proteoglycan, entactin and type IV collagen in the rat anterior pituitary. II. An in vitro study on primary cultures
Authors: Vila‐Porcile E. , Picart R. , Vigny M. , Tixier‐Vidal A. , Tougard C.
Published: February 2005

The distribution of four basement membrane components: laminin (LAM), type IV collagen (Coll. IV), heparan‐sulfate proteoglycan (HSPG), and entactin (ENT), was studied by immunocytochemistry in primary cultures of adult rat anterior pituitaries. In such cultures, the pituitary cells are deprived of their normal environment of adjacent cells and basement membranes (BM), and of the connectivo‐vascular system of the hypophysis. In this dissociated system, pituitary cells grow as small clusters upon a monolayer of fibroblasts.

LAM was found highly expressed in endocrine and in folliculo‐stellate cells. Very small amounts of Coll. IV, but neither HSPG nor ENT, could be detected in endocrine cells. In contrast, in fibroblasts, very large amounts of Coll. IV, HSPG, and ENT, and a lower quantity of LAM were detected. At the ultrastructural level, the immunoreactive components present within the cells were located in the subcellular compartments involved in the elaboration of exported products. In addition to that intracellular distribution, the four constituents were observed in an extracellular matrix which appeared between the cultured cells, either as an amorphous material, or as a more or less dense reticular network, weakly stained with anti‐LAM, but strongly stained with the other antibodies.

Thus, the present immunocytochemical data support the implication of pituitary endocrine cells, at least for LAM secretion, in the elaboration of a novel extracellular matrix in primary cultures. In addition, a cooperation with non‐endocrine cells seemed to be required for the production of the four BM components. © 1992 Wiley‐Liss, Inc.
Development and cytodifferentiation of peritubular myoid cells in the rat testis
Authors: Palombi Fioretta , Farini Donatella , Salanova Michele , De Grossi Stefania , Stefanini Mario
Published: February 2005

The cytodifferentiation of peritubular myoid cells was studied in developing rats from fetal day 18 through approachment of puberty. The parameters taken into consideration were (1) the presence of desmin, a component of intermediate filaments in contractile cells; (2) the expression of alkaline phosphatase, a cell surface enzyme present in no other cell type of the seminiferous tubule; (3) the expression of the smooth muscle specific isoform of alpha‐actin, a marker of terminal differentiation in smooth muscle cells; (4) cell proliferation rate, evaluated in radioautography as labeling index after incorporation of 3H‐thymidine in short‐term organ culture; and (5) cytoarchitectural changes detected with scanning electron microscopy. By means of immunofluorescence and cytochemistry it was observed that the three markers are expressed early during life, long before the onset of the first spermatogenic wave; in particular desmin is already present in fetal samples and alkaline phosphatase activity appears a few days after birth, whereas α‐smooth muscle isoactin is first detected around birth. As for myoid cell replication, the high prenatal labeling index was found to drop soon after birth and to further slow down during the first month of postnatal life, suggesting that myoid cell proliferation is not a major factor in peritubular expansion. SEM examination of developing peritubulum has shown that, when approaching puberty, the myoid cell undergoes a dramatic change in cytoarchitecture, consisting in extreme flattening and cytoplasmic expansion resulting in an apparent increase in peritubular surface. © 1992 Wiley‐Liss, Inc.
Postnatal development of the cervical epithelium in the Mongolian gerbil
Authors: Kress A. , Mardi L.
Published: February 2005

This study analyzes the postnatal development of the Mongolian gerbil's cervical epithelium, in relation to its future functions.

In the newborn gerbil the outline of the cervical canal is smooth, showing hardly any signs of folding. The epithelium consists of 1 to 3 layers. The cervical cells have rounded apices of regular outline and contain a large amount of glycogen.

The first secretory products of specific mucus type appear about day 23 postnatally (p. n.). Initially two types of vesicles can be identified, as compared with only one type in sexually mature animals. The process of mucification begins in the vagina and the external os of the cervix and spreads towards the cervical horns. The cervical canal, besides growing longer, becomes increasingly folded during development.

At about day 50 p. n., with the onset of sexual maturity, an upper endocervix and a lower ectocervix can be distinguished within the cervical canal. In the fully mature animal, the endocervix consists of 4 to 5 layers, in which apical cells mucify and exfoliate. In the ectocervix, the epithelium can be divided into 4 to 5 basal layers and 5 to 7 upper layers which mucify, keratinize, and exfoliate, according to the cyclic phases of the vagina. Diapedesis of leucocytes through the epithelium starts around day 45 p. n. © 1992 Wiley‐Liss, Inc.
Structural differentiation of the epithelial cells of the testicular excurrent duct system of rats during postnatal development
Authors: Hermo L. , Barin K. , Robaire B.
Published: February 2005

The light and electron microscopic appearance of the various epithelial cells lining the efferent ducts and different regions of the epididymis were examined in rats on postnatal days 21, 39, 49, 56, and 90 to determine the role of androgens and/or spermatozoa, as well as other possible factors, on the structural differentiation of these cells. Five conclusions may be drawn from the observations made. First, on day 21 epithelial cells of all regions are structurally undifferentiated. Second, it was not until day 49 that nonciliated cells of the efferent ducts resembled those of adult animals, suggesting that more than one factor, such as androgens, testicular products, and/or spermatozoa, is needed for their full structural differentiation. Third, principal cells of the epididymis become structurally differentiated by day 39, i. e., these cells contained an elaborate Golgi apparatus, endoplasmic reticulum cisternae, and numerous 200–400 nm electron lucent secretory vesicles, as well as a full complement of endocytic organelles; this occurred in spite of the absence of spermatozoa in the epididymal lumen. The differentiation of these epididymal cells may be under the influence of androgens, which are known to be high at this time, but may also be due to specific secretions from Sertoli cells secreted directly into the efferent ducts. Fourth, clear cells of the cauda epididymidis are fully differentiated by day 39. The presence of degenerating germ cells in the lumen of the cauda epididymidis and various cellular debris, as well as high androgen levels, may be factors causing the differentiation of the cells of this region. Finally, clear cells of the corpus and cauda epididymidis only become fully differentiated by day 49, at a time when spermatozoa appear in the lumen, despite high levels of androgens at day 39; this observation indicates that the presence of spermatozoa in the lumen may be a necessary factor in causing their differentiation. Overall, these results suggest that a combination of different factors are necessary for the structural differentiation of the various epithelial cell types of the different regions of the epididymis. © 1992 Wiley‐Liss, Inc.
Comparative anatomy and phylogeny of the cloacae of salamanders (Amphibia: Caudata) IV. Salamandridae
Authors: Sever David M.
Published: February 2005

Cloacae were examined from male and female salamanders representing 12 genera and 22 species in the Salamandridae. All female salamandrids possess numerous sperm storage glands, spermathecae, in the roof of the cloaca, but intergeneric variation exists in the occurrence of additional cloacal glands. Pleurodeles and Tylototriton possess both vent and anterior ventral glands, and secondary loss has occurred of vent glands in all other genera and anterior ventral glands in Chioglossa, Cynops, Paramesotriton, and Triturus The most highly derived cloaca occurs in Euproctus asper, in which the cloacal tube extends through a conical projection, and ventral glands secrete onto the dorsolateral surface of the projection rather than into the cloaca. Marked intergeneric variation occurs in males in conformation of the cloacal cavities and in extent of the dorsal gland. In Cynops, Euproctus, Pachytriton, Paramesotriton, Taricha, and Triturus, the pseudopenis (a broad, posteriorly projecting evagination of the dorsal roof) fills much of the cavity of the anterior cloacal chamber. In most salamandrids, distal ends of the dorsal glands occur lateral to pelvic glands in the anterior end of the cloaca, and dorsal gland tubules descend to secretory sites at the posterior end of the vent. Salamandra and Mertensiella possess a unique, bifurcated dorsal gland in which distal ends of tubules lie dorsal to the other cloacal glands, and proximal ends curve ventrally in the anterior end of the cloaca to secretory sites along the cloacal orifice. Cladistic analyses indicate that the variation in presence of anterior ventral glands is due to homoplasy. The occurrence of female vent glands, bifurcated dorsal glands, and the pseudopenis supports a phylogeny based upon noncloacal characters. © 1992 Wiley‐Liss, Inc.
Cell renewal and gene expression in the trachea of hamster at different ages
Authors: Chopra D. P. , Cooney R. A. , Joiakim A. P.
Published: February 2005

The tracheal mucosa of the Syrian golden hamster has been extensively employed as a model system for respiratory tract cell renewal, injury, and carcinogenesis. However, baseline cell kinetic data are not available for normal juvenile and adolescent animals in which the mucosa and cartilage are rapidly enlarging. The objective of this research was to elucidate alterations in cell kinetics, epithelial morphology, and gene expression in the trachea of hamsters at different ages. Cell kinetics were examined by 3H‐thymidine labeling indices, morphology by light and electron microscopic examination, and gene expression by slot blot analysis. Results showed that mucosal epithelium of the young and adolescent hamster undergoes cyclic necrosis and cell shedding, exposing portions of the elastic basal lamina. Epithelial shedding was associated with hyperplasia and squamous metaplasia. Additionally, the labeling indices of mucosal epithelial cells and chondroblasts also exhibited variable patterns which were associated with a cyclic pattern of expression of c‐fos and c‐erB2 proto‐oncogenes and epidermal growth factor receptor. © 1992 Wiley‐Liss, Inc.
Regional variability of colonocyte growth and differentiation in the rat
Authors: Sato Masaki , Ahnen Dennis J.
Published: February 2005

The location of stem cells and the direction of colonocyte migration in the normal rat colonic crypt were investivageted using a serial bromodeoxyuridine (BrdU) and [3H]thymidine labeling protocol. The results demonstrate that in the distal colon the stem cells are located in the crypt base and that cells migrate up toward the luminal surface. In the proximal colon, however, the stem cells are located in the midcrypt, and the colonocytes migrate in two directions, up toward the luminal surface and down toward the crypt base. © 1992 Wiley‐Liss, Inc.
Radiographic analysis of the arteries of human lumbar lymph nodes
Authors: Sasaki Katsunori
Published: February 2005

Twenty‐seven cadavers (12 male, 15 female aged 28 to 94 years, average 75 years) were dissected to analyze the arterial supply of the lumbar lymph nodes with angiography and an image processor‐analyzer. The lymph nodes on the left side of the abdominal aorta fused to form several elongated nodes. The lymph nodes on the right side remained separated. A few lymph nodes aggregated below the bifurcation of the abdominal aorta. They received a few branches directly from the abdominal aorta or from the renal, gonadal and/or iliac arteries, which anastomosed with each other to form an arterial arc. This anastomosis gave small paired twigs to the parenchyma continuously. In the case of well developed lymph nodes dorsal to the inferior vena cava, a vessel from the lower abdominal aorta passed upward to supply them. The diameter of these vessels in the angiogram was 0.09–0.27 mm, measured with the image processor‐analyzer.

These results show that the lumbar lymph nodes do not receive a single artery through the hilus, but through several branches, whose anastomoses form a collateral system associated with the abdominal aorta. © 1992 Wiley‐Liss, Inc.
Forms of lung lymphatics: A scanning electron microscopic study of casts
Authors: Schraufnagel Dean E.
Published: February 2005

In a recent study, rats given monocrotaline underwent angiogenesis on their pleural surfaces. The rats also had novel structures in their bronchovascular bundles that were detected by scanning electron microscopy of vascular casts. These vessels could have been either new blood capillaries or dilated lymphatic capillaries. To determine if these structures were lymphatics or new blood vessels, specimens from animals that were undergoing angiogenesis were compared to those that were not. Finding similar structures in normal animals would imply that they were lymphatic. The second purpose of this work was to describe the three‐dimensional anatomy of the lymphatics of the lung. Cast lymphatics were found in most lungs with edema or angiogenesis, but were rare in other conditions. The vascular structures in question were found in animals not undergoing angiogenesis and were, therefore, lymphatic. Additionally, scanning electron angiogenesis and were, therefore, lymphatic. Additionally, scanning electron microscopy of casts showed several distinct forms of lymphatics in the lung. Prelymphatics are tissues planes beneath the pleura and around bronchovascular structures. They join reservoir, conduit or tubulo‐saccular lymphatics. Reservoir lymphatics are broad ribbon‐like structures with textured surfaces and small laterally branching pouches. They occur on the pleural surface, are closely linked with prelymphatics, and join conduit lymphatics. Conduit lymphatics are tubular structures that may contain valves, twist and go great distances without accepting tributaries. On the pleural surface, they may wind around blood vessels and vary greatly in diamater. Sacculo‐tubular lymphatics surround arteries, veins and bronchioles. They have thin walls with wide saccular segments. They may be so dense that they form cylinders around the vessels or airways. Different forms of lung lymphatics suggest different function and potential. © 1992 Wiley‐Liss, Inc.
Follicle‐associated epithelium and medullary epithelial tissue of the bursa of Fabricius are two different compartments
Authors: Olah Imre , Glick Bruce
Published: February 2005

The bursae of Fabricius from the chicken and turkey were studied by light and electron microscopy and immunohistochemical methods. The study focused on the relationship of follicle‐associated epithelium to the medulla. The follicle‐associated epithelium was supported by 3 to 5 layers of stratified epithelial cells which were a continuation of the corticomedullary epithelial cells. The follicle‐associated epithelium consisted of M cells and scattered secretory dendritic cells. The network of the reticular epithelial cells of the medulla was filled with secretory dendritic cells, B cells, and a few T cells and macrophages. The cellular content of the follicle‐associated epithelium and the medulla suggested that they were different cellular compartments. Communication between the follicle associated epithelium and medullary epithelial compartment occurred through the supporting cells of the follicle‐associated epithelium.

When the supporting layers of the follicle‐associated epithelium infolded into the medulla, they formed lamellated epithelial bodies similar to the thymic Hassall bodies. The lamellated bodies enclosed secretory dendritic cells but not lymphocytes. The infolding of supporting cells varied from follicle to follicle. The asynchronization of infolding contributed to heterogeneity of follicle composition. Follicle heterogeneity was demonstrated by differences in reactivity with a battery of monoclonal antibodies. © 1992 Wiley‐Liss, Inc.
Postnatal development of the harderian gland in the Syrian golden hamster (Mesocricetus auratus): A light and electron microscopic study
Authors: López José M. , Tolivia Jorge , Alvarez‐Uría Manuel
Published: February 2005

The main objective of the present investigation was to study the morphological and chronological aspects of the development of the Harderian gland in the Syrian golden hamster. Tissues were obtained from male and female hamsters at days 1,3,5,7,10,12,15,17,20,27,37,46, and 90 after birth and processed for light and transmission electron microscopy. The present observations indicate that a well‐defined temporal sequence in microscopic and ultrastructural modification is recognizable in the development of the hamster Harderian gland. Four stages of development were proposed. Between days 1–5 (first stage), the gland shows characteristics of an immature structure. The glandular cells contain many free ribosomes, few and small organelles, and large irregular‐shape nuclei. Between days 7–17 (second stage), there is a marked increase of organelles involved in synthesis and secretion. The gland begins the secretion of lipids and porphyrins, but no morphological differences between male and female glands are observed. Between days 20–36 (third stage), the morphological differences between the two sexes appear and progressively develop. In 45‐day‐old hamsters, the Harderian gland possesses the structural characteristics of adult glands, and further developmental changes are essentially quantitative in nature (fourth stage). At all stages of development, the population of secretory cells has a uniform appearance. The morphological results are discussed as well as the possible relationship of this temporal sequence with hormonal changes. © 1992 Wiley‐Liss, Inc.
Bone and cartilage resorption in relation to tooth development in the anterior part of the mandible in cichlid fish: A light and TEM study
Authors: Huysseune Ann , Sire Jean‐Yves
Published: February 2005

This paper presents ultrastructural features of the contact region between particular tooth germs and Meckel's cartilage prior to, during, and after initial resorption of the perichondral bone and of the cartilage in the cichlids Hemichromis bimaculatus and Astatotilapia burtoni. Imminent resorption opposite such teeth is announced by the presence, in this region, of a particular cell type, considered to be a stage in the cytodifferentiation of osteoclasts. Slightly later, an osteoclast with typical ruffled border is seen to open a fenestra in the perichondral bone which surrounds Meckel's cartilage. Although the action of the osteoclast is directed primarily towards the bone, it may also affect, to a much lesser extent, the underlying uncalcified cartilage. Typically, fibroblast‐like cells invade the resorption cavity along with the osteoclast; the tooth germ soon follows. Capillaries are seen to invade the cartilage only at a later stage when a large cavity has been established. It is proposed that the fibroblast‐like cells may have a dual function: degradation of cartilage and deposition of new bone. Although these processes are normally limited to the area surrounding tooth germs at specific loci, tooth germs in other positions may sometimes be seen to invade the cartilage. They do so either passively, because of the existence of such a cavity, or as a result of their own resorption‐inducing activity. Whatever the mechanism, attachment bone is being deposited within the erosion cavity and on the surface of the exposed perichondral bone. The stimuli possibly eliciting resorption of Meckel's cartilage are discussed. It is hypothesized that pressure exerted by the growing tooth germ may stimulate the osteoblasts covering the bone surface and, in this way, provoke osteoclastic bone resorption. © 1992 Wiley‐Liss, Inc.
Immobilization‐induced muscle atrophy is not reversed by lengthening the muscle
Authors: Maxwell L. C. , Enwemeka C. S.
Published: February 2005

In clinical practice, repaired tendocalcaneus (Achilles tendon) ruptures are often protected in immobilization casts for 4 weeks in the fully plantar flexed position and for up to another 4 weeks after returining the ankle to joint neutral. Moderate to severe muscle atrophy occurs within 4 weeks of immobilization in plantar flexion, but it is not known if this atrophy is minimized or reversed following restoration of joint neutral position. We tested the hypothesis that the extent of atrophy could be reduced by returning the ankle to joint neutral after 4 weeks of immobilization. Eighteen rabbits were anesthetized, and their right hindlimbs were casted with the knee flexed 90° and the ankle fully planter flexed. Three animals each were studied after 3, 4, 6, or 8 weeks of immobilization. After 4 weeks of immobilization, the immobilization casts of the remaining six rabbits were modified to reture the ankle to joint neutral for another 2 or 4 weeks. For muscle studies, the animals were anesthetized, and the soleus (SOL), plantaris (PLN), and gastrocnemius (GST) muscles were removed and weighed; the SOL and PLN were quick frozen and processed for histochemical fiber typing and fiber cross‐sectional area measurement. All three muscles showed significantly reduced muscle weight to body weight ratios after 3 weeks of immobilization. SOL was the most affected, and GST was least affected. There was no significant further atrophy through 8 weeks of immobilization. The atrophy corrolated with a significant reduction of mean fiber area (MFA) for Types I, IIo, and IIc fibers in SOL and PLN. In PLN, Type IIg fiber area was not significantly reduced. MFAs of fibers of SOL and PLN muscles that were lengthened by returning to ankle joint neutral for 2 or 4 weeks were not different from those from those of limbs kept at planter flexion for 6 or 8 weeks. These data indicate that atrophy had reached a near‐maximal extent within 4 weeks and that subsequent lengthening of the muscles did not reverse the atrophy. © 1992 Wiley‐Liss, Inc.
Effect of cyproterone acetate on structure and function of rhesus monkey reproductive organs
Authors: Kaur Jagdeep , Ramakrishnan P. R. , Rajalakshmi M.
Published: February 2005

A low dose of Cyproterone acetate (CPA; 1 mg/kg body weight/day for 70 days) was administered to adult male rhesus monkeys to assess its effects on testicular and epididymal structure and function in a nonhuman primate species. CPA caused extensive degenerative changes in morphology of seminiferous, efferent duct, and epididymal epithelia, including decrease in diameter of seminiferous and epididymal tubules and their lumen, height of epididymal epithelium, and an increase in intertubular connective tissue. The protein profile of spermatozoa showed alterations during their epididymal transit in control and CPA‐treated monkeys. In CPA‐treated animals, 19 polypeptides were acquired and nine were eliminated during epididymal transit in contrast to acquisition of 12 and loss of 14 polypeptides in control animals. Treatment with CPA also resulted in the appearance of 14 new polypeptides in epididymal cytosol and luminal fluid, probably of lysosomal origin. The protein pattern of caput and cauda epididymal tubule cytosol, maintained in organ culture and exposed to 100 μM CPA for 3 days, showed absence of eight polypeptides.

These results indicate that even at the low dose used in this study, CPA has caused spermatogenic arrest, degenerative changes in the epididymal structure, and alterations in epididymal and sperm protein profile. Suppression of serum testosterone levels indicates the need for androgen supplementation if CPA is to be used for male contraception. © 1992 Wiley‐Liss, Inc.
Transplatation of fetal mouse colon under the kidney capsule of an adult mouse: A model for the study of colonic development
Authors: Gabriel Anastasia , Robinson Peter M. , Whitehead Robert H.
Published: February 2005

Fourteen‐day fetal mouse colon was transplanted under the kidney capsule of an adult mouse to determine whether this system could be used as a model of embryonic colonic development. The 14‐day fetal colon was transplanted and left for a period of 7 days. Comparisons of the normal one day postnatal colon and the transplanted colon were made morphologically and morphometrically. It was found that the transplanted fetal colon resembled its postnatal counterpart with respect to morphology; the cell types seen in the transplanted colon were similar to those observed in the in situ colon of the same age. However, morphometric analysis showed that the transplanted colon was significantly smaller than its postnatal counterpart, suggesting that conditions in the host were not optimal to support the full growth of the colon. In spite of this, it appears that the fetal colon can differentiate normally under the kidney capsule and this model can be used to study both epithelial‐mesenchymal interactions and the role of hormones in fetal colonic development.© Willey‐Liss, Inc.
Coronary artery development in the chick: Origin and deployment of smooth muscle cells, and the effects of neural crest ablation
Authors: Hood Lisa C. , Rosenquist Thomas H.
Published: February 2005

Previous studies of coronary artery ontogeny have stressed early development and therefore have dwelt mainly upon the origin of the endothelium of the nascent coronary artery stem. This study has analyzed the ontogeny of the vascular smooth muscle cells (VSMC) in the coronary arteries of the domestic chicken, by establishing the timing and deployment of smooth muscle alpha‐actin (SMAA). Anti‐SMAA was applied to sections of normal embryos, and to sections of experimental embryos that had undergone surgical ablation of the neural crest over somites 1–3. The results show an orderly symmetrical deployment of SMAA in control coronary arteries. SMAA was expressed significantly earlier in the coronary artery VSMC compared with those of the cardiac outflow vessels; this early expression may indicate a unique responsiveness to induction of the smooth muscle phenotype. The normal orderly development of coronary artery VSMC was dependent upon the presence of the neural crest, and therefor was disrupted in the experimental embryos whose neural crest was ablated.© Willey‐Liss, Inc.
Effects of prostaglandin inhibition on the bone activities associated with the spontaneous drift of molar teeth in the rat
Authors: Lasfargues J. J. , Saffar J. L.
Published: February 2005

Little is known about local bone regulation that enables spontaneous molar tooth drift. In this study the role of prostaglandins (PGs) were investigated in the rat by inhibiting PG‐synthesis with indomethacin (7 mg/kg/d). Untreated animals were killed at the start of the experiment, while treated ones were killed after 3, 7, or 14 days of treatment. Mandibles were processed for histomorphometry without demineralization. Changes in osteoclasts and extent of the different steps of the bone remodeling sequence (resorption, reversal, and formation) were assessed along the remodeling side of the socket of the buccal root of the first molar. The total number of osteoclasts decreased after 7 days of PG inhibition (P<0.01 vs controls) and then partially recovered. This change was due to a sharp decrease in active cells on day 7 (P<0.01), while inactive cells remained unchanged throughout the experimental period. The extent of resorption fell on day 7 (P<0.01) and then recovered almost to the control level on day 14. Reversal at first increased insignificantly and thereafter decreased (P<0.02) for the remaining 7 days. Formation was modified only on day 14; at that time it had doubled compared with controls. These results show that PGs are involved in the local regulation of bone remodeling accompanying tooth drift. Resorption inhibition was partial, indicating that other factors participate with PGs in this regulation; in addition, the trend to recovery observed at the end of the experimental period suggests that these factors can take over from PGs to achieve the necessary remodeling of the socket.© Willey‐Liss, Inc.
Elastic fibers in the duct system of the rat submandibular salivary gland
Authors: Lorber Mortimer
Published: February 2005

The submandibular salivary gland originates from the floor of the mouth whose mucosa contains elastic fibers. Therefore, such fibers were sought in the duct system of the derivative organ. In adult rats, light microscopy has indeed revealed fine, circumferential, elastic fibers near the basement membrane of the duct epithelium. In the larger extralobular ducts, they were separated from several layers of longitudinal elastic fibers by a capillary‐rich zone sparse in elastic fibers except for fine angular ones. More peripherally, larger angular‐appearing fibers were frequently present near the submandibular parasympathetic ganglia in the duct wall. As duct diameter decreased, elastic fiber size and number diminished. Intralobularly, the smaller striated ducts, granular and intercalated ducts, and acini generally lacked such fibers. Electron microscopy of the extraglandular portion of the main duct revealed fibrils extending from both fibroblasts and elastic fibers that were close to the epithelium. Microfibrils coursed from them toward the lamina densa. Anchoring filaments joined the lamina densa to the basal plasma membrane of the epithelium. Elastic fibers also appeared to connect to both capillaries and collagen via finer intermediate structures. These associations might permit dynamic interactions of fibroblasts, fibers, smaller fibrillar components, vasa, and the duct epithelium. This interplay could occur during feeding and grooming when tongue protrusion and neck extension stretch the submandibular duct and the gland itself. As a result, the tensile forces engendered could modify cell geometry and the calibers of the larger ducts' lumens and intercellular spaces, thus affecting the flow and composition of salivary secretion.© Willey‐Liss, Inc.
Structural analysis of fetal rat lung development
Authors: Burri Peter H. , Moschopulos Michael
Published: February 2005

The primary aim of this morphological investigation was to elaborate a concept allowing us to coherently define reference spaces for morphometric analysis of fetal lung development. Beyond this quantitative goal, morphological analysis of cell types, definition of compartments, and reflection about the prospective fate of their constitutents provided per se new insights into the developmental processes.

Lungs of rat fetuses aged 17–23 days and newborns aged 20 hours were fixed with an osmium tetroxide and glutaraldehyde mixture and their volume determined. Left lungs were embedded in Epon and investigated by light and electron microscopy. The right lung of one animal per group was embedded in methacrylate and step sections obtained to precisely locate the airways within the mesenchyme.

The various cell types, their topographical relationships, and their morphological alterations with ongoing development were analyzed with regard to their prospective potentials of differentiation.

The developing lung could be partitioned into four zones further subdivided into defined compartments. Zone I forms a superficial mantle around the lobes and the future acini. Consisting of primitive mesenchymal cells, it represents a zone of growth which disappears with the onset of the saccular stage. Zone II is mainly a zone of differentiation. Its interstitium stains intensely due to a dense population of dark cells. Up to gestational day 19, zone II contains future conductive airways with their vessels. After day 21, it comprises the whole prospective gas exchange region. Zones III and IV contain the elements of the airway tree and vascular system, zone IV corresponding to the most proximal generations with an adventitial layer. For all differentiation processes, a centrifugal directionality is manifested.© Willey‐Liss, Inc.
Ultrastructure and immunocytochemistry of the neuroepithelial bodies in the lung of the tiger salamander, Ambystoma tigrinum (Urodela, amphibia)
Authors: Goniakowska‐Witalińska L. , Lauweryns J. M. , Zaccone G. , Fasulo S. , Tagliafierro G.
Published: February 2005

Light and electron microscopy of the lungs of Ambystoma tigrinum (Urodela) revealed a relatively complex pattern of the neuroendocrine (NE) cells. In the apical parts of smaller septa single NE cells not associated with nerve fibres were covered and surrounded by pneumocytes. The larger septa possessed small areas of ciliated epithelium, in which the NE cells were grouped in a form of neuroepithelial bodies (NEB) consisting of 3–5 cells and covered by goblet cells. NE cells possessed a large nucleus with patches of condensed chromatin, clear cytoplasm, and membrane‐bound vesicles of variable morphology and size, of these dense core vesicles (DCV) ranged from 70–140 nm, while rarely the larger ones exhibited a diameter of 300–600 nm. In some NEB a second type of NE cells was observed for the first time in an amphibian species: these cells communicated with the air space and exhibited on their surface microvilli and a single modified cilium with a 8+1 microtubule arrangement. Their cytoplasm contained two types of DCV: dense core granules with a diameter of 140–260 nm and vesicles 320–700 nm in diameter with a moderately electron dense interior. The NEB were associated with intracorpuscular, sensory nerve terminals morphologically afferent and efferent. By immunocytochemistry, the NE cells revealed the presence of serotonin, met‐en‐kephalin, and leu‐enkephalin. A paracrine and chemoreceptor role is proposed for NEB of Ambystoma tigrinum.© Willey‐Liss, Inc.
Distribution of p21ras in postimplantation rat embryos
Authors: Brewer Linda M. , Brown Nigel A.
Published: February 2005

Expression of ras cellular oncogenes during the early postimplantation period in the rat was investigated using immunohistochemistry to p21ras was used in an indirect avidin‐biotin‐peroxidase (ABC) technique. Positive staining indicating the presence of p21ras was found in embryos from 6.5 to 12 days embryonic age. In early egg cylinders (6.5 days), positive staining for p21ras was observed on the ectoplacental cone, primitive ectoderm and trophectoderm, while primitive endoderm and parietal endoderm appeared paler. In later egg cylinder stages (7.5 days), strong positive staining was observed in the primitive embryonic ectoderm and ectoplacental cone, but parietal and visceral endoderm still appeared to be devoid of positive staining. As development proceeded during primitive streak stages, the visceral and parietal endoderm became positively stained. By 10 days, all tissues appeared to be positive for p21ras, with strong staining appearing in the heart and neural elements. Therefore, p21ras does not appear to be ubiquitous in the rat conceptus prior to gastrulation, but shows differential distribution, appearing later in endodermal derivatives. Possibly p21ras is involved in determination of the ectodermal and endodermal lineages.© Willey‐Liss, Inc.
An extracellular matrix infrastructure provides support for murine secondary palatal shelf remodelling
Authors: Morris‐Wiman J. , Brinkley L.
Published: February 2005

A cricial part of secondary palate morphogenesis is the movement of the palatal shelves from an initial vertical position on either side of the tongue to a final horizontal one above it to achieve palate closure. The immunocytochemical localization of extracellular matrix (ECM) molecules in the palatal shelf during this remodelling and reorientation revealed the existence of an ECM infrastructure within the mesenchyme. The major components of this infrastructure were collagen III, fibronectin, and hyaluronate (HA). With remodelling, HA's domain within the mesenchyme was expanded, whereas those of fibronectin and collagen III became more circumscribed. The expansion of an HA‐rich matrix within the mesenchyme is thought to be crucial for palatal reorientation. The results of this study suggest that, as this expansion occurs, it is modulated by collagen and fibronectin components of the ECM infrastructure. Prior to shelf remodelling, this infrastructure may be anchored by a specialized region of the midoral epithelial‐mesenchymal interface and the subjacent mesenchyme which is characterized by the unique distribution of collagen III, fibronectin, and tenascin. The midoral palatal epithelium also may play a role in directing shelf expansion. This epithelial region undergoes changes in cell packing and epithelial cell layering that correlate with shelf remodelling. These changes occur concomitantly with changes in the expression of collagen III, collagen IV, and laminin within the underlying basement membrane. The localization and patterning of tenascin within the developing palate suggests that it not only contributes to the postulated anchoring structure of the midoral epithelial‐mesenchymal region, but also plays a role in the determining the fate of the medial edge epithelial cells during the final stage of palate closure.© Willey‐Liss, Inc.
Accuracy and precision of computerized models of the anterior cranial base in young mice
Authors: Lozanoff Scott
Published: February 2005

The quantitative analysis of craniofacial growth in experimental animals relies on computerized reconstructions in order to measure changes in form. The purpose of this study was to determine the validity of computerized three‐dimensional models of the anterior cranial base in mice. Ten 1‐day‐old non‐littermates were collected and the anterior cranial base was dissected free from surrounding connective tissues. Eleven measurements were recorded from these cartilages. Twenty developmentally equivalent mice were collected and fixed with either glutaraldehyde or formalin and the anterior cranial base from each specimen was subjected to computerized reconstruction. The corresponding 11 measurements were recorded from these models. Results showed that the measurements recorded from the computerized models were not significantly different from those recorded directly from the actual anterior cranial bases. Therefore, the reconstructions were considered accurate. An analysis of the coefficients of error revealed that measurements derived from the computerized models were significantly more precise than those recorded directly from the actual tissue. The computerized three‐dimensional reconstruction method provides accurate and precise models of the anterior cranial base in young mice.© Willey‐Liss, Inc.
Epithelial reorganization and irregular growth following carbendazim‐induced injury of the efferent ductules of the rat testis
Authors: Nakai Masaaki , Moore Billy J. , Hess Rex A.
Published: February 2005

Occlusions of the rat efferent ductules were induced by an oral gavage of carbendazim and the capacity for regeneration or recanalization of the ductules was histologically evaluated between 2 and 70 days post‐treatment. At 2 days post‐treatment, the efferent ductules were occluded by sloughed materials and showed various degrees of inflammation. Severely damaged epithelium showed few regenerative features at later intervals. On the other hand, epithelia with medium inflammation often exhibited irregular epithelial growth along the luminal contents or the formation of multiple abnormal ductules. These abnormal ductules were formed by migrated and original epithelia at the periphery of the occluded lumen at 16 days post‐treatment, indicating attempted recanalization. At later time periods, 32 and 70 days post‐treatment, the occluded original lumen was filled in by fibrotic connective tissue and surrounded by a series of abnormal ductules. These abnormal ductules were characterized by cuboidal epithelia, a small luminal diameter, fewer cilitated cells than normal, less developed organelles in the epithelial cells, and basal laminae of irregular thickness. However, there was no evidence that occluded ductules formed patent re‐connections via abnormal ductules. The results suggest that occluded efferent ductules have the ability to initiate epithelial regrowth and to form new ductules, but the newly formed ductules are abnormal and are not adequate to recover from azoospermia at least at 70 days post‐treatment. © 1993 Wiley‐Liss, Inc.
Cellular proliferation in the anterior pituitary gland of normal adult rats: Influences of sex, estrous cycle, and circadian change
Authors: Oishi Yuji , Okuda Minoru , Takahashi Hideki , Fujii Toshiyuki , Morii Sotokichi
Published: February 2005

Proliferative activity of the anterior pituitary gland in 10 week‐old male and female rats under normal conditions was investigated by counting mitotic figures and using single and double immunostaining of 5‐bromo‐2′‐deoxyuridine (BrdU), proliferating cell nuclear antigen (PCNA), and six pituitary hormones. To determine which proliferative changes depend on the estrous cycle and circadian changes, respectively, six groups of female and two groups of male rats were studied at various times of day. Additionally, BrdU‐incorporated cells were further classified by the six types of hormones they contained, or as immunonegative cells. Cell proliferative activity in the females fluctuated drastically with the highest activity in estrus and the lowest in diestrus. In the males, proliferative activity was at a relatively low level, and was similar to that in females in proestrus or early estrus, with the greater activity at night. Identified by their pituitary hormones, the distribution of the proliferating cells was almost the same in each sex, with prolactin (PRL) cells accounting for the highest proportion, followed by growth hormone (GH) cells, and adrenocorticotropic hormone (ACTH), luteinizing hormone (LH), follicle stimulating hormone (FSH), and thyroid stimulating hormone (TSH) cells. These percentages agreed well with previously reported levels of cell types among all pituitary cells of the rat. It is therefore suggested that the life span and cycle of rat pituitary cells does not differ among cell types. In another test, male and female rats were given BrdU continuously via an osmotic pump for 8 days to compare cell proliferative activity between sexes, exclusive of the influence of estrous cycle and circadian changes. In this way, we were able to demonstrate that the cumulative incorporation of BrdU in females was consistently twice as high as in males over a constant period of time, and to conclude that cell renewal occurs at a doubled rate in the pituitary of female rat. © Wiley‐Lis, Inc.
Development of the liver in the chicken embryo. II. Erythropoietic and granulopoietic cells
Authors: Wong Gene K. , Cavey Michael J.
Published: February 2005

Hepatic hemopoiesis is apparent in the chicken embryo on day 7 of incubation (Hamburger and Hamilton Stage 30), and a peak in hemopoietic activity occurs on day 14 (Stage 40). During this period, the differentiation of hemopoietic cells was examined by light microscopy and by transmission and scanning electron microscopy. Glycol methacrylate sections were used in lieu of smears to study hemopoietic cells, thus minimizing the problems of cell shrinkage and rupture. The sections were superior to smears for close examination of nuclear and cytoplasmic morphologies and for precise localization of hemopoietic cells to intravascular and extravascular sites. The avian liver is involved directly with erythropoiesis and granulopoiesis only. Erythropoietic cells, occurring in intravascular and extravascular locations, appear throughout the time frame examined. Blood islands with granulopoietic cells were not observed until days 8–9 (Stage 35). Granulopoiesis in the liver produces only eosinophilic leukocytes. Individual granulopoietic cells appear first in the connective tissue sheaths of hepatic vessels, and these cells subsequently congregate into blood islands. Endothelial cells of the sinusoidal linings, through asymmetric divisions, frequently release daughter cells into the circulation, and Kupffer cells are actively engaged in phagocytosis of erythrocytes. From a comparative standpoint the elements deemed critical to hemopoiesis in the mammalian liver–prehepatocyte population, hepatic vasculature, and compartments for stem cell differentiation–may not hold the same importance in the bird, owing to an inordinate reliance on intravascular hemopoiesis in this vertebrate class. © 1993 Wiley‐Liss, Inc.
Possible nonlinear effects of exercise on bone in male subjects over age 60 years
Authors: Vico Laurence , Bourrin Sandrine , Chatard Jean‐Claude , Palle Sabine , Very Jean‐Michel , Lacour Jean‐Rene , Alexandre Christian
Published: February 2005

We investigated the relationships among bone mass, bone cell activities, and exercise level in 20 healthy 61–77 year old male volunteers divided into three groups according to the time they physically trained per week: nine subjects training less than 3 hr/week, five subjects between 3 and 6 hr/week and six subjects more than 6 hr/week. Physical performance was evaluated by Vo2 max (ml min−1 kg−1). After tetracyline double labeling, iliac crest biopsy was obtained from each subject. The longer the physical activity, the higher the Vo2 max. Subjects exercising between 3 and 6 hr/week revealed higher adjusted appositional and bone formation rates than all the others; mass and structural parameters also showed higher (nonsignificant) values. For the whole population V̇o2 max appeared negatively related to cortical thickness, cancellous bone volume, and trabecular thickness. These alterations were accompanied by increased cancellous bone turnover; this was evidenced by an increase in activation frequency and in resorption and formation rates as V̇o2 max increased. The bone remodeling periods tended to decrease also. Whatever the bone turnover rate, subjects were in steady state as far as their bone balance was concerned. Relationships between V̇o2 max and mineral apposition rate on the one hand and V̇o2 max and resorption surface on the other hand were best fitted by a quadratic model, suggesting a possible nonlinear effect of physical training on bone mass. We hypothesize that there is a threshold (6 hr/week) determining different effects. Adjustment of bone mass and trabecular arrangement were completed at time of biopsy and reflected probably past and transient bone imbalance. Other studies are needed to corroborate this assumption. © 1993 Wiley‐Liss, Inc.