bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structure of the human respiratory acinus
Authors: Schreider Jay P. , Raabe Otto G. 
Published: February 2005

AbstractSilicone rubber corrosion casts of the human lung in a state of end inspiration were used to study several specimens of the human pulmonary acinus. Four of the acini were measured in detail with respect to duct length and diameter, the number of alveoli per duct, and the branching pattern of the ducts. The acini were found to have irregular branching patterns, including dichotomous, trichotomous, and side branches. There were, on the average, eight to 12 duct generations and about 7.1 × 103 alveoli per acinus. The polygonal alveoli had an average diameter of 250 μm. The lengths and diameters of the ducts varied considerably; however, the dimensions tended to decrease in the more proximal portions of the acini. The number of alveoli per duct also varied, with an average of ten alveoli per duct. On the basis of the measurements, two models, a “surrogate path” model and an “average path” model, were used to summarize the data, with the surrogate path model being more useful for calculations such as particle desposition in the airways, and the average path model being most illustrative of the anatomical structures.
Development and phylogenetic significance of the fetal membranes and placenta of the African hystricognathous rodents Bathyergus and Hystrix
Authors: Luckett W. Patrick , Mossman Harland W. 
Published: February 2005

AbstractMorphogenesis of fetal membranes in African and American hystricognathous rodents is essentially the same, even in the possession of such uniquely derived features as a subplacenta and a capillary ring on the inverted yolk sac, features that are unknown in any other rodent group. This is good evidence that the African and American hystricognaths comprise a monophyletic group. Certain interesting features of the decidua, decidual giant cells, periplacental bilaminar omphalopleure, and epamnion are described in Bathyergus and Hystrix. Of special interest in Bathyergus is the widespread decidualization of the uterine connective tissue, even that of the myometrium and perimetrium; and the presence of numerous, usually binucleate, decidual giant cells.
Regeneration of mouse digital corpuscles
Authors: Idé Chizuka 
Published: February 2005

AbstractChanges in morphology and nonspecific cholinesterase (ChE) activity during the reinnervation of digital corpuscles of mouse toe pads after transection of the sciatic nerve were examined by light and electron microscopy. Reinnervation occurred about 30 days after nerve section. A small‐diameter axon was present near the shrunken atrophic lamellae of the previously denervated corpuscle. From 40 to 60 days after nerve transection, the ingrowing axons branched; and the enlarged tip of each branch contained numerous mitochondria. Lamellar cells and cytoplasmic lamellae at this stage were still smaller than normal. Lamellar cells had normal structure by 4 months after nerve section. Following reinnervation, evidence of ChE activity in the interlamellar spaces at first remained unchanged in intensity and distribution from that of the denervated corpuscle. About 10 days after reinnervation, enzyme activity increased in the perineural spaces and was evident, as in the normal corpuscle, in the cisternae of the rough endoplasmic reticulum and nuclear envelope of the lamellar cell body. By 4 months after nerve division, the intensity and distribution of the ChE activity were almost the same as in the normal corpuscle. From the above findings the following conclusions could be drawn: (1) The shrunken atrophic lamellar cells remaining after denervation are utilized by the ingrowing axons to regenerate normal digital corpuscles. (2) The lamellar cell is dependent on the well‐developed axon terminals to maintain its normal morphology and to synthesize ChE.
The testis and its excurrent ducts in American caenolestid and didelphid marsupials
Authors: Rodger J. C. 
Published: February 2005

AbstractThe present study examines and compares the structure of the testis and its excurrent ducts in a caenolestid and four didelphid marsupials. Of particular interest was the site of sperm pairing in the epididymis and whether this feature, shared by both American marsupial families but not by any Australian marsupial, was associated with changes in the morphology of the duct.In contrast to the testes of most Australian marsupials, except the peramelids (bandicoots), the intertubular space in the American marsupials was filled by Leydig cells (around 20% of testis volume). The opossum testes were unusual compared with those of eutherian mammals in that histological sections of individual seminiferous tubules contained only a single cellular association irrespective of the length of the tubule sectioned. The rete testis, as in the Australian dasyurids (devil, quoll, etc.), was a simple branching duct system that arose deep within the testis and emerged as a single duct at the testicular hilus. This arrangement is completely different from that in kangaroos and Australian possums, indicating a diversity of rete form in the marsupials similar to that seen in eutherian mammals. The rete emptied into a single, essentially straight, efferent duct that became convoluted towards the epididymis, where it formed a distinct structure adjacent to the caput epididymidis. The efferent ducts were highly variable in diameter and epithelial height, suggesting that the duct was not of uniform character along its length, or that the initial single duct had divided to form ducts of different characters. Sperm pairs were first seen in the proximal cauda epididymidis, and their appearance was correlated with changes in the character of the duct and its epithelium. The distal ductus deferens of Caenolestes, in contrast to those of the didelphids and indeed all other marsupials, was a convoluted ampulla‐like structure adjacent to the prostate gland. In the other marsupials the only accessory sex glands are a segmented prostate and bulbourethral glands.
Microvasculature of the mouse testis and excurrent duct system
Authors: Suzuki Fumie 
Published: February 2005

AbstractThe microvascular architecture of the mouse testis and excurrent duct system was examined by a casting method with the aid of scanning electron microscopy and by sectioning techniques for light and transmission electron microscopy. Two fundamental types of peritubular capillary arrangements were noted in relation to the tubules. The first type most typically appeared in the testis. In this type, peritubular capillaries interconnected intertubular blood vessels to form a rope‐ladder‐like structure. The length of the individual peritubular capillaries was short, and a number of the capillaries encircled eachtubule. Adjacent tubules shared a single layer of capilaries. The vascular organization of the ductuli efferentes and of the middle segment of the epididymis was also of this type, but the number of peritubular capillaries was much fewer compared with that of the testis. In the second type, the peritubular capillaries formed a network encircling each tubule in its subepithelial layer. The capillary organization in the initial and terminal segments of the epididymis and the ductus deferens belonged to the second type. In the distal part of the ductus deferens, a prominent venous plexus was formed in the most peripheral subepithelial layer.
A fine‐structural study of interstitial cell changes in the testes of Necturus maculosus during a portion of the annual cycle, and possible evidence for local feedback control by seminiferous epithelium
Authors: Ucci Angelo A. 
Published: February 2005

AbstractThe developmental stages of the interstitial cells of Leydig in Necturus maculosus were studied in testes of animals obtained in November and December. As a consequence of the caudal to cranial progression of the wave of spermatogenesis, samples obtained from cranial, central, and caudal portions of these testes exhibit regional differences in the morphology of their Leydig cells. In these samples, fibroblast‐like stromal cells with large, dense, elongated nuclei and thin sheets of cytoplasm surround the cranial seminiferous lobules that usually contain spermatozoa. Such stromal cells possess a small juxtanuclear Golgi apparatus, profiles of smooth and rough endoplasmic reticulum, and mitochondria with tubular and shelf‐like cristae.In the central area of the testis, interstitial cells with oval nuclear profiles and a finer chromatin pattern surround degenerating seminiferous lobules. The abundant cytoplasm of these cells contains predominantly smooth endoplasmic reticulum interspersed with a few lipid droplets. These cells contain mitochondria that are packed with tubular cristae.In the caudal part of the testis, the Leydig cells have a round nucleus with finely dispersed chromatin. Numerous lipid droplets accumulate in the ample cytoplasm, which is filled with smooth endoplasmic reticulum. The juxtanuclear Golgi apparatus becomes enlarged; associated with it are vesicles with an electron‐dense content. The cristae of the mitochondria are more numerous and have tubules of 50‐nm diameter mixed with arrays of small tubules 25–30 nm in diameter.The appearance of morphologically mature interstitial cells of Leydig only adjacent to degenerated seminiferous lobules in the caudal portion of the testis suggests the possibility of local feedback control of Leydig‐cell development.
Corneal splitting in the developing lamprey Petromyzon marinus L. eye
Authors: Dickson D. Howard , Graves Debra A. , Moyles Michael R. 
Published: February 2005

AbstractThe cornea of the adult lamprey has both dermal (spectacle) and scleral components. These are separated by a thin mucoid layer that allows free movement of the globe.This study has shown that during the larval (ammocoete) stage, the lamprey cornea develops in a manner similar to that of other lower vertebrates. Just prior to the period of transformation to the adult parasite, the outer dermal portion of the ammocoete cornea (spectacle) consists of an anterior stratified columnar epithelium with goblet cells at the surface. The stroma of the dermal cornea consists of a thick outer layer of orthogonally oriented collagen with branching fibroblasts and a thin, loosely organized inner layer with slender elongated fibroblasts. The scleral cornea is lined internally by a flattened monolayer of mesodermal cells, the corneal endothelium. Its narrow stroma is composed entirely of thin, orthogonally aranged, collagen‐fiber lamellae, and is bounded externally by a thin continuous mesothelial layer of cells that abuts directly onto the loose stromal component of the dermal cornea.During the early stages of transformation, the anterior epithelium of the dermal cornea becomes stratified squamous in type. Later, the inner loose stroma of the dermal cornea (spectacle) begins to separate from the scleral cornea components, and a third complete mesothelial layer forms a distinct inner border for the dermal cornea. A mucoid layer is formed between the dermal (spectacle) and scleral corneas and remains throughout the adult life.
The formation of the primitive choanae and the junction of the primary and secondary palates in the mouse
Authors: Tamarin Arnold 
Published: February 2005

AbstractThis study has followed the development of the primary choanae in the mouse and has shown that they originate at the developmentally strategic position of junction between the primordia of the primary and secondary palates and that this basic anatomic relationship is maintained throughout further development. Involution of the oronasal membrane begins late in the 11th day (stage 19) with the formation of interstitial gaps. The gaps enlarge and coalesce so that a completely patent opening between nasal passage and stomodeum is established by 13 days (stage 21). The membrane consists of two layers of simple squamous epithelium which become separated as involution progresses. The form of the choanal antrum changes from a simple funnel‐shaped ellipse early in the 13th day to a complex slitlike opening within the following 24 hours. This coincides with the completion of a definitive primary palate and the enlargement and elevation of the shelves of the secondary palate. The maturation of the incisive papilla and interchoanal columella is related to the final stages of choanal morphogenesis. Thus, by stage 22 (14 days) the shape of the primary choanae and their anatomic relationship to the primary and secondary palates are established, and they remain essentially unchanged in later stages.
Splenic white pulp and associated vascular channels in chicken spleen
Authors: Oláh Imre , Glick Bruce 
Published: February 2005

AbstractWe have studied the chicken spleen by light and transmission electron microscopy. Germinal centers are located at the beginning of the central artery which is surrounded by the periarterial lymphatic sheath (PALS). The central artery has no branch crossing the PALS, and there is no histologically identifiable marginal zone in the chicken spleen. The central artery continues as penicilliform capillaries.The mid‐portion of the penicilliform capillary is surrounded by the ellipsoid or Schweigger‐Seidel sheath. The endothelial lining of this part of the pencilliform capillary contains small channels, formed between neighboring endothelial cells, which enter the ellipsoid. These channels allow circulating substances to accumulate in the ellipsoid.The cells of the ellipsoid are reticular cells, round or ovoid in shape, exhibiting a limited number of cell junctions. At the surface of the ellipsoid are ellipsoid‐associated cells (EAC) which have an affinity for toluidine blue. After perfusion fixation, the majority of the cells in the ellipsoid are lost; this suggests weak cellular connections between the ellipsoid cells. The ellipsoid‐associated cells remain in loco. On the basis of their shape and cytological features, two stages of EACs can be distinguished. The round or ovoid EACs elaborate active Golgi zones surrounded by numerous small vesicles containing an electron‐dense substance. Occasionally, mitotic figures can be seen among them which may suggest that they are immature forms. In the second or more mature stage, the EACs assume an elongated spindle shape. The spindle‐shaped EACs reveal inactive Golgi cis‐ternae and fewer but larger granules than the round or immature EACs. Unmyelinated nerve fibers and nerve ending were observed in the ellipsoid.Perfusion fixation reveals that the distal portions of the penicilliform capillaries extend into the red pulp and become the sinuses. Therefore, the circulation of the chicken spleen is anatomically closed except for the channels in the mid‐portion of the penicilliform capillary.The periellipsoid white pulp (PWP) possesses a few small lymphocytes, macrophages, and plasma cells with the majority of cells being young blastlike cells which may replenish the EACs and ellipsoidal cells.Carbon, injected intravenously, appears on the EAC membrane by 30 minutes, while Brucella abortus is completely phagocytized at this time. Binding the carbon triggers the EAC to detach from the ellipsoid and migrate to the periellipsoidal white pulp (PWP). The EACs phagocytize carbon by 2 hours, and by 5 and 8 days are present in the red pulp and surround the germinal centers at the border of the periarterial lymphatic sheath, respectively. Secretory cells which have been identified in germinal centers might originate from EACs.
Ultrastructural configuration of sarcomeres in passive and contracted frog sartorius muscle
Authors: Bergman Ronald A. 
Published: February 2005

AbstractThe structural configuration of passive and contracted sarcomeres from frog sartorius muscle was determined for sarcomere lengths between 1.4 and 3.07 μm. Sarcomeres fixed with glutaraldehyde, without detectable contractile activity, were invariably rectangular in shape in longitudinal section regardless of sarcomere length. The structure of sarcomeres excited by osmium tetroxide and contracted depended upon sarcomere length. For lengths greater than 1.6 μm, longitudinally sectioned sarcomeres were convexoconvex (or barrel‐shaped). At 1.6 μm, contracted sarcomeres were invariably rectangular in shape. Below 1.6 μm, sarcomeres were compressed and appeared concavoconcave. The results of this study provide models for isovolumetrically contracted sarcomeres which differ significantly from those previously reported.
The gill in the spiny dogfish, Squalus acanthias: Respiratory and nonrespiratory function
Authors: De Vries R. , De Jager S. 
Published: February 2005

AbstractAspects of functional anatomy with respect to water and blood flow through the gills of Squalus acanthias and one specimen of Mustelus mustelus are described. A reconstruction of an entire filament has been made. (1) The cavernous body in the proximal segment of the filament is relatively small, contains a small amount of elastic tissue, and has no connections with the underlying afferent filament artery, except at its junction to the middle segment. In the middle segment of the filament, the wall and columns of the cavernous body are well supplied with elastic tissue. The size of the cavernous body increases gradually distally. The underlying afferent filament artery opens into it with numerous pores and eventually becomes incorporated in the cavernous body. The distal segment of the filament is characterized by the rapid increase in size of the cavernous body. Toward the free edge of the filament it almost reaches the efferent filament artery; toward the diaphragm it forms an anastomosing bridge with the neighboring filaments. Wall and columns in the distal segment of the cavernous body are richly supplied with elastic tissue. The afferent filament artery is no longer discernible. (2) In living specimens the tips of opposite filaments are in close apposition during the whole respiratory cycle. Application of artificial ventral aortic pressure to freshly killed specimens evoked the same reaction in the filament tips. The cavernous bodies provide the hydrostatic skeleton, necessary to keep the gill sieve closed. Lamellae are equipped with finger‐like appendages to facilitate adherence to the opposite filament tips. Lamellar appendages also reduce the dead space between lamellae of neighboring filaments. (3) The whole of cavernous bodies may also serve as an elastic blood reservoir with a function similar to that of the bulbus arteriosus in teleost fish. (4) Of all suitable places, only the lamellar streambed was clear and convincing in its response to perfusion with adrenalin or acetylcholine. (5) Structural details of the nonrespiratory circulation within the gills are described.
Ultrastructural characterization of the nasal respiratory epithelium in the rat
Authors: Monteiro‐Riviere Nancy A. , Popp James A. 
Published: February 2005

AbstractThis ultrastructural study of the respiratory epithelium of the rat nasal mucosa revealed six morphologically distinct cell types: goblet cells, basal cells, ciliated cells, nonciliated columnar cells, cuboidal cells, and brush cells. The latter three have not been previously characterized in the rat nasal mucosa by transmission electron microscopy. Cuboidal cells observed on the conchaeThe term “conchae” has now been accepted by NOMINA ANATOMICA VETERINARIA (1983) to replace the word “turbinate”. Therefore, dorsal nasal conchae = nasoturbinates and ventral nasal conchae = maxilloturbinates.
and lateral wall had short apical microvilli which were less dense than the microvilli of the nonciliated columnar cells. Nonciliated columnar cells also identified on the conchae and lateral wall had short microvilli and an extensive network of smooth endoplasmic reticulum in the apical region. The brush cell had distinct ultrastructural features; it was pear‐shaped, with the broad base adjacent to the basement membrane and large microvilli on the surface. Microfilaments, microtubules, vesicles, and paired cisternae were found in the apical cytoplasm. Brush cells occurred singly on the conchae and lateral wall but were not identified in the respiratory epithelium of the nasal septum. These findings indicate the complexity of cell types composing the rat nasal respiratory epithelium.
Role of binucleate cells in fetomaternal cell fusion at implantation in the sheep
Authors: Wooding F. B. P. 
Published: February 2005

AbstractIn the sheep conceptus, individual intraepithelial binucleate cells first appear at 14 days post‐coitum (d.p.c.); and by 16 d.p.c. they form 15‐20% of the trophectoderm where it is apposed to the caruncular sites of initial attachment to the uterine epithelium. These binucleate cells and their derivatives can be recognized in the placenta by electron microscopy after selective staining of their Golgi body and its products, the numerous characteristic granules. Between 16 and 24 d.p.c. the uterine epithelium transforms to syncytial plaques. Evidence from ultrastructure and serial semithin sections indicates that this transformation is initiated by migration of fetal binucleate cells up to the microvillar junction and their fusion with individual uterine epithelial cells, producing trinucleate fetomaternal hybrid cells. These cells then appear to release their granules to the endometrium. It is suggested that continued binucleate‐cell migration and fusion with the trinucleate cells, together with displacement and/or death of the remaining uterine epithelial cells, produces the plaques of syncytium that cover the entire caruncle by 20‐24 d.p.c. This caruncular syncytium, in which no nuclear division has been found, expands enormously in area during the formation and maintenance of the cotyledons, deriving its nuclei from binucleate migration.
The early changes of parietal cell structure in the course of secretory activity in the rat
Authors: Vial Juan D. , Garrido Jorge , González Alfonso 
Published: February 2005

AbstractThe fine structure of the rat parietal cell was studied, both at rest and after stimulation by refeeding or insulin administration. Experiments on fixation procedures showed that whenever the fixative contained sucrose at a concentration higher than 0.2 M, the system of cytoplasmic membranes was clearly tubular in arrangement, whereas the omission of sucrose in the fixative usually resulted in a vesicular structure. The study with the high‐voltage electron microscope of thick sections prepared by conventional techniques or by impregnation with zinc iodide‐osmium (ZIO) revealed that the tubules are grouped into fascicles, and that these form a feltwork that is especially thick toward the cell apex. The development of the secretory canaliculus after stimulation appears to take place by an in situ remodeling of the cytoplasmic domain occupied by the tubular system. Cells examined after short periods of stimulation (5–15 min) showed images of the tubular system and of the canalicular structure which differed both from the nonstimulated and from the fully active (30–45 min of stimulation) cell. These features include the formation of wide cisternae and of pericanalicular cytoplasmic trabeculae or laminae, whose fine structure bears close resemblance to that of the intracanalicular processes in the same cells. These images can be ordered into a hypothetical sequence which is proposed as a model to explain the transformation of the tubular system and intervening cytoplasmic matrix into secretory canaliculus.