bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hormonal control of the deciduomal response of the golden hamster uterus
Authors: Harper M. J. K. 
Published: February 2005

AbstractWhen pseudopregnant hamsters were ovariectomized and their uteri traumatized on day 4, deciduomal growth (not significantly different from that seen in intact controls) could be maintained by daily injections of 1, 2 or 4 mg of progesterone either alone or in combination with 1, 2 or 5 μg of estrone. When ovariectomy was performed on day 1 of pseudopregnancy and uterine traumatization on day 4, induction and maintenance of a deciduomal response could be achieved with 1 or 2 mg/day of progesterone alone (or in some cases in combination with 1 μg/day of estrone) from days 1 to 3 followed by 1 or 2 mg/day of progesterone in combination with 1, 2 or 5 μg/day of estrone from days 4 to 7. The best results were obtained with progesterone alone (2 mg/day) before trauma and estrone (2 μg/day) and progesterone (2 mg/day) after trauma.
The cytology of hofbauer cells
Authors: Enders Allen C. , King Barry F. 
Published: February 2005

AbstractCytological investigation of Hofbauer cells in various stages of gestation reveals that they are similar to normal macrophages except for unusually large cytoplasmic flanges and included vacuoles. The system of vacuoles is apparently the result of macropinocytotic activity. The individual vacuoles undergo asymmetrical collapse in regions adjacent to small juxtavacuolar tubules thought to be derived from the agranular endoplasmic reticulum. In addition, coated micropinocytotic vesicles are common. Hofbauer cells thus appear to be a type of macrophage with an unusual capacity for fluid ingestion. In younger placentas, Hofbauer cells are usually associated with extracellular compartments within the stroma. These compartments are relatively free of collagen fibrils and demonstrable ground substance and are clearly demarcated from the rest of the stroma by processes of fibroblasts. The abundance of these cells in early placentas, their location in the stroma, and evidence of their pinocytotic activity suggest that these cells may play a role in removal of proteins from interstitial fluid. Hofbauer‐like cells were also studied in the guinea pig and the little brown bat. Of these two species, the Hofbauer‐like cells of the bat more closely resemble human Hofbauer cells in that they show evidence of extensive macropinocytotic activity.
The cell population in pancreatic islets of amphisbaenidae — a light and electron microscopic study
Authors: Rhoten William B. 
Published: February 2005

AbstractA diversity of cell types have been found in the pancreatic islets of three species of Amphisbaenidae in a light and electron microscopic investigation. The A cells have been characterized as having phosphotungstic acid hematoxylin and orange G positive secretory granules which are electron opaque and 450–500 mμ, in diameter. The B cells possess aldehyde fuchsin reactive granules which are slightly larger than A granules, approximately 550 mμ, and have a variety of profiles in the electron microscope. The D cells are characterized as being fast green positive and argyrophilic in the light microscope, and in the electron microscope have small, 200–300 mμ, secretory granules with a core of moderate electron opacity. In D cells the Golgi apparatus is more highly developed than in A or B cells. Bipes islets contain a presumptive fourth cell type possessing large secretory granules with irregular profiles and focal internal densities. An additional cell type, found in Amphisbaena manni and Bipes, has small, electron opaque granules.
A histochemical and fine structural study of early extracellular connective tissue in the chick embryo
Authors: O'connell James J. , Low Frank N. 
Published: February 2005

AbstractThe histochemistry of developing connective tissues and its relation to early connective tissue fibrils was investigated in the perinotochordal area of the chick embryo. Chick embryos were sacrificed at one, two, three, four, six and ten days of incubation and were prepared for both light and electron microscopy. Five histochemical stains (PAS, alcian blue, Hale colloidal iron, metachromatic toluidine blue, methenamine silver) were used to demonstrate polysaccharides, mucoproteins and mucopolysaccharides. Mature connective tissue elements were demonstrated by Mallory's connective tissue stain and Weigert's resorcin‐fuchsin stain. Routine electron microscopic techniques served to demonstrate extracellular connective tissue fibrils.The first positive response for all histochemical stains occurs on the third day of incubation. Moderate microfibrillar growth precedes this by one day. Light microscopic staining patterns differ from electron microscopic fibrillar arrangements. In the perinotochordal area microfibrils later contribute to the cartilaginous model of the future vertebral body. By the sixth day, dense microfibrillar concentrations appear in the precartilage area where acid mucopolysaccharides are intensely concentrated. Staining for mature connective tissue fibrils does not occur until the tenth day.
Migration of bone marrow lymphocytes demonstrated by selective bone marrow labeling with thymidine‐H3
Authors: Brahim F. , Osmond D. G. 
Published: February 2005

AbstractThymidine‐H3 was injected into the femoral and tibial marrow (labeled marrow) of guinea pigs while the hind limb circulation was arrested temporarily and non‐radioactive thymidine was administered systemically. Blood and lymphoid tissue radioautographs were subsequently examined for the presence of marrow‐derived labeled cells.Small lymphocytes in the labeled marrow showed a wave of labeling, maximal at two to three days. Concurrently, labeled small lymphocytes appeared in the blood and lymphoid tissues, mainly the spleen and mesenteric lymph node. Their numbers were greatest at four to five days, and declined rapidly thereafter. At first they appeared predominantly in the splenic red pulp and throughout the lymph node cortex, including the subcapsular sinus. By four to five days they were also concentrated in the splenic white pulp, including periarteriolar lymphoid sheaths, and in the lymph node medullary cords. They were detected within medullary sinuses, hilar lymphatics and thoracic duct lymph. Labeled monocytes and large lymphoid cells also appeared in the blood and lymphoid tissues, mainly in the spleen.It is concluded that bone marrow is a major source of circulating newly‐formed small lymphocytes many of which migrate rapidly into the spleen and mesenteric lymph node.
Phenobarbital‐induced proliferation of smooth endoplasmic reticulum after administration of triparanol
Authors: Loker Edward , Scallen Terence J. , Dietert Scott E. 
Published: February 2005

AbstractThe effect of triparanol, an inhibitor of cholesterol synthesis, on the phenobarbital induced proliferation of the smooth endoplasmic reticulum (SER) is reported. Hepatocytes of hamsters treated with phenobarbital alone display the expected proliferation of the SER. Those given triparanol alone do not show this phenomenon but appear similar to controls with the exception of increased numbers of dense bodies characteristic of this treatment. Hepatocytes of hamsters receiving triparanol followed by phenobarbital display a SER proliferation of approximately the same magnitude as that achieved with phenobarbital alone. The effectiveness of the triparanol blockade is documented by the administration of labeled mevalonic acid and the subsequent quantitation of the amount of labeled cholesterol and labeled desmosterol. Desmosterol is the primary end product after triparanol treatment. Greater than 95% of the labeled sterol appears as desmosterol indicating a high degree of blockade. It is concluded that newly‐synthesized cholesterol is not a prerequisite for the phenobarbital induced proliferation of the SER. Several possible explanations for these results are discussed.
Effects of sex hormones on diet‐induced atrial thrombosis
Authors: Wilson Jack L. , Ashburn Allen D. , Williams W. Lane 
Published: February 2005

AbstractMale and female Taconic Swiss mice were fed a high‐fat (28%), low‐protein (8%), hypolipotropic diet. Intact mice and gonadectomized mice, with and without injections of estrone or testosterone phenylacetate were studied.The sex of the animals did not alter the incidence or type of diet‐induced cardiovascular lesions. During the 6–12 weeks of feeding thrombi developed in the atrial lumina of 75%–88% of intact and gonadectomized male and female mice. The only prominent decrease in the incidence of such thrombosis was in gonadectomized animals of both sexes receiving estrone where it was reduced to 6%–16%. In castrated males receiving injections of testosterone phenylacetate (Perandren) the incidence of thrombosis was 65%.
Two unique features of the anterior cerebellum in the higher primates, including man
Authors: Dillon Lawrence S. , Atkins David L. 
Published: February 2005

AbstractTwo morphological traits of the anterior cerebellar lobe unique to the higher anthropoid primates are described, and a search for their possible origins is made among representatives of the major subdivisions of the Anthropoidea. One trait involves the gradual reduction and migration of lobule II until it ultimately becomes located upon and fused with lobule I. Hence, in the higher anthropoids, the lingula actually consists of lobules I and II combined. This reduction and migration of lobule II from its normal position places lobule III adjacent to the lingula in the location occupied by lobule II among other mammals. The second distinctive feature concerns the inclusion of the anterior cerebellar peduncle on each side into the anterior medullary velum, so that they form a continuous morphological unit, separate and distinct from the remaining components on the ventral surface. This modification is found only in the members of the Hominoidea. In addition, several observations upon certain ontogenetic changes in lobular structure are reported.
Association of tendon organs with spindles in muscles of the cat's leg
Authors: Marchand R. , Bridgman C. F. , Shumpert E. , Eldred E. 
Published: February 2005

AbstractThe incidence and patterns of association of tendon organs (TO's) with muscle spindles was studied in serial histological sections of the extensor digitorum brevis (EDB) muscles of an adult cat. Some observations were obtained from the medial gastrocnemius and soleus muscles of a second cat, and the EDB muscle of a two‐toed sloth. An intimate relation of a TO to a nearby spindle, wherein the “spindle tendon” passes alongside the TO to attach to the aponeurosis, was found for 50% of cat EDB TO's, and 20 to 25% of the TO's in the other muscles. In cat EDB samples both TO's and spindles found in “tendon organ‐spindle dyads” had larger cross‐sectional areas at the equator than “solitary” units, and dyad TO's received the attachments of more extrafusal fibers than did solitary TO's. A number of the “solitary” TO's were found to be in line at a greater distance with spindles that lay along the extrafusal fibers inserting onto the TO. The possible developmental and functional significance of these findings is discussed.
Early differentiation of the chick embryo spinal cord in organ culture: Light and electron microscopy
Authors: Lyser Katherine M. 
Published: February 2005

AbstractChick embryo spinal cord has been explanted at two‐day stages, when few or no cells have formed axons, and cultured for five to seven days. The effects of various culture methods and the presence or absence of other tissues on differentiation have been studied. Many cells with axons and numerous nerve fibers were seen in silver‐stained sections of completely isolated neural tube cultured in a fold of vitelline membrane, as well as in neural tube explanted with adjacent tissues and in isolated neural tube recombined with somites. Electron micrographs of corresponding cultures showed cell bodies similar to those of fairly early nerve cells in vivo and processes with the structure of axons. Some characteristic differences in cell fine structure and in histological organization among these types of cultures were observed. Isolated neural tube cultured directly on a millipore filter did not survive or differentiate as well. These observations indicate that initial phases of nerve cell differentiation can proceed in organ culture and that there is no specific requirement for interaction with adjacent mesodermal tissues. This system can be used profitably for further investigation of factors controlling various aspects of differentiation in the central nervous system.
The fine structure of monkey and human spermatozoa
Authors: Zamboni L. , Zemjanis R. , Stefanini M. 
Published: February 2005

AbstractThe fine structure of spermatozoa of two species of monkey, Macaca mulatta and Macaca nemestrina, and man was studied following fixation of seminal fluids in buffered picric acid‐formaldehyde (PAF). The various components of the sperm have been studied mostly in light of the behavior of this cell at the time of conjugation with the ovum.The possible equivalence between acrosome and lysosomes has been discrussed considering the origin, enzymatic activity, and mechanism of action of these two classes of organelles. The fine morphology of the post‐acrosomal cap has been found to be comparable to that of a septate desmosome. We have introduced the hypothesis that the cap plays a role in establishing and maintaining adhesion between the spermatozoon and the ovum at the time of gamete conjugation. The formation of the scrolls of the nuclear membrance in the posterior region of the nucleus has been put into relation with the modifications of volume and shape of the spermatid nucleus. The function of the scrolls could be to increase the surface through which nucleocytoplasmic exchanges take place. The possibility that the presence of a voluminous cytoplasmic droplet in human spermatozoa is a sign of cellular immaturity has also been discussed.
The fine structure of the neck of mammalian spermatozoa
Authors: Zamboni L. , Stefanini M. 
Published: February 2005

AbstractThe study of the fine structural organization of the various components of the neck of mature spermatozoa of rabbit, monkey and man has demonstrated that the striated columns of the connecting piece implant on the proximal centriole, that the distal centriole does not disappear but persists albeit in a modified form and that the central tubules of the axoneme of the flagellum terminate at the lower vault of the proximal centriole. Of the two centrioles, the most plausible candidate for the role of basal body of the flagellum and center of the sperm motility appears to be the proximal centriole. This hypothesis is supported directly by the apparent continuity of this centriole with all the contractile elements of the flagellum, and indirectly by the consideration that the distal centriole cannot be a basal body in that its lumen is traversed throughout by a central pair of tubules. The orientation of the proximal centriole at an angle to the flagellum, a unique situation since basal bodies are normally oriented on the same axes of cilia and flagella, has been tentatively accounted for by the particular type of motility of the spermatozoon.
The epithelium of the vaginal introitus in the rat
Authors: Gitlin Gershon 
Published: February 2005

AbstractThe epithelium in the region of the vaginal introitus in the rat (“introital epithelium”) was examined in sexually mature animals in different stages of the estrous cycle. It was found to be stratified squamous in type and invariably cornified, irrespective of the state of the vaginal epithelium above it. Thus, it failed to undergo the estrous cyclic changes seen in the rest of the vaginal epithelium. The introital epithelium extends for a distance of 1.5 to 5 mm above the vaginal orifice.
Cytoarchitecture of rat liver during compensatory growth
Authors: Iatropoulos Michael J. 
Published: February 2005

AbstractThe possibility of the formation of new lobules in rat liver during the course of compensatory growth has been investigated. Two methods inducing regeneration were used: the method of subtotal hepatectomy and the method of porcelain bead implantation. Observations were made at 28, 42, 56, 68, 84 and 112 days after subtotal hepatectomy, and at 28 and 42 days after implantation of the bead.The results obtained from subtotal hepatectomy were expressed as the lobular radius (or portal‐central vein distance) measured in micra. The values were 404 μ at the twenty‐eighth day after hepatectomy and 324 μ at the one‐hundred‐twelfth day. The results obtained from bead implantation were 352 μ at the twenty‐eighth day after implantation and 305 μ at the forty‐second day.It is concluded that regenerating rat liver undergoes structural changes involving new lobule formation between the fifty‐sixth and the one‐hundred‐twelfth day after subtotal hepatectomy, and sometime after the fourth week after bead implantation. The difference in times after which structural changes occur is explained by the difference in intensity of stimulus in the two methods.
The spermatogonial stem cell population in adult rats. I. Their morphology, proliferation and maturation
Authors: Huckins Claire 
Published: February 2005

AbstractWhole mounted segments of seminiferous tubules from rat testes have been used to investigate the morphology and proliferative activity of the undifferentiated type A spermatogonial population. This has led to the formulation of a new model for spermatogonial stem cell renewal. Three groups of undifferentiated A spermatogonia were classified according to their topographical arrangements as isolated, paired, and aligned spermatogonia. It was proposed that the isolated (as well as a few paired) spermatogonia, which were always present throughout the seminiferous epithelium, are the functional stem cells and should therefore be designated as As. Through sporadic divisions, the As spermatogonia both maintain their own numbers and give rise to pairs of cells which are destined to eventually differentiate. The latter undergo several synchronous divisions in succession, thereby forming increasingly longer chains of aligned spermatogonia. The proliferation of these chains, primarily in stages I–V, leads to a gradual expansion in the size of the undifferentiated type A population. When the population attains its maximal size in stage V, mitotic activity among the aligned cells ceases, and all of these cells morphologically transform without further division into typical A1 spermatogonia. Subsequently, the cohort of A1 cells synchronously divides in stage IX to begin the long process of spermatogonial maturation. The isolated (and a few paired) cells, which do not undergo this transformation and remain quiescent during the stage IX peak of mitosis, form a residual stock of stem cells, that, during the course of another cycle, rebuild the population of aligned A spermatogonia. In this way, a continual supply of type A1 spermatogonia which will cyclically differentiate is insured.
A three‐dimensional reconstruction of the rods in rat maxillary incisor enamel
Authors: Warshawsky H. , Smith C. E. 
Published: February 2005

AbstractA three‐dimensional reconstruction of the rod profiles seen in inner and outer rat incisor enamel was made from serial 1 μ cross sections of a decalcified upper incisor. The enamel rod was found to be an elongated structure which travelled incisally relative to its origin and ran continuously from the dentino‐enamel junction to the enamel surface. The rod was divisible into an inner and outer enamel portion. The inner enamel portion began at the dentinoenamel junction and travelled incisally for about 20 μ with either a mesial or lateral tilt towards the outer enamel. The outer enamel portion of the rod was straight and ran incisally for about 60 μ as it gradually approached the enamel surface.Inner enamel portions of rods were arranged in rows parallel to the cross sectional plane of the incisor. All the rods in each row were tilted either mesially or laterally such that individual rods of adjacent rows crossed each other at 90°. Outer enamel portions of rods were not arranged in rows but all passed incisally parallel to one another.
Fine structure of rat pituitary cilia
Authors: Carpenter Esther 
Published: February 2005

AbstractPituitary glands of 30 ♀ rats from one to seven and one‐half months old were fixed in glutaraldehyde followed by osmium tetroxide. One five‐month gland was fixed in Karnovsky's paraformaldehyde mixture.Cilia in the residual cleft at all ages and in the electron lucid vesicles found in the pars distalis during the first two months occur in great numbers per cell and show the 9 + 2 pattern (9 peripheral doublets around 2 central tubules slightly separated from each other) characteristic of kinocilia. The spaces into which these cilia project may contain disintegrating cells as well as colloid‐like material of variable density.Cilia found in or between parenchymal cells of the pars distalis usually occur one per cell and lack central tubules. One of the doublets is often displaced toward the center. Cilia have been seen in three types of granular as well as in non‐granular cells. A pair of cilia enclosed in the same membrane was found once within and twice between parenchymal cells.Central tubules appear to develop only in locations (cleft and vesicles) where motility is possible. The single cilia found in parenchymal cells may be considered immature and are presumably non‐functional.
Ultrastructural aspects of the main excretory duct of rat submandibular gland
Authors: Shackleford John M. , Schneyer Leon H. 
Published: February 2005

AbstractRecent data indicate active transport of Na+ and K+ by the main excretory duct (MED) of the rat submandibular gland. In view of these data submandibular MED's of four adult rats were investigated by transmission electron microscopy. Luminal surfaces of two MED's were examined with the scanning electron microscope. The duct is surrounded by connective tissue, blood vessels and neuron perikarya. Blood supply to the ductal epithelium consists of a plexus of sinusoidal capillaries. Three principal cell types compose the epithelium: light cells, dark cells, and basal cells. The basal cells resemble those of striated ducts except for the presence of numerous hemidesmosomes along basal plasma membranes of MED basal cells. Light cells show basal infoldings, and bulbous enlargements may occur at their distal aspects. Dark cells are narrow, electron dense cells with prominent microvilli at the luminal surface. Intercellular clefts penetrate MED epithelium from the lumen to a depth of one‐third the epithelial thickness. Surfaces of the clefts are lined by dark and light cells. Intercellular tissue spaces are present at lateral boundaries of all cells and extend from the epithelial base to distal cytoplasmic levels.