bluuebunny/crossref_metadata_2025 huggingface dataset:
Autoradiographic evidence of primary projections to the caudal cochlear nucleus in cats
Authors: Kane Eileen S.
Published: February 2005

Six adult cats received unilateral cochlear injections of 30–70 μCi 3H‐leucine (3‐H‐leu) in saline. After 20–48 hours, their brains were prepared for autoradiography. The octopus cell area (OCA) and the dorsal region (DCN) of the cochlear nucleus of both the injected and uninjected sides were studied in detail. Grain counts of autoradiographs always showed much greater label in the injected side. Autoradiography confirmed uniform distribution of primary afferents in the OCA, as seen in grain counts over the whole area (both somata and neuropil); however, grains were more densely packed over somata than neuropil of the OCA. In DCN, grain counts showed a gradient of label from the deep to superficial layers, a greater density of label over somata than neuropil of the deep DCN, and uniform distribution of label over the whole fusiform cell layer of the DCN. These results showed (1) best resolution and localization in cats that survived 24 hours and with exposures of two weeks, (2) no significant diffusion of label to other CNS regions than the auditory nuclei,and (3) transneuronal transport of label after 48‐hour survival times. Liquid scintillation counts (LSC) of cochlear nerve roots ipsilateral and contralateral to the injection showed at least a 10:1 ratio in all cats. This report not only gives new autoradiographic evidence of the distribution of primary afferents within the caudal cochlear nucleus, but also provides a useful approach to the study of distribution of specific amino acids implicated in central neurotransmission by cochlear terminals.
A morphological study of the human prepubertal and pubertal larynx
Authors: Kahane Joel C.
Published: February 2005

Measurements were made from ten Caucasian male and ten Caucasian female cadaveric larynges ranging in age from 9 to 18 years. The sample was divided into prepubertal and pubertal groups of each sex, respectively. Each specimen was dissected and measured according to a specified protocol so that data on linear and angular dimensions of the laryngeal cartilages and the weight of each cartilage were obtained. Results from this study highlighted differences in the developmental morphology of the circumpubertal larynx. With few exceptions, pubertal laryngeal measurements were significantly larger than prepubertal counterparts in both sexes. No clear sexual dimorphism was found between male and female prepubertal larynges though measurements of the prepubertal female larynx were closer to adult counterparts in size and weight than were those in the male. Thus the female larynx requires less growth per unit time to reach maturity than the male. By puberty, clear sexual dimorphism was evident in the larynx. Linear and weight measurements of the pubertal male larynx were significantly larger than in the female. Though the angle of the thyroid laminae was not significantly different in pubertal male and female cartilages, the thyroid eminence was clearly more prominent in the male. The vocal folds in both sexes reached essentially their adult length by puberty; however, the absolute length of the male vocal folds had increased by over two times that of the female.
Ultrastructure of Octodon degus spermatozoon with special reference to the acrosome
Authors: Berrios M. , Flechon J. E. , Barros C.
Published: February 2005

The ultrastructure of spermatozoa from the cauda epididymidis and vas deferens of Octodon degus — a Chilean hystricomorph rodent—is presented. The head of spermatozoa measured 7.7 μm long by 5.9 μm wide and the tail was 41 μm long. The head was flattened dorso‐ventrally and ovate in outline. The acrosome was the most distinctive feature of O. degus spermatozoa. In a frontal view of the head, the rim of the acrosome surrounding the nucleus had the shape of an inverted U. The acrosomal region covering the plane of the flattened head exhibited dome‐shaped protrusions. Transverse or sagittal sections of acrosomal protrusions showed that the plasma membrane and outer acrosomal membrane were evaginated, while the inner acrosomal membrane followed the contour of the nucleus. The protrusions were not distributed at random and they were absent in the equatorial segment and in the rim of the acrosome.

In frontal views, near the boundary between the acrosome and post‐acrosomal region, fine rods about 170 nm long ran obliquely on the caudal part of the equatorial segment. Behind the same boundary, the post‐acrosomal region showed a serrated border.

Phosphotungstic acid treatment at pH 0.3 produced staining at the surface of the sperm as well as within a superficial layer of the marginal thickening of the acrosome and on the acrosomal protuberances.
Macrophages and epithelial cells in human amniotic fluid: Transmission and scanning electron microscopic study
Authors: Cutz E. , Conen P. E.
Published: February 2005

This combined light, transmission and scanning electron microscopic study describes and correlates the morphologic features of various types of cells present in normal human amniotic fluid (AF), during various stages of gestation. The aim of this investigation was to identify and characterize the viable cell population of AF cells as they pertain to the origin of AF cells growing in culture and their use for prenatal diagnosis.

In all AF samples, including those obtained during the time period critical for prenatal diagnostic tests (14–16 weeks gestation), the majority of AF cells had the morphologic features of large squamous epithelial cells. By transmission and scanning electron microscopy these cells were characterized as keratinizing or non‐keratinizing squamous epithelial cells and resembled the cells found on various fetal surfaces (i.e., buccal mucosa, skin, etc.). As judged by Trypan blue stainability and the presence of nuclear and cytoplasmic degenerative changes, the AF squamous cells were considered non‐viable, and thus unlikely to grow in culture.

The AF cells considered to be viable, because of their excellent ultrastructural preservation and exclusion of Trypan blue stain, formed only 10–15% of AF cells. Amongst this viable population, at least two morphologically distinct cell types were identified. One type had morphologic and functional characteristics of macrophages. The AF macrophages differed from other AF cells by the presence of a strong acid phosphatase reaction, numerous phagosomes and an ability to phagocytose in vitro, both latex particles and bacteria. Although AF macrophages appear to be a normal cell constituent of human AF, their origin and significance is unknown. The second type of viable AF cells appeared as single cells or in clusters and resembled the epithelial cells of amniotic lining. The amniotic cells showed excellent ultrastructural preservation of nuclei and cytoplasmic components. In contrast to AF macrophages, the amniotic cells contained cytoplasmic glycogen, possessed fine, regular surface microvilli and lacked both phagosomes and phagocytic capacity in vitro. It is proposed that these two types of viable AF cells may be the sources of cells growing in culture and could be responsible for the morphologic and biochemical heterogeneity of cultured AF cells.
Histological analysis of the growth of the mandibular condyle in the rhesus monkey (Macaca mulatta)
Authors: Carlson David S. , McNamara James A. , Jaul Douglas H.
Published: February 2005

Qualitative and quantitative data on the growth of the mandibular condyle in the rhesus monkey (Macaca mulatta) are limited. The purpose of this investigation was to provide such data, with emphasis on variation in the size of the cartilaginous layers in the condyle and on condylar growth at five maturational levels (i.e., neonate, infant, juvenile, adolescent and young adult).

Two regions of the mandibular condyle, the articular tissue and the prechondroblastic‐chondroblastic (growth) layer, were examined histologically in 38 rhesus monkeys. The absolute area of the articular layer increased dramatically from the neonatal through the juvenile age groups and then decreased gradually through the adult group. When the absolute values were expressed relative to condylar size, the first three maturational levels shared a common trend of increasing growth of the articular layer, with a cessation of growth in this tissue occurring during the adolescent period. This variation in articular layer tissue is probably the result of progressive alteration in the function of the temporomandibular joint.

The size of the prechondroblastic‐chondroblastic (growth) cartilage increased dramatically between the neonatal and juvenile age groups, and subsequently decreased in older age groups. The relative thickness of the prechondroblastic‐chondroblastic cartilage reached its peak within the infant and juvenile levels, being greatest in the posterior region among the infants and in the postero‐superior region among the juveniles. This corresponds to previous investigations which have shown that greater vertical growth of the rhesus monkey mandible occurs during the infant period, while the direction of mandibular growth is more horizontal in subsequent age groups.
Studies of the cellular cure for osteopetrosis by transplanted cells: Specificity of the cell type in ia rats
Authors: Marks Sandy C.
Published: February 2005

Spleen cells from normal rats are known to cure osteopetrosis in ia littermates within 3 weeks. In this study cell suspensions from liver, thymus, bone marrow, salivary gland, skeletal muscle and brain from normal rats were tested for their ability to cure osteopetrosis in ia littermates whose ability to reject these cells had been suppressed by whole‐body irradiation. Cells from liver, thymus and bone marrow cured the disease as effectively as spleen cells from normal littermates. Mutants that received cells from salivary gland, muscle and brain remained osteopetrotic. These data suggest that some cell found in spleen, liver, thymus and bone marrow of 10‐day‐old normal rats, such as a lymphoid cell or stem cell, can restore hemopoiesis and bone resorption in osteopetrotic (ia) rats.
An electron microscopic study of the cavernous bodies in the lamprey gill filaments
Authors: Nakao Taisuke
Published: February 2005

The cavernous body in the lamprey gill filament was studied by electron microscopy. This body lies along the outer border of the axial plate of each gill filament and freely communicates with an afferent filament artery. Two series of blood channels run alternately, passing through the cavernous body, and lead to the marginal channels in the secondary lamellae. On the other hand, narrow blood spaces left in the cavernous body lead to the blood lacunae in the axial plate (osmoregulatory region) and to those in the secondary lamellae (respiratory region). All the blood in the cavernous body is finally collected by an efferent filament artery.

The cavernous body is traversed by numerous trabeculae and collagenous columns which run diagonally in the blood spaces to connect the walls of the cavernous body. All the walls of the cavernous body, including trabeculae and collagenous columns, are completely surrounded by the cytoplasmic flanges of specialized cells called here “cavernous body cells.” These cells are about 30 μm in diameter and characterized by (1) association with collagenous columns or trabeculae and also by the presence of (2) coated caveolae and vesicles, (3) vacuoles and (4) cytoplasmic granules in their cytoplasm. These cells are considered to be related to the pillar cells in origin because of their close association with collagenous columns or trabeculae. The functional significance of the cavernous body and the cavernous body cells is discussed.
Isolated perfused dog lungs: A comparative stereologic comparison with normal dog lungs
Authors: Defouw David O. , Berendsen Peter B.
Published: February 2005

Established stereologic techniques were used to evaluate the morphologic integrity of isolated dog lungs perfused with plasma for periods of 30 minutes, 1 hour and 2 hours. The morphometric data from the isolated lung preparations were compared to similar morphometric evaluations of dog lungs fixed immediately after removal from the thorax. In the isolated lungs capillary surface and volume densities were both substantially decreased. These estimations of capillary surface density provide a morphologic definition of capillary surface area which should be useful in the estimations of endothelial permeability in isolated lungs. This morphometrically defined decrease in capillary volume density was attributed, in part, to swelling of the endothelial cells. Alveolar surface density was also decreased and the type‐I epithelial cells were increased in thickness. In both the endothelial and epithelial cells, cytoplasmic volume densities of the mitochondria and smooth endoplasmic reticulum were increased, while those of the rough endoplasmic reticulum and micropinocytotic vesicles were unchanged. The thickness of the interstitial compartment of the air‐blood barrier and the volume densities of the peribronchial, peribronchiolar, and perivascular connective tissue sleeves were unchanged; there was no evidence of interstitial edema in the isolated lungs. These morphologic changes must be considered in the interpretation of physiologic studies which employ isolated perfused dog lung preparations.
Scanning electron microscope studies of the papilla basilaris of some turtles and snakes
Authors: Miller Malcolm R.
Published: February 2005

The papillae basilares of three species of turtles and four species of snakes were studied by SEM. The papillae of turtles are relatively large among reptiles and are characterized by a long, horizontal middle section resting on a wide basilar membrane. Both terminal ends of the papilla extend onto the surrounding limbus in the form of a forked or “T”‐shaped end or as a curved, “hook”‐like process. Details vary with the species. In the three species of turtles studied, there were between 1,100 and 1,400 hair cells on a papilla. The tectorial membrane covering the horizontal portion of the papilla is heavy in appearance and tightly attached to the kinocilial bulbs. The terminal ends of the papilla are covered by a thin gelatinous material. In addition, a mat‐like tectorial network covers the supporting cells and extends from the microvilli of the supporting cells to the overlying tectorial membrane. All hair cells are unidirectionally and abneurally oriented. The supporting cell surfaces form a large part of the papilla and, thus, hair cell density is low.

The papillae of the two boid snake species studied are moderately long among snakes and contain a moderate number of hair cells (574 in Epicrates and 710–780 in Constrictor). Papillar form is elongate, ovoid, or canoe‐shaped. The tectorial membrane may be either highly fenestrated or moderately dense and covers all but a few of the terminal hair cells. A tectorial‐like mat covers all but a few of the terminal hair cells. Most hair cells are unidirectionally and abneurally oriented. A few terminal cells in boids may show reverse orientation. Hair cell density is similar to that of turtles.
Decidual cells in the human ovary at term. I. Incidence, gross anatomy and ultrastructural features of merocrine secretion
Authors: Herr John C. , Heidger Paul M. , Scott James R. , Anderson John W. , Curet Louis B. , Mossman Harland W.
Published: February 2005

Decidual tissue occurring within the human ovarian cortex was examined by light and electron microscopy. Of 21 ovarian specimens obtained at term (36–42 weeks of gestation), decidual cells were confirmed in each. Decidual cells were found within the tunica albuginea as single cells, in nodules, in polyps or in confluent sheets. Decidual cells exhibited several characteristics of cells engaged in secretory activity: abundant rough and smooth endoplasmic reticulum, numerous profiles of the Golgi complex and a large, euchromatic nucleus devoid of heterochromatin and displaying a prominent fibrous lamina. Peduncular protrusions at the periphery of the cell contained numerous dense bodies 0.4–0.9 μm in diameter. These dense bodies were bounded by a single membrane and contained granular subunits 30–60 nm in diameter. These granular subunits were observed in the process of apparent exocytosis, as well as free in the extracellular space. Secretory bodies and their granular content also were observed both in the region of the Golgi complex and partially extruded into peduncular processes. By far the greatest number of secretory bodies occurred within peduncular processes where they may be stored prior to release. Migration of a secretory body into a peduncular process and exocytosis from such a process appears to be an unusual mode of meocrine secretion, perhaps unique to decidual cells.
Origin and differentiation of the yolk sac and extraembryonic mesoderm in presomite human and rhesus monkey embryos
Authors: Luckett W. Patrick
Published: February 2005

Reexamination of presomite human and rhesus monkey embryos in the Carnegie Collection provides no evidence to corroborate the hypothesis that the trophoblast is the source of all extraembryonic tissues in these embryos. Instead, the present study indicates that the developmental pattern of the yolk sac and extraembryonic mesoderm is homologous to that in other eutherian mammals. The primary yolk sac of 10‐ to 11 ‐day human blastocysts is partially filled with a meshwork of extraembryonic endoderm, whereas such a meshwork is absent in the rhesus monkey. It is suggested that this endodermal meshwork develops as the result of interstitial implantation in the human embryo. A small secondary yolk sac develops in 12‐ to 13‐day human and macaque embryos as the result of pinching off of a portion of the larger primary yolk sac. Development of a secondary yolk sac in higher primates appears to be related causally to differential rates of expansion of the blastocyst and primary yolk sac within the simplex uterus.

The caudal margin of the primitive streak develops precociously in 12‐ to 14‐day human and macaque embryos, and this appears to be the source of all the extraembryonic mesoderm of the chorion, chorionic villi, and body stalk. It is suggested that the peripheral spread of extraembryonic mesoderm plays an inductive role in the development of chorionic villi, similar to other types of epithelial‐mesenchymal inductive interactions. In contrast to previous hypotheses, the human and macaque trophoblasts appear to give rise only to additional trophoblast.
Evidence of a role for cell death in the disappearance of the embryonic human tail
Authors: Fallon John F. , Simandl B. Kay
Published: February 2005

The development and disappearance of the human tail between stages 14 and 22 were studied using scanning and transmission electron microscopy, supravital staining and light microscopy. The tail is a prominent feature of the human embryo during stage 14 and is composed of paired somites, mesenchyme and extensions of the neural tube, notochord and gut. The tail grows with the embryo through early stage 17 when it extends more than a millimeter from the trunk. Overgrowth by the trunk at the base of the tail may account for the loss of part of its length during late stage 17 and stage 18. However, during stage 17 cells begin to die in all structures throughout the tail. Cell death continues in the succeeding stages reaching massive numbers by stages 18 and 19, and the tail becomes less and less prominent with developmental time. Most of the dead cells are phagocytosed. The debris‐laden macrophages appear to migrate from the tail to the body. By late stage 21 or early stage 22 there is no free tail. We conclude that cell death has a major role in the destruction of tail structures and the concurrent loss of the human tail.
Myocardial morphology in spontaneously hypertensive and aortic‐constricted rats
Authors: Lund Donald D. , Tomanek Robert J.
Published: February 2005

The cellular and subcellular adaptations in the myocardium of spontaneously hypertensive rats (SHR) were compared with those in Kyoto‐Wistar normotensive rats with cardiac hypertrophy induced by constriction of the abdominal aorta (ACR). Hypertensive blood pressure levels were attained at eight weeks of age in SHR and coincided with the surgically‐induced pressure‐overload in ACR at this age. Specimens from the subepicardial and subendocardial regions of the myocardium from glutaraldehyde‐perfused‐fixed hearts of 16‐week‐old animals were compared.

Spontaneous hypertension and aortic constriction are associated with significant and comparable increases in heart rate, blood pressure, heart weight, and left ventricular muscle fiber diameter. While the cardiomegaly in both models was accompanied by a decrease in capillary density, the decrement was greater in the aortic‐constricted rats. Stereological analysis of cardiocytes revealed an increase in myofibril/cell‐volume, and a decrease in mitochondria/myofibril‐volume ratios in both models of cardiomegaly. In addition, double intercalated discs and subsarcolemmal foci containing abundant sarcoplasm with numerous small mitochondria, free filaments and Golgi complexes were commonly observed in both experimental groups. Cell diameter increased by a larger increment in the subendocardium than in the subepicardium, but capillary density was similar in these two regions. While aortic constriction was associated with dilatation of T‐tubules and the non‐specialized junctions of the intercalated disc, the myocardial ultrastructure of SHR was characterized by a greater number of lipid droplets and an increased folding of the intercalated discs comprising the subendocardial region.

These findings suggest that data based on surgically‐induced pressure‐overload should be extrapolated cautiously to cardiomegaly associated with spontaneous hypertension. The differences between the adaptations in the two models may be due to either (1) the rate at which hypertrophy occurs or (2) some other, possibly genetic, factors unique to SHR.
Localization of human pancreatic polypeptide in an argyrophilic fourth cell type in islets of the rat pancreas
Authors: Schweisthal Michael R. , Schweisthal Janet V. , Frost Cecil C.
Published: February 2005

An argyrophilic fourth cell type in the rat pancreatic islet can be differentiated from other silver‐staining cells by using a modification of the Grimelius aqueous silver nitrate technique. Restaining of the tissues using fluorescent techniques with anti‐HPP (Human Pancreatic Polypeptide) serum results in bright fluorescence in the fourth cell type.
Developmental change in a basicranial line and its relationship to the upper respiratory system in living primates
Authors: Laitman Jeffrey T. , Heimbuch Raymond C. , Crelin Edmund S.
Published: February 2005

This study investigated the relationship between alterations in a basicranial line and changes in the upper respiratory system of selected non‐human primates and of man. This was done through multivariate analysis of craniometric measurements which describe midline exocranial flexion, and compares the analytical results with previous postmortem findings on upper respiratory structure and function.

Craniometric analysis has shown that the skulls of the non‐human primate species studied and those of newborn human infants are relatively non‐flexed exocranially between the posterior border of the hard palate and foramen magnum. This finding corresponds to the relatively high position of their upper respiratory structures. In this group the tongue lies entirely within the oral cavity, and the epiglottis is found intranarial.

After approximately the second year, humans exhibit marked exocranial flexion between the hard palate and foramen magnum. These basicranial changes coincide with concomitant changes occurring in the positional relationships of the upper respiratory system. After the second year the tongue and larynx have descended considerably into the neck, greatly altering their functional relationships.

There thus appears to be a relationship between the exocranial orientation of the basicranium and the positioning of upper respiratory structures. There also appears to be a direct structural, and possible functional, relationship between (1) the position of the larynx, (2) the orientation of the pharyngeal constrictor muscles, and (3) the orientation of the basiocciput.
Neonatal muscle growth: A quantitative study
Authors: Ontell Marcia , Dunn Robert F.
Published: February 2005

Various growth parameters of the rat extensor digitorum longus muscle were studied during the first week of neonatal growth, including changes in weight, length, girth and fiber number. These quantitative studies were supplemented by ultrastructural analysis of fiber diameter and morphology in an attempt to determine the source of “new” muscle fibers in the neonate. In the 2‐day‐old extensor digitorum longus many of the myofibers were enclosed with other filamented cells (a satellite myofiber and/or myotube) in a common basement membrane, forming a cluster. Clusters accounted for 40% of the total independent filamented cells and clusters in 2‐day‐old muscles, for 2% in the 5‐day‐old, and for less than 1% in the 8‐day‐old. The decrease in the percentage of clusters occurred concomitantly with an increase in the number of independent filamented cells. In the 2‐day‐old there were 2,932 ± 130 independent cells and clusters; this number increased by 90% in the 8‐day‐old muscle. Mean diameters of filamented cells (whether found independently or as part of a cluster) increased from 6.5 μm to 7.4 μm and to 9.5 μm on days 2, 5, and 8 respectively. Increased filamented cell diameter between days 2 and 5 was a result of growth of the smallest filamented cells into the medium‐size compartment. Between the fifth and eighth day postpartum, the increase was due to the growth of both small and medium‐size filamented cells. The largest fibers did not increase in diameter during the first week of postnatal development, maximal fiber diameter in the 2‐day‐old being 15.9 μm and in the 8‐day‐old, 16.1 μm. At two‐days the area through the widest girth of the muscle occupied by filamented cells was 35% of the total cross‐sectional area of the extensor digitorum longus. At eight days muscle fibers occupied 59% of the cross‐sectional area. To accommodate the myofibers the muscle belly increased its girth, and there was a decrease in the percentage of the area occupied by interstitial tissue, nerves, and blood vessels.
Histochemical dichotomy of extrafusal and intrafusal fibers in an avian slow muscle
Authors: Ovalle W. K.
Published: February 2005

The avian anterior latissimus dorsi (ALD) is unique amongst vertebrates since it has been considered to be a true slow (or tonic) skeletal muscle. While the structure and function of the extrafusal fibers in the ALD have been intensively investigated, the intrafusal fibers of its muscle spindles and their relationship to the surrounding extrafusal fibers in this muscle have been virtually neglected. Serial frozen sections of this muscle from normal adult domestic chickens were tested for two separate enzymes: myosin ATPase after preincubations at differing pH (Brooke and Kaiser, '69) and NADH‐tetrazolium reductase, a mitochondrial‐bound oxidative enzyme. Both enzyme reactions were able to detect two distinct categories of extrafusal fibers in this muscle, as well as two classes of intrafusal fibers in its muscle spindles.

Neither of the extrafusal fiber‐types reacted like typical fast (or twitch) fibers for myosin ATPase; they did not show a characteristic reversal in their relative staining patterns throughout the alkaline (pH 9.4) to acid (pH 4.6 and 4.3) preincubation range. The majority of fibers (type 1) were significantly larger in their cross‐sectional size, consistently stained lightly for ATPase, and showed high NADH‐TR activity. They represented about 84% of the total fiber population (n = 3540 ± 75). The other set of extrafusal fibers (type 2) constituted the remaining 16% of the total fiber population. They were smaller in diameter, exhibited high myosin ATPase activity, and reacted less intensely for the oxidative enzyme.

The histochemical characteristics of the two kinds of intrafusal fibers were profoundly different from those observed in the extrafusal fibers. Their crosssectional fiber diameters were not significantly different from each other, and they exhibited a reversal in their staining reactions for myosin ATPase following acid preincubation for this enzyme.

The results of this study concur with recently published reports of extrafusal fiber heterogeneity in the slow ALD muscle of the chicken. In addition, this work clearly demonstrates a histochemical dichotomy amongst the intrafusal fibers of muscle spindles in this muscle.
Spermatogonial intercellular bridges in whole‐mounted seminiferous tubules from normal and irradiated rodent testes
Authors: Huckins C.
Published: February 2005

Whole‐mounted seminiferous tubules from normal and irradiated rodent testes were examined by light microscopy. These studies reveal the presence of intercellular bridges in all classes of spermatogonia except for the single As stem cells. It was demonstrated that As stem cells divide to produce new As spermatogonia or paired daughter cells that are united by a cytoplasmic bridge. Evidence was given that all subsequent progeny of these paired A's up to and including the production of type B spermatogonia remain linked by cytoplasmic bridges in increasingly larger and more complex syncytial networks.

It is proposed that the intercellular bridges mediate both differentiation and degeneration of spermatogonia. The maintenance of synchronous development within cohorts of spermatogonia is attributed to the bridges. Moreover, the fact that spermatogonia in both normal and irradiated testes degenerate in clusters is determined by the presence of intercellular bridges. Lastly, the integrity of the bridges appears essential for normal germ cell development.
Localization of vitamin A‐storing cells in the mouse adrenal gland: An electron microscopic autoradiographic study
Authors: Hirosawa Kazushige , Yamada Eichi
Published: February 2005

Radioactive vitamin A acetate was stored in specific cells in the mouse adrenal gland. Radioactivity was detected in lipid droplets of fibroblast‐like cells, whose distribution was from the capsule to the medulla. Their population was highest in the cortex. The morphology of these labeled cells was similar to that of vitamin A‐storing cells in other organs of mouse (Yamada and Hirosawa, 1976).

Though functions of these cells are obscure, the fact that they are found in organs where metabolic activity of vitamin A is high suggests that they bear some role in the metabolism and storage of the vitamin.
Scanning electron microscopy of the kidney glomerular epithelium after treatment with polycations in situ and in vitro
Authors: Andrews Peter M.
Published: February 2005

Changes in fine structure of glomerular epithelial cells (podocytes) were examined after treatment in situ and in vitro with polycations (i.e., protamine sulfate and poly‐l‐lysine). Scanning and transmission electron microscopic observations indicate that polycation‐induced alterations of the glomerular epithelium are similar in many respects to those resulting from puromycin aminonucleoside nephrosis. These alterations include the formation of junctional complexes between adjacent podocyte processes, flattening and retraction of podocyte processes, extensive folding of the slit diaphragms, formation of interpedicular microbridges, and development of irregular knobby surface‐microprojections. Prolonged treatment in vitro with high concentrations of polycations results in nearly complete loss of podocyte processes and the transformation of these once elaborate cells into simple polyhedral cells. The foregoing observations support the view that pedicel loss in puromycin aminonucleoside nephrosis may be due to a reduction in the glomerular epithelial polyanionic sialic acid surface coat.
Cerebral localization of insulin by immunofluorescence
Authors: Pansky Ben , Hatfield James S.
Published: February 2005

An immunohistochemical procedure was used to detect cells which appear to bind insulin in the mouse brain. Strong fluorescence was observed in the cell bodies and processes of tanycytes lining the third ventricle and in the choroid plexi. These findings suggest that insulin enters the central nervous system, and indicate a route for its possible transport. This adds credence to earlier observations that the hypothalamic ependymal cells and processes form a highly organized and functional system, with different cells selectively absorbing (or sensing) particular substances from the systemic and ventricular circulations and transporting them (or information about them) to specific neuron receptors in the hypothalamus.
Somatostatin‐containing neurons in the rat brain: Widespread distribution revealed by immunocytochemistry after pretreatment with pronase
Authors: Finley James C. W. , Grossman Gail H. , Dimeo Pia , Petrusz Peter
Published: February 2005

Immunocytochemical staining after controlled proteolytic treatment of the sections with pronase revealed widespread distribution of neuronal cell bodies with somatostatin‐ like immunoreactivity (SLI) in the rat forebrain. SLI‐positive neurons were found in regions of the neocortex, the pyriform cortex, the cingulate cortex, the striatum, the olfactory tract and tubercle, the nucleus accumbens, the septum, and the hypothalamus. These results are consistent with previous radioimmunoassay findings and suggest the presence of large somatostatin‐like (possibly precursor) molecules in the neurons stained for SLI after pronase treatment.
Hypertrophy of astroglial processes in the dentate gyrus of the senescent rat
Authors: Geinisman Yuri , Bondareff William , Dodge John T.
Published: February 2005

Quantitative electron microscopic analysis of the supragranular zone of the dentate gyrus molecular layer has shown that the number and volume fraction of profiles of astroglial processes are significantly increased in senescent rats relative to young adults. These ultrastructural modifications, which are not associated with significant age‐related changes in the number of astrocytes or in the width of the molecular layer, may result from a formation of new astroglial processes and/or elongation of existing ones. In either case, the increase in the number and volume fraction of astroglial process profiles is an indicator of age‐related astroglial hypertrophy. Hypertrophy of astroglial processes, which seems to develop with advanced age as a response to partial deafferentation of neurons, may compensate for a decrease in the dendritic volume fraction, thereby preventing changes in the dimensions of the dentate gyrus molecular layer in senescence.
Quantitative morphology and environmental responses of the pineal gland in the collared lemming (Dicrostonyx groenlandicus)
Authors: Quay W. B.
Published: February 2005

Collared lemmings from Churchill, Manitoba, and their descendants were studied in captivity to define neuroendocrine and related histophysiological characteristics and responses, particularly in relation to photic and temperature conditions. Relatively great pineal size (0.1755 ± 0.0167 mm3, or 3.08 ± 0.30 = pineal volume in mm3 × 103/body weight in gm; N = 16) shown in this arctic rodent is consistent with the suggestion that pineal size and significance may tend to be greater in more northern (higher latitude) species. Total number of nucleated cells per pineal averaged 137,000 ± 10,500. Pinealocytes (105,000 ± 8,700/pineal) and other cell types were present in relative numbers typical of mammalian pineal glands, and were not numerically correlated with age, sex, or location or circumstances of birth and early postnatal life. Chronic exposure to warmer (21–27°C) in comparison with colder (−9 to −6°C) environments, whatever the illumination, led to greater pinealocyte activity, as shown especially by nucleolar diameter, throughout most of the nine regions of the organ analyzed cytologically (all regions combined: P < 0.001). Increased pinealocyte activity in chronic darkness was suggested by similar evidence (P < 0.01), but in comparison with the thermal effects, was less marked and more variable in different regions of the organ. These and other findings of this study indicate that the Dicrostonyx pinea organ is morphologically unique, relatively large in size, and cytologically responsive to environmental conditions.
Morphological development of the epithelium of the embryonic chick intestine in culture: Influence of thyroxine and hydrocortisone
Authors: Black Betty L.
Published: February 2005

A culture system with defined medium has been utilized to elucidate the role of thyroxine (T4) and hydrocortisone (HC) in growth and differentiation of the epithelium of embryonic chick duodenum during the third week of development. Duodenal explants maintained a basically normal morphology for 48 to 72 hours, but during subsequent culture, muscle and mesenchyme deteriorated, previllous ridges shrank, the epithelial surface became pitted, and the tissue lost weight. These degenerative processes were retarded by addition of HC to the culture medium.

Previllous ridges of cultured duodenum failed to develop into true villi and ridge growth was subnormal. Epithelial mitotic counts were increased by T4 or HC, as compared to cultured control tissue, but dropped below values in vivo, by 72 hours in culture.

Epithelial differentiation proceeded more rapidly in duodenum cultured without hormones than in vivo. Increase in cell height, flattening of the epithelial surface, attainment of uniform staining of the brush border with periodic acidSchiff, increase in microvillar density, and formation of a terminal web were accelerated by 24 to 48 hours in culture. In the presence of T4, cell height and microvillar growth were stimulated further, reaching the state found at 19 to 21 days in vivo.
The effects of continuous direct current on the growth of the antler
Authors: Lake F. T. , Davis R. W. , Solomon G. C.
Published: February 2005

The long‐term application of low levels of cathodal direct current to the growing deer antler produced abnormal branching patterns and antlers which grew in atypical directions. The experimental antlers were significantly reduced in length when compared to control antlers.
Regression of the larval opisthonephros during metamorphosis of the sea lamprey, Petromyzon marinus L.
Authors: Ooi E. C. , Youson J. H.
Published: February 2005

The opisthonephric kidney of larval anadromous sea lamprey, Petromyzon marinus L., undergoes a programmed regression during metamorphosis. Degeneration is initiated in the anterior end of each kidney and progresses posteriorly until the kidneys are reduced to short, pigmented strands by the end of metamorphosis.

The first sign of degeneration in both the epithelium of the renal corpuscles and the tubules is a folding of the basal lamina. Autolysis then occurs throughout the entire epithelium of the nephron with the gradual accumulation of larger and greater numbers of acid phosphatase‐containing autophagic vacuoles, cytosomes, and myelin figures. Cytoplasmic debris and electron‐dense material accumulates in the tubular lumina and in the urinary space. Although no definitive evidence is provided for the method of removal of the tubular epithelium, macrophages play a large part in the phagocytosis of the components of the renal corpuscle. Mesangial cells appear to engulf debris from the capillaries while a second type of macrophage is involved in the destruction of podocytes and parietal epithelial cells. The method of programmed degeneration of the renal corpuscle closely resembles descriptions of the mammalian renal corpuscle in diseased conditions. The sole surviving element of the degeneration of the entire nephron epithelium is a pleated basal lamina.

The regressing larval opisthonephros has potential as an alternative system for studying a normal developmental pattern such as tissue regression.
The development of the atrioventricular node and bundle in the ferret heart
Authors: Marino Thomas A. , Truex Raymond C. , Marino Deborah R.
Published: February 2005

The development of the atrioventricular (AV) node and bundle in the ferret heart was examined at the light microscopic level. The AV node develops from two primordia which were first observed in the posterior wall of the common atrium during the stage when the single heart tube convolutes. During septation of the heart, the AV nodal primordia eventually fuse and come to lie at the base of the interatrial septum. The right AV nodal primordium is located below the attachment of the right venous valve to the interatrial septum. The left AV nodal primordium maintains a position anterior to the prospective ostium of the coronary sinus. At 16 days of gestation, large pale cells were seen in the dorsal AV canal. By 21 days of gestation these AV canal cells have been replaced by AV bundle cells. At this time the bundle is continuous with both nodal primordia. At birth the AV bundle is continuous mainly with the component of the AV node that is derived from the right AV node primordium. The anulus fibrosus begins to undergo the greatest developmental change after the AV node and bundle attain their final position in the AV junction. However, the anulus does not completely separate the atria from the ventricles during the later stages of development nor at birth, so that accessory AV pathways are present in the newborn ferret heart. Both the AV node and the AV bundle also demonstrated continuity with the myocardial cells of the interventricular septum in the neonatal heart. During development there was no evidence that rings of specialized tissues at the junctions of the cardiac chambers give rise to any component of the cardiac conduction system.
Influence of iron upon the development of tetracycline‐treated mouse tooth germs in vitro
Authors: Kerley Michael A. , Kollar Edward J.
Published: February 2005

The inhibitory action of tetracycline on the development of embryonic mouse incisors cultured in vitro was examined. Explants exposed to tetracycline were severely inhibited in development. In contrast, tooth germs cultured in the presence of both tetracycline and iron escaped inhibition and attained a stage of development which compared favorably with the controls.
Influence of development on the number of calcitonin‐containing cells in the mouse thyroid
Authors: Wechbanjong Nualnoi , McMillan Paul J. , Dalgleish Arthur E.
Published: February 2005

Calcitonin‐containing cells in serial, 6‐μm sections of the thyroid glands of Swiss Webster mice, at 1 day, 2 weeks, 4 weeks and 8 weeks of age, were demonstrated by an immunoperoxidase method, using antiserum to human calcitonin. C‐cell nuclei were counted in every sixth section of both left and right lobes. The average number of C‐cells counted in the thyroid glands of 8‐week‐old animals was 18‐fold, 5.5‐fold and 2.5‐fold greater than the number observed in 1‐day, 2‐week and 4‐week‐old animals, respectively. C‐cell concentration was found to be greatest in 4‐week‐old mice. Mitoses of C‐cells were observed in animals which were 1 day, 2 weeks and four weeks old. No mitotic figures were seen in 8‐week‐old animals. A few C‐cells were seen in close association with neurons. The volume of the thyroid glands of 8‐week‐old animals was about 14‐, 4‐ and 3‐fold greater than the volume in the 1‐day‐old, 2‐week‐old and 4‐week‐old mice, respectively.

These changes in the C‐cell population during development provide a model for the study of C‐cell proliferation and storage of calcitonin.
Changes in the fine structure of tanycytes during the annual reproductive cycle of the male little brown bat Myotis lucifugus lucifugus
Authors: Brawer James R. , Gustafson Alvar W.
Published: February 2005

The hypothalamic arcuate nucleus in the male little brown bat Myotis lucifugus lucifugus was studied with the electron microscope. Animals were killed by intracardial perfusion at each season throughout the year so that the arcuate nucleus could be examined for seasonal variations in morphology. Striking seasonal changes in the fine structure of ependymal tanycytes lining the arcuate nucleus were observed. Tanycytes in animals collected in the fall and early winter exhibited pale processes characterized by a scant internal framework of microtubules and fine filaments. These processes, which were found throughout the arcuate nucleus, exhibited simple irregular shapes. In animals collected between January and June, tanycyte processes contained dense accumulations of fine filaments intermingled with microtubules, and projected long attenuated extensions that often formed multilamellar sheets around axodendritic terminals or other neuronal elements. Tanycyte processes of animals collected in July and August were densely packed with microtubules and fine filaments. The processes radiated elaborate multilamellar extensions that encapsulated axons, dendrites and even entire neuronal perikarya. Multilamellar sheets consisted of as many as 10 or 12 closely spaced gyres. The seasonal variations in tanycyte structure are suggestive of astrocyte‐like behaviour. These changes are discussed with respect to seasonal changes in hypothalamic neuroendocrine activity.
Fine structural studies of rat seminal vesicle in castrated and intact animals following estrogen treatment
Authors: Thompson Sue Ann , Rowley David R. , Heidger Jr. Paul M.
Published: February 2005

The effect of estradiol and/or testosterone upon secretion by seminal vesicle in castrated and intact rats was assessed in young adult Sprague‐Dawley rats, using light microscopy (LM), transmission (TEM) and scanning (SEM) electron microscopy. Hormones were injected daily for ten days beginning ten days after castrations were performed. The normal rat seminal vesicle, as revealed by SEM, was characterized by a large saccular lumen with highly folded walls. Cell surfaces were covered with microvilli, or occasionally displayed a protruding, ruffled surface, sparsely covered with short microvilli. Cytology was normal in testosterone‐treated animals. Estradiol treatment of castrated animals stimulated secretion by seminal vesicle epithelial cells as evidenced by the presence of normal secretory bodies, the presence of RER, and moderately hypertrophied Golgi complexes. These glands were not heavier than were glands from castrated, untreated animals, although the epithelial cells were significantly taller. Secretion was maintained in intact animals treated with estradiol, although glands were smaller and epithelial height was reduced. Estradiol and testosterone treatment in combination did not appear to have an additive effect on secretion, weight of the gland, or epithelial height. The following results support the hypothesis that estrogen‐induced prolactin synthesis and release may be involved in the mechanism by which estradiol effected stimulation of seminal vesicle epithelium. Prolactin‐treated, castrated animals exhibited focal areas of stimulated epithelium. In hypophysectomized animals (untreated controls), the seminal vesicle epithelium retained some secretory bodies and secretory fluid in the glandular lumen; epithelial height was taller than that in castrated controls. Estrogen treatment reduced the epithelial height to that of castrated controls; there was no evidence of secretion. This suggests that in the absence of anterior pituitary hormones, including prolactin, the stimulatory effect of estradiol on seminal vesicle epithelium was nullified. In adrenalectomized/castrated animals, estradiol treatment stimulated secretion in seminal vesicle epithelium just as in non‐adrenalectomized/castrated animals. This indicates that the adrenal gland plays a non‐essential role in the action of estrogen on seminal vesicle epithelium.
Freeze‐fracture demonstration of communicating junctions between interstitial cells of the pulmonary interalveolar septa
Authors: Bartels H.
Published: February 2005

Interstitial cells in the interalveolar septa of lungs, which are considered to be myofibroblasts, are coupled by communicating junctions.