bluuebunny/crossref_metadata_2025 huggingface dataset:
A circadian rhythm of mitotic activity in the uterine luminal epithelium of the rat: Effect of estrogen
Authors: Krueger Wayne A. , Bo Walter J. , Hoopes Phillip C.
Published: February 2005

The study was designed to determine whether or not the rat uterine luminal epithelium exhibits a mitotic circadian rhythm and to ascertain the effect of estrogen treatment at different time periods on the uterine epithelial mitotic response. Immature rats were injected with either sesame oil (controls) or 60 ng of estradiol‐17 β at eight time periods and were necropsied 24 hours after treatment. Colchicine was administered IP two hours before autopsy. Peak mitotic activity was observed during the nocturnal phase (0300) for both the control and estrogen‐treated rats. The nadirs were recorded during the diurnal phase (1800 and 1200 for the control and estrogen groups, respectively). The differences between low and high values were 1100% for the control rhythm and 101% for the estrogen animals. The data demonstrate the existence of overt circadian rhythms in the uterine epithelium for both control and estrogentreated rats.
The fine structure of the trophospongial layer of the kangaroo rat placenta
Authors: Tibbitts F. Donald , King Barry F.
Published: February 2005

The trophospongial layer of the near‐term kangaroo rat placenta was examined in the electron microscope. Two ultrastructurally different cellular zones were distinguishable – an inner zone adjacent to the labyrinth and a basal zone located mesometrial to the inner zone. Inner zone cells contained a well developed granular ER and Golgi apparatus as well as polymorphous membrane‐limited granules. The cells also contained modest amounts of glycogen and lipid droplets. Basal zone cells were also rich in ER; some cells had dilated ER cisternae containing a highly structured material which appears as a sheet of hexagons when viewed en face. Basal zone cells may, among other things, function as glycogen storage cells, since they had large cytoplasmic accumulations of glycogen. Unlike the situation in some other rodents, maternal blood draining from the trophospongial layer was always contained in channels lined by a layer of squamous cells which, in turn, was separated from the trophospongial cells by a basal lamina. The trophospongial zones are compared with the trophosngial regions of other rodent placentas and possible functions are considered.
Comparative ultrastructural analysis of two tortoise bladders, Testudo graeca and Geochelone carbonaria
Authors: Strum Judy M. , Danon David
Published: February 2005

Urinary bladders from the desert tortoises, Testudo graeca and Geochelone carbonaria were removed at specific times during the year and studied by electron microscopy. Three epithelial cell types were found in both species in all bladders examined: (1) granular cells, (2) mitochondria‐rich cells, and (3) basal cells. Cells analogous to these three types have also been observed in amphibian bladders (from to ad Bufo marinus and bullfrog, Rana catesbiana) and reptilian bladders (from Pseudemys scripta and Clemmys caspica). Both tortoises have an incomplete layer of basal cells so that the granular and mitochondria‐rich cells extend from the lumen to the basement membrane: some thing not observed in bladders from bullfrog or turtles. A flask‐shaped light cell was observed in the Geochelone carbonaria bladder obtained in April. No counterpart of this cell was seen in the same species sacrificed in January, or in any of the Testudo graeca bladders, although a similar cell has been described in the turtle, Pseudemys scripta (Rosen, Expt. Molec. Path., 12: 286–296, 1970). This study was undertaken to characterize the cell types present in tortoise bladder and to compare them with cell types in the bladder of the turtle, bullfrog and toad.
Effect of uterine artery ligation on ovulation in the rat
Authors: Peppler Richard D.
Published: February 2005

Female rats were divided into six groups: (1) control, (2) one uterine artery (a.) ligated near the utero‐tubal (U‐T) junction, (3) one uterine a. ligated at the level of the cervix, (4) both uterine aa. ligated separately at the U‐T junction, (5) both uterine aa. ligated separately at the cervix and (6) both uterine aa. tied with one ligature at the cervix. Segmental aa. were disrupted in all experimental groups except group 6. Animals were allowed to recover for ten days and killed the first metestrus thereafter. Number of eggs ovulated was determined by flushing the oviduct with saline solution and counting the ova.

Control rats ovulated 5.0 ± 0.4 eggs per ovary. Groups 2 and 3 had an increase in the number of eggs shed from the ovary on the non‐ligated side. In contrast, a decrease in the number of ova shed occurred on the ligated side. When both aa. were ligated separately (groups 4 and 5), irrespective of location, a decrease in the number of eggs shed by both ovaries was evident. No effect was found when only one ligature was placed near the cervix (group 6).

The data demonstrate that blood supply to the ovary via the uterine artery is essential for the full complement of eggs to be shed.
Response of tanycytes of rat median eminence to intraventricular administration of colchicine and vinblastine
Authors: Schechter Joel , Yancey Barbara , Weiner Richard
Published: February 2005

The effects of colchicine and vinblastine on tanycytes of the rat median eminence have been studied using the electron microscope. Colchicine and vinblastine were administered by intraventricular cannulation into the third ventricle and demonstrated distinct morphological effects on tanycyte microtubules. Highest drug doses administered were 50.0 μg in 5.0 μl of saline initially, followed by an additional 50.0 μg of these agents infused in a volume of 13.0 μl saline over an hour. Colchicine treatment resulted in the formation of large crystalloids within tanycytes, coincident with the disappearance of microtubules, all along the ventricular surface. Nonetheless the tanycytes appeared able to maintain a continuous tight lining, as in controls, although some crystalloids were observed beneath the ventricular surface, either within tanycyte processes or within neuronal processes. Vinblastine treatment also resulted in the formation of identical crystalloids but at highest doses thoroughly destroyed the tanycyte lining of the median eminence and exposed cellular elements below the surface to the drug. Portal capillaries approaching the ventricular surface were generally free of any signs of drug response to either colchicine or vinblastine.
Circadian influence on the frequency of labeled mitoses method in the stratified squamous epithelium of the mouse esophagus and tongue
Authors: Burns E. Robert , Scheving Lawrence E. , Fawcett Deborah F. , Gibbs William M. , Galatzan Russell E.
Published: February 2005

The frequency of labeled mitoses method (FLM) was used to study the cell kinetics in the stratified squamous epithelium of the mouse esophagus and tongue. FLMs were generated by injecting tritiated thymidine (TdR) at two different phases of the mouse circadian system: TdR was injected into one group of mice at 0900 and into a different, second group of mice at 2100. Three variables were monitored for each group; (1) the FLM, (2) the mitotic index and (3) the grain count over the labeled mitotic figures. In both the esophagus and the tongue there was a circadian rhythm in the mitotic index with the peak occurring during the first half of the diurnal phase and the trough occurring during the first half of the nocturnal phase. The FLM curves from each group revealed the following data:

Transit time in G2+1/2M (TG2+1/2M)
Transit time in S phase (TS)

hours
hours

Esophagus — TdR at 0900
2.5
5.3

Esophagus — TdR at 2100
4.5
3.5

Tongue — TdR at 0900
4.2
5.1

Tongue — TdR at 2100
4.2
5.5

Second waves of labeled mitoses were seen in the esophagus and tongue when TdR was injected at 0900. No second wave of labeled mitoses occurred in either the esophagus or the tongue when TdR was injected at 2100. For the esophagus the grain counts of the labeled mitotic figures in each group indicated that the rate of DNA synthesis was greater during late S phase, whether the TdR was injected at 0900 or 2100. During most of the S phase the rate of DNA synthesis was significantly greater in the TdR at 2100 group, which is the time of the circadian system when the esophagus demonstrated a relatively short Ts. In the epithelium of the tongue there were a few statistical differences in the rate of DNA synthesis between the groups and during the duration of the S phase within either group, but these data were difficult to interpret.

The data demonstrate the influence of the circadian system in cell kinetic work and in the interpretation of data obtained with the FLM in renewing populations of cells which are not totally asynchronous.
Localization of rabbit gamma globulins in the mouse visceral yolk sac placenta
Authors: Gardner Martha M.
Published: February 2005

The yolk sac placenta has been implicated previously in transmission of passive immunity to the fetus. This work uses an immunohistochemical technique devised by Sternberger et al. (1969) to study this problem. Rabbit serum containing gamma globulins was injected into the uterine lumen of the White Swiss mouse during the last third of pregnancy. Two or four hours later yolk sacs were removed and fixed in 2% paraformaldehyde or freeze‐dried and fixed with paraformaldehyde vapors. Finely chopped tissue was treated with (1) sheep antiserum to rabbit gamma globulin, (2) an antigen‐antibody complex consisting of horseradish peroxidase and rabbit anti‐horseradish peroxidase and (3) hydrogen peroxide and 3,3′‐diaminobenzidine. Reaction product was heavily concentrated in visceral yolk sac endodermal cells, frequently deposited in endothelial cells of vitelline vessels, and rarely in the serosal basement membrane and mesothelial cells which border the exocoelomic cavity. This supports evidence of other workers that the yolk sac membrane rapidly absorbs substances with which it comes in contact, transport into vitelline vasculature is a route of transfer from mother to fetus, and possible transfer into the exocoelomic cavity and thence to the amniotic cavity may occur in mice.
DNA synthesis and cell proliferation in the simple liver acinus of 10 to 20‐day‐old rats: Evidence for cell fusion
Authors: LeBouton A. V.
Published: February 2005

Radioautography after 3H‐thymidine injection, mitotic arrest by colchicine and camera lucida drawings were used to study DNA synthesis, mitosis, formation of binucleated cells and morphogenesis in the simple liver acinus of Rappaport in 10–20‐day old rats. By ten days the arrangement of hepatic cell plates had already attained the adult configuration — irregular and thick in acinar zone 1 (periportal), straight and thin in acinar zone 3 (pericentral). The DNA synthetic index of parenchymal and bile duct cells slowly decreased during the observation period. Zonal labeling remained steady in the relationship: zone 1 > zone 2 > zone 3. Mitosis of parenchymal and bile duct cells reached a peak at 12 days, decreasing slowly thereafter. Mitosis also exhibited the relationship zone 1 > zone 2 > zone 3. The number of binucleated cells remained constant until after day 14 when it increased rapidly. Zonal distribution of binucleated cells was just the reverse of that for DNA synthesis and mitosis, that is zone 3 > zone 2 > zone 1. Radioautographic studies of binucleated cells labeled with 3H‐thymidine indicated that a small percentage of them were formed by fusion of mononucleated cells.

Conclusions are: (1) the 10–20‐day old rat liver is expanding its cell population primarily in acinar zones 1 and 2 while overt differentiation is occurring in acinar zone 3, (2) ingestion of solid food around day 16 may be related to binucleated cell production due in part to altered portal venous blood changing the cellular microenvironments, (3) binucleated cells arise by suppression of cytokinesis, cell fusion and/or other non‐mitotic routes.
Specialized junction in the distal convoluted tubule of rat kidney
Authors: Giacomelli Filiberto , Wiener Joseph
Published: February 2005

The ultrastructure and permeability of the apical junctions between epithelial cells of the distal nephron have been studied in rat kidney using a colloidal lanthanum tracer and uranyl acetate staining en bloc. The apical intercellular junctions of the macula densa and juxtaglomerular segment of the early distal convoluted tubule measure up to 0.5 μ in length and about 50 Å in width. Lanthanum permeates the occluding portion of these junctions in a discontinuous manner, defining a series of closely spaced and parallel lines of fusion that run in a direction perpendicular to the apical‐basal axis of the tubular cells. The apical junctions of the remainder of the distal convoluted and cortical collecting tubules are impermeable to lanthanum. This distinctive apical tight junction can account for the greater permeability to ions of the early distal convoluted vs. late distal convoluted and cortical collecting tubules.
Cellular composition of the bone marrow in the chicken. I. identification of cells
Authors: Glick Bruce , Rosse Cornelius
Published: February 2005

Incorporation of Fe55 in vivo was used for verifying on radioautographs the identity of chicken bone marrow cells that are in the process of heme syntheses. Under the experimental conditions all labeled cells may be considered to be linked with erythroid differentiation. They were classified into five maturational stages according to their morphology and capacity for DNA synthesis. Granulocytes were identified by the presence of specific granules. All mononuclear cells were classified as lymphocytes which had a pachychromatic nucleus, a high nucleocytoplasmic ratio, lacked the capacity for DNA synthesis, and resembled small lymphocytes of the bursa, spleen and bone marrow that bound, in vitro, anti‐chicken gamma globulins labeled with I125. Radioautography with H3TdR was used to identify proliferating and non‐proliferating members of each cell population.

With the use of the morphological criteria thus established, reproducible differential counts could be performed on chicken bone marrow smears also in the absence of specific labeling. In normal, 3, 4, and 8 week old White Leghorn chicks, such counts revealed the bone marrow as a member of the lymphomyeloid complex preferentially adapted to the production and maturation of erythroid cells, while the reserve of granulocytes was found to be small compared to that of mammalian marrow. The percentage of lymphocytes appears to increase with age but, in contrast to rodent marrow, a proliferating precursor cell pool for lymphocytes could not be identified in chicken marrow up to the age of eight weeks.
The growth of the oocyte and follicle in the ovaries of monotremes and marsupials
Authors: Lintern‐Moore Sue , Moore G. P. M. , Tyndale‐Biscoe C. H. , Poole W. E.
Published: February 2005

Oocyte growth in relation to follicular growth in marsupials conforms to the uniform biphasic pattern characteristic of eutherian mammals. However, the oocyte of the marsupial is larger and completes growth in a correspondingly larger follicle. At the completion of oocyte growth the follicle, like that of eutherians, shows no appreciable accumulation of follicular fluid. The ratio of oocyte/follicular diameter in marsupials at this stage is 0.59, a value close to that of 0.55 for eutherian mammals. The oocyte nucleus of the marsupial is also significantly larger than that of the eutherian, but the oocyte nucleolus is approximately the same diameter.

By contrast, the growth of the oocyte in relation to the follicle in monotremes is linear throughout the whole period of follicular growth. However, like eutherians and marsupials oocyte nuclear and oocyte nucleolar growth are arrested in the early stages of follicular growth. The diameters of the oocyte nucleus and nucleolus at the completion of growth are approximately twice those found in marsupials.

It is concluded that the growth patterns of the oocyte nucleus and nucleolus are common to all mammals but that the biphasic pattern of oocyte and follicular growth which is characteristic of eutherian and marsupial ovaries is not found in the monotremes.
Crystalloid configurations in the adrenal cortex of the Siamese tree shrew (Tupaia glis)
Authors: Hostetler Jeptha R. , Cannon M. Samuel , Belt W. Duane
Published: February 2005

Crystalloids of what appear to be smooth reticulum have been observed in the zona fasciculata and zona reticularis in both the stressed and nonstressed adrenal gland of the Siamese tree shrew (Tupaia glis). No crystalloids are observed in the zona glomerulosa. Similar crystalloids have been described in other steroid‐secreting organs, including the antebrachial organ of the lemur (Lemur catta), the parotoid gland of Bufo alvarius and in sebaceous gland cells of the Galagos and Macaques. Moreover, the crystalloids in the present investigation resemble the paracrystalline arrays of smooth reticulum present in the adrenal cortex of the fetal guinea pig. The crystalloids show much variation in degree of organization, sometimes appearing as wavy tubules parallel with one another or as fused tubules having a “donut” configuration. In addition, the crystalloids are nearly identical to configurations which have been described in mitochondrial cristae of the protozoan, Pelomyxa carolinensis.
The postnatal development of the junctional complexes of the mouse Sertoli cells as revealed by freeze‐fracture
Authors: Nagano Toshio , Suzuki Fumie
Published: February 2005

Mouse testes of newborn to adult were examined by freezefracture. Between the newborn Sertoli cells, gap junctions consisting of aggregations of the intramembranous particles (about 8 nm in diameter) are frequently found. Some of the junctions are about 1 μm in diameter and show particle‐free regions in the aggregation. Linear arrangements of a few particles, which appear to be the initial formation of the occluding junctions, are seen in the newborn Sertoli cells. The occluding junctions are arranged in a meshwork, in which the gap junctions are situated between the stages of newborn to six days of age. The particles of the occluding junctions are predominantly located on the B face in the center of the groove instead of the A face of the ridge. The occluding junctions do not appear to surround the entire circumference of the Sertoli cell of the 6‐day‐old mouse. The gap junctions decrease in size. In later stages, many parallel occluding junctions (up to forty in number) are found over one Sertoli cell surface and are distributed circumferentially around the entire cell surface, indicating establishment of the blood‐testis barrier. The occluding junctions dominate and the gap junctions diminish in number as development proceeds.
Liver hepatocyte mitotic activity after a single injection of phenobarbital in immature male rats
Authors: Argyris Thomas S. , Miller Anne
Published: February 2005

In contrast to multiple injections of phenobarbital, a single injection of 50 mg/kg body wt of phenobarbital into immature male rats results, after a transient increase in hepatocyte mitotic activity, in a marked decrease in hepatocyte mitotic activity to below control levels by day 3, followed by a return to control levels by day 5. This unusual pattern of hepatocyte mitotic activity can be called forth again by a second injection of 50 mg phenobarbital/kg body wt.

However, a single injection of 50 mg/kg body wt of phenobarbital into immature male rats results in a pattern of change of liver wet weight, protein, and aminopyrine demethylase activity which is similar to that observed after multiple injections of phenobarbital, except that the changes are smaller in magnitude. Liver wet weight, protein, and aminopyrine demethylase activity increase and reach a peak within two days after phenobarbital injection, and then they return to control levels by five days. The same pattern of change in liver wet weight, protein, and aminopyrine demethylase activity can be elicited again by a second injection of 50 mg phenobarbital/kg body wt.
Zonulae occludentes of the rat nephron under conditions of experimental expansion of blood and/or fluid volume
Authors: Evan Andrew P. , Baker Jeffrey T. , Bengele Howard H.
Published: February 2005

The zonula occludens (Z.O.) has been implicated as a major pathway for passive fluid movement from lateral intercellular spaces to lumen in response to an expansion of blood or fluid volume. The present study examines the Z.O. of adult rat nephrons in control and Ringer‐Locke or whole blood infused animals to determine whether varying the conditions of passive fluid movement would influence the structure of the Z.O. Rats were infused over 20 minutes with Ringer‐Locke (7% body weight) or whole blood (2.3% body weight). In the controls, 92%–94% of all Z.O. observed in proximal tubules and 100% of Z.O. from distal tubules and collecting ducts had fused outer leaflets. The approximate linear extent of the Z.O. was 140 Å for proximal tubules, 2,500 ÅR for distal tubules and 3,000 ÅR for collecting ducts. There was no significant difference in any of these values following the infusion with either Ringer‐Locke or whole blood. We conclude that expansion of blood or fluid volume causes no detectable alteration in the fine structure of Z.O. under the conditions used in the present study.
Monosodium glutamate induced lesions of the arcuate nucleus. I. Endocrine deficiency and ultrastructure of the median eminence
Authors: Holzwarth‐Mcbride M. A. , Hurst E. M. , Knigge K. M.
Published: February 2005

Monosodium glutamate was administered daily on days 5 through 10 postnatally at a dose of 2.5 mg/gm body weight. Counts of remaining perikarya in the arcuate nucleus of adult mice indicated approximately an 80% decrease in the number of perikarya. The arcuate lesion resulted in endocrine deficits; reproductive capacity was reduced, animals were smaller in stature and obese, and the weights of the anterior pituitary, ovaries and testes were significantly decreased while adrenals were unaffected. Light microscopic studies revealed no significant changes in thickness or general histological appearance of the median eminence. At the electron microscope level, there were no alterations in the number of nerve terminals or dense core vesicles per unit area in the contact zone. These observations suggest that afferents to the median eminence from the arcuate nucleus may form a relatively small portion of its total nerve terminal population.
Monosodium glutamate induced lesions of the arcuate nucleus. II. Fluorescence histochemistry of catecholamines
Authors: Holzwarth‐Mcbride M. A. , Sladek J. R. , Knigge K. M.
Published: February 2005

The effect of the monosodium glutamate (MSG) induced lesion of the arcuate nucleus on catecholamines in the arcuate nucleus and median eminence of the mouse hypothalamus was determined using the Falck‐Hillarp histofluorescence technique. The number of fluorescent perikarya in the arcuate nucleus of treated animals was decreased approximately 60%; the fluorescence intensity of surviving neurons was notably reduced. These changes were accompanied by a reduction in the intensity of fluorescence in the median eminence. Pretreatment of control and MSG‐lesioned animals with a monoamine oxidase inhibitor (pargyline) greatly increased fluorescence in the median eminence and arcuate nucleus of both groups. However, the number of fluorescing perikarya of the arcuate nucleus of the normal pargyline treated group far exceeded that of the pargyline MSG animals. It is concluded that neonatally administered MSG caused destruction of a large number of dopaminergic arcuate perikarya.
Erythropoiesis in the yolk sac of the bat Tadarida brasiliensis cynocephala
Authors: Stephens Robert J. , Cabral‐Anderson Linda J.
Published: February 2005

The process of erythropoiesis and vasculogenesis in the yolk sac of the bat (Tadarida brasiliensis cynocephala) has been studied through the use of both light and electron microscopy. Stem cells arise from the leading edge of the migrating splanchnic mesoderm and transform into primitive erythroblasts. Differentiation involves either contact or association with the endodermal cells, since all erythropoietic activity occurs on the endodermal side of the expanding vascular bed, and many of the cells are in close apposition to the lateral or basal plasma membranes of the endodermal cells. Endodermal cells also phagocytize developing primitive erythroblasts during the later stage of the process when erythropoiesis is subsiding in the yolk sac.

Cells destined to become the endothelium of the expanding vascular bed also arise from the leading edge of the migrating splanchnic mesoderm. Their process of differentiation involves the development of cytoplasmic extensions that may surround a group of differentiating erythroblasts, enclosing them in the newly formed lumen of the blood vessel. The cytoplasmic extensions make contact and develop junctional complexes with similar processes from other cells to complete the lumen of the lengthening vascular bed.

Cells of the granulocyte series or megakaryocytes are not observed in the yolk sac of the bat as has been described in certain other species.
Structural characterization and rapid manual isolation of a reptilian testicular tunic rich in Leydig cells
Authors: Neaves William B.
Published: February 2005

During the annual breeding season, the testes of the lizard Cnemidophorus gularis are yellow‐orange, ovoid organs measuring almost 1 cm in greatest diameter. The pigment is confined to the testicular tunic, which contains a zone of Leydig cells and vascular channels more than 50 m̈ thick. Leydig cells constitute approximately 60% of the zone, with remaining space occupied by capillaries, sinusoids, and lymphatic vessels. Lymphatics are concentrated at the interface between tunic and seminiferous tubules. Interstitial space is poorly developed among the tubules, accounting for less than 3% of tissue volume. Capillaries, lymphatics, and a few widely scattered Leydig cells occur in the sparse interstitial space. Leydig cells in the tunic and elsewhere in the testis show ultrastructural features commonly found in mammalian Leydig cells. Separation of the tunic from the seminiferous tubules is achieved in a few seconds by manual decapsulation of the testis and yields an enriched preparation of Leydig cells that is essentially uncontaminated by tubular elements.
Electron microscopic study of the developing lateral‐line organ in the embryo of the newt, Triturus pyrrhogaster
Authors: Sato Atsuko
Published: February 2005

The morphological sequence of events occurring in the development of the lateral‐line organ was investigated in the embryo of the newt, Triturus pyrrhogaster, by means of electron microscopy. Six stages of development have been defined for convenience of description. The primordium of the lateral‐line organ migrating from the pre‐ and post‐auditory placodes is segmented into a small cell mass accompanied by a few Schwann cells enveloping nerve fibers. In the clump of cells of the lateral‐line primordium, three kinds of cells are already distinguished by different degrees of darkness, i.e., dark, light and slightly dark cells (stage I). Both clump and Schwann cells enter the epidermis together (stage II). The two groups of cells are separated by the inner layer of the epidermis (stage III). The organ‐forming cells elongate and the inner layer of the epidermis separates the Schwann cells from the clump (stage IV). The apexes of the organ‐forming cells are exposed out of the epidermis (stage V). The lateral‐line organ is almost matured. The dark cells correspond to type II of the supporting cells, the light cells correspond to type I of the supporting cells and the slightly dark cells correspond to the receptor cells because of the existence of cilia and a cuticular plate. The afferent nerve endings are found on the basal surface of the receptor cell (stage VI).
The fine structure of the interstitial tissue of the testis of the nine‐banded armadillo
Authors: Weaker Frank J.
Published: February 2005

The interstitial tissue of the testis of the nine‐banded armadillo is composed of blood vessels, clusters of Leydig cells, the usual connective tissue elements, and a network of lymphatic sinusoids. The endothelial walls of the sinusoids are separated from the peritubular contractile cell layer surrounding the seminiferous tubules by a thin layer of collagen. The peritubular contractile cell is characterized by filaments and dense bodies within the cytoplasm, whereas the endothelial cells lack these structures. Within each cluster, several Leydig cells surround one or more blood vessels. Adjacent Leydig cells are joined by 2‐ to 3‐nm wide gap junctions and desmosome‐like specializations. The Leydig cell is polygonal in shape with an ovoid nucleus. The cell is characterized by an abundance of smooth endoplasmic reticulum which appears as sheets of membranes, concentric whorls around vacuoles, and a random tubular network. Only a few short cisternae of rough endoplasmic reticulum are observed. Centrioles are closely associated with the Golgi apparatus. Rod‐like mitochondria with tubular cristae are scattered throughout the cytoplasm. In addition, the cells contain vacuoles resulting from lipid extraction, filaments, microtubules, and glycogen. The surfaces of the cell exposed to the intercellular spaces exhibit numerous pinocytotic vesicles and cell processes which indicate active movement of material across the plasma membrane. In comparison to other mammalian species, the ultrastructural organization of the interstitium and the fine structure of the Leydig cell of the armadillo resemble those of the guinea pig.
The fatty ridge and fatty cushion of the human pulmonary trunk
Authors: Nadkarni Shrirang D. , Inamdar Madhavamurti H. , Ayya M. K. Chandrashekhar
Published: February 2005

Presence of a ridge of fatty tissue running obliquely upwards and backwards over the left aspect of the pulmonary trunk was observed. It started from the left end of the infundibulo‐truncal junction and after running parallel adjacent to free anterior border of the left auricle, terminated into an expanded, oval and discoid structure, a little above the level of the tip of the left auricle. The structure was found to be of constant occurrence, position and form.

A comparison between similar structure reported in relation with the aorta and the right auricle was attempted.
Efferent arterioles in the cortex of the rat kidney
Authors: Evan Andrew P. , Dail William G.
Published: February 2005

Although a number of morphological studies have investigated the vascular system of the rat kidney, minimal data are available on the detailed anatomy of the efferent arterioles located throughout the cortex of the kidney. In the present study, the renal vascular system was filled with Microfil and the various efferent arteriole patterns were examined extensively. The efferent vessels of the entire cortex appear to form three major patterns which in turn divided the cortex into three separate regions: the outer, middle and inner cortex. The efferent arterioles of the outer cortex leave the glomerulus and run perpendicular to the kidney capsule. However, as the efferent arterioles ascend, they may show three variations in the way they branch: (1a) the efferent arteriole does not branch until directly beneath the capsule, (1b) the efferent vessel begins to divide into its major branches 100–200 μm below the surface of the kidney and (1c) the efferent vessel has only a short course before giving off many side branches. In the middle cortical area, the branches of the efferent arteriole run lateral to the glomerulus. However, the efferent arterioles of the inner cortex have a few branches which run lateral to the glomerulus while most of them descend into the medulla as vasa rectae. The unique morphological features of the efferent arterioles of the outer cortex are of particular interest in light of the functional data which suggests that the reabsorption of fluid by peritubular capillaries may indeed regulate the rate of net tubular sodium reabsorption.
Ultrastructural localization of peroxidase in leukocytes of rat bone marrow and blood
Authors: Bentfeld Mary E. , Nichols Barbara A. , Bainton Dorothy F.
Published: February 2005

The differentiation of leukocytes in the bone marrow and blood of normal adult male rats was studied by electron microscopy and peroxidase cytochemistry. Tissue samples were fixed in glutaraldehyde, or paraformaldehyde‐glutaraldehyde, and incubated in a peroxidase medium containing 3,3′‐diaminobenzidine and H2O2 at pH 7.6. Mature cells of blood were identified, and then the earlier stages of maturation in bone marrow were analyzed. In immature cells of four cell lines, neutrophils, monocytes, basophils, and eosinophils, peroxidase is synthesized and could be demonstrated in the rough endoplasmic reticulum (RER), Golgi complex, and in cytoplasmic granules. Later in maturation, reaction product for peroxidase could not be found in RER or Golgi complex, indicating that peroxidase synthesis had ceased. In two cell lines, neutrophils and monocytes, peroxidase‐negative granules were formed, and the mature cells contained two populations of cytochemically distinct granules. All granules of mature eosinophils were peroxidasepositive. In mature basophils, some granules were clearly peroxidase‐positive; others displayed variable density, making interpretation uncertain. Mast cells were never seen in blood, but were abundant in bone marrow; peroxidase was never found in their granules by either electron microscopic cytochemistry or a variety of light microscopic methods. Hence, these cells differ from basophils, not only in morphology but also in the enzyme content of their granules.
Effects of denervation and tenotomy on the gastrocnemius muscle in the frog: A histologic and histochemical study
Authors: Sarnat Harvey B. , Portnoy Jay M. , Chi David Y. K.
Published: February 2005

The effects of denervation on the gastrocnemius muscle of the frog were studied by histologic and histochemical methods. Thirteen Rana pipiens underwent unilateral sciatic neurotomy and were sacrificed weekly as long as 46 days. Of the three normal populations of muscle fibers, the small fibers underwent atrophy, the intermediate sized fibers remained unchanged in size, and the large fibers either did not change or underwent hypertrophy between 21 and 46 days. Necrosis of muscle fibers did not occur. Histochemical stains showed persistence of the normal pattern after denervation. The small fibers continued to have a high concentration of both oxidative and glycolytic enzyme activity (NADH‐TR, SDH, phosphorylase), and the large fibers continued to have a low concentration of these enzymes. Depletion of glycogen stores was seen with PAS. Hypertrophic muscle fibers had mostly subsarcolemmal nuclei and few internal nuclei, suggesting that they may be physiologically tonic rather than twitch fibers. Achilles tenotomy at the time of denervation prevented the hypertrophy of large fibers. Abnormal inclusions have been demonstrated in mammalian muscle following tenotomy alone, but were not seen in the frog.
Compensatory responses in the development of the brachial lateral motor column in triploid Rana pipiens
Authors: Pollack Emanuel D. , Koves Judi
Published: February 2005

Responses of the lateral motor column (LMC) in the frog spinal cord to various experimental manipulations generally are manifested in an adjustment of the number and sizes of the motor neurons. Analysis of the brachial LMC in induced‐triploid Rana pipiens larvae as compared to diploid controls revealed a significant increase in nuclear size with a concomitant reduction in cell counts at all stages of development examined. These compensatory responses of the LMC to polyploidy in normal size frog larvae are consistent with results reported for other amphibian polyploid tissues and serve as a basis for exploring mechanisms of plasticity in the developing central nervous system.
A method for quantitative histological evaluation of neural cell populations
Authors: Duncan Gary H. , Gregg John M. , Galich John W.
Published: February 2005

In an attempt to facilitate quantitative analysis of neural peri‐karya, an inexpensive system of gridded coverslips has been developed to permanently map sections of tissue on microscopic slides. Utilizing common photographic copying techniques with Kodalith film, a mylar coverslip is produced which is imprinted with a grid of known dimensions. The exact scale of the grid can be varied precisely for compatibility with a particular field of magnification. The versatility and economy of this technique make it useful in many microscopic studies requiring superimposition of discrete landmarks.
Serous cysts of the aging guinea pig ovary I. Light microscopy and origin
Authors: Quattropani Steven L.
Published: February 2005

Ovaries from guinea pigs of different ages have been examined by light microscopy. Serous cysts measuring between 1 mm and 2.5 cm are present in all animals over one year of age. The cysts are fewer in number and size at six months, are least developed at ten weeks and are not apparent in the nearterm fetus. The cysts arise from the rete ovarii. They are lined with a simple cuboidal to columnar epithelium composed of cells bearing solitary cilia or tufts of cilia. The structure and origin of these cysts is discussed and compared with what is known of the human serous cystadenoma.
Development of neural elements in apical portions of cat primary and permanent incisor pulps
Authors: Johnsen D. C. , Karlsson U. L.
Published: February 2005

Pulp development was studied with light and electron microscopy in apical portions of cat primary and permanent incisors at various stages of development in order to qualitatively assess hypothesized differences during maturation. Primary and permanent tooth pulps passed through similar stages up to when the primary teeth began to resorb. At that point permanent tooth pulps continued to develop in complexity relative to myelinated axons and developed thin epineurial sheaths. Although the stages were similar in several regards, the time needed by the permanent tooth pulps to reach each stage was considerably greater than for the primary tooth pulps. It is of interest that the young permanent teeth had only a small portion of their final complement of nerves in spite of their relatively complete development.

Individual axons, especially myelinated axons, appeared more immature in younger primary and permanent teeth. This suggests a less mature sensory capability for erupting primary teeth as compared to fully developed primary teeth as well as for erupting and young permanent teeth compared to old permanent teeth.
Light and electron microscopic histochemistry of the serous secretory granules in the salivary glandular cells of the mongolian gerbil (Mongolian meridianus) and rhesus monkey (macaca irus)
Authors: Ichikawa Misao , Ichikawa Atsushi
Published: February 2005

Light and electron microscopic histochemistry was carried out on the serous secretory granules of the parotid acinar and sublingual demilunar cells of the Mongolian gerbil. These are bipartite in structure with a central dense core and a rim of lower density. Light microscopic techniques included staining of sections with Alcian blue and PAS reaction before and after sialidase digestion. PA‐methenamine silver, dialyzed iron, colloidal thorium and ruthenium red reactions for mucosubstance were compared on control and pronase digested materials. The results obtained have been interpreted to indicate that the peripheral rim of the granules contained mainly sialomucin whereas the central dense core was rich in protein. Freeze‐etched replicas and frozen thin sections of the gerbil salivary glands revealed the bipartite substructure of the granules to be a consistent structure regardless of specimen preparation procedures.

The secretory granules in the serous acinar cells of the monkey submandibular gland which also have a central dense spherule and a rim of lower dense matrix were tested in the same way with the PA‐methenamine silver method. A positive reaction was limited to the rim of lower density matrix, indicating that this granular matrix is rich in carbohydrates in contrast to an unstained dense central spherule which is digested with pronase. Morphological and cytochemical similarities of the granule content between species are compared.
Secretion of granules by the luteal cells of the sheep and the goat during the estrous cycle and pregnancy
Authors: Gemmell R. T. , Stacy B. D. , Nancarrow C. D.
Published: February 2005

The fine structure of luteal tissue from sheep and goats at the mid‐stage of the estrous cycle and during pregnancy was examined. At the mid‐stage of the estrous cycle, when the corpus luteum of both species is secreting progesterone, the ultrastructure of the luteal cells is similar in that granule secretion is prevalent. In late pregnancy, the corpus luteum of the sheep produces very little progesterone and there is an absence of granule secretion. In the pregnant goat, the production of progesterone from the corpus luteum is high and there is plentiful evidence of granule formation and secretion.
Sarcoplasmic reticulum in the conducting fibers of the dog heart
Authors: Rybicka Krystyna
Published: February 2005

The ultrastructure or sarcoplasmic reticulum (SR) was studied in the conducting fibers of the dog heart. A dense network of sarcoplasmic tubules occurred in well preserved cytoplasmic areas. Some of the tubules extended into large sacs filled with finely filamentous material. The sacs often appeared in subsarcolemmal apposition connected to the sarcolemma by electron dense projections. The flattened cisternae of SR occurred beneath the sarcolem‐ma in the myofibrillar region of the cell. Long flattened cisternae only partially apposed to the sarcolemma were quite common in one specimen. Sarcoplasmic reticulum was continuous throughout the interfibrillar spaces surrounding each myofibril. At the level of the Z‐line the SR formed a quasi tubular flattened structure surrounding the Z‐line and closely adhering to it.
Differentiation and migration of endoderm in the rat and mouse at implantation
Authors: Enders Allen C. , Given Randall L. , Schlafke Sandra
Published: February 2005

The initial differentiation of endoderm at the time of onset of implantation, and the subsequent rapid differentiation of visceral and parietal endoderm were studied in the rat and mouse. Transmission electron microscopy illustrates the reorientation and loosening of embryonic cell mass cells during implantation, as well as cytological evidence that endoderm cells have differentiated. Using scanning electron microscopy, parietal endoderm consists of individual stellate cells with numerous peripheral branching filopodia. As these cells migrate abembryonically, the rest of the embryonic cell mass becomes recom‐pacted. The visceral endoderm proliferates and forms a columnar epithelium which has the cytological characteristic of an absorptive epithelium and is able to ingest exogenous proteins. Thus, by 24 hours after implantation, the two endo‐dermal derivatives have assumed widely diverse shapes and different types of associations and rates of replication, and are probably performing different functions.
A cytological study of plasma membrane modifications, intercellular junctions, and endocytic activity of amniotic epithelium
Authors: King Barry F.
Published: February 2005

The purpose of this study was to examine some cytological features of guinea pig amniotic epithelium which may be related to epithelial permeability. In addition to fine structural studies, the amnion was stained with ruthenium red to demonstrate the glycocyalyx and exposed to an exogenous protein (peroxidase) to ascertain some of the permeability characteristics of the intercellular junctions. The apical microvillous border had a distinct glycocalyx of filaments 3‐5 nm in diameter and up to 0.3 μm in length. These filaments stained with ruthenium red as did a narrower zone of glycocalyx adjacent to the outer leaflet of the plasma membrane. Epithelial cells were joined laterally by numerous desmosomes and by tight junctions; no evidence of a classical junctional complex was observed. When cells were exposed to ruthenium red or peroxidase, the tracer was impeded in its penetration between cells, probably by tight junctions. The presence of tight junctions indicates that the intercellular space is not continuous from the amniotic cavity to the underlying connective tissue, and undoubtedly the junctions play a role in controlling transepithelial permeability. The experiments with peroxidase also demonstrated the capacity of the cells to endocytose protein, especially at their lateral and basal surfaces. Late in gestation, increasing numbers of cells underwent cytological changes similar to cells undergoing keratinization. These changes included the disappearance of most of the cell organelles and the thickening of the plasma membrane by the addition of an electron‐dense layer to the inner (cytoplasmic) leaflet. The apparent keratinization of cells may result from increased abrasive trauma caused by the fetus or may be related to accumulation of various waste products in the amniotic fluid. In any event, the cytological modifications, especially of the plasma membrane, may indicate a change in cell permeability properties late in gestation.
The effects of vitamin B6 deficiency on the bone marrow of the rat1
Authors: Cassel Susan , Robson Linda , Rosse Cornelius
Published: February 2005

Bone marrow from adult rats fed a vitamin B6 deficient diet for two weeks was found to have reduced numbers of neutrophils, erythroid cells and small lymphocytes. The numbers of transitional cells were not reduced. Since the small lymphocyte population in the bone marrow consists of B cells and null cells in approximately the same proportion, it was concluded that both cell types were reduced as a result of the deficiency. A complete recovery in the cellularity of the bone marrow was brought about by returning the vitamin B6 deficient animals to a normal diet for four weeks. Other effects of the two‐week vitamin B6 deficient diet included a failure to gain weight, a decrease in thymus weight and a reduction in the numbers of white blood cells in the peripheral blood. All of these defects were corrected after the animals had been fed a normal diet for four weeks.
Ultrastructure of the anterior medial glands of the rat nasal septum
Authors: Tandler Bernard , Bojsen‐Møller Finn
Published: February 2005

The anterior medial glands lying in the submucosa of the rat nasal septum were studied by light and electron microscopy. The glands consist of a single long duct, which is studded with numerous solitary acinar formations connected perpendicularly to the main duct by short intercalated ducts. Proximal acini (those furthest from the stoma of the main duct) consist of typical serous cells with many dense secretory granules and an extensive rough endoplasmic reticulum. The most distal acini consist of cells whose major feature is the enwrapment of each mitochondrion by a cisternal profile of rough endo‐plasmic reticulum. Myoepithelial cells are absent from proximal acini, but are abundant on distal acini. Intracellular nerve terminals are extremely common, particularly in distal acini. The main ducts resemble, to a degree, the striated ducts of salivary glands.