bluuebunny/crossref_metadata_2025 huggingface dataset:
The wall structure of the arteries in the corpora cavernosa penis of rabbits; light and electron microscopy
Authors: Fujimoto Sunao , Takeshige Yoshio
Published: February 2005

Wall structures of the arteries in the corpora cavernosa penis were observed in rabbits. The deep (central) arteries in the proximal part of the penis have five or more independent ridges of the wall which are formed by the internal layer of the media consisting of almost longitudinal muscle cell layers. Electron microscopy of these regions revealed that the endothelial cells are connected to each other by many maculae and zonulae adherentes, and that smooth muscle cells of the media are separated from one another by a wide intercellular space embedding abundant collagenous fibers.

The epithelioid cells constituting the media of the helicine branches of the deep artery vary in their fine structure from close resemblance to muscle cells, to cells with easily identified special features. Frankly epithelioid cells have few scattered cytoplasmic filaments of a single type, 60–90 Å in diameter, abundant ribosomes, active Golgi, and other features different from the typical smooth muscle cells. There is no suggestion that these epithelioid cells are either degenerative or undifferentiated forms of smooth muscle cells, as postulated by light microscopists. Transitions froms muscle to epithelioid cells are consistent with, but not proved by, our data.
Spatial distribution of mitosis in mouse epidermis
Authors: Mackenzie Ian C.
Published: February 2005

The cells of the upper strata of mammalian epidermis are flattened and aligned to form regular columnar units. It has been suggested that the position of the smaller underlying basal cells is related to the overlying cell columns. Examination of the position of metaphase figures in sheets of mouse epidermis indicated that mitosis occurs principally in cells lying just within the periphery of the cell columns but that there is no alignment of interphase basal cells within the columnar peripheries which could account for this position of mitosis.
Permeability barriers to cytochrome‐c in nerves of adult and immature rats
Authors: Malmgren Leslie T. , Brink John J.
Published: February 2005

Nerves in the tongues of adult and immature rats were examined with respect to their permeability to exogenous cytochrome‐c (mol wt 12,000) injected into the tongue. The distribution of cytochrome‐c was determined in cryostat sections on the basis of the peroxidase activity of this protein. Nerves of 14‐day‐old rats were permeable to injected cytochrome‐c. The larger nerves of older animals showed only localized accumulations of cytochrome‐c reaction product both between and within axons adjacent to endoneurial blood vessels. Reaction product was not found, however, in association with blood vessels penetrating nerves of the tongue that were not within the limits of tracer spread. In the smallest nerve branches, thin linear strands of reaction product filled the interstices between the nerve fibers.
Cyclicity in tumescence of the perineal labia of female lowland gorillas
Authors: Nadler Ronald D.
Published: February 2005

The first group norms on the periodic occurrence of tumescence in the perineal labia of female lowland gorillas were obtained in 9 captive subjects. Individual mean cycle lengths for 8 adult females in 2 experiments ranged from 25.9–36.3 days with overall means of 31.1 and 32.5 days. The one subadult female had a mean cycle length of 40.7 days. The median and modal duration of maximal labial tumescence were 1.8 and 1 day, respectively. Data from 3 animals on which menses were recorded during 6 cycles yielded relatively consistent postswelling phase durations of 8–11 days and durations of menstruation of 1–2 days. The data from 2 conceptions of 1 female suggested that time of ovulation was closely associated with the day of detumescence. These data are discussed in terms of certain differences as well as similarities which exist between the gorilla and its closest relative, the chimpanzee. The contribution of these data to the area of comparative reproduction is enhanced because of the significant taxonomic affiliations of the gorilla species.
Substructure in rod photoreceptor membranes
Authors: Nir Izhak , Pease Daniel C.
Published: February 2005

Frog retinae, fixed only in buffered glutaraldehyde, were embedded for sectioning in glutaraldehyde polymerized with urea. In suitably thin sections globular substructures were seen in negative contrast after ionic staining with uranyl acetate and lead citrate, or after staining with neutralized phosphotungstic acid. Efforts to extract at least some of the lipid from sections before ionic staining enhanced the visualization of the “globules.” Exposure to KMnO4 solution, used as an oxidative section stain, also outlined globular substructure in negative contrast, but with the additional feature that positively stained surface “leaflets” associated with the aqueous compartment were well defined. Staining sections with OsO4 vapor resulted in positively stained membranes, but without any evident substructure. However, when sections which previously had been exposed to OsO4 vapor were secondarily stained with uranyl acetate and/or lead citrate, positively stained globular substructures then were revealed.

The globular substructures always were centered in the hydrophobic core region of the disc membranes, and symmetrically spanned the full thickness of this layer. The diameter of individual particles approximated 50–55 Å. Reasons are presented for the supposition that the evident globules incorporate at least hydrophobic components of rhodopsin molecules. Findings are discussed in relation to various models of disc membrane organization that have been proposed in recent years.
A smooth muscle plexus associated with the aqueous outflow pathway of the rabbit eye
Authors: Knepper Paul A. , Farbman Albert I. , Bondareff William
Published: February 2005

Smooth muscle cells were demonstrated adjacent to the aqueous outflow pathway in rabbit eyes. The cells were arranged as a discontinuous band, one to three layers thick and extended from the termination of Descemet's membrane to the ciliary body. Most of the cells were oriented with their long axes at right angles to the aqueous plexus, but many were arranged in a direction parallel to the plexus. The organization of the cells suggests that their contraction would exert a bi‐directional force, and therefore, affect aqueous outflow resistance.
Ultrastructure of the developing fetal hepatocyte of Macaca arctoides: A proposed model for studies of fetal drug metabolism
Authors: Quattropani Steven L. , Stenger Vincent G. , Dvorchik Barry H.
Published: February 2005

The ultrastructure of the hepatocyte of the fetal stumptail monkey was examined with the aim of defining a possible model for studies of fetal drug metabolism. Hepatocytes from fetuses of 80 and 160 days gestation, as well as from one animal one week of postnatal age, were examined and compared to human fetal hepatocytes at 12 and 16 weeks gestation. Marked variation was observed in the amount of lipid and the distribution of organelles within the cytoplasm of the hepatocyte in the monkey population. These differences were attributed to genetic variation. Two changes were seen which correlated with developmental age. The amount of hemopoietic tissue decreased and the amount of smooth endoplasmic reticulum increased as the animal matured. The problems of genetic variation and the relative number of hepatocytes at different stages of development were discussed relative to the use of this animal as a model for fetal durg metabolism studies. Attention to both of these problems is considered necessary for the interpretation of biochemical data in future studies.
Regeneration of single skeletal muscle fibers in vitro
Authors: Bischoff Richard
Published: February 2005

A culture system utilizing single skeletal muscle fibers from adult rats was developed to study the origin and behavior of mononucleated myoblasts during muscle regeneration. The single fibers are removed manually from the leg and thigh muscles of 300–400 gm rats and maintained in vitro embedded in a fibrin clot overlain with culture medium. Regenerative events were monitored by continuous observation of the cultured fibers. During the first few hours in vitro the fibers undergo degenerative changes including the formation of myofibrillar contraction clots and pyknosis of myonuclei. The endomysial tube (basement lamina) remains intact along the entire length of the fiber and forms transparent chambers bridging the contraction clots. Single fibers are free of endomysial cells and display no cellular outgrowth in culture, except at the cut ends. In contrast, a rich outgrowth of endomysial connective tissue cells is found with bundles consisting of two or more fibers. Isolated mononucleated cells, presumed to be muscle satellite cells, are present within the endomysial tube of single fibers at the onset of the culture period. There is no evidence that myonuclei contribute to the formation of mononucleated cells. The satellite cells enlarge and begin to proliferate during the second day in vitro to form clones of presumptive myoblasts within the endomysial tube. The early clones have a cell doubling time of about 22 hours and exhibit mitotic synchrony. After 5–7 days in vitro the satellite cell progeny begin to fuse to from multinucleated myotubes within the endomysial tube of the original fiber. The myotubes display spontaneous contractile activity and may extend throughout the length of the endomysial tube.
Early embryology and implantation in the california leaf‐nosed bat, Macrotus californicus
Authors: Bleier William J.
Published: February 2005

Female reproductive tracts from 84 bats were examined by light and/or electron microscopy to observe early embryology and implantation in Macrotus. The earliest pregnancy was observed in October and by the end of October all bats were pregnant. Implantation had begun in most specimens from late October. In late November females were carrying implanted blastocysts in which differentiation of endoderm was noted. Reichert's membrane was first observed in November.

In early December the trophoblast had begun to differentiate into cytotrophoblast and syncytiotrophoblast and by the end of January this differentiation was most evident. Reichert's membrane persisted until late January. Endoderm in the January sample completely surrounded the yolk sac cavity.

By late February the embryos were at the embryonic disc stage and had differentiated mesoderm. The uterine‐fetal relationship was complex and an early placenta was recognized.

In late March the embryos spanned a range of development from neural plate to limb‐bud stages. Parturition occurred in June.

This lengthy gestation period is characterized by an embryonic diapause of approximately four and one‐half months. The roles of food supply and/or temperature in controlling this growth rate and the evolutionary implications of this development are discussed.
Correspondence of silver nitrate staining patterns in decalcified bone with the microradiographic image
Authors: Tappen Neil C. , Simmons David J.
Published: February 2005

A procedure for differential staining of decalcified bone with silver nitrate showed major histological features which appeared to correspond closely to microradiographic images. The extent to which this is actually the case was investigated directly by preparing microradiographs of ground sections of baboon and dog radii and then decalcifying and staining the same sections. The many detailed similarities indicate that this staining procedure is a useful adjunct to microradiography. Thus, poorly mineralized osteons or layers of circumferential lamellae are darker stained by silver nitrate, and the variably mineralized layers of circumferential lamellae are closely duplicated by light and dark bands in the stained sections. These similarities imply that there is a relationship between the mineral density of bone and some condition of the organic matrix which is probably related to maturation changes in the collagen.
Fine structure of mammalian renal cilia
Authors: Webber W. A. , Lee J.
Published: February 2005

Studies were carried out, using transmission electron microscopy, of the cilia of the nephrons of rat and human kidneys. Cilia were observed in the parietal layer of Bowman's capsule, in the proximal tubule, the distal tubule, including the macula densa, and the collecting duct. They had a number of characteristic features, including the presence of a centriole adjacent to the basal body, long, slender cross‐striated rootlets, and a typically organized basal body. The shaft of the cilia differed from the typical 9 + 2 pattern of organization. Near the base of the cilia the pattern was 9 + 0. In the middle portion, one or more of the peripheral doublets had been displaced centrally to give an 8 + 1 or a 7 + 2 pattern, while towards the tip the pattern became more irregular and the doublets were reduced to single microtubules. We have hypothesized that these cilia may be vestigial. They may, if motile, have some minor stirring function, or they may play a sensory role, as has been postulated for similarly structured cilia in other sites.
Structure of rat bile canaliculi as revealed by scanning electron microscopy
Authors: Motta Pietro , Fumagalli Guido
Published: February 2005

Bile canaliculi in the rat liver have been studied by scanning electron microscopy. They appear as half tubules carved out of the hepatocytes' surface. In several cases the bile channel bifurcates to form two or three long branches running on the same face of the cell. Therefore, by SEM it seems obvious that the same side of an hepatocyte may be used for bounding two or more bile canaliculi.

Some bile canaliculi display a flexuous course and show lateral sacculations. Some of them are large and apparently similar to the short lateral branches of the bile canaliculus; others are smaller and arise obliquely from the subjacent cortical areas of the hepatocyte cytoplasm. These latter structures are best observed in stereo‐views in which they appear as narrow intracellular projections bordered with a few microvilli, actually opening into the lumen of the bile canaliculus. The SEM results suggest that these sacculations probably correspond to short intracellular branches of the bile canaliculi.

Zones of minimal distance (0.1 μ) between the space of Disse and the bile channel have been frequently observed. They are actually the zones where the intercellular clefts arising from the subendothelial space of Disse come into closest contact with the bile canaliculus and might serve as sites of simple diffusion of substances.
The “imaged‐desmosome”: A component of intercalated discs in embryonic guinea pig myocardium
Authors: Forbes M. S. , Sperelakis N.
Published: February 2005

A heretofore undescribed structural variation of the desmosomes of the intercalated disc is found in myocardial cells of the embryonic guinea pig. These desmosomes consist of the usual pair of opaque leaflets, each of the pair contributed by one of the apposed muscle cells. In addition, in the cytoplasm of one of the cells there appears a pair of linear densities (facsimile‐lines) parallel to the nearest desmosomal plaque and separated from it by a 60 nm space. The facsimile lines superficially resemble the desmosomal leaflets in length and thickness, thus forming a cytoplasmic “image” of the desmosome. These “imaged‐desmosomes” are found predominantly in the longitudinally‐running portions of the intercalated discs and are common in 7‐week embryos. Their incidence drops sharply by eight weeks of gestation, and they are virtually absent from the heart of the newborn animal. Often tubules of the sarcoplasmic reticulum (SR) are found in apposition to the facsimile‐lines; thus it appears that association of SR tubules with desmosomes is responsible for the formation of imaged‐desmosomes.
The effect of strontium, cobalt and fluoride on rat incisor enamel formation
Authors: Neiman Abraham , Eisenmann Dale R.
Published: February 2005

This investigation examined ultrastructurally the entire period of development of alterations in formative ameloblasts and the enamel which they produce following injection with fluoride, strontium, and cobalt ions. Rats injected with these ions were sacrificed at intervals of 1, 2, 4, 8, 16, 24 and 48 hours to elucidate the sequence and detail of cytologic and cell product alterations which occur. Undecalcified sections of rat incisor teeth were studied using electron microscopy and microradiography. All three ions initially produced disturbances in cell morphology and enamel formation consisting of dark globules, vacuoles, and pooling of stippled material on the enamel surface. While a period of decreased crystal formation occurred after injection with all three ions, only cobalt responses included a period of apparently complete absence of crystal formation. The hypermineralized layers occurring in the altered enamel are attributed to changes in the rate of enamel matrix formation and duration of its exposure to tissue fluids. Morphologic changes in Tomes' process were observed at the time of formation of abnormal enamel following injection of all three ions. These observations are compared with previous studies of altered enamel formation and analyzed with the goal of learning more about the mechanisms of amelogenesis.
Surface epithelium of the fetal guinea‐pig ovary: A light and electron microscopic study
Authors: Jeppesen Th.
Published: February 2005

The surface epithelium in fetal guinea‐pig ovaries was examined from the time of early sexual differentiation, about 34 days, until approximately ten days before birth.

At day 34 the epithelium varied greatly in apperance as seen in the light microscope and possessed a superficial layer of flattened or cuboidal cells. By day 58 the epithelium had changed into one layer of regularly arranged columnar cells. During the same period the number of germinal cells decreased. Connections between the germinal cords and the surface epithelium were observed from day 34, being especially numerous and broad at days 34 and 42 and decreasing in number and size from day 46 onwards. The basement membrane beneath the epithelium gradually increased in thickness.

In the electron microscope two types of somatic cells could be distinguished. One type formed a superficial single layer connected by junctional complexes and exhibited intracellular bundles of 60 Å microfilaments running straight through the apical part of the cell, attached to junctional complexes on either side. These bundles were found frequently between days 34 and 42, but were rarely seen after the forty‐sixth day. Microvillous projections into the coelomic cavity were especially numerous from day 34 to day 46.

The other type of somatic cells lay in close proximity to the germinal cells: microfilaments or junctional complexes were not observed.

The subepithelial basement lamina was continous with that surrounding the connections and the germinal cords.
Cellular mechanisms involved in cyclic stromal renewal of the uterus. I. The opossum, didelphis virginiana
Authors: Padykula Helen A. , Taylor J. Mary
Published: February 2005

At the close of a uterine cycle, the remodelling of the endometrial stroma of the North American opossum involves removal of extracellular material by macrophages. This study provides cytochemical and ultrastructural evidence which indicates that the laden macrophages are eliminated from the endometrium through emigration across the glandular and luminal epithelia. During diestrus or the early postpartum period, the abundant uterine glands relinquish their secretory function to acquire a transient function in the transportation of emigrating stromal cells.

During the first three postpartum days endometrial regression in the stroma is marked by sudden appearance of monocytes, macrophages, lymphocytes, and plasma cells. Ultrastructural and cytochemical evidence indicates that the macrophages engulf the extracellular macromolecular material which, in the opossum, consists primarily of ground substance. Macrophages filled with ingested extracellular material aggregate beneath the glandular and luminal epithelia, where they acquire an extracellular coat that resembles the material of the basal lamina elsewhere. A fibroblast‐like cell closely invests the macrophage at the time the extracellular material appears. Simultaneously, the secretory glandular epithelium is being converted to a highly ciliated one. Macrophages, often accompanied by lymphocytes, acquire intraepithelial positions in the glands. From here these stromal cells gain entrance to the glandular lumens. At this time the luminal contents are rich in acid phosphatase activity which most likely reflects the high lysosomal content of the emigrating macrophages. Evidence suggests that these intraluminal macrophages and lymphocytes are swept, by the recently differentiated ciliary lining, toward the glandular orifices and into the uterine cavity. It is hypothesized that this cyclic appearance and transepithelial elimination of macrophages is a cellular mechanism for removing large amounts of extracellular material without disruption of the endometrium.
Three‐dimensional organization of testicular interstitial tissue and lymphatic space in the rat
Authors: Clark Richard V.
Published: February 2005

Rat testes fixed by vascular perfusion were examined by scanning and transmission electron microscopy. This revealed a complex organization of the interstitial tissue and an extensive “testicular lymphatic space” composed of continuous “peritubular lymphatic sinusoids.” No cellular connections exist between the interstitium and the tubules. Each sinusoid completely surrounds an individual seminiferous tubule, and adjacent sinusoids communicate freely through fenestrae in the interstitium. Thus, material must enter the lymph to gain access to the tubules. The sinusoids are delimited by separate endothelial cell layers over the tubules and interstitium. The layer over the interstitium is discontinuous in specific areas according to the geometry of the tubule packing. Interstitial tissue located in the flattened biconcave interstices between two adjacent tubules is consistently covered with endothelial cells, while that located in the open, triangular interstices between three or more tubules consistently lacks an endothelium. Most of the Leydig cells are located in the “open interstitium” and are directly exposed to the lymph. Physiological implications of the “testicular lymphatic space” and additional features of the interstitium are discussed.
Demonstration of a cytochemical difference between the tubulovesicles and plasmalemma of gastric parietal cells by ATPase and NPPase reactions
Authors: Rubin Walter , Aliasgharpour Ali A.
Published: February 2005

Pieces of rat and human gastric mucosa were fixed in glutaraldehyde and paraformaldehyde and were processed by the methods of Wach‐stein‐Meisel and of Ernst for the cytochemical demonstration of adenosine triphosphatase (ATPase) and p‐nitrophenylphosphatase (NPPase) respectively. Electron microscopic examination of reacted sections revealed the ATPase reaction to be localized to the plasmalemma and to mitochondrial cristae and the NPPase reaction to the plasmalemma. The tubulovesicles were unreactive. By thus demonstrating a cytochemical difference between the plasmalemma and tubulovesicle membrane, this study suggests that the tubulovesicles do not represent an extension of or reserve of mature plasmalemma. If the tubulovesicles represent a reserve of membrane that can be rapidly utilized to expand the plasmalemma, then these studies suggest that additional membrane constituents are added, activated, or unmasked in the process.
Ciradian rhythm in DNA synthesis in mouse thymus: Effect of altered lighting regimens, restricted feeding and presence of Ehrlich ascites tumor
Authors: Pauly John E. , Scheving Lawrence E. , Burns E. Robert , Tsai Tien‐Hu
Published: February 2005

A circadian rhythm in the incorporation of tritiated thymidine into DNA of the mouse thymus has been described. This same rhythm in animals bearing an 8‐day Ehrlich ascites tumor (EAT) was altered in its phasing, wave‐form and over‐all 24‐hour mean; the most striking alteration seen in four out of five studies was a reduction in the over‐all DNA synthesis rate in tumor‐bearing animals.

Mice subjected to an altered light‐dark cycle did not show a complete phase shift in their thymus DNA rhythm within two weeks, but during this time the rhythm in the mitotic index of their corneal epithelium completely phase shifted; the presence of the tumor had no effect on this latter rhythm. In mice subjected to a daily 4‐hour restricted feeding schedule, the rhythm in DNA synthesis in the thymus became synchronized in that the peak occurred toward the end of the 4‐hour restricted feeding span in both tumor and non‐tumor‐bearing animals. The rhythm in the mitotic index in the cornea was not phase shifted or altered by the restricted meal timing.

The DNA synthesis rhythm in the normal thymus demonstrated a phasing similar to (1) the rhythm in the length of survival time in untreated mice challenged with EAT and (2) the rhythm in DNA synthesis in the normal spleen.
Quantitative studies of lymphocytes and other cell populations in the bone marrow of neonatally thymectomized C3H mice
Authors: Miller S. C. , Osmond D. G.
Published: February 2005

The effects of neonatal thymectomy on the development of the lymphoid, erythroid and granulocytic cell populations in mouse bone marrow have been assessed by quantitative techniques. The numbers per unit volume of bone marrow of 17 cell types were determined in neonatally thymectomized and sham thymectomized C3H mice at two, four and eight weeks of age, and compared with those of normal C3H mice. After neonatal thymectomy the numbers of small lymphocytes, large and medium‐sized lymphoid cells, and erythroid cells reached normal levels at two weeks but fell progressively to 18%, 22% and 42% of normal, respectively, by eight weeks. In sham thymectomized mice these cell populations did not differ significantly from normal. Immature and mature granulocytes were elevated in numbers two weeks after either neonatal thymectomy or sham thymectomy, suggesting a transient non‐specific stimulation of granulocytopoiesis. During continuous infusion of 3H‐thymidine for ten days in neonatally thymectomized mice aged four weeks and eight weeks many bone marrow small lymphocytes remained unlabeled. The results demonstrate that early postnatal development of bone marrow lymphoid and erythroid cells proceeds normally in the absence of the thymus, in accord with the concept of the bone marrow as a primary site of lymphocyte production and differentiation. In addition, some slowly‐renewing small lymphocytes in bone marrow appear to be thymus‐independent cells.
Reproductive biology of the male leaf‐nosed bat, Macrotus waterhousii in Southwestern United States
Authors: Krutzsch Philip H. , Watson Robert H. , Lox Charles D.
Published: February 2005

The reproductive biology of the bat Macrotus waterhousii was investigated anatomically and physiologically several times monthly throughout the year.

The male spermatogenic cycle is initiated in June; sperm are available in August. Testicular hypertrophy is accompanied by increased levels of testicular ascorbic acid and circulating plasma testosterone. Sperm are present in the seminiferous tubules and later the epididymides from August to early December. Regression in testicular size begins in late September and testes are involuted by early December. Levels of testicular ascorbic acid and plasma testosterone decline at this time, although detectable amounts of both are present year‐round. Mature sperm are absent from the male tract after late November or early December.

The accessory sex gland complex and Cowper's glands undergo an annual cycle in synchrony with the testicular cycle. The accessory complex contains fructose, the concentration of which varies seasonally in direct proportion to glandular hypertrophy. Only trace levels of fructose are elaborated by Cowper's glands.

In contrast to vespertilionid bats, where the accessory glands remain enlarged and active when testes involute, those in Macrotus regress.

The penis differs structurally from that of other temperate North American bats, primarily by lacking a bony baculum and specialized erectile accessory corpus cavernosus bodies.

Males are not reproductively active in their first autumn.
Uterine vasculature of the pregnant pig: A scanning electron microscope study
Authors: Macdonald Alastair A.
Published: February 2005

Colored cold setting acrylic cement was injected through catheters into the arteries and veins of sixteen gravid uteri obtained from pigs at various stages of pregnancy. After the cement had set hard, the reproductive tracts were macerated in concentrated acid and the vascular casts resulting were washed clean of digested tissues. Small pieces of cast were coated with gold and viewed by means of a scanning electron microscope.

Early in pregnancy the capillary network consists of low parallel ranks of ridges and troughs; later, cross ridging was observed which developed in complexity as pregnancy progressed. The density of capillaries comprising the microvascular network also increased towards term. No comparable changes were noted in the relatively less well vascularized areas surrounding the mouths of the uterine glands.

This technique surmounted the problems of obtaining an adequate depth of focus for viewing the capillary network of the gravid uterus with the light microscope. The relationships that the blood vessels bore to the overlying epithelial layers were discussed and the inference tentatively drawn that blood flow at the capillary level was from ridge top to trough base.
Folliculogenesis in the ovary of the mature mouse: A radioautographic study
Authors: Hoage Terrell R. , Cameron Ivan L.
Published: February 2005

Studies on the growth sequence of follicles in mature mice four to six months old were conducted by giving three injections of 16 μCi tritiated thymidine (3H‐T) / gm body weight at four hour intervals over a period of eight hours. Subsequent radioautographic analysis on ovaries obtained 1, 3, 5, 9 and 17 days after the last injection showed an overall follicle growth time of 17 to 19 days. The duration of the different follicle stage times were also estimated from radioautographic data. Intense 3H‐T incorporation was noted in the developing antra and zona pellucida of follicles of animals sacrificed one and three days after treatment suggesting that these areas serve as precursor storage sites during development. Oocytes of follicles in early antrum formation also showed juxtanucleolar 3H‐T incorporation concomitantly with rapid and massive oocyte and follicular growth. The findings further indicate that the earliest follicular cells surrounding the oocyte originate at some distance from the developing primordial follicle.
Microblebs of intestinal epithelial cell microvilli of Citellus tridecemlineatus
Authors: Dougherty William J.
Published: February 2005

The presence of microblebs arising from the lateral surfaces and tips of microvilli of intestinal epithelial cells of thirteen‐lined ground squirrels. Citellus tridecemlineatus, is reported. Microblebs measure ∼ 50 nm in diameter and are bounded by a unit membrane which is continuous with the unit plasma membrane of the microvilli. It is suggested that such microblebbing reflects the rapid turnover of microvillar contents, membrane and surface coat.
Fine structure of tracheo‐bronchial epithelial nerves of the cat
Authors: Hung Kuen‐Shan
Published: February 2005

The nerves in and immediately under the epithelial layer of the trachea and primary bronchi of the cat are studied with the electron microscope. The axons are unmyelinated and contain microtubules and mitochondria. Epithelial axons are observed throughout the entire epithelial layer, but, are usually concentrated in the basal area immediately above the basal lamina. Most axons are near the basal cells; others are in the vicinity of granulated cells or occur in the intercellular spaces between other columnar cells. A few of the epithelial axons are large and crowded with axoplasmic mitochondria. The possibility that some epithelial axons may have sensory functions is discussed.
Ciliated and secretory epidermis produced from embryonic mammalian skin in organ culture by vitamin A
Authors: Sweeny Phillip R. , Hardy Margaret H.
Published: February 2005

When skin from the upper lip of 12‐day embryonic mice was grown for ten days in organ culture with 5.7 μg retinol added per ml of biological medium, keratinization was suppressed and a ciliated and secretory epithelium was produced. Ultrastructural features of this epithelium are described. At this very early stage mouse epidermis is thus similar to chick epidermis in its ability to undergo radical metaplasia in response to vitamin A.
Variation in form of circle of willis: Some anatomical and embryological considerations
Authors: Puchades‐Orts A. , Nombela‐Gomez M. , Ortuño‐Pacheco G.
Published: February 2005

This work is based on a study of 62 circles of Willis (circulus arteriosus cerebri) from patients dead from diverse causes. We have described the wide diversity of variations found to be present in the arterial vessels that form the circle, we presented the frequency of the different variations, and finally we discuss the possible ontogenic cause of these variations.
Catecholamine‐sensitive adenylate cyclase in the developing golden hamster palate
Authors: Waterman Robert E. , Palmer Gene C. , Palmer Shelby J. , Palmer Susan M.
Published: February 2005

The present study was initiated to determine whether specific hormones would influence adenylate cyclase activity within the maxillary‐palatal complex during formation of the hamster secondary palate. Stages from initial appearance of the palatal processes to shortly after birth were studied. Highest basal adenylate cyclase activities occurred during the earliest periods of palate development. This basal enzyme activity began to diminish as palatal fusion occurred and remained lowered until birth. Activation of adenylate cyclase by fluoride was maximal at concentrations of 5–10 mM, and was observed throughout the span of palatal development. Fluoride activation of adenylate cyclase was greatest prior to fusion of the palatal processes, then decreased until birth when a slightly increased enzymatic stimulation was seen. Norepinephrine and epinephrine were the catecholamines most capable of inducing increased activation of adenylate cyclase at most periods of palatal growth. Increased enzyme activity in the presence of norepinephrine was more susceptible to antagonism by the beta adrenergic agent, propranolol, than to the alpha adrenergic agent, phentolamine. The remaining catecholamines, namely isoproterenol and dopamine, displayed a lesser ability to activate the enzyme, and adenylate cyclase was not equally responsive to these catecholamines at identical developmental stages. Other hormones, i.e., histamine, serotonin, thyrotropin, growth hormone, thyroxine and glucagon were generally ineffective in activating the enzyme. Phosphodiesterase activity was not detected until shortly before birth.
Surface morphology of human aorta as revealed by the scanning electron microscope
Authors: Albert E. N. , Nayak R. K.
Published: February 2005

Human aorta was prepared for scanning electron microscopy using critical point drying. The aortic surface is lined by a continuous layer of squamous endothelial cells. The luminal surface of these cells contains many microvilli or microappendages and pinocytotic vesicles. In addition, at the periphery of each cell, larger marginal appendages or microfolds are present which allow the observer to see the cell boundaries clearly. The marginal folds are superficial to the cell junctions and could be observed without any staining procedures. These observations on human aorta are generally in agreement with our findings on the rabbit and guinea pig aorta and vena cava but are in contrast to others who have reported the presence of ridges, intercellular bridges, and “hair‐like” processes on the endothelial surfaces.
The biosynthesis and secretion of precursor enamel protein by ameloblasts as visualized by autoradiography after tryptophan administration
Authors: Slavkin Harold C. , Mino William , Bringas Pablo
Published: February 2005

The incorporation of 3H‐tryptophan into the inner enamel epithelium of newborn mouse incisor tooth organs has been studied in situ by light and electron microscopic autoradiography to determine the sites and kinetics of biosynthesis, migration, and secretion of precursor enamel protein during newborn mouse incisor tooth formation. Maxillary and mandibular incisor tooth amelogenesis was studied 5, 30, 60, 120, 240 minutes and 24 hours following the intraperitoneal injection of 3H‐tryptophan. By 5 minutes, 40% of the total silver grains associated with the secretory ameloblasts were localized over the rough endoplasmic reticulum and 50% of the silver grains were localized over the Golgi apparatus. By 30 minutes, silver grains were observed predominately over condensing vacuoles and secretory granules within the forming Tomes' processes, and were also localized over the extracellular “granular” pre‐enamel matrix. The enamel proteins were synthesized on membrane‐bound polysomes, transferred within the cisternae of the rough endoplasmic reticulum and then accumulated in the inner saccules of the Golgi apparatus. The enamel proteins were then packaged in condensing vacuoles which subsequently became secretory granules which migrated to the lateral and apical secretory regions of the forming Tomes' processes. It was concluded from these in vivo studies that enamel proteins were synthesized and subsequently secreted within 30 minutes. The initially secreted precursor enamel protein was localized over a material which demonstrated a granular or stippled ultrastructure. The labeled protein then was localized over the amorphous enamel matrix per se which contained the forming calcium hydroxyapatite crystals. We assumed, therefore, that there are two different ultrastructural forms of 3H‐tryptophan containing extracellular enamel proteins and suggest that the granular or “stippled” form represents newly secreted precursor enamel protein.
The exfoliating cervico‐vaginal surface. II. Scanning electron microscopical studies during the estrous cycle in mice
Authors: Rubio C. A.
Published: February 2005

The exfoliating epithelial surface of the ectocervix (pars vaginalis) and the vagina from normal mice was studied by scanning electron microscopy during the four main phases of the ovulatory cycle, and after estrogen administration. At proestrus, the epithelial surface usually presented cobblestonelike structures furnished with thin microvilli; at estrus, large, flat mosaics covered by long, convoluted microrugae; at metestrus, the presenting cellular surfaces were of intermediate size (i.e., between cobblestone and mosaics) having fragmented microrugae; and at diestrus, by mosaics or intermediate structures covered by microvilli. Estrogen administration to intact and oophorectomized animals resulted in flat mosaics and large numbers of loosely attached cells with rolled‐up borders which permitted the observation of the basal surface of the cells. In those animals the apical aspect of the cells which lined the lumen showed convoluted microrugae with circular configuration, while the basal aspect of such cells had club‐tipped microvilli. The findings were correlated with post‐scanning histological examination in all animals.
Adrenergic and cholinergic innervation of the arteriovenous anastomosis in the rabbit's ear
Authors: Iijima Tadahiko , Tagawa Takasuke
Published: February 2005

The distribution of adrenergic and cholinergic nerves in the arteriovenous anastomosis in the rabbit's ear was studied light microscopically using specific histochemical techniques for catecholamines and acetylcholinesterase.

Histochemical observations were made with whole stretch preparations and cryostat or paraffin sections. Both kinds of nerves showed similar distribution, though the adrenergic innervation was denser than the cholinergic one. The intermediate segments of the anastomoses, which were characterized by a very thick wall, had the most dense innervation. The small arteries and arterial segments had a moderate innervation, whereas most of the small veins and venous segments had few nerve fibers.

The segmental variation in the vasomotor nerve supply clearly suggests that the intermediate segment has the most active contractility. An unusually rich innervation in the anastomosis, therefore, indicates the significance of the neurogenic mechanisms in the vasomotor control of the anastomosis.
A scanning electron microscope study of the interstitial tissue of the canine testis
Authors: Connell Carolyn J.
Published: February 2005

Scanning electron microscopy (SEM) is a potent tool that is especially valuable in interpreting the three‐dimensional relationships of cells within tissues. This type of information is obtainable from thin sections in transmission electron microscopy (TEM) only by reconstructions of serial sections. The arrangement of the interstitial cells of the testis in relation to the capillaries and lymphatic channels, in particular, is easier to visualize in SEM than in TEM. Cytoplasmic constituents, as well as cell surface modifications, are demonstrable by this technique. The presence of droplets, presumably lipid droplets, both within and on the Leydig cells and the lymphatic endothelial cells, is quite evident. Other cytoplasmic structures are also apparent. For example, the possible functional significance of “openings” that are seen by SEM on the septa that surround lipid droplets is discussed relative to the appearance of the same area as seen in thin sections or in freeze‐fracture replicas. SEM should become a very useful method for studying cytological and morphological alterations that occur in testicular tissue that is subjected to physical or chemical manipulation.
Analysis of cell populations of normal and injured mouse lens epithelium. I. Cell cycle
Authors: Rafferty Nancy S. , Smith Richard
Published: February 2005

Using a combination of single isotope and double isotope autoradiography after injection of 3H‐thymidine and of 3H‐ + 14C‐thymidine, respectively, the cell cycle of normal and injured lens epithelial cells in the mouse was determined. Progenitor cells in the peripheral region of normal lens epithelium were found to traverse the replicative cycle in the same amount of time as the injury‐stimulated cells in both peripheral and central (wound) regions. The individual phases were also the same length, except for a slight shortening of G2 in the injured epithelium. The durations of the phases were: S: 11–12 hours; G2: 1.5–2 hours; M: 4.2–5 hours; G1 (derived): 38–44 hours; and total cycle: 55–61 hours. Two findings were significant in view of previous observations that injury to mouse lens seldom induces lens opacity. First, while the cell cycle duration was not affected by injury, a burst of proliferation of potentially active cells ensued. And, secondly, this burst of proliferation involved only one cell cycle. Only a small number of cells, equivalent to the normal progenitor compartment, continued into a second replicative cycle. The wound was healed, therefore, mainly by one division cycle involving a large number of cells.
Histochemical evidence of mucosubstances in the metaplastic epidermis and hair follicles produced in vitro in the presence of excess vitamin A
Authors: Bellows Carlton G. , Hardy Margaret H.
Published: February 2005

Pieces of upper lip and lower jaw from 13‐day old mouse embryos grown in organ culture with excess vitamin A showed metaplastic changes in epidermis and hair follicles after 7 to 21 days. Changes were less marked in upper lip explants from 15‐day old embryos. Areas of keratinizing epidermis showed a much higher incidence of Alcian blue‐positive bodies when excess vitamin A was present. Histochemical tests with Alcian blue at critical electrolyte concentrations indicated moderately sulfated acidic mucosubstances in these bodies. Other patches of epidermis were transformed into stratified cuboidal epithelium producing PAS‐positive. Alcian blue‐negative, mucosubstances. The hair follicles, transformed by vitamin A into glands, developed three types of epithelium with apical granules, luminal borders and occasional goblet cells, all showing mucosubstances. Tests suggest that both metaplastic epidermis and glands secrete either neutral mucosubstances or non‐sulfated acidic mucosubstances. Another response to vitamin A was a rapid loss of glycogen, particularly in hair follicles and the epidermal basal layer. It was concluded that excess vitamin A alters not only the morphogenesis but also the distribution and synthesis of polysaccharides in developing skin.
Concanavalin a binding to the epithelial surface of the developing mouse olfactory placode
Authors: Smuts Marybeth S.
Published: February 2005

Concanavalin A (Con A), a lectin binding to mannosyl and glucosyl residues of glycoproteins and glycolipids, was used to study the appearance of carbohydrate‐rich cell surface material on the olfactory placode and nasal processes which contribute to formation of the primary palate. In vivo incorporation of 3H‐thymidine was also used in an attempt to correlate changes in labeling index with formation of the olfactory placode and nasal processes.

The cell surface of the early frontonasal epithelium binds Con A very little, if at all, but Con A binding was observed when the olfactory placode could be identified as a plate of cuboidal cells that exhibited a reduced labeling index. During the period of formation of the nasal processes, Con A binding was observed on the facial epithelium including the presumptive contact region. There was also a decline in the labeling index throughout primary palate formation.

This study provides three criteria by which the olfactory placode can be identified: a morphological change of placode cells to a cuboidal shape, a synthesis or rearrangement of surface coat material that binds Con A, and a reduced labeling index.
The ultrastructural histochemistry of the basement membranes of the exocrine pancreas
Authors: Katsuyama T. , Poon K‐c , Spicer S. S.
Published: February 2005

The basement membranes in the exocrine pancreas were examined by routine electron microscopy, by fixation for electron microscopy with a glutaraldehyde‐tannic acid solution and by staining for ultrastructural demonstration of mucosubstances with the dialyzed iron, high iron diamine, ruthenium red and Concanavalin A‐horseradish peroxidase procedures. The basement membranes are considered from morphologic and histochemical observations to consist of an inner lamina lucida, an intermediate lamina densa and an outer lamina diffusa. Sulfated mucosubstance was found in the lamina diffusa of the basement membrane of all epithelial cells and capillary endothelial cells but was encountered in the lamina lucida of the duct cells exclusively. Bridging structures, presumably polypeptides, were also seen connecting the lamina densa and the basal plasma membrane in specimens fixed with the glutaraldehyde‐tannic acid solution. The findings demonstrated that the histochemical and morphological qualities of the basement membrane are uniform for a given cell type but differ considerably among the several cell types in the pancreas.