bluuebunny/crossref_metadata_2025 huggingface dataset:
Developing innervation of the chick heart: A histofluorescence and light microscopic study of sympathetic innervation
Authors: Kirby Margaret L. , McKenzie John W. , Weidman Thomas A.
Published: February 2005

The available descriptions of the development of sympathetic innervation of the chick heart conflict with the known sympathetic innervation of the adult chicken heart. The adult heart is innervated by bilateral sympathetic cardiac nerves originating from the first thoracic sympathetic ganglia. These nerves travel lateral and anterior to the lung and join the vagi just before entering the pericardium along the great vessels. Using catecholamine histofluorescence techniques and silver preparations, we have observed the development of the sympathetic cardiac nerves. The sympathetic cardiac nerves arise from the first thoracic sympathetic ganglia on the 7th day of incubation. They grow lateral and then ventral to the developing lungs to join the vagi, and are found in the bulbar region of the heart and atrium on the 10th day of incubation. Fluorescent cells without processes mark the course of the sympathetic cardiac nerves and are present in the bulbar region on the 10th day and thereafter. Sympathetic ganglion cells lose their fluorescence between day 8 and day 16 of incubation. This is presumably due to dilution of the transmitter in the rapidly increasing volume of cytoplasm in the sprouting neurons. Small intensely fluorescent (SIF) and adrenal medullary cells do not undergo a diminution of fluorescence during this period. SIF cells appear well differentiated at 16 days.
The dependent and independent relationships between cytodifferentiation and morphogenesis in developing salivary gland secretory cells
Authors: Cutler Leslie S.
Published: February 2005

The mesenchymal capsule was removed from the epithelial anlage of 15 day (unbranched) and 16 day (initially branched) fetal rat submandibular gland (SMG) rudiments. The undifferentiated epithelial portion of the SMG rudiments was placed in tissue culture and examined by light and electron microscopy and histochemistry for secretory peroxidase. The 15 day fetal SMG epithelial rudiments failed to attach, and spread over the culture dish and degenerated by 3 days in culture. The 16 day epithelial rudiments attached to the dish and the cells spread radially from the explant. Mitotic activity was minimal. Cells spreading from the 16 day rudiments underwent cytodifferentiation, giving rise to two secretory cell types: (1) peroxidase containing “proacinar cells,” and (2) secretory “terminal tubule” cells. The results suggest that in the developing SMG, morphogenesis and cytodifferentiation are partially coupled but independently regulated processes. The earliest phases of morphogenesis (rudiment down growth and primary branching) seem to be required to initiate cytodifferentiation. Once initiated, cytodifferentiation can proceed in the absence of continued morphogenesis (tissue organizatation) or significant amounts of connective tissue elements.
The effect of short term incubation in vitro on the RNA content of regenerating mouse epidermis
Authors: Tormay Margaret Anne , Argyris Thomas S.
Published: February 2005

The effect of short term incubation in vitro on RNA content in regenerating and normal epidermis has been investigated. Regenerating mouse epidermis was incubated for three hours, either attached to its underlying dermis or by itself, in either buffered sucrose or Roswell Park Memorial Institute culture medium at 26°C or at 37°C. There is a significant loss of RNA when regenerating epidermis is incubated without being attached to its underlying dermis, at either 26°C or 37°C, although there was little loss of DNA, good incorporation of (3H) orotic acid into RNA, as well as good preservation of epidermal histological details. In contrast, when regenerating epidermis was incubated attached to its dermis, little loss of RNA occurred. Similarly, incubating normal epidermis attached to its dermis results in no loss of RNA. These conditions also result in no significant loss of DNA, good incorporation of (3H) orotic acid into RNA, and preservation of epidermal histological details.
The visualization of myosatellite cells in normal and denervated muscle: A new light microscopic staining technique
Authors: Larocque Alan A. , Politoff Alberto L. , Peters Alan
Published: February 2005

A new light microscopic staining technique allows the visualization of satellite cells on the surface of myofibers. Either prior to or during fixation, whole frog sartorius muscles are bathed in an acidic buffered solution containing lead nitrate and subsequently exposed to ammonium sulfide. The staining of the satellite cells resulting from this procedure reveals their positions, and the outlines of their cell processes which occasionally branch. Electron microscopy shows that the staining is due to lead deposits localized between apposing membranes of satellite cells and associated myofibers. Prior exposure to N‐ethyl‐maleimide (NEM) does not alter the formation of the lead deposits on the satellite cell, but reduces the amount of Pb deposits on the muscle surface and connective tissue.

This technique has been applied to determine the effects of denervation on the satellite cells of frog sartorius muscles. Four weeks after denervation, the number of satellite cells is essentially the same in both denervated muscles and the intact muscles of the contralateral side. However, denervation results in a subpopulation of satellite cells with altered shapes. They have elongated cytoplasmic processes which often branch. It is suggested that these supernumerary cytoplasmic processes represent an intermediate phase in the transition of satellite cells to myoblasts.
Three large dissectable rat glomerular models reconstructed from wide‐field electron micrographs
Authors: Yang Grace C. H. , Morrison Ashton B.
Published: February 2005

Three very large styrofoam models of glomerular capillary tufts have been built, based on serial ultrathin sections which cut through three complete rat glomeruli isolated from all regions of renal cortex. The images of glomeruli are enlarged on 20" × 24" wide‐field electron micrographs, from which each capillary is traced on styrofoam discs and then individually connected. These models can be disassembled to measure the width and length of each capillary segment and to map the complicated glomerular vascular arrangement. Each of the three randomly selected glomeruli has three arteriolar openings passing through the Bowman's capsule–‐e.g., an afferent opening and two closely situated efferent openings. Each of the three glomeruli consists of three major lobules, e.g., two larger lateral lobules and a smaller central lobule. Assuming the model is positioned so that the vascular pole is superior and the afferent arteriole is closer to the observer than the two efferent vessels, the lobule occupying the frontal right portion originates from the right major branching of the afferent arteriole and reconverges at the right efferent opening. The lobule occupying the frontal left portion originates from the left major branching of the afferent arteriole and reconverges at the left efferent opening. The lobule occupying the central portion originates from the central major branching and connects both lateral lobules with a few interlobular anastomoses. The diameter and the length of interlobular anastomoses, and the volume of major lobules are listed. The technique of the isolation and reembedment of glomeruli and the construction of models is described in detail.
Presynaptic bodies of auditory hair cells in old world monkeys
Authors: Bodian David
Published: February 2005

Presynaptic bodies of auditory hair cells of Old World monkeys are separately differentiated in inner, as contrasted with outer, hair cells. The pre‐synaptic bodies of outer cells are spherical and of variable electron density, and are thus similar to those of the labyrinth of vertebrates from fish to man. The difficulty in finding them, as compared with the relative ease of finding the presynaptic bodies of inner hair cells, suggests either that they are not present in all outer hair cells or that they undergo a regression‐reconstitution cycle. The presynaptic bodies of simian inner hair cells are almost always ring‐shaped. The few exceptions reinforce the impression of a later evolutionary development of the inner hair cell system. In any event, our findings serve to reemphasize the remarkable differentiation of outer and inner hair cell systems, and to deepen the mystery of their separate roles in audition.
Histology of the canine uretha II. Morphometry of the male pelvic urethra
Authors: Cullen W. Craig , Fletcher Thomas F. , Bradley William E.
Published: February 2005

Urinary bladders and pelvic urethrae were collected from six adult and two juvenile male dogs. Within two vesical and six urethral sampling regions, volume densities were estimated for smooth and striated muscle, connective tissue and elastic fibers, stratum cavernosum, luminal epithelium, and prostate. The neck had significantly less smooth muscle and more connective tissue than the body of the bladder. In the prostatic urethra, smooth muscle was associated principally with trabeculae surrounding prostate lobules. Smooth muscle was sparse superficially in the prostatic capsule and practically absent in relation to the mid‐prostatic urethra. Thus there was no mechanism for active closure of the middle prostatic urethra, and elastic fiber density was correspondingly high in this region. The smooth muscle sphincter needed to maintain urinary continuence and prevent semen reflux was primarily the vesical neck. Caudal to the body of the prostate, striated muslce comprised more than 50% of the urethral wall. Juvenile and adult postprostatic urethrae were similar except for a decreased quantity of stratum cavernosum in the pups.
Foetal haemopoiesis during the hepatic period. I. Relation between in vitro liver organogenesis and erythropoietic function
Authors: Nessi Analía C. , Bozzini Carlos E. , Tidball Morris V.
Published: February 2005

Cultures of the hepatic bud, under different experimental conditions, show a direct relation between foetal age at the time of dissection and the further organogenesis of the explant. In cultures of the septum transversum plus hepatic bud—with or without splanchnic mesenchyme—obtained from embryos of four to 25 somites, the capacity of endodermic cells to differentiate into hepatocytes appears only in a small number of samples; whereas, in the hepatic bud from older embryos (26 to 40 somites), this differentiation occurs in all cases.

The amount of time cultures were allowed to grow was important for hepatic organogenesis, as measured by cord‐like organization of hepatocytes plus their storage capacity for glycogen. The possibility of the explants showing complete haemopoiesis was also a condition of foetal age at the time of explant. Haemopoiesis was not found in cultures from embryos of less than 25 somites. On the other hand, development of haemopoiesis did not show a direct relation to days of culture, since the peak of this activity was observed towards the third day in vitro. Most explants showed a generalized haemopoiesis (both interstitial and vascular) with a decay towards the sixth day.

Endodermal cells of the hepatic bud were capable of both proliferation and differentiation into hepatocytes, even in those mesenchymes considered inadequate such as limb mesenchyme. In the latter case we were unable to find haemopoiesis at any time. The septum transversum, when cultured alone, did not contain haemopoietic cells.
The oculomotor nucleus and extraocular muscles in a mutant anophthalmic mouse
Authors: Paterson J. A. , Kaiserman‐Abramof I. R.
Published: February 2005

The object of this study was to determine whether the oculomotor nucleus and the extraocular muscles are present in the adult of a mutant mouse strain in which eye formation fails early in development (Chase and Chase, '41). Neuronal counts for the oculomotor (IIIrd) nucleus were obtained from serial paraffin sections made through the midbrains of seven mice of the anophthalmic mutant group (ZRDCT‐An) and seven mice of the same strain in which eyes were present (ZRDCT‐N). The orbital structures of the anophthalmic and control groups were reconstructed from 1‐μm plastic serial sections. There was in the anophthalmic mouse, in the same location as in the normal, an oculomotor nucleus whose mean neuronal cell number was 206 (± 40). The normal mouse had a mean value of 262 (± 63) oculomotor neurons. On the basis of these results, this difference between the two groups was not statistically significant (P = 0.073). The neuronal number per cubic millimeter was similar in the two groups (P = 0.81). In the orbit of the anophthalmic mouse, several bundles of striated muscle occupied a location comparable to that of extraocular muscle in the normal mouse. Neuromuscular junctions were present on fibers of this orbital muscle. It is concluded that the early failure of eye formation does not prevent the development of extraocular muscles and the oculomotor nucleus, and their retention in the adult.
Immunoshistochemical localization of gonadortropin releasing hormone (GnRH) in the bovine hypothalamus and infundibulum
Authors: Dees W. L. , McArthur N. H.
Published: February 2005

Neural structures containing gonadotropin‐releasing hormone (GnRH) in the bovine brain and infundibulum were characterized by light microscopic immunohistochemistry. GnRH‐positive perikarya were localized singly or in small groups within the infundibular nucleus and were seen grouped in large discrete clusters within the ventromedial nucleus. Positive axons were localized within the brain from the nucleus of the rostral commissure to the medial mammillary nuclei, and in specific areas of the infundibulum and infundibular stalk.
The effects of the carcinogen, 1,2‐dimethylhydrazine, on turnover 3H‐thymidine labeled cells from mucosal glands of mouse colon
Authors: Richards Thomas C.
Published: February 2005

1,2‐dimethylhydrazine (DMH), administered weekly to mice for 20 weeks, induces tumors in the distal segment of colon. Tumors are preceded by enlargement of the mucosal glands resulting from increases in the number of total cells and 3H‐thymidine labeled cells/crypt. Cells located in the crypt base normally undergo 2–3 divisions as they migrate toward the lumen, and they become post‐mitotic in the upper crypt. It is not known if cells in these eniarged crypts have rates of turnover similar to cells in normal crypts. Groups of w/s female mice were treated with DMH (20 mg/kg body wt) for 3,8, or 16 weeks; controls were given 0.001 M EDTA. After treatment, the animals were injected with 3H‐thymidine and killed one hour or 1,2,4,7 or 17 days later. Autoradiographs were prepared from sections of distal colon. The total cells/crypt column in 30 crypts/animals were counted. Crypts were divided into 10 equal segments based on the crypt length and the labeled cells/segment were counted. The relative number of labeled cells and the distribution of these cells within crypts were similar in DMH‐treated and control animals after one hour. However, as the cells migrated toward the lumen, the number of labeled cells doubled after 2 days and tripled after 4 days in DMH‐treated animals but only doubled during the 4 days in controls. This difference was caused by retention of an increased number of dividing cells in the lower 4 segments of the crypts and suggests an increase in those cells that divide twice. In addition, increased numbers of labeled cells were retained in the upper 3 segments of DMH‐treated animals after 4 days. These findings indicate that the crypt cells of DMH‐treated animals are generally more immature than those of controls and this immaturity contributes to the enlargement of mucosal glands during carcinogenesis.
A method for culturing canine tracheal smooth muscle cells in vitro: Morphologic and pharmacologic observations
Authors: Avner Barry P. , Delongo Judi , Wilson Steve , Ladman A. J.
Published: February 2005

A method of culturing canine tracheal smooth muscle cells in vitro is described. The morphology of these cells is monitored up to 60 days in culture and selected stages are illustrated. The characteristics of these cells are numerous mechanical attachments, the presence of thick filaments in suitably processed cells, and their contractile response to in vitro administration of carbachol, a cholinomimetic drug. They also possess nexus formations and both thin (actin) filaments and 10‐nm filaments. Mitosis is found in the nonconfluent preparations up to 16 days after culturing. Cultures of 2 to 8 days appear to be most useful as pharmacological test vehicles. This system will be used to explore the phenomenon of adrenergic beta‐2 receptor desensitization in airway smooth muscle, to attempt to localize these receptor sites and to determine how receptor affinity and/or number may be regulating cell response to pharmacologic agents.
The incidence of dentinal tubules containing more than one process in the cuspal dentin of cat canine teeth
Authors: Holland G. R.
Published: February 2005

The incidence of multiple processes within the tubules of the cuspal dentin of the cat's canine has been measured by counting directly from ultrathin sections examined in the electron microscope. The incidence is highly variable. The greatest incidence was found 1 mm below the cuspal dentino enamel junction where up to 75% of tubules in some areas contain more than one process. On average 33.6% of the tubules at this level contain multiple processes. The incidence declines linearly toward the apex with virtually no multiple processes occurring at 4 mm below the tip dentino enamel junction or beyond. Half of the “second processes” contain either mitochondria and/or vesicles. They are restricted to predentin where many of them end and to inner calcified dentin. Their distribution is similar to that described for nerve fibers in other studies. None of the processes participated in specialized junctions.
Cellular composition of the bone marrow in the chicken: II. The effect of age and the influence of the bursa of fabricius on the size of cellular compartments
Authors: Glick Bruce , Rosse Cornelius
Published: February 2005

The blood and bone marrow of New Hampshire chicks were analyzed quantitatively from the time of hatch to 8 weeks of age. Hormonal bursectomy was performed by treating embryonating eggs on the 11th day of incubation with testosterone propionate (TP) which resulted in severe hypogammaglobulinemia and complete atrophy of the bursa of Fabricius. TP‐treated birds exhibited some lymphocytopenia, reduced splenic weight, and lack of plasma cells in their bone marrow. The number of cells per milligram bone marrow was comparable in normal and TP‐treated birds, falling in the range reported for laboratory rodents. The chick medullary hemopoiesis is characterized by the predominance of erythroblasts throughout early development; granulocytes and lymphocytes represent much smaller cellular compartments than in rodents. In the chick granulocytes tend to decrease after hatch, whereas in rodents they tend to increase. The normal chick shows a temporary increase in marrow lymphocytes after hatch, similar to that observed in some young rodents, but on a much smaller scale. Hormonal bursectomy did not prevent the development of a lymphocyte population in the bone marrow. These cells were fewer in TP‐treated birds at hatch and at 4 weeks than in normal birds, but at 8 weeks of age normal and bursectomized chicks had comparable numbers of lymphocytes in their marrow. Although some lymphocytes in avain bone marrow may depend on the bursa of Fabricius for their development, a substantial proportion of bone marrow lymphocytes in the chick are bursa independent. The cell surface phenotype and site of origin of these cells remains to be investigated.
Ependymal cells of the filum terminale in fish (poecilia sphenops) adapted to freshwater and saltwater: Electron microscopic study
Authors: Kriebel Richard M.
Published: February 2005

The ependymal lining of the central canal of the filum terminale and spinal cord in the vicinity of the caudal neurosecretory system in P. sphenops was examined in this study. Two general cell types based on shape and location were observed in the ependymal lining: cuboidal ependyma located in dorsal aspects of the filum terminal and columnar to pseudostratified ependymal cells found in ventrolateral and ventral aspects of the filum terminale. Comparison of the ependymal lining was made in animals adapted to saltwater and freshwater. In animals adapted to saltwater there was an increase in the basal infoldings of the cell membrane of the dorsal cuboidal ependyma. Infolding of the basal cell membrane is a phenomenon shared by cells known to participate in transport of electrolytes. Since a possible functional relationship between the ependyma of the third ventricle and median eminence has been shown, in future studies on the osmoregulatory function of the caudal neurosecretory system the ependymal lining of the central canal in this region should be considered.
Ultrastructural immunocytochemistry of nascent albumin topology: Proposed cytosolic folding and membrane transit of the protein
Authors: LeBouton A. V. , Masse J. Peters
Published: February 2005

The relationship of nascent albumin and hepatocyte organelles was studied with the immunoperoxidase reaction in rats given various drugs to alter cellular albumin content. Colchicine was used to increase intracellular albumin. Cycloheximide inhibited synthesis but allowed nascent albumin to remain with its ribosome of origin. Puromycin also inhibited synthesis but released albumin from its ribosome. There was no difference in the appearance of attached ribosomes in hepatocytes from saline‐injected rats and those given colchicine or cycloheximide. In these cases, membranes of the endoplasmic reticulum were consistently decorated with ribosomes positive for the presence of albumin antigenicity on their cytosolic surface. The cisternal and cytosolic compartments were negative. The situation after puromycin was different. Here the membranes appeared to be denuded of ribosomes and reaction product, indicative of albumin, was present only on the lumenal surface. To determine whether puromycin had caused the release of ribosomes, sections from puromycin‐treated cells were stained nonspecifically with uranyl acetate. This showed that the normal amount of ribosomes was still bound but that they could not be seen when a probe specific only for albumin was used. It appears that nascent albumin can associate with its ribosome within the cytosol. Also, apparently after albumin passes through the membrane of the rough endoplasmic reticulum, it remains attached to its lumenal surface. A model incorporating cytosolic folding of albumin followed by its entropic membrane transit is presented.
Electron microscopic studies of rat sperm heads treated with urea, dithiothreitol, and micrococcal nuclease
Authors: Sobhon Prasert , Thungkasemvathana Pornpilai , Tanphaichitr Nongnuj
Published: February 2005

Urea and dithiothreitol can decondense the chromatin in some of rat sperm heads. By this treatment, we have observed that in the nuclei of rat sperm the chromatin is organized into two morphologically distinct portions, namely: the compact chromatin rods of about 450 to 1,000 Å thick, and the interlacing fibers about 250–290 Å in thickness. When these treated sperm are further digested with micrococcal nuclease, the small fibers disappear, whereas the chromatin rods are still present in the “urea‐nuclease pellet.” From the available evidence, we suggest that the chromatin rods represent the highly packed nucleoprotamine, whereas the small fibers represent the more loosely organized nucleohistone.
Shunting in renal microvasculature of the rat: A scanning electron microscopic study of corrosion casts
Authors: Casellas D. , Mimran A.
Published: February 2005

We reinvestigated the still controversial existence of arterial pathways by‐passing glomeruli within kidneys of rats from weaning to more than 12 months old (i.e., body weight ranging from 39 g to 643 g). For this purpose, the arterial injection of microspheres 7.5 μm to 17 μm in diameter was combined to corrosion‐replication of the arterial bed of a vasodilated perfused kidney preparation. This procedure allowed easy detection of arterial by‐passes with light microscope and detailed observation with scanning electron microscope. Our results clearly demonstrate the existence of various categories of arterial by‐passes throughout renal cortex regardless of age. Some of them had never been described before. These vascular by‐passes were found with increased frequency from superficial to juxtamedullary cortex. In the latter area, frequency was not agedependent, and approximately 10% (range 4–22%) of juxtamedullary glomeruli were involved. Data derived from previous microsphere studies would suggest that these structures are (partially) nonfunctioning in basal physiological conditions, but more information is needed to assess their possible functional role in the rat.
Autoradiographic demonstration of ipsilateral and contralateral sensory nerve endings in cat dentin, pulp, and periodontium
Authors: Byers M. R. , Matthews B.
Published: February 2005

In order to determine the location of sensory nerve endings in cat teeth, 3H‐proline and 3H‐leucine were injected into the left trigeminal ganglion of eight cats aged 6.5–10 months; 24 hours was allowed for axonal transport of radioactive protein to dental nerve endings, and the endings were then detected by autoradiography. The pulps of most ipsilateral (left) teeth contained some labeled axons. These axons ended in the odontoblastic layer and predentin of roots and crown; at the tip of the pulp horn of each cusp, nerve endings also extended as far as 150 μm into dentinal tubules.

Labeled nerve endings were extremely rare in contralateral (right) teeth; only one tooth of 83 studied (eight cats) contained heavily labeled axons, and one other had faintly labeled axons. Both labeled contralateral teeth were central maxillary incisors. Their labeled axons were unbranched in the root and arborized in the crown to end among odontoblasts and many adjacent dentinal tubules.

Labeled periodontal nerve endings were most numerous in the apical one‐third of the ligament, with some endings extending as far as the gingiva. The nerve endings in the periodontal ligament were often clustered and appeared to end freely between the collagen bundles; their radioactivity varied in the same way as that of pulp nerves in the adjacent root.
Surface coat material associated with the cells of the developing lens vesicle in the chick embryo
Authors: Van Rybroek John J. , Olson Mark D.
Published: February 2005

Ruthenium red (RR) and cetylpyridinium chloride (CPC) were used to demonstrate the distribution of cell surface coat material (SCM) on the free epithelial surface of the developing lens vesicle in stages 14–17 (50–64 hours) chick embryos. Observations were made by light microscopy and transmission (TEM) and scanning (SEM) electron microscopy. A progressive increase in SCM is observed on cellular apices within the epithelium of the lens vesicle by means of RR staining, particularly at the margins of the aperture which are the sites of presumptive fusion. In contrast, a relatively thin layer of SCM persists on the adjacent surface ectoderm. Ruthenium red‐positive SCM extends across the aperture of the lens vesicle prior to initial contact between the advancing epithelial surfaces. The presence of abundant SCM is interpreted as a possible significant prerequisite to invagination and to epithelial adhesion and fusion prior to detachment of the lens from surface ectoderm. When CPC is added to the fixative, a flocculent precipitate over the aperture of the lens visicle and an associated band of modified surface ectoderm which extends ventrally from its lower margin are observed. The modified ectoderm and associated SCM likely represent a presumptive region of active coordinated cellular migration.
A light and electron microscopic study of the innervation of pulmonary arteries in the cat
Authors: Knight David S. , Ellison Jeffrey P. , Hibbs Richard G. , Hyman Albert L. , Kadowitz Philip J.
Published: February 2005

Nerve terminal‐smooth muscle relationships were studied in pulmonary arteries of the cat using 5‐hydroxydopamine to help differentiate adrenergic and nonadrenergic terminals. There was a periarterial plexus of nerves in the walls of pulmonary arteries that extended into the lung to innervate even small arteries having a single layer of smooth muscle cells. Adrenergic nerves surrounded all arteries and extended into the tunica media of the large arteries. There were also apparent cholinergic nerves around the pulmonary arteries, although this was confirmed by electron microscopy for medium‐ and small‐sized arteries only. The relationships of nerve terminals to smooth muscle cells in pulmonary arteries suggest that release of norepinephrine by adrenergic terminals can produce both decreased compliance and increased resistance in the pulmonary vascular bed, and that acetylcholine released by cholinergic terminals may act directly on vascular smooth muscle or on adrenergic terminals to modulate release of norepinephrine. These results suggest that both sympathetic and parasympathetic nerves may have a regulatory role in the pulmonary circulation.
A model of the inguinal canal
Authors: Jacobs John J. , Alvarado Donald M.
Published: February 2005

Medical students often find it difficult to conceptualize and learn the anatomy of the inguinal region and canal. A model of the inguinal canal, appropriate for lecture and laboratory presentations, has been used for many years by one of the authors (J.J.J.), and based on student and staff feedback, is judged a successful visual learning aid. This paper outlines a step‐by‐step procedure for constructing the model out of plexiglass and colored, felt‐tipped marking pens.
Ultrastructural localization of nicotinamide adenine dinucleotide phosphatase (NADPase), thiamine pyrophosphatase (TPPase), and cytidine monophosphatase (CMPase) in the Golgi apparatus of early spermatids of the rat
Authors: Clermont Y. , Lalli M. , Rambourg A.
Published: February 2005

At the early steps 3–7 of spermiogenesis the hemispherical Golgi apparatus elaborates and is closely associated to the acrosomic system which grows at the surface of the spermatid's nucleus. It shows two distinct zones, a cortex made up of flattened saccules and related membranous tubules, and a medulla containing various types of vesicular profiles. The various components of the cortex of the Golgi apparatus were tested for their reactivity to three phosphatases. Nicotinamide adenine dinuclèotide phosphatase activity (NADPase, Smith, 1980) was observed in the middle two to six saccules in the stack with a midsaccule being more reactive than the saccules above and below. A weak and spotty reaction was also noted in the remaining saccules on the trans‐face of the stack and in the thick elements making up the GERL on the trans aspect of the stacks of saccules. Thiamine pyrophosphatase activity (TPPase, Novikoff and Goldfisher, 1961) was found in one or two saccules on the trans‐face of the stacks but was absent from the other Golgi components. Cytidine monophosphatase activity (CMPase, Novikoff, 1967) was observed in the GERL, in vesicles of the medulla and in the developing acrosomic system. In the intersaccular regions of the cortex the branching membranous tubules showed the same reactivity for the phosphatases to that of the saccules to which they are connected. ER cisternae associated with the Golgi apparatus, anastomotic membranous tubules seen in the peripheral Golgi region, small vesicles, as well as the first saccule on the cis‐face of the stacks were all negative for the three enzymes studied. These data indicated that in the cortex of the Golgi apparatus there were several distinct compartments that could be distinguished on the basis of structural and cytochemical features.
Fiber contribution from the mesencephalic nucleus of the trigeminal nerve to the trochlear nerve in the cat: A histological quantitative study
Authors: Sherif M. F. , Papadopoulos N. J. , Albert E. N.
Published: February 2005

The fiber connections between the trigeminal mesencephalic nucleus and tract and the trochlear nerve root of 15 cats were examined after silver impregnation of the pontomescencephalic region of the brains. The results revealed that: (a) some of the mesencephalic root fascicles join the trochlear root, (b) some of the mesencephalic root cells contribute their processes to the trochlear root, and (c) some mesencephalic cells are found amidst the fibers of the trochlear nerve during its intrabulbar course. The fibers of the trochlear nerve were counted at certain preselected sites before and after crossing the mesencephalic nucleus. The statistical data obtained indicated that the trigeminal mesencephalic root contributes 4–10% of the fibers of the trochlear nerve, before it crosses the mesencephalic nucleus.
An electron microscopic study on the extraocular muscles of a lamprey, Lampetra japonica
Authors: Nakao Taisuke , Aoki Shinichi
Published: February 2005

This paper reports an EM study on the observations of the extraocular muscles of the lamprey, Lampetra japonica. Individual muscles consisted of numerous subunits, each being surrounded by a common external lamina and containing two, S and F‐types, of muscle fibers. A subunit contained an average of 8.25 muscle fibers consisting of 5.58 S‐type fibers and 2.67 F‐type fibers. In a rectus anterior muscle, the total number of the S‐type fiber was 852, the average cross‐sectional area being 144 μm2. The total number of the F‐type fiber was 397, the average cross‐sectional area being 300 μm2. The S‐type fiber was characterized by the arrangement of myofibrils as a single layer in the cortical sarcoplasm as well as by the development of peripheral couplings. The F‐type fiber was characterized by the presence of central myofibrils in the juxtanuclear sarcoplasm in addition to peripheral myofibrils and by the development of the T‐system and triads at the level of the Z line. M lines appeared distinct in the F‐type fibers and less distinct in the S‐type fibers. Muscle fibers within individual subunits were separated from each other by a space about 20 nm, but no membrane specializations such as gap junction or desmosome have been determined to exist between adjacent muscle fibers.
Restricted mobility and endocytosis of anionic sites on newborn rat jejunal brush border membranes
Authors: Jersild Ralph A.
Published: February 2005

The distribution and mobility of anionic sites on the microvillous surface of newborn rat jejunal absorptive cells were studied using polycationic ferritin (PCF) as a visual probe and were compared with anionic sites previously described for adult jejunum. Segments from 5‐ to 26‐day‐old rats were incubated in PCF for 5 minutes either before or after fixation for electron microscopy. From days 5 to 20, anionic sites were distributed diffusely along the lengths of the microvilli and did not show random translational mobility. In contrast, microvilli examined from animals at weaning (21 to 26 days) resembled those from adults in which most binding sites were capable of lateral mobility and were induced by PCF to cluster into discrete patches. The diffuse pattern was altered by cortisone administration, paralleling a premature reduction in the endocytic apparatus of the cell.

The difference in mobility of anionic sites with age coincides with differences in absorptive function. Evidence is presented showing that in the neonate binding of PCF to the microvilli was followed with time by endocytosis into an apical system of tubules for intracellular transport, incorporation into coated vesicles, and release through the lateral cell surface. The results suggest that endocytosis is accomplished by a mechanism that includes a directionally controlled movement for the selective internalization of PCF binding sites from the membranes of the microvilli to those of the tubular cytoplasmic channels.
Endoderm/mesoderm multiplication rates in stage 5–12 chick embryos
Authors: Rosenquist Glenn C.
Published: February 2005

Multiplication rates for the endoderm/mesoderm layer of the head‐process to 17‐somite‐stage chick embryo were studied by implanting essentially identical transplants labeled with tritiated thymidine into paired recipient embryos. One recipient was fixed as soon as the transplant had healed (after 30 min) and the other was reincubated an additional 3.5 to 22.5 hr; the ratios of labeled cells in the paired embryos provided points on a graph that indicated that doubling of endoderm/mesoderm cells in head‐process‐stage chick embryos occurs at approximately 4.0 and 17.2 hr of reincubation.
Preliminary observations on the role of the mesonephros in the development of the adrenal cortex
Authors: Upadhyay Shakti , Zamboni Luciano
Published: February 2005

The interrelationship between mesonephros, adrenal cortex, and gonads was studied in 28‐ and 31‐day old sheep fetuses by means of light microscopy on plastic sections. At these stages, the adrenal cortex is just beginning to develop and the mesonephros is undergoing involution; its regression is accompanied by mobilization of cells from the glomerulus of a peculiar nephron situated in the proximal third of the organ, and referred to as “giant” because of its large size. The mobilized cells egress from this glomerulus organized in trabeculae, some of which reach the cranial extremity of the adrenal cortex while others coalesce into a prominent cellular formation which extends uninterrupted toward and into the developing gonads. In previous studies we have shown that the mesonephric cells which colonize the gonads differentiate into sustentacular and interstitial steroidogenic cells; the presence of an analogous cellular migration from the mesonephros to the adrenal cortex now suggests that also the adrenal cortical cells may be of mesonephric origin.
Third ventricle suprachoroidal cells
Authors: Kemali Milena
Published: February 2005

Using transmission electron microscopy two types of cells on the choroid plexus of the third ventricle of the frog Rana esculenta have been located. They lie on the microvilli and cilia of the choroid epithelium. Their free surface is in contact with the cerebrospinal fluid. One type, Kolmer‐like, has large, dense bodies in its cytoplasm. The cytoplasm of the other type is completely filled by large, ovoidal structures which have a limiting membrane and a polymorphic filamentous content. Their functional significance is unknown.
Vascular turnover of a continuously growing organ: The rat incisor
Authors: Pitaru S. , Michaeli Y. , Zajicek G.
Published: February 2005

The vascular tissue supplying the pulp of the continuously growing and developing rat incisor was quantitatively analyzed in six female rats, weighing approximately 200 gm each. One hour after a single administration of 3H‐TdR, 1 μCi/gm body weight, the rats were sacrificed and the lower left jaws excised and processed histologically. Every 20th section was evaluated for venular and arterial count, endothelial cell count, and percentage of labeled endothelial cells. It was found that the proliferative capacity of the vascular tissue of the rat incisor is confined to its most apical 3.0 mm‐a zone defined as the vascular progenitor compartment. Daily production of endothelial vein cells and of veins within the progenitor compartment were calculated to be 7,392 cells/day and two veins/day, respectively. Generation time of these cells was found to be 3.56 days.

Endothelial cell production within the progenitor compartment provides for the formation of new vessels and for the enlargement and elongation of existing ones. The vessels originating within the progenitor compartment move in an incisal and centripetal direction, while simultaneously undergoing a continuous process of aging, until their ultimate disintegration.
Fine structural criteria of prolactin cells identified immunohistochemically in the male rat
Authors: Nogami Haruo , Yoshimura Fujio
Published: February 2005

Immunoreactive prolactin (PRL) cells in the adult male rat pituitary were observed by light microscopy to be scattered throughout the gland without special localization but sometimes to form small clusters consisting of five to ten cells. The cells had oval, polygonal, and cuplike shapes. Using the “superimposition technique,” the fine structural properties of the PRL cells were examined on ultrathin sections just adjacent to the thick plastic section for immunostaining. Four cell types were distinguished: (1) oval, polygonal, and elongate cells with only small spherical granules, 130–200 nm in diameter; (2) oval or polygonal cells with both medium‐sized spherical granules (250–300 nm) and about same size of polymorphic granules; (3) polygonal cells containing only large polymorphic granules (300–700 nm in maximal diameter); (4) cup‐shaped PRL cells with spherical and small polymorphic granules. Furthermore, the prolactin immunoreactivity of these cell types was confirmed by the electron immunohistochemistry. Type 1 cells resemble, in fine structure, Kurosumi‐Oota LH‐gonadotrophs, but the former are not stained with anti‐rat LHβ serum, but with anti‐rat PRL serum. Although the functional relationship between these four types of cells is still unclear, it is concluded that the polymorphic shape of the granules is not necessarily an absolute criterion for identification of the PRL cell in the male.
Effects of fluorodeoxyuridine on the developing inner ear of the rat
Authors: Khan Khalid M. , Marovitz William F.
Published: February 2005

The inner ear in rats develops from the surface ectoderm on day 8 of a 22‐day gestational period. Labeled thymidine incorporation studies have indicated that in the developing inner ear most of the cells undergo terminal mitosis between gestational days 13 and 15. During this period the developing inner ear would be particularly vulnerable to environmental hazards. To test this hypothesis, pregnant rats were given a single intraperitoneal injection of 5‐fluoro‐2′‐deoxyuridine (FUdR), an antimitotic substance, on gestational days 12 to 16. The rats also received one injection of 3H‐thymidine 1 h prior to the removal of the fetuses. The animals were killed after various time intervals following the treatment, and the otocysts or inner ears were prepared for morphologic observations and biochemical assays. The cells in the inner ear of rats exposed to FUdR exhibited pyknotic nuclei and chromatolytic degeneration, and they eventually died. By 4 h after the administration of FUdR, pyknotic nuclei were seen in the antiluminal zone of the otic epithelium, and there was a substantial decrease in the number of the otic cells. This decline in cell number was seen until 24 h after treatment. However, the inner ears from the fetuses exposed to FUdR during gestational days 12–15 showed complete recovery from the toxic effects of the drug when examined on day 21 of gestation. The phenomenon of programmed cell death observed in the developing inner ear of the rat indicates that more cells are produced during the earlier stages of development than are required for the definitive adult structures. This phenomenon may represent an important protective feature. The redundant production of cells perhaps allows the developing otocyst to respond to an environmental stress by subtotal destruction of cells from the pool of undifferentiated cells, resulting in relatively fewer congenital anomalies of the inner ear.
The cellular organization of fibroblastic cells and macrophages at regions of uncalcified cartilage resorption in the embryonic chick femur as revealed by alkaline acid phosphatase histochemistry
Authors: Sorrell J. Michael , Weiss Leon
Published: February 2005

Resorption of uncalcified cartilage in the embryonic chick femur appears to be mediated by two types of mononuclear cells. One cell type lies flattened and adherent along the surface of the cartilage matrix into which it extends cellular processes. Cytological characteristics of a large, euchromatic nucleus containing a nucleolus, and cytoplasm containing moderate to extensive amounts of rough endoplasmic reticulum indicate that these are protein synthetic cells. Macrophages, characterized by a pleomorphic shape and cytoplasm containing numerous mitochondria and vesicles, comprise the second cell type. These may be seen lying in contact with cartilage matrix, but are more likely located in the nonhematopoietic marrow adjacent to resorbing cartilage, where they establish close cellular associations with protein synthetic cells.

Alkaline and acid phosphatase histochemical studies differentiate these two cellular types. Marrow alkaline phosphatase activity is restricted to the cartilagemarrow interface from which it diffuses a short distance into cartilage matrix, but does not diffuse into nearby marrow. Intracellular alkaline phosphatase is present only in protein synthetic cells that line the surface of cartilage, and thus appears to be produced by these cells. Acid phosphatase positive macrophages are scattered throughout the marrow, but are found in greatest concentrations in the region of cartilage resorption. They are rarely in direct contact with cartilage, and there is no evidence that acid phosphatase is released from these cells. The relative localizations and the presence of cellular interactions of these two cell types suggests that protein synthetic cells may be of fibroblastic origin, and may play a primary role in cartilage degradation, while macrophages, in keeping with biochemical evidence, play an adjunct or possibly a regulative role.
Direct correlation of histochemical profile to the ultrastructure of single myofibers and their neuromuscular junctions from a mixed muscle
Authors: Galvas Patrick E. , Neaves William B. , Gonyea William J.
Published: February 2005

It has been demonstrated that there are significant differences in the ultrastructural morphology of the three mammalian myofiber types and their neuromuscular junctions (NMJ). The description of these ultrastructural differences was based primarily on samples taken from muscles that were composed of predominantly one fiber type. The objectives of this study were 1) to determine if previously described ultrastructural characteristics could distinguish between the three fiber types and the NMJ in a mixed muscle containing similar percentages of each fiber type and 2) to determine if there were significant differences in the morphology of like fiber types when compared between two histochemical regions in a muscle with a compartmentalized fiber‐type distribution. The muscle used in this study was the flexor carpi radialis (FCR) of the cat. The objectives were achieved by a direct correlation of ultrastructure to histochemical profile on the same isolated myofibers. This study revealed a wide range of morpohological variation among fiber types in the FCR. Although many fibers from the FCR could be classified by using accepted ultrastructural criteria, most could not. Compartmental differences were present in several of the ultrastructural parameters measured. The slow‐twitch oxidative (SO) and fast‐twitch oxidative‐glycolytic (FOG) fibers in the oxidative compartment had a significantly larger myofiber core volume when compared to the fast‐twitch glycolytic (FG) fibers from both compartments. Also, the FG fibers in the glycolytic region had a significantly larger membrane volume (terminal cisternae, T tubules, and sarcoplasmic reticulum) when compared to the FOG fibers in the oxidative compartment and the SO fibers in both regions.

This study has demonstrated that considerable variation exists in the most commonly accepted ultrastructural features used for distinguishing the three myofiber types when sampled from a mixed muscle that is not dominated by one fiber type. These results suggest the possibility of a greater functional range in the same type of histochemically identified motor units from mixed muscle than in those from muscles containing predominantly one fiber type.