bluuebunny/crossref_metadata_2025 huggingface dataset:
Epithelio‐mesenchymal interactions in primordial gland structures which become responsive to androgenic stimulation
Authors: Cunha Gerald R.
Published: February 2005

The morphogenetic tissue interactions between epithelium and mesenchyme of male accessory sexual gland primordia were investigated by standard culture methods. Seminal vesicle (SV), urogenital sinus (UGS), and preputial gland (PP) rudiments were excised from 13‐ to 19‐day old embryonic mice. After tryptic‐separation, the epithelium and mesenchyme of these rudiments were recombined into control (homotypic) and experimental (heterotypic) recombinants which were subsequently grown in the anterior chamber of the eye of adult male hosts.

In recombinants composed of accessory sexual gland epithelium (SV, UGS, or PP) and urogenital gland mesenchyme (SV or UGS), the histotypic pattern of the recombinants reflected the source of the epithelium. Normal differentiation of SV, UGS, and PP epithelium occurred consistently when these epithelia were associated with SV or UGS mesenchyme. On the other hand, urogenital gland epithelium (SV or UGS) did not develop normally when associated with the integumentally‐derived preputial gland mesenchyme. Instead, seminal vesicle epithelium was maintained as a columnar epithelium arranged in a simple tubular structure, while urogenital sinus epithelium formed a keratinized epithelium despite the presence of androgens. These data illustrate (1) the supportive properties common to urogenital mesenchyme, (2) the stability of accessory sexual gland epithelium, and (3) the lack of strict mesenchymal requirements of these epithelia. Furthermore, the data suggest that urogenital and integumental mesenchyme differ significantly in their ability to mediate hormonally‐dependent developmental processes.
Autoradiographic and chemical localization of 5‐hydroxytryptamine in identified neurons in the leech
Authors: Coggeshall Richard E.
Published: February 2005

The large leech neurons known as Retzius cells contain substantial amounts of 5‐hydroxytryptamine (5‐HT) stored in granules. Previous studies show that these cells are able to make 5‐HT from precursors. The present study, which is a combined chemical and autoradiographic analysis of these cells after the administration of radioactive 5‐HT or 5‐HTP, confirms that the cells make 5‐HT from precursors. In addition, this study shows that the cells can acquire and store 5‐HT when it is present in the environment. Thus, if 5‐HT is available, these cells need not manufacture this compound from precursors. Furthermore, the newly acquired 5 HT seems to be stored in the granules that characterize these cells. Finally, this study shows that the Retzius acquire or make the 5‐HT in vivo.
The trigeminal nerve in the baboon
Authors: Gasser Raymond F. , Miller Wise D.
Published: February 2005

The definitive course, relations, branches and communications of the extramedullary part of the trigeminal nerve in baboons are described and illustrated. The nerve was dissected in five animals and the location of all related parasympathetic ganglia was verified microscopically. Variable branching patterns were observed in some areas of the nerve field. Comparisons are made with other primates including man.
The ultrastructure of neonatal calf intestine and absorption of heterologous proteins
Authors: Staley Theodore E. , Corley Lane D. , Bush Linville J. , Wynn Jones E.
Published: February 2005

The ultrastructural morphology of the jejunal and ileal cells of newborn calves was similar to the intestinal absorptive cells of other newborn ungulates. Microvilli were well developed, tubules or invaginations in the apical cytoplasm were extensive. Large supranuclear vacuoles were limited to the ileal cells. After injection of ferritin‐IgG or ferritin into ligated intestinal loops, the ferritin particles were found around the microvilli and within the tubular system. After 2‐6 hours ileal vacuoles containing ferritin were found near the basal membrane. In the jejunal cell ferritin was found only in the tubules. No ferritin could be detected in calf sera after injection into the intestinal loops. To establish that heterologous proteins were absorbed, calves were given human serum via stomach tube and their sera subsequently was found to contain circulating levels of human albumin and gamma globulin. Also newborn pigs and suckling rats also were given ferritin; but it could not be detected in their sera. The results of these experiments suggest that while the neonatal intestine is permeable to some het‐erologous proteins, ferritin is not transported across the absorptive cell into the circulation.
The relationship of ultrastructural and cytochemical features to absorptive activity in the goldfish intestine
Authors: Gauthier Geraldine F. , Landis Story C.
Published: February 2005

In the adult goldfish, Carassius auratus (a stomachless freshwater teleost), there is a striking proximal‐to‐distal gradient in the microscopic appearance of the intestine. This gradient is correlated, moreover, with differences in the site of absorption of lipid and protein. The proximal regions (intestinal bulb and anterior intestine) have a greater surface area, manifested by elongated mucosal ridges in which the epithelial cells have regularly arranged closely spaced microvilli. The distal region (posterior intestine) has less overall surface area, but the epithelium exhibits the typical ultrastructural features of pinocytosis, namely extensive invagination of the luminal surface membrane and massive accumulation of vesicles and vacuoles in the apical cytoplasm. In addition, a conspicuous PAS‐positive supranuclear “body” is visible with the light microscope. Administered triglyceride is absorbed exclusively by the epithelium of the anterior regions, where presumably, it must be hydrolyzed prior to uptake. Protein (horseradish peroxidase), on the other hand, is absorbed primarily in the most distal region, where the epithelium appears to be equipped for the uptake of large intact molecules. These regional differences are discussed in relation to comparable differences in the mammalian intestine, especially during development.
The action of extrinsic penile muscles during copulation in the male dog
Authors: Hart Benjamin L.
Published: February 2005

Electromyographic activity of the bulbocavernosus (BC), ischiocavernosus (IC), and ischiourethral (IU) muscles was recorded during copulation in male dogs to examine the role of these muscles in the vascular engorgement process as related to the mechanisms responsible for initiating and maintaining the genital lock. In other dogs the IU muscle was severed to ascertain the influence this would have on the genital lock. No particular function in the engorgement process could be assigned to the IC muscle. Recordings from the BC muscle are consistent with the suggestion that rhythmic contraction of this muscle plays a role in pumping blood from the proximal parts of the corpus spongiosum into more distal parts of this cavernous erectile body. This would facilitate rapid engorgement of the bulbus glandis which is the structure that locks the dogs together. Recordings from the IU muscle reveal that this muscle contracts tonically just after intromission apparently also facilitating erection of the bulb by occluding venous return. Section of this muscle prevented engorgement of the bulb and eliminated the genital lock.
The development of the folia in the human cerebellar vermis
Authors: Loeser John D. , Lemire Ronald J. , Alvord Ellsworth C.
Published: February 2005

The development of the folial patterns of the human cerebellar vermis has been studied in 44 mid sagittal sections of fetuses (14 weeks gestational age to term), infants (one to three months) and adults. The differentiation of each of the lobules of the vermis has been plotted as a function of age. The gestational age at which each lobule has attained half the adult average number of folia has been determined and varies between 24 and 37 weeks; the more anterior and posterior vermian lobules reach this half‐way point first even though the largest lobules (culmen, declive and pyramis) form more folia per unit time. Thus, different criteria may be used to evaluate growth rates and yield different conclusions concerning the validity of the concept that ontogeny recapitulates phylogeny. The adult numbers of folia are not attained until more than two months after birth. The normative data reported in this study provide a baseline for comparison with other species or with abnormal developmental patterns in autopsy specimens of any fetal or post‐natal age.
Distribution of muscle spindles in the human first dorsal interosseus
Authors: Sahinen Frederic M. , Kennedy William R.
Published: February 2005

The problem of accurately locating muscle spindles within the bulk of skeletal muscle has been the major difficulty in histological evaluation of human muscle spindles and in attempts to record their physiological activity. Entire first Dorsal Interossei were taken from full‐term infants, stained in toto by deCastro's silver technique, serially sectioned or squashed, and individual spindles microdissected for study. A model of the muscle with its extrafusal innervation was constructed and the average number of spindles in five muscles was found to be 47 (range 4C–54). The first Dorsal Interosseus muscle is a bi‐pinnate structure divided by a central tendon which inserts on the proximal first phalanx. The spindles within this muscle are nearly equally distributed between the halves. Most of the spindles are concentrated in two well‐defined regions, a lateral, more distal spindle‐rich region and a medial, more proximal, grouping. Each of these two concentrations consists of approximately one‐third of the spindles present, the remaining one‐third being rather uniformly distributed throughout the muscle mass. An idea of the degree of concentration usually seen is illustrated by finding as many as eight spindles present in a 100X field in cross‐section. This density of concentration and apparent consistency of location within the muscle is expected to facilitate procurement of more adequate numbers of spindles at muscle biopsy and to aid the intramuscular recording from human muscle spindles.
The effects of high altitude on the reproductive cycle and pregnancy in the hamster
Authors: Printz Richard H.
Published: February 2005

Mature female golden hamsters, which had demonstrated regular reproductive cycles, when exposed to 23,000 feet simulated altitude for eight or more days became acyclic. Their ovaries, which were polyfollicular, suggested that LH release or synthesis by the hypophysis had been blocked. Human chori‐onic gonadotrophin (which has LH activity) caused similarly exposed animals to ovulate. When animals which were exposed to high altitude for nine days were returned to control altitude, they ovulated five days later. Starvation for nine days, which has no significant effect on adrenal weight but does cause increased LH dependent ovarian interstitial development at control altitude, failed to do so at 23,000 feet. It is hypothesized that high altitude selectively blocks LH secretions by the hypophysis.

High altitude also interrupted pregnancy when treatment lasted four or more days and was begun before day 12. Since follicular development of pregnancy continued normally but corpora lutea regressed and both FSH and prolactin are needed to maintain the hamster corpus luteum, this study suggests the possibility that prolactin secretion is blocked in the pregnant animal at high altitude.
Possible division of cardiac mitochondria
Authors: Tandler Bernard , Hoppel Charles L.
Published: February 2005

Numerous examples of partitioned mitochondria were present in cardiac muscle cells of mice, rats, guinea pigs, and canaries. The partitions, which usually bisected the mitochondria, consisted of two parallel membranes in direct continuity with the inner mitochondrial membrane. Some of these mitochondria showed varying degrees of constriction at the level of the partitions. In many partitioned organelles, the two sets of cristae on opposite sides of the septum were positioned at right angles to one another, so that if one set was seen in profile, the other appeared en face. This arrangement of cristae simplified the detection of partitioned mitochondria even at low magnifications.

The number of mitochondria and the frequency of occurrence of partitioned mitochondria were considerably enhanced in heart muscle cells of some weanling mice by feeding them the copper‐chelating agent, cuprizone. The mitochondria, both with and without partitions, were identical to those in untreated animals. Based on this and other experimental evidence, and by analogy with other organs, notably mammalian liver and insect fat body, it was concluded that partitioned cardiac mitochondria are in fact dividing.
An in vitro and in vivo study of single palatal processes
Authors: Smilay Gary R. , Koah William E.
Published: February 2005

Single palatal processes were grown in organ culture to test whether epithelial contact was a prerequisite for the cytological alterations observed during midline epithelial disruption. Observations were made with the light and electron microscopes. Palatal processes from 14 day C57BL mice were cultured on Millipore filters and fixed in paraformaldehyde and osmium tetroxide. Fine structure studies of 24 hour cultures revealed a thick basal lamina beneath an intact epithelium. Epithelial cells were absent along the medial edge of the palatal process in 48 hour cultures. Mesenchymal cells, not covered by a basal lamina, ultimately occupied the original position of the epithelial cells. Single palatal processes taken from spontaneous cleft A/Jax fetuses showed epithelial cell death along the medial edge similar to that in vitro, although an epithelial‐free surface was not observed. We interpreted these observations to indicate that epithelial cell disruption was an inherent process of medial palatal epithelium. This disruption was exaggerated during organ culture by the mesenchymal cells spreading on the filter membrane.
Electron microscopic observations on eosinophil leukocyte granules in dog blood
Authors: Hung Kuen‐Shan
Published: February 2005

The eosinophil granules of the dog have a dense matrix with or without a light peripheral rim. Lamellated crystalloids are demonstrated in their dense matrix. The lamellation consists of alternating dark and light bands resembling crystalloids of other species. The center to center distance between the consecutive dark bands measures approximately 107 Å. The crystalloids appear to take rather variable forms ranging from large, triangular to small, elongated or irregular shape.
Mast cells in the central nervous system of several rodents
Authors: Dropp John J.
Published: February 2005

Mast cells were detected in the brains of kangaroo rats, gerbils and albino rats. They were most numerous in diencephalic structures (leptomeninges, choroid plexuses, nuclei, tracts); moderately abundant in telencephalic and mesencephalic structures (leptomeninges, choroid plexuses, nuclei, tracts); and least plentiful in metencephalic and myelencephalic structures. They were not detected in the spinal cord. In all cases the mast cells were closely associated with the blood vessels in these regions.
In Vivo incorporation of choline‐3H, leucine‐3H and galactose‐3H in alveolar type II pneumocytes in relation to surfactant synthesis. A quantitative radioautographic study in mouse by electron microscopy
Authors: Chevalier Gaston , Collet Andre J.
Published: February 2005

A quantitative time study of the incorporation of choline‐3H, leucine‐3H and galactose‐3H in lung epithelial cells, was undertaken in vivo with electron microscopic autoradiography. Type II pneumocytes were selectively labeled with choline‐3H, a specific precursor of phosphatidylcholine, which is the main component of pulmonary surfactant. Choline was initially localized in endoplasmic reticulum, then was rapidly transferred through the Golgi complex and stored in lamellar bodies. Previously undescribed small lamellar bodies are suggested as phospholipid carriers between Golgi complex and lamellar bodies. After initial incorporation in the endoplasmic reticulum, the leucine label migrated through the Golgi complex into lamellar bodies by fusion of multivesicular bodies, which are the carriers between the two structures. Galactose was modestly incorporated into lamellar bodies via the Golgi complex. Intra‐alveolar myelin figures, recognized as excreted surfactant, were labeled 120 minutes after injection with the three precursors.

These findings indicate that the synthesis of a secretory product by type II pneumocytes involves phospholipid, protein and polysaccharide precursors; the secretory product is segregated as lamellar bodies which are destined to be excreted into the alveolar cavity to become part of the lining layer.
The fine structure of subarachnoid macrophages in the rat
Authors: Morse Dennis E. , Low Frank N.
Published: February 2005

Macrophages associated with the subarachnoid space have fine structural characteristics which distinguish them from macrophages found elsewhere. The specific location of a macrophage in this area influences its morphology. Macrophages found in the subarachnoid space characteristically have a highly vacuolated cytoplasm. When cells of the pia mater separate the macro‐phage from the subarachnoid space, the extreme vacuolization is not present and a more compact cytoplasm prevails. Frequently macrophages found in the median longitudinal fissure contain compound reticulated inclusions. Extracellular bodies resembling compound reticulated inclusions have been observed.

The presence of lobulated nuclei, lysosome‐like inclusions, phagosomes, and other characteristics of these cells is reported. The possible origin and function of subarachnoid space macrophages is discussed.
Quantitative studies on motoneurons: Hypoglossal neurons in the boa constrictor, Constrictor constrictor
Authors: Ulinski Philip S.
Published: February 2005

This study gives a quantitative description of hypoglossal neurons in the common boa, Constrictor constrictor. In this animal the hypoglossal nuclei are spatially distinct from the ventral horns and do not contain subnuclei. They contain a mean ± S.D. of 942 ± 162 neurons, many of which have double nucleoli. The neurons are shaped like prolate ellipsoids which are oriented with their long axes perpendicular to the ventricle. An average hypoglossal neuron has a major axis of 21.8 μ and a minor axis of 19.6 μ. Although neurons show a considerable range of sizes, neurons of different sizes are not segregated into different regions of the nucleus. Developmental differences in the size, distribution in the medulla, and the percentage of doubly nucleolated neurons occur, but the shape and orientation of hypoglossal neurons do not vary with age.
The ultrastructure of intradental nerves in developing mouse molars
Authors: Corpron Richard E. , Avery James K.
Published: February 2005

The purpose of this investigation was to study the nerves in mouse molar teeth during their development to observe their distribution and their relationship to the odontoblast and its process. The specimens were first assessed by light microscopy using silver staining techniques. It was found that by nine days after birth, major nerves appeared in the pulp organ and extended to the basal region of the odontoblasts. At 15 days, a subodontoblastic neural plexus had developed, and by 25 days, isolated nerves penetrated into the predentin of the pulpal horns. From 25–70 days, a highly organized subodontoblastic plexus was apparent with branches extending into the odontoblastic layer, predentin and inner dentin.

Ultrastructural study revealed small, nonmyelinated nerves at the basal region of the odontoblasts by nine days. Both myelinated and small, nonmyelinated nerves appeared in the subodontoblastic plexus. Small nerves closely associated with the odontoblastic process were found within the predentinal tubules by 25 days. These processes contained occasional mitochondria, numerous microvesicles and small dark granules. From 35–50 days of age, similar nerves which exhibited alternate constrictions and dilations along their lengths were found in the tubules of circumpulpal dentin. By 60 days, both Schwann cell covered and naked axons appeared among the odontoblasts, and by 70 days Schwann cell covered axons appeared in predentin.
Spermatozoa in rouleaux in the female guinea pig genital tract
Authors: Martan Jan , Shepherd Benjamin A.
Published: February 2005

Single spermatozoa and spermatozoa in rouleaux were found throughout the genital tract of 21 female guinea pigs killed 15 minutes to 24 hours after copulation. Three females killed three to five minutes postcopulation had single spermatozoa and spermatozoa in rouleaux in the vagini, cervix, and uterus but not in the oviduct. The number of rouleaux and the number of spermatozoa in individual rouleaux decreased after copulation in all parts of the female genital tract with time while a corresponding increase in single spermatozoa was evident. The rate of rouleaux dissociation was faster in uteri than in oviducts. Only single spermatozoa were found near ova in the oviducts. The uterotubal junction appeared to act as a barrier to multitudes of spermatozoa passing from the uterus to the oviducts. However, some single spermatozoa and some rouleaux passed this barrier. Unusually large rouleaux were observed up to 12 hours after copulation in the pockets of the uterotubal junction. Single spermatozoa and few rouleaux of two spermatozoa in the uteri of females killed 8 to 24 hours postcopulation were phagocytised. No phagocytosis of spermatozoa was observed at any time in the oviduct.
Gross and light microscopic features of the pelvic plexus in the rat
Authors: Purinton P. T. , Fletcher T. F. , Bradley W. E.
Published: February 2005

Nerves and major accessory ganglia of the pelvic plexus are described from 12 rats perfused with methylene blue. Nerves to ventral and dorsal aspects of the urinary bladder, and three groups of nerves to the penis (clitoris) are reported in detail.

Myelinated nerve fiber diameters ranged from 1–10 μ in the pelvic nerve and 1–6 μ in the hypogastric nerve. When the pelvic nerve was deafferentated, by spinal ganglionectomy 28 days previously, 80% of myelinated fibers degenerated, and the remaining fiber‐size spectrum resembled that of the hypogastric nerve. Myelinated fibers ranged from 1–7 μ in nerves to bladder and 1–3 μ in the lateral nerve to the penis. Myelinated fibers were afferent in these nerves, since spinal ganglionectomy eliminated all of them. In the main nerve to the penis, myelinated fibers ranged from 1–8 μ in diameter. A few fibers remained after deafferentation by spinal ganglionectomy. Since these were preganglionic efferent fibers, they indicate that terminal ganglia were present in the penis. All myelinated fibers degenerated with transection of pelvic and hypogastric nerves. The mode diameter of myelinated fibers was 2 μ in all pelvic plexus nerves.
Cellular reactions in a SRBC‐induced inflammatory exudate
Authors: Slonecker Charles E.
Published: February 2005

Acute inflammatory exudates which are induced by the intra‐peritoneal injection of sheep red blood cells contain a variety of connective tissue cell types. Granulocytes, macrophages and lymphocytes constitute the vast majority of the exudate cells. The peritoneal macrophages are principally involved in the phagocytosis and clearance of the whole SRBC from the peritoneal cavity. The exudate lymphocytes which accumulate during the first 24 hours are derived from a pool with a fast turnover rate and are newly formed. While these lymphocytes undergo an enlargement and increase their basophilic cytoplasm during this response, they fail to show increases in their DNA synthesis while in the inflammatory exudate.
A wet‐lung technique for obtaining silastic rubber casts of the respiratory airways
Authors: Kilpper Robert W. , Stidd P. J.
Published: February 2005

A technique for obtaining accurate casts of the bronchial tree and alveolar region is presented and several of the uncertainties involved in bronchial tree casting are discussed. Tompsett's basic casting technique is modified to use silicone rubber; supportive trays and a shape‐preserving gelatine injection are eliminated by suspending the lungs in a water bath. Fresh or frozen lungs may be used and prior fixation is not necessary. No elaborate apparatus, beyond usual laboratory items, is required. The slow, low pressure injection of rubber into the bronchial tree minimizes overdistension due to high translumenal pressures. The resulting cast is flexible and durable. Linear shrinkage is minimal with resulting volumetric errors of less than 2%. If desired, one may simultaneously inject the pulmonary arterial and venous systems with colored rubber, yielding a cast of greater educational utility.
Fine structural changes in the placental membrane of the marmoset with increasing gestational age
Authors: Jollie William P.
Published: February 2005

Marmoset placentas were obtained surgically from early, mid and late pregnancy and examined with the electron microscope. At each stage both inner cytotrophoblastic and outer syncytiotrophoblastic layers were identified at the surfaces of the labyrinthine trabeculae. The trabecular cores contain very little connective tissue and are made up primarily of allantoic blood vessels of the peripheral umbilical circulation. Although a subepithelial basal lamina consistently is seen underlying the trophoblast, no subendothelial basal lamina has been identified at any stage. In early stages, the cytotrophoblast cells form a contiguous layer; consequently, the syncytium does not reach the basal lamina; and the placental membrane is hemodichorial. In the latest stage, since cytotrophoblast, though present, forms an interrupted layer and syncytiotrophoblast reaches the lamina, the membrane properly can be considered hemomonochorial. Not only in the gradual reduction in numbers of cytotrophoblast cells, but also in the fine structure of each constituent cellular layer, the membrane of this primitive anthropoid is strikingly like that of higher primates.
The normal development of the blood‐testis barrier and the effects of clomiphene and estrogen treatment
Authors: Vitale Roberto , Fawcett Don W. , Dym Martin
Published: February 2005

Previous work with electron opaque intercellular markers has indicated that in adults occluding junctions between adjacent Sertoli cells are the principal morphological basis of the blood‐testis barrier (Dym and Fawcett, '70). Since the barrier of not present at birth this study was undertaken to determine when it is established during postnatal development of the rat and to correlate its appearance with other developmental events in the seminiferous epithelium. From birth to 16 days of age interstitially injected tracers, such as horseradish peroxidase, freely entered the seminiferous epithelium and permeated the 200 Å intercellular clefts between presumptive Sertoli cells and germ cells, reaching the center of the seminiferous cords and site of the future tubule lumen. Between day 16 and 19 occluding junctions between Sertoli cells appear and thenceforth interstitially injected electron opaque tracers were effectively prevented from reaching the tubule lumen. Therefore, in rats, the blood‐testis barrier is established between 16 and 19 days of age.

In an attempt to determine whether the development of the Sertoli cell junctions and the blood‐testis barrier is under hormonal control circulating gonadotropins were suppressed using daily injections of clomiphene or estrogens from birth. The appearance of blood‐testis barrier was delayed approximately seven days in the absence of gonadotropins. However, by day 26 the Sertoli cell junctions did appear and interstitially injected tracers were prevented from reaching the tubule lumen. Thus the development of the occluding junctions between Sertoli cells that constitute the permeability barrier does not appear to be directly dependent upon gonadotropins.
Melanocyte activity in the epidermis of the Boa constrictor (Constrictor constrictor) during the sloughing cycle
Authors: Szabo George , Maderson Paul F. A. , Roth Sanford I. , Kostick Ruth M.
Published: February 2005

Epidermal melanocytes are easily identifiable in the skin of the Boa Constrictor throughout the whole skin cycle. Intensity of the dopa reaction, however, varies. It is at its peak just before the skin enters its resting phase when the melanization of the beta layer of the epidermis is complete. There is no pigment transfer when those layers of the epidermis are formed which contain alpha keratin. The melanocytes accumulate melanosomes, retain them throughout the resting phase of the epidermis, and donate them again during the subsequent growing period of the epidermal keratinizing system when beta keratin is again formed. Thus, when a new beta layer is formed, most of the melanosomes which are donated to this layer have been formed during a previous cycle. The dermal melanophores do not show morphological or histochemical changes during the shedding cycle of the epidermis.
Morphogenetic and proliferative changes in the regenerating lung of the rat
Authors: Fisher Jean M. , Simnett John D.
Published: February 2005

Unilateral extirpation of the lung in rats is followed by increased mitotic activity in alveolar cells of the contralateral lung, reaching a maximum six to seven days after operation. The response is delayed if the cavity created by the operation is packed with plastic sponge. Unilateral collapse of the lung without removal of tissue also leads to a contralateral mitotic response. Changes in the rate of cell proliferation evidently are not directly dependent on changes in tissue mass and it is suggested that compensatory growth in the lung may be controlled by chemical factors whose local concentration depends on variations in the rate of blood flow.

Other changes which follow partial extirpation, observed particularly in the residual tissue of resected lungs, include high rates of proliferation in pleural cells, sub‐pleural tissue and bronchial epithelium. It appears that in the regenerating lung new tissue may be formed partly by the proliferation of cells in the main mass of residual tissue and partly by more localized changes in specific tissues.
The degeneration and disappearance of the centrioles during the development of the rat spermatozoon
Authors: Woolley David M. , Fawcett Don W.
Published: February 2005

An intensive search has failed to locate a proximal centriole in the neck of the rat spermatozoon. This centriole is present in late spermatids but disappears before spermiation. The distal centriole also degenerates during spermiogenesis, though more gradually; it is no longer demonstrable by the time the spermatozoa reach the cauda epididymidis (except as a few remnants in a small minority of the cells). The rat spermatozoon is thus exceptional among mammals in being effectively acentriolate. The implications of this are discussed. Since there are no centrioles, the activity and control of the flagellum cannot depend on a centriole as a kinetic center. Furthermore, since no centrioles are introduced by the rat spermatozoon at fertilization, there can be no paternal inheritance of a formed centriole through the cytoplasm. And, in this species at least, paternal centrioles have no role in the first cleavage of the fertilized egg.
The ultrastructural morphology and possible functional significance of mesothelial microvilli
Authors: Andrews Peter M. , Porter Keith R.
Published: February 2005

The serosal surfaces of major organs and tissues of the body cavities have been examined by scanning electron microscopy following fixation and critical point drying. The micrographs show that these surfaces are covered with microvilli and that the population is most dense on tissues that move about most actively in the body cavities. Radiating from the sides of the microvilli are many fine strands (150 Å, average diameter) which interconnect with each other and adjacent microvilli. Transmission electron microscopic studies of material treated with thorium dioxide at low pH or stained with ruthenium red, reveal these strands to be (1) polyanionic in nature and (2) to arise from a surface glycocalyx which coats the microvilli and intervillar surfaces. It is proposed that the serosal microvilli, together with their glycocalyx, harbor a layer of serious exudate and thereby create a slippery cushion designed to protect the thin mesothelium from frictional damage.
Myoid cells in the capsule of the adrenal gland and in monolayers derived from cultured adrenal capsules
Authors: Bressler Robert S.
Published: February 2005

Previous studies have demonstrated the presence of myoid cells in monolayers derived from cultured testicular fragments. In order to determine if monolayers of myoid cells can also be produced by other types of tissue cultures, monolayers derived from fragments of mouse adrenal capsules, cultured in McCoys modified 5A medium, were examined for the presence of myoid cells. The cells of the resultant monolayers contained numerous free ribosomes and abundant profiles of granular endoplasmic reticulum, as well as 40–60 Å thick filaments and associated dense bodies. In these respects they are identical to myoid cells found in monolayers in testis cultures. Contrary to earlier reports indicating that the adrenal capsule is composed of fibroblasts, this study demonstrates that myoid cells are a major component of the capsule of the rat and mouse adrenal gland.
Histochemistry of granular (poison) secretion in the skin of the frog, Rana pipiens
Authors: Dapson Richard W. , Feldman Ada T. , Wright Oscar L.
Published: February 2005

There are two types of granular glands in the skin of leopard frogs (Rana pipiens). Cellular glands produce fine intracellular granules rich in carbohydrate, carboxylic acids, tyrosine and sulfur‐containing amino acids. Luminal glands consist of peripherally located nuclei with scant cytoplasm. Fine granular material in these glands resembles cellular gland secretion, except that the carbohydrate is less susceptible to periodate oxidation and that a diphenol (DOPA?) is present instead of tyrosine. The prominent lumen contains large granules composed of phospholipoprotein, and are also rich in primary catecholamine and a sulfur‐containing amino acid. There was no evidence of 5‐hydroxy‐tryptamine or steroids.
I segment lengths and thin filament periods in skeletal muscle fibers of the rhesus monkey and the human
Authors: Walker Sheppard M. , Schrodt G. Randolph
Published: February 2005

The I segment length has been measured and the number of thin filament periods per I segment has been counted in electron micrographs of Rhesus monkey and human leg muscle fibers. The number of I segment periods in the monkey fiber (60) and in the human fiber (66) multiplied by axial periodicity (385 Å) in thin filaments of living fibers (Huxley and BROWN, '67) plus 1,000 Å allowed for Z line width in living fibers, provided a formula for calculation of I segment lengths in living fibers. The calculated I segment lengths are 2.41 μ for the monkey and 2.64 μ for the human fiber. The ratio of calculated I segment length over an assumed constant thick filament length (1.6 μ) among vertebrates is in close agreement with the ratio of measured I segment length over measured thick filament length in micrographs of frog, rat, monkey and human leg muscle fibers. The calculated I segment length in the frog (1.95 μ) is compared with that of the human (2.64 μ) to show the relation of I segment length to the length‐developed tension diagram and to the series elastic components of the skeletal muscle fiber.
Scanning electron microscopy of the fimbriae and ampullae of rabbit oviducts
Authors: Rumery Ruth E. , Eddy Edward M.
Published: February 2005

An initial study of the effects of long‐term ovariectomy on fimbrial and ampullar epithelia from rabbit oviducts has been made with the scanning electron microscope. Several of the rabbits were given estradiol benzoate before they were killed. These observations were compared with those of epithelial cells from similar oviductal segments from post‐ovulatory rabbits that served as controls.

Fimbriae from oviducts of control animals were densely ciliated, partially concealing the bulbous processes of the secretory cells. In the ampullae the processes of the secretory cells were the predominant structure, their bulbous apices rising frequently above the tips of the cilia.

When rabbits had been spayed for 16–18 months, the epithelial cells of both fimbriae and ampullae showed a remarkable change. A few cilia in small clumps were scattered among the secretory cells. The free surface of the secretory cells had become flattened and hexagonal in shape. Their microvilli were short, and from the center of each cell a thick, stubby central cilium protruded.

Estrogen given the long‐term spayed rabbits caused almost complete reciliation as well as restoration of the bulbous processes of the secretory cells.
Revision of the incidence of congenital absence of dorsalis pedis artery by an ultrasonic technique
Authors: Chavatzas Demetrios
Published: February 2005

Ultrasound studies of dorsalis pedis artery in 400 feet showed the artery to be absent in 2.25%, i.e., much less frequently than it was commonly claimed. Clearer understanding of this variation and its frequency may facilitate the diagnosis of peripheral circulatory disease.
A cephalometric investigation of the sagittal growth of the second‐trimester fetal face
Authors: Johnston Lysle E.
Published: February 2005

It has often been reported that facial proportions remain constant throughout the fetal period. Such conclusions, however, have been based largely on the erroneous assumption that two dimensions are growing isometrically if one bears a statistically significant linear relation to the the other. In order to test the hypothesis that proportion is independent of time, sagittal histologic sections from 32 human fetuses (12–25 weeks) were analyzed cephalometrically. The linear regression on head length (HL) and the associated coefficient of correlation were calculated for each of a variety of craniofacial measures. In addition, all linear dimensions were transformed so that the size of the anterior cranial base was held constant throughout the series. It was assumed that if shape be constant, all Y‐intercepts should be zero, and angular and transformed linear dimensions should show no statistically significant linear correlation with HL. These three criteria were met uniformly by facial and anterior cranial base dimensions, but not by measurements which involved the posterior cranial base. It is concluded, therefore, that in the sagittal plane the second trimester mandible, midface, and anterior cranial base grow isometrically, while the posterior cranial base becomes relatively smaller.
Fine structural observations on the form and distribution of nuage in germ cells of the rat
Authors: Eddy E. M.
Published: February 2005

Germ cells of the rat have been studied at the fine structural level from the time they are present in the epithelium of the embryonic gut until near the time of production of mature gametes in the adult. Particular attention has been paid to the form and location of dense, fibrous material (nuage) in the germ cells during that period of the life cycle. The nuage either exists as small discrete bodies in the cytoplasm or as “cementing material” situated in the interstices of mitochondrial clusters. It is present in primordial germ cells in the gut epithelium, in germ cells in indifferent gonads and in germ cells in sexually differentiated fetal, neonatal and adult rat gonads. It is sometimes associated with nuclear pores. Because it is present throughout much of the life cycle of the germ cells of male and female rats and it has been observed in various other mammals by previous workers, it is suggested here that it is a characteristic morphological feature of mammalian germ cells. In addition, there is considerable similarity in form and distribution of the nuage to the “polar granules” in insects and the “germinal plasm” in amphibians which are suggested to play a role in the determination of germ cells in these animals. The possibility that nuage may play a comparable role in mammals is considered.
Collagen and dermal patterns in the hypertrophic scar
Authors: Kischer C. Ward
Published: February 2005

Hypertrophic scar, mature scar, normal skin and granulation tissue were studied by transmission (TEM) and scanning (SEM) electron microscopy for characteristics and differences in fine structure, especially the collagen filaments and their physical association with each other and with interstitial components of the ground matrix.

The shape of the collagen filaments is irregular and angular in granulation tissue, irregular to ovoid in hypertrophic scar, ovoid to round in mature scar, and round in normal skin. The mean diameter of the collagen filaments measures approximately 440 Å in granulation tissue, 600 Å in hypertrophic scar, 1000 Å in mature scar, and 1050 Å in normal skin.

Interstitial filaments are prominent in hypertrophic scar by TEM. In nodular areas where collagen is examined in cross section the interstitial filaments often appear to interconnect long chains of collagen filaments. The interstitial filaments are not observed by SEM. Rather, by this method of observation, the demis of hypertrophic scar is seen as a homogeneous matrix, and individual collagen filaments are not observed.

It is suggested that the hypertrophic scar is characterized by an unusually firm intercollagen binding by interstitial filaments, which are probably protein‐polysaccharides of the ground matrix. This relationship could account for the clinical quality of extreme hardness of the scar, and might also suggest an aberration important in the etiology of the scar.
The sheep heart: Coronary and conduction system anatomy with special reference to the presence of an os cordis
Authors: Frink R. J. , Merrick Bruce
Published: February 2005

Each of the major coronary arteries of 25 fresh sheep hearts was injected with a different colored barium gelatin mass. Histologic sections were made of the AV node and His bundle in nine hearts. The blood supply to this region was traced radiographically, photographically and histologically. X‐rays of the upper ventricular septum were taken before and after coronary injection to demonstrate an os cordis.

The sinus node is always supplied by a branch of the right coronary artery. The crux of the heart, and subsequently the AV node, is always supplied by the circumflex artery. The unbranched His bundle, unusually long in sheep, receives a dual blood supply from both the anterior septal branches and the AV node artery. The proximal part of the left and right bundle branches is supplied by the anterior septal branches in the majority of hearts. Intercoronary anastomoses are present in the majority of hearts, particularly in the upper ventricular septum.

An os cordis, deep in the atrial septum and directly adjacent to the AV node, was found in all 25 hearts. Occasionally, a second bone was found in the anterior part of the left atrioventricular ring.
Myoneural junctions in the extraocular muscles of the mouse
Authors: Salpeter Miriam M. , McHenry Frances A. , Feng Hsuan‐Hua
Published: February 2005

The very fast extraocular muscles have both singly and multiply innervated fibers. The former are among the fastest vertebrate muscle fibers on record, whereas the latter are very slow. In this study single and multiple myoneural junctions were first identified in whole eye muscles of the mouse after staining for cholinesterase. Each group was then embedded separately for electron microscopy. Approximately 10% of the fibers were found to be multiply innervated. The multiple endings and the fibers they innervate resemble those of the tonic bundles of the frog. The majority single endplate is very large in surface view, has sparse junctional folds, and innervates a fiber very rich in mitochondria. These observations were contrary to some frequently held views regarding neuromuscular junctions of very fast fibers. A minority single endplate is smaller, has more junctional folds and innervates a large fiber with fewer and smaller mitochondria.
On the synaptogenic sequence in the chick retina
Authors: Hughes W. Frank , LaVelle Arthur
Published: February 2005

Study of the developing chick retina with the electron microscope revealed that dyad ribbon synapses begin to form in the inner plexiform layer before synaptic ribbons begin to appear in photoreceptor terminals of the outer plexiform layer. This centrifugal (inner to outer) sequence of synaptogenesis in the predominantly cone retina of the chick differs from the centripetal sequence that has been reported for the predominantly rod retinas of the mouse and rat. This difference does not favor the hypothesis, suggested by others, that the photo‐receptor may influence the maturation of inner retinal elements. The different patterns of synaptogenesis are discussed briefly with reference to anatomical differences between the retinas of different species.
Anatomy of the ferret heart: An animal model for cardiac research
Authors: Truex Raymond C. , Belej Rhoda , Ginsberg Linda M. , Hartman Rickey L.
Published: February 2005

The hearts of 38 black‐footed ferrets (Mustela nigripes) were studied with the use of physiologic, microdissection, vascular injection and histologic methods. These animals had a mean heart rate of 265 per minute, a heart weight of 3.7–5.2 gm, and a mean aortic pressure of 139.5 mm Hg. The predominant left coronary artery supplied usually both the SA and AV nodes, as well as the AV bundle, bundle branches and most of the ventricular myocardium. The cells of a well differentiated cardiac conduction system increase in cytoplasmic diameter from the SA node to the distal bundle branches. A cartilaginous right fibrous trigone and thick anulus fibrosus form useful landmarks for delineating AV node and AV bundle relationships. Small size, discrete nodal masses and a unique coronary arterial pattern make this heart an ideal model for histochemical, ultrastructural, electrophysiologic and pathologic circulation research.
The functions of semispinalis capitis and splenius capitis muscles: An electromyographic study
Authors: Takebe Kyoichi , Vitti Mathias , Basmajian John V.
Published: February 2005

The functions of the normal semispinalis capitis and splenius capitis muscles of fifteen subjects were evaluated electromyographically with bipolar fine‐wire electrodes. The voltage‐output data were integrated and analyzed by computer and showed that the main function of semispinalis capitis is limited to extension of the head. However, splenius capitis both extends the head and rotates it to its own side.
Perineal musculature in the cat
Authors: Martin William D. , Fletcher Thomas F. , Bradley William E.
Published: February 2005

Muscles of the perineal region were dissected in 20 cats. Levator ani muscle was composed of two parts: iliocaudalis and puboischiocaudalis; both parts inserted entirely on caudal vertebrae, as did the coccygeus muscle. A well developed band of smooth muscle, the pars analis of retractor penis (clitoridis), inserted on the anal canal to retract the anus. The external anal sphincter had pars caudalis and pars cranialis divisions, the latter covered paired anal sacs. In addition, a distinct sphincter encircled each anal sac duct. In the male, levator scroti muscle originated from external anal sphincter. There was no continuity between external anal sphincter and bulbospongiosus muscles. Cremaster muscles were absent in the cat. In the female, pars cranialis of external anal sphincter gave origin to the constrictor vestibuli muscle, and pars caudalis to constrictor vulvae muscle. Bulboglandularis muscles were present in both sexes. Urethralis, ischiourethralis, and ischiocavernosus muscles in the cat were similar to other quadripeds.