bluuebunny/crossref_metadata_2025 huggingface dataset:
Morphologic heterogeneity of mouse Paneth cell granules before and after secretory stimulation
Authors: Staley Mary W. , Trier Jerry S.
Published: February 2005

Paneth cells from fasted, fed and pilocarpine stimulated mice were studied with the light and electron microscopes. While human and rat Paneth cells contain structurally homogeneous granules, most mouse Paneth cell granules were found to be structurally heterogeneous both by light and electron microscopy. These structurally heterogeneous granules consisted of an outer rim or halo which surrounded the central core of the granule. These halos varied strikingly in electron density ranging from much paler to much darker than the granule core. Electron density of the halos correlated well with their affinity for toluidine blue in light microscopic preparations. The granule halo could be stained with both alcian blue and with PAS indicating that it contained acid mucopolysaccharide while the central core of the granule could be stained only with PAS and not with alcian blue.

While actively secreting Paneth cells were seen in preparations from fasting mice, the secretory activity was increased after feeding and after stimulation with pilocarpine. The actively secreting mouse Paneth cells discharged their granules into the crypt lumen by merocrine secretion. The fine structure of mouse Paneth cell granules was the same in resting and in actively secreting cells.
Vestibular projections to the nuclei of the extraocular muscles Degeneration resulting from discrete partial lesions of the vestibular nuclei in the monkey
Authors: McMasters Robert E. , Weiss Arthur H. , Carpenter Malcolm B.
Published: February 2005

In 35 monkeys attempts were made to produce localized unilateral lesions in individual vestibular nuclei in order to study vestibular projections to nuclei of the extraocular muscles. Portions of the medial, superior and inferior vestibular nuclei were destroyed selectively; lesions in Deiters' nucleus involved small portions of either the superior or inferior vestibular nuclei. Fiber degeneration was studied by the Nauta‐Gygax technic.

Exclusively ascending fibers from the superior vestibular nucleus project to ipsilateral extraocular nuclei. Ascending fibers from the inferior vestibular arise only from rostral portions of the nucleus, are not numerous and pass to all extraocular nuclei. The medial vestibular nucleus projects ascending fibers via the MLF bilaterally, asymmetrically and differentially to all extraocular nuclei. Prominent projections pass to: (a) the contralateral trochlear nucleus, and (b) the contralateral intermediate cell column and the ipsilateral ventral nucleus of the oculomotor complex. Ascending fibers from Deiters' nucleus, arising only from ventral portions of the nucleus, project primarily to: (a) the contralateral abducens and trochlear nuclei, and (b) specific asymmetrical portions of the oculomotor complex.

Ascending vestibular fibers from the medial and lateral vestibular nuclei appear capable of mediating all patterned eye movements resulting from stimulation of ampullary nerves from individual semicircular canals. Vestibular projections to nuclei of the extraocular muscles are most abundant to those nuclei innervating muscles whose primary functions concern horizontal and rotatory eye movements.
Histogenesis of choroid plexus in man
Authors: Shuangshoti Samruay , Netsky Martin G.
Published: February 2005

Four stages of development can be recognized in the histogenesis of the human telencephalic choroid plexus. Division into stages is based on alterations of outline of the plexus, characteristic appearance and biochemical content of the epithelial cells, and the components of the stroma. The stages are less distinctive in the myelencephalic and diencephalic plexus where differentiation is accomplished sooner than in the telencephalic plexus. Neuroepithelial‐lined tubules are common in the choroid plexus, and are formed by folding of choroidal epithelium into the stroma. Some tubules are large enough to be designated as incipient neuroepithelial (colloid) cysts. Cysts having only connective tissue walls are also present. The choroidal epithelial cells proliferate focally, stratify and desquamate into intervillous clefts, or flow into the stroma by disruption of the epithelial basement membrane or tubular wall. These findings are confirmed by use of serial sections. The size of the developing telencephalic plexus relative to the ventricular system is small at first, then large, occupying almost the entire telencephalon, but gradually decreases during development. Glycogen is prominent in developing choroidal epithelial cells, but disappears in the mature plexus. Both epithelial and mesenchymal mucin and muco‐polysaccharides are identified in the plexus. The paraphysis is re‐emphasized as an extraventricular choroid plexus on the basis of a common neuroepithelial origin. It is rudimentary and inconstant in man.
On anatomy of nerves by galen of pergamon
Authors: Goss Charles Mayo
Published: February 2005

In this treatise Galen gives a synopsis of the description of the nerves contained in his long anatomical work “On Anatomical Procedures.” He omits the olfactory nerves from the cranial group, considering them a part of the brain. Out of loyalty to his teacher, Marinos, he numbers seven cranial nerves but actually identifies ten, misconstruing the fourth, omitting the sixth, and describing all the others. The sympathetic is linked with the trigeminal but most parts of it are described. The spinal nerves and their plexuses are briefiy but quite accurately described. He leaves no doubt that he identified these nerves anatomically and understood much of their function.
The fine structure of the stria vascularis of the cat inner ear
Authors: Hinojosa R. , Rodriguez‐Echandia E. L.
Published: February 2005

The fine structure of the cat stria vascularis was studied with the electron microscope. It consists of three layers of epithelial cells in close association with intraepithelial capillaries. The cells of the superficial row have a convex luminal surface bordering on the cochlear duct lumen. The apical cytoplasm contains numerous coated vesicles and vesicular invaginations which are interpreted as a type of micropinocytosis. Deep infoldings of the plasmalemma divide the lower two‐thirds of these cells into thin compartments containing numerous mitochondria. It is suggested that marginal cells are well adapted by their fine structure to participate in regulation of the ion composition of endolymph. The cells of the intermediate and basal rows have pale cytoplasm and numerous processes Ascending processes of the basal cells form cup‐like structures which partially isolate each apical cell from the rest of the epithelium.

The endothelium of the strial capillaries is not remarkable and no discontinuities of the endothelial lining were observed. The endothelial basement lamina sends out numerous extensions into a system of interconnected extracellular passages that permeate the epithelium. These are interpreted as pathways for the rapid diffusion of materials from the capillaries.
On the occurrence of a fibrous lamina on the inner aspect of the nuclear envelope in certain cells of vertebrates
Authors: Fawcett Don W.
Published: February 2005

The fine structure of the fibrous lamina on the inner aspect of the nuclear envelope in cells of various invertebrates is reviewed, and attention is drawn to the common occurrence of a similar but thinner layer in nuclei of cells in vertebrates. Certain superficial similarities are pointed out in the relations of fibrous lamina to the nuclear pores and of the basement lamina to the endothelial capillary pores. It is suggested that in future considerations of the physiological exchange of materials between nucleoplasm and cytoplasm the properties of the fibrous lamina must be taken into account.
Bone fractures produced by high velocity impacts
Authors: Huelke Donald F. , Buege Lynn J. , Harger James H.
Published: February 2005

The effects of high velocity impact to the distal end of 122 human femurs were studied using one‐quarter inch steel spheres as projectiles, with impact velocities from 500 to 1700 feet per second. In the lower velocity range, a “drill hole” fracture was produced with low energy expenditure, and the diameter of this type of fracture was increased as a function of increasing velocity. At the higher impact velocities the bone exploded with a violent radial displacement of the material surrounding the missile path, similar to the cavitation effect often seen in soft tissues. At increasing impact velocities, increasing amounts of energy were expended in producing the fracture.
Morphogenesis of the palate in normal human embryos with special emphasis on the mechanisms involved
Authors: Burdi Alphonse R. , Faist Kathleen
Published: February 2005

The aim of this study was to re‐evaluate the classical description of fusion as the closure mechanism of both the hard and soft palates in normal human embryos. Does the soft palate develop by a posterior continuation of shelf apposition, epithelial lamination and disintegration, and by mesenchymal cell fusion as described for the hard palate? Or does the soft palate develop by proliferation and migration of subepithelial mesenchymal growth centers at the posterior edge of the fused hard palate so that the early furrow which separates the two primordial processes of the soft palate is progressively obliterated by mesenchymal merging at the furrow base?

Observations of human embryos prior to, during, and after palatal closure (7–12 wks, 18–75 mm C‐R length) indicated (1) an anteroposterior gradient of palatal closure beginning at the primary palate and (2) epithelial fusion remnants found only in the hard palate regions. These observations suggest that the soft palate develops by a displacement of epithelium by mesenchymal merging rather than by epithelial fusion of the entire secondary palatine processes.
The development of the facial muscles in man
Authors: Gasser Raymond F.
Published: February 2005

Morphogenesis and histogenesis of the facial muscles is described in human embryos and fetuses 4.2–360.0 mm (crown‐rump length). The microscopic study was performed on 50 specimens that had been variously serially‐sectioned and stained. Graphic or wax reconstructions were made from transverse serial sections at 11 representative ages. Three late fetuses and a term infant were studied grossly.

Second branchial arch mesenchyme in early embryos (4.2–6.5 mm) becomes increasingly dense, but is not subdivided into distinct premuscle masses. By 8–20 mm, sheet‐like collections (laminae) of premyoblasts and early myoblasts extend from the superficial part of the arch into the temporal, occipital, cervical and mandibular regions. Premuscle condensations deep in the arch become the stapedius, posterior digastric and stylohyoid muscles. The infraorbital lamina and the occipital platysma appear by 20–23 mm. The superficial muscles differentiate rapidly between 26 and 37 mm. Most are composed of myoblasts at 41 mm. By 80 mm, all the muscles contain myotubes and are in their definitive positions. At 80–140 mm, the myotubes become young muscle fibers. From 140 mm to 360 mm (term) the muscles increase in size and gain definitive attachments. Superficial muscles differentiate later than the deep and those in the cervicomandibular and occipital regions differentiate earlier than those in the frontal and midfacial regions. The muscle masses form pari passu with the muscular branches of the facial nerve which develop deep to them.
A light and electron microscopic study of the pecten of the pigeon eye
Authors: Raviola Elio , Raviola Giuseppina
Published: February 2005

The pecten in the pigeon is a pleated lamina that consists of blood vessels and interstitial pigment cells. Arterioles with thin, unspecialized endothelium give origin to an exceedingly dense capillary network. The endothelial cells of the capillaries are provided on both the luminal and basal surfaces with thin lamellar processes, constricted at their origins from the cell body. Luminal lamellae are long, erect and have a prevailing longitudinal orientation. Basal lamellae are shorter, more irregularly oriented and more closely compressed. Besides the usual complement of cytoplasmic organelles, a moderate number of coated vesicles and of coated and uncoated inpocketings of the plasmalemma is present in the endothelial cells. A labyrinthine system of interstices surrounds the stalks of the basal lamellae and contains a material that resembles the substance of the basement lamina in density and texture. A similar material is found on the outer surface of the basal lamellae and imperceptibly merges with the ground substance of an unusually thick adventitial layer that is permeated by numerous unit fibrils of collagen. The capillary network is drained by venules, whose wall resembles the capillary wall. The pigment cells contain melanin granules, large mitochondria and many bundles of filaments. They are sandwiched between two basement laminae and separate the blood vessels from the vitreous body. The bridge of the pecten consists of pigment cells with a few interspersed capillaries.
Ultrastructure of mouse olfactory mucosa
Authors: Frisch Donald
Published: February 2005

The fine structure of the olfactory mucosa has been investigated with particular reference to those aspects of the morphology which may be significant in chemoreception. Morphology of the supporting cells of the epithelium indicate that they function in mucus production or regulation. Bowman's glands were found to consist of two cell types, both of which also seem to contribute to mucus production. Olfactory receptor cells were found to be completely covered by the mucus including the atypical olfactory cell cilia that project above the surface of the epithelium. The potential role of these cilia in initial reception is discussed. Lack of intervening cytoplasm between adjacent olfactory cell cytoplasm has been noted with the consequent possibility that electrical interaction between cells may occur. This may be significant in subsequent evaluations of electrical potentials recorded from the mucosa.
The relationship between the dimensions of the fibres and the number of nuclei during normal growth of skeletal muscle in the domestic fowl
Authors: Moss F. P.
Published: February 2005

Between 0 and 266 days of age the weight of the pectoral and gastrocnemius muscles of chickens increased 300–600‐ and 40–90‐fold respectively depending on the breed and sex. In both muscles the mean cross‐sectional area of the fibres and the total number of nuclei (estimated from DNA determination) maintained a constant ratio during growth. This suggests that for individual fibres the cross‐sectional area increased in proportion to the number of nuclei. This phenomenon is discussed in relation to current knowledge concerning the mode of growth and multinucleation of skeletal muscle fibres.

In the pectoral muscle, between 0 and 266 days, the cross‐sectional area of the fibres increased in proportion to the two‐thirds power of the muscle weight, which suggests that the length and diameter of the fibres maintained a constant ratio. The same relationship existed for the gastrocnemius for two months, after which the fibre cross‐sectional area increased in proportion to the muscle weight, which suggests that the fibre length was then constant.
Involution and regeneration of the thymus in mice, induced by bacterial endotoxin and studied by quantitative histology and electron microscopy
Authors: Gad Palle , Clark Sam L.
Published: February 2005

Lipopolysaccharide from S. typhosa, injected intraperitoneally into Swiss albino mice, produced acute thymic involution—maximal at 48 hours after injection, followed by regeneration that was complete within 5 to 7 days. Using tissues fixed and embedded for electron microscopy, cell counts were made with the light microscope and cytological details were examined in electron micrographs. The cellular events of involution and regeneration were similar to those produced by injection of adrenal glucocorticoids, but it remains to be determined whether or not endotoxin acts on the thymus by inciting adrenal cortical secretion.

Involution appeared to be the result of both the death of small lymphocytes and reduced lymphopoiesis in the thymus. Within 48 hours, macrophages had cleared away the cellular debris and medullary epithelial cells showed signs of hypertrophy and increased putative secretory activity. Subsequently, large lymphocytes proliferated at an accelerated rate in the subcapsular cortex, the cortex grew in width by the accumulation of small lymphocytes, and regeneration ceased when the thymus had reached its former size.

These observations provide circumstantial evidence for the hypothesis that in regeneration, medullary epithelial cells increase their production of a lymphopoietic hormone which stimulates mitotic proliferaton of cortical lymphocytes.
Morphogenesis of the placenta and fetal membranes of the tree shrews (family tupaiidae)
Authors: Luckett Winter Patrick
Published: February 2005

The paucity of information on the early developmental stages and the necessity for re‐evaluation of the phylogenetic implications of the tupaiid fetal membranes have stimulated the present study.

Neonatal tupaiids possess prominent bilateral endometrial pads that run the length of each uterine horn. These gland‐free pads are the sites of implantation and placentation in adults. Implantation is bilateral and superficial. Multinucleated giant cells differentiate from the cytotrophoblast of the attachment sites; they facilitate the marginal expansion of the placental disc by detaching the paraplacental epithelium from its basement membrane.

Prominent bilateral chorio‐vitelline placentae develop and remain functional through early limb bud stages. Decidual cells fuse to form “decidual knots” during this period.

The bilateral chorio‐allantoic placentae are labyrinthine endotheliochorial. The trophoblast of the labyrinth is entirely syntrophoblastic, similar to the condition in the armadillo placenta. Epithelioid mesenchymal cells in the labyrinth are strikingly similar to those of the shrew placenta. The large allantoic vesicle and free vascular yolk sac persist. Amniogenesis occurs by folding.

Uterine glands remain secretory throughout pregnancy; iron is probably supplied to the fetus in this manner.
The development of the extracellular space in neonatal rat inferior colliculus: An electron microscopic study,
Authors: Pysh Joseph John
Published: February 2005

Rat inferior colliculi were fixed by intracardiac perfusion of 4% methanol‐free formalin in an isotonic phosphate‐sucrose buffer, dehydrated in ethanol and studied during the first two weeks of postnatal life. The extracellular space during the first week was made up of intercellular gaps about 100–150 Å wide and large intercellular lakes (1–3 μ long) which diminished in size and number as maturation proceeded. Similar intercellular lakes were found in tissue fixed by immersion in glutaraldehyde containing ruthenium red. In these tissues an intense ruthenium red reaction product, distributed extracellularly, suggested an intercellular substance comparable to that described in adult brain. Intercellular lakes were also found in tissue dehydrated in acetone. Morphometric estimations indicated the extracellular space of neuropil during the first week to be about twice that of the adult, which was approached progressively.
Cytological studies of muscle dedifferentiation and differentiation during limb regeneration of the newt Triturus
Authors: Lentz Thomas L.
Published: February 2005

During limb regeneration of the newt Triturus, muscle first dedifferentiates giving rise to mesenchymal cells which, subsequently, differentiate to reform normal muscle. In dedifferentiating muscle, myofibrils and elements of the sarcoplasmic reticulum decrease gradually in number. Myofilaments become less distinct and seem to be supplanted by zones of amorphous material. Large masses of glycogen accumulate in dedifferentiating cells and mitochondria show a transient enlargement. In the later stages of dedifferentiation, glycogen decreases in amount while cytoplasmic ribosomes and cisternae of rough‐surfaced endoplasmic reticulum appear. Mesenchymal cells are formed by disappearance of all traces of myofilaments, by further elaboration of rough endoplasmic reticulum, and increase in number of Golgi complexes.

During the earliest stages of differentiation, muscle has less endoplasmic reticulum and many more free ribosomes which occur in clusters or linear chains. Thin (−70 A) and thick (−135 A) filaments appear in the cytoplasm, often in association with ribosomal olusters, and shortly thereafter aggregate into small fibrils. In early fibrils, the thin filaments overlap the thick to produce I and A bands and the free ends of the thin filaments converge and cross to mark the site of the Z line. Fibrils enlarge by addition of filaments along their sides and at their ends. In larger fibrils, the H band and M line are apparent. Initially, the transverse tubular system develops by the confluence of vesicular inpocketings of the surface plasma membrane. The smooth sarcoplasmic reticulum is continuous with rough‐surfaced membranous cisternae. Some of the smooth tubules, probably sarcoplasmic reticulum, contain intracisternal masses of dense granular material and are situated adjacent to the Z line. When dense material occurs in the membranous structures, material of similar density and texture appears within the adjacent Z line. Normal muscle fibers are formed by fusion of myoblasts, increase in number and size of myofibrils, organization of transverse tubules and sarcoplasmic reticulum into triads, loss of ribosomes, and appearance of glycogen.
Relation of types of dietary fat to cardiovascular damage in mice
Authors: Wicks Mark S. , Ball Carroll R. , Williams W. Lane
Published: February 2005

Nine edible oils or fats (hydrogenated coconut, cod liver, Wesson, linseed, olive, butter, lard, corn and cocoa‐butter) were fed for 50–90 days to study the relation of saturation, chain length and essential fatty acid content to production of cardiovascular lesions. The specific oil or fat (selected for ranges in the above variables) was used as the dietary lipid in a high‐fat (28%), low‐protein (8%), hypolipotropic diet. Half of the animals received identical diets containing choline chloride (2 gm/100 gm of diet) as a lipotropic supplement.

Atrial mural thrombosis and ventricular myocardial necrosis and calcification developed in all dietary groups. Atrial thrombosis was the most frequent lesion. The greatest incidence of atrial thrombosis occurred in mice fed the choline‐deficient, butter‐containing diet (92%) and the lowest incidence with the supplemented cod liver oil diet (20%). The diet containing unsupplemented hydrogenated coconut oil produced the greatest incidence of ventricular necrosis (79%) and that with choline‐supplemented cocoa‐butter the lowest (8%). Ventricular calcification was most extensive within the unsupplemented cod liver oil group (83%), most limited in the supplemented lard group (5%). In general, choline‐supplemented diets produced a lower incidence of cardiac damage. Little correlation existed between the composition and characteristics of specific fats and their activity in producing the specific cardiac lesions observed here.
Fine structure of the developing trout erythrocytes and thrombocytes with special reference to the marginal band and the cytoplasmic organelles
Authors: Sekhon Sant S. , Beams H. W.
Published: February 2005

The cytological changes accompanying the development of red blood cells of trout were studied. These changes appear to parallel closely those seen in the maturation of red blood cells of mammals. Immature erythrocytes of the trout contain mitochondria, Golgi complex, rough and smooth endoplasmic reticulum, centrioles, bundles of microtubules and numerous ribosomes in their cytoplasm. With progressive differentiation and maturation such cells appear to shrink in size, acquire a biconvex ellipsoid form, lose most of their cytoplasmic organelles and concomitantly increase their hemoglobin content. Mitochondrial degradation begins early in the process of maturation and usually consists of the following sequence of morphological changes within them: the appearance of small dense bodies, degeneration of the cristae and the formation of lamellar bodies. Degenerating mitochondria are often observed bulging from the surface of the cell, suggesting that they are in the process of being extruded from it. However, this observation does not preclude the possibility that mitochondria may also be disposed of in situ through the action of lysosomal enzymes. It is suggested that the disappearance of mitochondria and other cytoplasmic organelles contributes to the volumetric shrinkage which accompanies the maturation of trout red blood cells. The existence of an equatorially oriented “marginal band” of microtubules has been confirmed in this material in agreement with studies on other species. A band of microtubules was also observed in trout thrombocytes. It is concluded that the marginal band plays an important role in the maintenance of the flat ellipsoidal shape of these cells as has been suggested by other investigators studying other vertebrate forms.
Development of the lateral musculature in the teleost, Brachydanio rerio: A fine structural study
Authors: Waterman Robert Earle
Published: February 2005

The lateral musculature in the midbody region of the teleost, Brachydanio rerio, was examined by light and electron microscopy in the adult and six developmental stages. Two main divisions of the adult lateral musculature are described: (1) a superficial portion composed of small, dark fibers with high fat content and succinic dehydrogenase (SDH) activity; and (2) a deep portion composed principally of larger, pale, “deep fibers” showing little SDH activity and containing little fat. Some “intermediate fibers” are also present in the deep portion near the horizontal septum. Myofibrils of all cell types appear ultrastructurally similar.

A general outline of myotomal differentiation has been established for the midbody somites. Myogenesis begins at the medial surface of the somite between the 20‐ and 25‐somite stages and progresses laterally. Shortly before hatching, the myotome contains two structurally dissimilar types of young muscle cells. The appearance of these two muscle cell populations in larvae and fry supports the hypothesis that they develop into the superficial and deep portions of the adult lateral musculature. The intermediate fiber population is present by 2 1/2 months. The most lateral cells of the somite form a layer of flattened cells covering the lateral myotomal surface in the 33‐somite embryo, and are considered to form the dermatome in this species.
The development of the baboon (Papio sp.) placenta during the fetal period of gestation
Authors: Houston Marshall L.
Published: February 2005

Baboon placentae ranging in age from 45 to 175 days were studied for progressive changes in their morphology. The baboon embryo implants superficially and develops a single, discoid, villous hemochorial placenta. The remainder of the chorion is membranous and a true decidua capsularis is not formed. A lobular structure is developed during the fetal period. At 45 days the amnion only partially fills the chorionic cavity but by 60 days has expanded and the two membranes are directly contiguous. Trophoblastic tissue is of two types: cytotrophoblast and syncytiotrophoblast. Cytotrophoblast is found primarily in the chorionic plate and cytotrophoblastic shell. The chorionic villi are originally composed of a double layer of trophoblast; cytotrophoblast internally and syncytiotrophoblast externally. The cellular layer gradually disappears so that by full‐term the villous walls are formed by a single layer of syncytiotrophoblast. Hofbauer cells are common within the villous cores, diminishing in number toward term. Large amounts of collagenous connective tissue develop in the chorionic plate and in the villi, and fibrin and fibrinoid materials accumulate in the basal plate and anchoring villi. The endometrium is decidualized to its greatest extent by the beginning of the fetal period and undergoes only minor cytological alteration throughout the remainder of gestation.
Two classes of spermatogonial stem cells in the monkey (Cercopithecus aethiops)
Authors: Clermont Yves
Published: February 2005

To analyze the behavior of spermatogonia in the monkey, the cytological features, topographical arrangement and frequency of the two classes of type A (A1, A2) and the four classes of type B (B1–B4) spermatogonia were determined in dissected tubules, fixed in Carnoy, stained with hematoxylin and mounted “in toto.” The capacity of spermatogonia to divide was also analyzed in radioautographed testicular sections from an animal injected with tritiated thymidine.

The type A1 spermatogonia, characterized by nuclei containing deeply stained, finely granulated chromatin, were found to be non‐dividing elements. The type A2 spermatogonia, characterized by nuclei showing palely stained, coarsely granular chromatin, all divided in stages IX–X of the cycle of the seminiferous epithelium to yield equal numbers of new type A2 cells and type B1 spermatogonia. The type B1, as the other type B cells, were characterized by nuclei containing granules or flakes of deeply stained chromatin. While the type A2 spermatogonia remained dormant until stage IX of the following cycle, the type B1 cells all divided during stage XII to yield twice their number of type B2 spermatogonia. These, in stage II, divided to give twice as many type B3, which, in stage IV, divided to produce twice as many type B4 spermatogonia. Lastly, in stage VI, the latter elements all divided to yield spermatocytes.

Thus, the type A1 spermatogonia, did not appear to be actively involved in the production of spermatocytes and were tentatively considered as “reserve stem cells;” the type A2 spermatogonia, were identified as “renewing stem cells.”
Cyclic changes in ovarian morphology during the menstrual cycle in Macaca mulatta
Authors: Koering Marilyn J.
Published: February 2005

Twenty‐seven mature female macaques were ovariectomized at various times during the menstrual cycle. The ovaries were sectioned serially and each vesicular follicle was measured and classified according to size and developmental state. Also noted was the presence of differentiated and undifferentiated glandular tissue.

The data showed that when the corpus luteum was active the largest follicle in each animal was not less than 1 mm in diameter, and that when the corpus luteum began to degenerate follicular enlargement commenced. Most follicles became atretic when under 1 mm in diameter, except for a few in the late follicular stage. The maximal diameter for an atretic follicle was 3.1 mm and for a developing follicle 6.3 mm.

Interstitial gland tissue (theca interna of atretic follicles) was noted in large amounts just before ovulation while minimal amounts were present throughout the rest of the cycle.

Other glandular types occasionally seen were aberrant and accessory corpora lutea, cords of cells in the stroma and adrenal rests.
The role of the parafollicular cell of the thyroid gland in the pathogenesis of congenital osteopetrosis in mice
Authors: Marks Sandy C. , Walker Donald G.
Published: February 2005

Congenital osteopetrosis as manifested in the grey‐lethal, microphthalmic and osteosclerotic stocks of the house mouse is characterized by an increased rate of bone matrix formation, hyperplasia of the parafollicular cell population of the thyroid gland and hypocalcemia. Osteopetrotic mice were abnormally resistant to the tendencies of parathyroid extract to promote hypercalcemia and to depress osteogenesis. The results of this investigation suggest that the parafollicular cell is the source of an osteoblast‐stimulating factor and that an excess of this factor results in osteopetrosis.
Features of trigeminal mesencephalic nucleus structure and organization. I. Light microscopy
Authors: Hinrichsen Colin F. L. , Larramendi Luis M. H.
Published: February 2005

The morphology and distribution of cells in the trigeminal mesencephalic nucleus were compared in newborn and adult mice, and in adult rats and cats. No gross morphological differences indicated a somatotypic subdivision of the nucleus. Changes in cell morphology in the adult mouse as compared with the newborn, are possibly related to the relatively late innervation of muscle spindles. Cell counts indicated that cell number increased not only with growth of the animal but also with increasing complexity of the jaw musculature. Analysis of the trigeminal motor root in the adult mouse showed a unimodal distribution of myelinated fibers that numericaly could not encompass both motor and mesencephalic fibers. No provision for the Y motor system appeared to be present. A substantial proportion (1:7) of cells were in soma‐soma contact. The possible functional implications of these cell clusters were discussed.
The opisthonephric kidney of the sea lamprey of the great lakes, Petromyzon marinus L. II. Neck and proximal segments of the tubular nephron
Authors: Youson John H. , McMillan Donald B.
Published: February 2005

The spatial arrangement of the five basic segments of the tubular nephron of the sea lamprey is reversed between ammocoetes and adults due to differences in the position of the glomus. The initial segment, the ciliated neck segment, resembles the pronephric nephrostome. The proximal segment is divided into two distinct regions, the pars convoluta followed by the pars recta, and has a brush border which reacts positively with the periodic acid‐Schiff stain.

Ultrastructurally the cells of the proximal segment resemble the corresponding cells of other vertebrates except that they lack the usual infoldings of the basal plasma membrane and they often show intercellular spaces. The mitochondria of these cells often contain filamentous and crystalline material and are usually associated with “flocculent bodies” resembling “non‐nucleoid” renal microbodies.

The structure of the cells of the proximal segment suggest that they are involved in endocytosis.
An ultrastructural study of human eosinophil granules: Maturational stages and pyroantimonate reactive cation
Authors: Hardin J. H. , Spicer S. S.
Published: February 2005

For ultrastructural study of the formation and maturation of human eosinophil granules, bone marrow and buffy coat specimens were fixed with an aqueous solution of potassium pyroantimonate and osmium tetroxide and by conventional methods. The antimonate‐osmium tetroxide method of fixation, which is thought to permit ultrastructural localization of sodium or other cations, offered an advantage over routine methods in that it permitted recognition of four rather than two varieties of cytoplasmic granules in human eosinophils at various stages of cell development. These four granule varieties, designated A, B, C, and D, differed primarily in distribution and content of crystalloids and antimonate deposits: A granules lacked antimonate deposits and cystalloids; B granules contained a rim of deposits but lacked crystalloids; C granules possessed deposits that were present in the peripheral matrices but not in the central crystalloids; and D granules lacked deposits but contained crystalloids. Evidence is provided that these four varieties of granules represent progressive stages in the maturation of a single granule type and that granules without crystalloids are transformed into granules with crystalloids. The results also provide evidence for the presence of an as yet unidentified pyroantimonate precipitable cation in human eosinophil granules.
An electron microscopic study of the entodermal cells of the yolk sac of the chick during incubation and after hatching
Authors: Lambson Roger O.
Published: February 2005

Normal and Thorotrast‐injected chick yolk‐sac specimens were prepared for electron microscopy and examined at intervals from early in the incubation period through the twelfth day after hatching. At all stages of development studied, it appeared that electron‐dense yolk granules, lipid droplets, and Thorotrast particles were phagocytosed by the entodermal lining cells through a complicated system of coated vesicles and apical canaliculi which were associated with larger vesicles situated more deeply in the cells. The numerous vesicles in these cells frequently appeared to have merged with one another, and absorbed yolk materials within many of them appeared to have become structurally altered.

In the late‐incubation and post‐hatching periods, numerous lightly osmicated lipid spherules (50–150 mμ diameter) were seen within cisternae of rough‐surfaced endoplasmic reticulum, in vesicles of the Golgi apparatus, and in membranous enclosures near the basal plasmalemma of the entodermal cells. These lipid spherules were also present within intercellular spaces and within endothelial cells of vitelline capillaries, suggesting a sequence of events in which spherules were released from entodermal cells into the extracellular space and then taken up by the vascular system for further transport.
The developing bronchial arteries in a fetus of the twelfth week
Authors: Boyden Edward A.
Published: February 2005

In the human fetus bronchial arteries appear, as such, between the ninth and twelfth week as highly variable arteriolar outgrowths from the aorta itself or from proximal portions of right (or left) posterior intercostal rami of the aorta. Thus, they constitute a secondary system implanted relatively late upon the peripheral coats of the bronchial tree and large pulmonary vessels. The process is thought to be an inductive one depending partly upon the approximation of parts during the descent of heart and lungs into the thorax and partly upon the advancing degree of maturity of the bronchial tree.

In the fetus of the twelfth week, to be described below, there are three bronchial arteries to the left lung and at least one to the right. The lowest of these (the left aorticobronchial artery) can be traced along the superficial coasts of the left lower lobe bronchus to the level just preceding that in which cartilages are differentiating: for example, to the third of what will comprise, eventually, some 25 generations of branches of the posterior basal segmental bronchus. Beyond this shifting level of differentiation the segmental pulmonary arteries constitute the sole arterial supply to the bronchi and parenchyma of the lung. It is assumed from recent reports in the literature that the bronchial arterioles will have established continuity with pulmonary arteries and with the pulmouary parenchyma not later than the twenty‐sixth week of gestation.
Adrenergic nerve elements in the hypogatric ganglion of the guinea pig
Authors: Watanabe Hiroshi
Published: February 2005

Adrenergic nerve elements in the hypogastric ganglion of the guinea pig were studied by fluorescence and electron microscopy. The ganglion contains two main elements exhibiting green to green‐yellow fluorescence for catecholamines. One consists of basket‐like, simple nerve endings around some of the ganglion cell bodies, and the other of small polyhedral cells with short axonic processes. Electron microscopy revealed the ultrastructure of these elements. The adrenergic nerve endings contain small granular vesicles, about 500 Å in diameter, as well as a few large granular and small agranular vesicles. They were more rare than the cholinergic endings, which contain numerous small agranular vesicles mixed with a few large granular vesicles. Both adrenergic and cholinergic endings submerge to a considerable depth into the cytoplasm of ganglion cells. The ganglion cells send spinous processes into these endings. The fluorescent polyhedral cells are probably in an intermediate position between adrenal medullary cells and ganglion cells. They contain numerous large granular vesicles. Their axonic processes extend for a short distance to end in close topographical relation to capillaries. According to the structure of the granulated vesicles, these cells were classified into four types. The function of the adrenergic elements in ganglionic transmission was discussed.
The effect of hydrocortisone on extracellular connective tissue fibrils in the early chick embryo
Authors: Carlson Edward C. , Low Frank N.
Published: February 2005

Two series of chick embryos were treated with hydrocortisone in an attempt to demonstrate the influence of this hormone upon microfibrils found free in the tissue space surrounding the notochord. Embryos in series I were explanted on agar‐albumen medium and permitted to survive 1–24 hours after Ringer's solution or hydrocortisone had been pipetted onto the area vasculosa. Doses of hydrocortisone ranged from 5 μg to 1 mg. Series II embryos were similarly treatedin ovothrough a small shell “window” and then incubated 12 or 24 hours. All embryos were sacrificed at 72 hours incubation age. Ringer‐treated embryos in both series exhibited a rich tangle of early extracellular connective tissue fibrils (microfibrils) surrounding the notochord. One hour after treatment with hydrocortisone, embryos in series I showed a reduction in perinotochordal microfibrils. At four hours the effect was maximal and by 12 hours, recovery had been initiated, the morphology of which suggested a re‐organization of amorphous material and extracellular debris to form fibrillar structures. Twenty‐four hours after treatment, recovery was complete and hydrocortisone‐treated embryos exhibited perinotochordal fibril populations that were indistinguishable from Ringer‐treated specimens. The results of the series II experiments roughly parallelled those seen in series I but were somewhat less predictable.

Possible modes of action of hydrocortisone on connective tissues and their relationship to the present study are discussed. It is suggested that the steroid may induce the release of a substance with an enzymatic activity capable of digesting microfibrils. This catabolic activity may be reflected as an inhibition of connective tissue production if it is assumed that microfibrils are precursors of larger, more mature fibrils. It is further suggested that since microfibrils are thought to contain connective tissue proteins, the initiation of microfibrillar reduction by hydrocortisone could indicate that this hormone may act in a similar manner on more mature connective tissue fibrils.
Renewal of the epithelium in the descending colon of the mouse. II. Renewal of argentaffin cells
Authors: Chang W. W. L. , Leblond C. P.
Published: February 2005

Argentaffin cells (defined as containing groups of fine, iron hematoxylin stained granules) were examined in the epithelium of the descending colon of the mouse at various times after the initiation of a continuous infusion of 3H‐thymidine, using radioautography of semithin Epon embedded sections.

These argentaffin cells do not show mitosis nor do they take up label one hour after injection of 3H‐thymidine. Therefore, they do not have the capacity to divide. Nevertheless. by two days and later after the beginning of continuous infusion of 3H‐thymidine, labeled argentaffin cells are present. It is, therefore, concluded that argentaffin cells arise from unidentified precursor cells containing no iron hematoxylin stained granules (or too few for identification with the light microscope).

The number of labeled argentaffin cells increases during the first few days after continuous infusion of 3H‐thymidine, while they migrate upward along the crypt wall, somewhat more slowly than vacuolated‐columnar and mucous cells do. The results demonstrate that at least some of the argentaffin cells undergo migration and renewal in the colonic epithelium.
Fine structure of the taste bud in the mud puppy, Necturus maculosus
Authors: Farbman Albert I. , Yonkers Jenny D.
Published: February 2005

The taste receptor of Necturus was studied because of its potential usefulness in electrophysiological intracellular recording. The taste bud has about twice the length and twice the diameter of buds in most other vertebrates. The large size can be attributed to both a greater number of cells and a greater size of the individual cells. The cells of Necturus taste buds appear to be homologous to those in other vertebrates. Three distinct cell types were found: dark cells (60%), light cells (30%), and basal cells (10%). Dark cells contained granular endoplasmic reticulum, Golgi bodies, and many clusters of characteristic granules that reacted positively when treated with the periodic acid‐silver methenamine technique. They are probably secretory cells. Light cells, found in the center of the taste bud, were virtually filled with agranular endoplasmic reticulum, mitochondria and Golgi bodies. Their morphology is similar to that of chloride cells in fish gills, and they may have an ion transport function important in the gustatory response. Basal cells, located at the periphery in the basal half of the bud, contained characteristic dense‐core vesicles about 70–90 mμ in diameter. The lower half of the taste bud contained many intraepithelial nerve processes adjacent to the cells.
Effects of red blood cell injections on diet‐induced atrial thrombosis in Swiss mice
Authors: Ashburn Allen D. , Weaver Macon M. , Summers Patricia A.
Published: February 2005

Female Taconic Swiss mice were fed a high‐fat (28%), low‐protein (8%), hypolipotropic diet. Some of the animals received intraperitoneal injections of washed, packed red blood cells or physiological saline while receiveing the diet. Mice that received only the experimental diet for ten weeks developed a high incidence of atrial thrombosis (84%) concurrently with severe anemia (hematocrit 6.7). Saline injections did not alter these changes significantly. Atrial thrombosis was prevented in mice maintained at a normal or slightly subnormal hematocrit level with injections of washed, packed erythrocytes.
The fine structure of the pia mater of the rat
Authors: Morse Dennis E. , Low Frank N.
Published: February 2005

Tissue from the central nervous system of 11 adult Sprague‐Dawley rats fixed by vascular perfusion with buffered aldehydes was used in a study of the fine structure of the pia mater. Surface tissue from the cerebral and cerebellar cortices, ventral pons, olfactory bulb, tuber cinereum, spinal cord, superior colliculus, optic chiasm, and median longitudinal fissure was examined. Variations in pial composition occurred within each of these selected areas although a basic pattern prevailed throughout.

The components of the pia mater are described under three categories: pial cells, extracellular elements, and macrophages. The pial cells are the more numerous cell type, possessing long, flattened cytoplasmic processes which contain few inclusions. These cells vary in thickness in any one area and there may be from one to six distinct cytoplasmic layers. Fenestrations between pial cell processes or total absence of pial cells are occasionally encountered. Unit collagen fibrils make up most of the extracellular material of the pia. These have a major period of about 550 Å and are about 400 Å wide. Macrophages are rounded up and contain various cytoplasmic inclusions. In normal animals evidence of active phagocytosis is rare.