bluuebunny/crossref_metadata_2025 huggingface dataset:
The distribution of osmiophilic lamellae within the alveolar and bronchiolar walls of the mammalian lungs as revealed by osmium‐ethanol treatment
Authors: Kikkawa Yutaka , Kaibara Manabu
Published: February 2005

Osmiophilia of the cellular elements of the alveoli and bronchioles was investigated using the new technique of second osmication with a solution containing a mixture of osmium tetroxide and ethanol. Previously this method was used to reveal osmiophilic periodic lamellae of synthetic dipalmitoyl lecithin and the surface film of the acellular alveolar lining layer of the mammalian lung in thin sections.

In the present experiments, much of the osmiophilic content of inclusions in type II epithelial cells became visible only after second osmication with osmium‐ethanol but was not visible with the initial osmium tetroxide fixation. The osmiophilic content of the inclusions showed 42 Å periodicity. These results are in accord with those obtained in the study of dipalmitoyl lecithin and the surface film, suggesting that the inclusions are the precursors of the pulmonary surfactant.

Several new observations were made with this technique. These include osmiophilic lamellae within Golgi saccules, within the multivesicular bodies of type II cells, in the vesicles of type I epithelial cells, and in the basement membranes of epithelial cells. These observations are consistent with the idea that the Golgi apparatus and multivesicular bodies are closely related to the production of surfactant and that the surfactant may be disposed of by type I epithelial cells after engulfment by pinocytosis. Thereafter, the surfactant may eventually be cleared through the lymphatics.

Clara cell granules behaved differently and were thought to be an unlikely site for the synthesis of the pulmonary surfactant.
Placental iron transfer: Relationship to placental anatomy and phylogeny of the mammals
Authors: Seal Ulysses S. , Sinha Akhouri A. , Doe Richard P.
Published: February 2005

Serum iron transfer from mother to fetus was measured in near‐term pregnant females from 16 species representing 15 families and 7 orders of eutherian mammals. The amount of transfer at 2 hr was 5% or greater in species with hemochorial placentation and less than 0.1% at 3 hr in species with epitheliochorial or endotheliochorial placentation.
The initial appearance of ossification in staged human embryos
Authors: O'Rahilly Ronan , Gardner Ernest
Published: February 2005

Serial sections of 36 embryos aged six to eight postovulatory weeks (12 to 31 mm C. R. length) were examined. The clavicle and the mandible began to ossify during stage 18, 19, or 20, the clavicle (at least frequently) by means of two centers. The maxilla followed rapidly (stages 19, 20). The premaxilla was in continuity with the maxilla proper, either as a mesenchymal condensation or as an ossific area (stages 20, 21). The next elements to commence ossification were the humerus (stages 21, 22), the radius (stages 21, 23), and the femur, tibia, and ulna (stages 22, 23). By stage 23 the following were also undergoing ossification in at least some cases: interparietal, supra‐occipital, anterior process of the malleus, the squamous temporal, palatine, medial pterygoid plate, zygomatic, frontal, vomer, scapula, and distal phalanges of the hand. Cellular invasion was found in the clavicle and in the bone collars of the radius, ulna, and femur at eight postovulatory weeks. The cartilages of the first pharyngeal arches (chondrifying at stages 18, 19) approached the median plane (stage 20) but did not fuse in the embryonic period proper; their cartilaginous tissue underwent localized hypertrophy by stage 23, but endochondral ossification did not occur until the fetal period.
The cellular origins of corticotropin and melanotropin as revealed by immunochemical staining
Authors: Baker Burton L. , Drummond Thérése
Published: February 2005

The cellular origins of corticotropin and melanotropin were studied by observing the response of the rat hypophysis to adrenalectomy and cortisol administration when stained immunochemically with peroxidase‐labeled antibody following application of antiserums to β1–24‐corticotropin, βP17–39‐corticotropin, human β‐melanotropin, and α‐melanotropin. The presence of corticotropin in the pars intermedia is indicated since this lobe, in addition to corticotropic cells of the pars distalis, stained with antiserum to βP17–39‐corticotropin. However, the concentration of corticotropin is less in the pars intermedia than in corticotropic cells since at higher dilutions of antiserum the latter cells stained intensely while the pars intermedia was unstained. Also, corticotropic cells exhibited striking hypertrophy after adrenalectomy and regression after cortisol administration, while morphological and tinctorial properties of the pars intermedia were minimally altered. These observations suggest that the pars distalis is primarily responsible for supplying the corticotropin required to meet the changing requirements of the body.

With antiserum to human β‐melanotropin, the pars intermedia stained intensely. Since the antiserum was ineffective after absorption the staining reaction appears to be specific for β‐melanotropin. Except for a rare cell, the pars distalis did not stain. Thus β‐melanotropin is restricted primarily to the pars intermedia.
Morphogenetic studies of the rabbit. XLII. Growth gradients, epigenetic variants, and function
Authors: Sawin P. B. , Hamlet Martha
Published: February 2005

Comparison of the effects of the Da gene upon the spheno‐occipital synchondrosis in rabbits of strain DA and unrelated strain IIIDa has made possible study of the relative effects of Da growth retardation and strain differences of primary and secondary growth gradients and their interaction. When Da is absent and parental border shift dosages (which portray the localization and magnitude of thoracic and lumbar gradients) are most anterior, synchondrosis fusion is minimal in both strains. Presence of Da in either Da/+ or Da/Da genotype significantly increases the penetrance and expression of fusion in both strains. Fusion tends to be additively increased when parental thoracolumbar and lumbosacral borders are shifted anteriorly, and antagonistically decreased when they are replaced by posterior border shifts. The interaction of these two (gene and genome) influences results in patterns of continuous distribution involving from two to five classes. Penetrance of fusion is outstandingly affected by Da whereas expressivity obviously is more specifically associated with vertebral border shifts. This differentiates their associations with primary and secondary gradients respectively. The study shows how such epigenetic variants and specific gene induced localized retardations could be used in genetic analyses of basic growth processes. Studied developmentally in time and relation to function, they could establish firm grounds for prediction and control of abnormal development.
Myocardial cell diameters in primate hearts
Authors: Truex Raymond C.
Published: February 2005

This light microscope study on the cell diameters of six myocardial structures was based 15 primate hearts. One hundred cell measurements were made of each cell category in each of five speciments of three primate species (monkey, baboon, man). Mean values of cell diameter, range and the standard error of each group of measurements are presented in graph form. The coefficients of variation between the cells in each of the five hearts of each species are presented. Microscopically the small cells of the SA and AV nodes constitute a more uniform population, while the atrium, AV bundle and left bundle branch have a heterogeneous admixture of large and small cells. Left ventricles of the human and baboon hearts had more uniform cell populations than did the left ventricle of the monkey. Representative examples of the more heterogeneous areas are demonstrated photographically. The sources of error, importance of several cardiac junction sites, significance of cell diameter in cardiac hypertrophy and the potential relationship between cell size and cardiac conduction velocities are presented.
Bidirectionality in the tongue processes of the oligodendroglial cell investment of axons in the albino rat
Authors: Stempak Jerome G. , Knobler Robert L.
Published: February 2005

Serial sections from the lumbar spinal cord of 5‐day old female albino rats were examined by electron microscopy. A change in direction of the inner and outer processes of the oligodendroglial cell investment of an axon within an internode was observed in two ribbons. The shorter of the two ribbons is described in this report.
Effect of vinblastine sulfate on the fine structure of cells of the rat renal corpuscle
Authors: Tyson Greta E. , Bulger Ruth Ellen
Published: February 2005

Vinblastine sulfate was administered intravenously to adult rats chiefly to study the effect of microtubule loss on the cell shape of renal podo‐cytes. After treatment which resulted in a nearly complete absence of normalsized microtubules (260 Å diameter) in podocytes, there was no evidence that any alteration in cell shape accompanied the disappearance of these organelles. Unlike podocytes, blood platelets did undergo a change in shape with exposure to the drug. After treatment, platelets seen within glomerular capillaries were more spherical and rarely contained microtubules.

Intracytoplasmic paracrystalline inclusions characteristic of vinblastine treatment were observed in visceral and parietal cells of Bowman's capsule, glomerular endothelial cells, blood platelets, mesangial cells, interstitial fibroblasts, mononuclear leukocytes, a granulated juxtaglomerular cell, and cells of the proximal and distal convoluted tubules. Unusually large microtubules, with an approximate diameter of 450 Å, were also seen in a variety of cell types after vinblastine treatment. In favorably oriented cross‐sectional profiles, 12–13 subunits were discernible within the wall of these large microtubules.
Vitality of chondrocytes in the mandibular condyle as revealed by collagen formation. An autoradiographic study with 3H‐proline
Authors: Silbermann Michael , Frommer Jack
Published: February 2005

Histological and autoradiographic studies using 3H‐proline indicate that cartilaginous tissue in the mandibular condyle maintains morphologic and metabolic characteristics of an embryonic type of tissue. Cartilage cells in the condyle lack the specific arrangement and cellular homogeneity characteristic of more differentiated endochondral growth sites. Through dedifferentiation many chondrocytes in the mandibular condyle appear to outlive the hypoxic conditions that are reported to prevail within the mineralizing zone. Chondrocytes in this zone reveal only a minimal amount of 3H‐proline uptake in comparison with the cells in the chondroblastic and premineralizing zones. The dedifferentiated chondrocytes appear to redifferentiate into more specialized cells, possibly osteoprogenitor cells, as they reveal a significant increase in 3H‐proline incorporation in the vicinity of the ossifying front. These observations on proline metabolism support the concept that calcification in the condylar cartilage is not necessarily accompanied by degeneration and death of the chondrocytes.
The arteries of the pancreas of the dog. An injection–corrosion and microangiographic study
Authors: Cadete‐Leite A.
Published: February 2005

The ramification of the pancreatic arteries, including the lobular vessels, was studied in 36 mongrel dogs by means of plastic injection and corrosion, as well as microangiography.

The left pancreatic lobe receives the left cranial pancreatic artery and other smaller branches from the splenic artery, and two to four twigs from the gastroduodenal artery. In addition, it receives very often a branch from the common hepatic artery. Branches arising from the cranial mesenteric artery and from the first jejunal artery may also be found. The right cranial pancreatic artery and the right gastroepiploic artery give branches to the pancreatic angle. The arteries to the right pancreatic lobe arise from the cranial and from the caudal pancreaticoduodenal arteries.

The interlobular arteries give origin to the intralobular arteries. The penetration and the distribution of the latter vessels differ in lobules of different shape. The intralobular course may be straight or curved. Branches arise generally at acute angles, forming Y or fork‐like patterns, ending into bundles of arterioles.
Scanning electron microscope studies of some lizard basilar papillae
Authors: Miller Malcolm R.
Published: February 2005

The papillae basilares of eight species of lizards representing four different families were studied by scanning electron microscopy.

The papilla of Eublepharis macularius (Gekkota; Eublepharidae) has a midaxial area devoid of hair cells separating anterior and posterior groups of hair cells, two types of tectorial membrane modifications, bidirectionality of each of the anterior and posterior groups of ventral hair cells, and unidirectionality of the dorsal hair cells. The papilla of Coleonyx variegatus (Gekkota; Eublepharidae) is essentially similar to that of Eublepharis, but shows anterior displacement of the axial hiatus and a considerable decrease in the number of hair cells in the dorsal part of the postaxial region. The papilla of Ameiva ameiva (Teiidae) has a dorsal enlargement almost constricted from the remaining portion of the papilla and the greater number (87%) of the hair cells oriented posteriorly. Tupinambis teguixin (Teiidae) exhibits multidirectional hair cell orientation in the expanded dorsal area, bidirectionality in the narrower central segment, and unidirectionality toward the ventral end of the papilla.

Gerrhonotus multicarinatus (Anguidae) shows a ventral expansion covered by a thick tectorial plate overlying short‐ciliated unidirectionally oriented hair cells and a longer dorsal segment with long‐ciliated bidirectionally oriented hair cells. The papillae of Iguana iguana, Crotaphytus collaris, and Basiliscus basiliscus (Iguanidea) have middle segments of short‐ciliated hair cells covered by a specialized tectorial plate and dorsal and ventral segments consisting of longciliated bidirectionally oriented hair cells. Basiliscus is divergent in lacking a part of the ventral long‐ciliated hair cell segment.
Fine structure of the differentiating acini in submandibular glands of isoproterenoltreted rats
Authors: Bressler Robert S.
Published: February 2005

Chronic treatment with isoproterenol, a β‐adrenergic drug, accelerates the postnatal differentiation of the rat submandibular gland. This report compares the ultrastructure of submandibular glands of acute and chronically treated, 2, 11 and 17‐day‐old rats with that of controls. In all cases a greater number of acinar cells were found in the treated glands. The correlation noted between changes in the nature of the contents of the condensing vaculoes and Golgi apparatus of some proacinar cells and the formation of secretory granules intermediate in appearance between those of proacinar and acinar cells, support the hypothesis that proacinar cells are the precursors of acinar cells in the young rat. Differences in the morphology of secretory granules in acinar cells of treated and control animals are described. It is concluded that precocious differentiation of the submandibular gland may be induced by the administration of isoproterenol as early as the first day of postnatal life, that proacinar cells become recognized as acinar cells following a change in the nature of their secretory product, and that the secretory material produced by acinar cells in the treated animals is not identical to that of the controls.
Effects of blinding, olfactory bulbectomy, and pinealectomy on prolactin and growth hormone cells of the rat, with special reference to ultrastructure
Authors: Shiino Masataka , Arimura Akira , Rennels Edward G.
Published: February 2005

The effects of combined blinding and olfactory bulbectomy alone or with pinealectomy on body growth, and pituitary and serum levels of growth hormone and prolactin were examined in young female rats. The animals were 23–24 days old at the time of the operations, and they were sacrificed 52 days later. Blind, anosmic rats had elevated serum and depressed pituitary stores of prolactin. The blind, anosmic rats which were also pinealectomized showed prolactin levels which were intermediate between those of the blind, anosmic and sham control animals. On the other hand, combined blindness and anosmia decreased serum growth hormone levels and again pinealectomy prevented this effect. The observed changes in the ultrastructure of prolactin and growth hormone cells were well correlated with these alterations in hormone levels.
Phagocytosis in the light‐damaged albino rat eye: Light and electron microscopic study
Authors: O'Steen W. Keith , Karcioglu Zeynel A.
Published: February 2005

Retinal photoreceptor degeneration was induced by exposing albino rats to fluorescent illumination at elevated environmental temperatures. Fine carbon particles were injected intravenously or directly into the vitreous body or anterior chamber of the eye. The resulting pattern of invasion, migration, and egression of carbon‐filled phagocytes in eyes with degenerated retinas was reconstructed from a time sequence series of light and electron microscopic tissue sections. Retinal debris, such as damaged photoreceptor outer segments and carbon particles, was most frequently removed by two populations of cells possessing phagocytic properties: mononuclear cells of vascular origin and pigment epithelial cells. After retinal damage, mononuclear cells appeared first in the vitreous body and later, in time sequence, progressively deeper in the inner plexiform layer and out to the bipolar nuclear layer, where they were seen within, or partially within, retinal capillaries. After intravenous carbon injection, however, marked phagocytes were not seen in the retina. Carbon‐filled phagocytic cells were observed in the choroidal connective tissue and blood vessels after intravenous injection, but not after intravitreal injections of carbon. Therefore, retinal phagocytes did not appear to leave the eye through the choroidal circulation. Pigment epithelial cells proliferated by mitotic activity, occurred as single cells separated from Bruch's membrane, and were seen among the degenerated outer segments. After direct exposure to carbon particles, pigment cell phagosomes contained both carbon and lamellated discs of degenerated outer segments. Whether these cells exited from the eye through retinal capillaries or returned to Bruch's membrane to reestablish continuity in the pigment epithelium could not be determined.
Development of the zona pellucida in the rat oocyte
Authors: Kang Yuan‐Hsu
Published: February 2005

Ovaries of weanling and juvenile rats were studied by electron microscopic and cytochemical techniques, with particular reference to the role of the Golgi complex in the formation of the zona pellucida. The zona pellucida type of material first appears in the perivitelline space at the stage when the oocyte acquires a single layer of flattened and cuboidal granulosa cells, and is completely formed when the granulosa cells attain a cuboidal shape. The intimate association of the Golgi complex with the oocyte plasmalemma and the presence of mucopolysaccharide in its saccules and vesicles suggests that the Golgi complex of the oocyte plays an important role in the synthesis of the zona pellucida. The zona pellucida of the rat egg consists of a single layer of acid mucopolysaccharide which is structurally distinguishable from the liquor folliculi. Formation of the primary liquor folliculi is attributed to the Golgi complexes in granulosa cells.
A scanning electron microscopic study of the nephron
Authors: Andrews Peter M. , Porter Keith R.
Published: February 2005

Scanning electron microscopy was used to study the ultrastructural morphology of the nephron. Material for observation was taken from rat kidneys which were fixed by vascular perfusion. Different techniques for splitting open the kidney, combined with stereoscopic viewing, provided many instructive views of nephron morphology. In addition, scanning electron microscopy revealed a number of new features including (1) the complex organization and structure of kidney podocytes; (2) the distribution of endothelial pores and the presence of endothelial microprojections and branching endothelial thickenings; and (3) the presence, distribution and morphology of microprojections and cilia on the luminal surfaces of Bowman's capsule and the uriniferous tubules.
A cluster of supraependymal neurons located within the infundibular recess of the rat third ventricle
Authors: Paull Willis K. , Scott David E. , Boldosser W. G.
Published: February 2005

A nidus of supraependymal cells was located within the infundibular recess of a rat's third ventricle. Upon transmission electron microscopic analysis, these cells were clearly identified as neurons. Neuronal processes, as well as end‐terminals that contained dense‐core and clear synaptic‐like vesicles, were also observed coursing around these cells. It is suggested that some of the supraependymal cells that have been observed in previous scanning electron microscopic studies could be neurons similar to those described here.
Annulate lamellae in hepatic and pancreatic beta cells of the chick embryo
Authors: Benzo Camillo A.
Published: February 2005

This study is concerned with the finding of cytoplasmic annulate lamellae in normally developing avian somatic tissues. Annulate lamellae were observed in hepatic parenchymal and pancreatic beta cells of the chick embryo on days five and eleven, respectively, of egg incubation. The presence of this cytoplasmic membrane system in normal embryonic tissues supports the view that annulate lamellae may represent normally occurring, transitory organelles common to virtually all cells during early embryonic differentiation.
Vinblastine‐induced aggregates of smooth endoplasmic reticulum in proximal tubular cells of rat kidney
Authors: Tyson Greta E. , Bulger Ruth Ellen
Published: February 2005

Vinblastine sulfate was given to adult rats by two tail‐vein injections. After a total treatment time of five hours, kidney cortex was fixed and prepared for examination by routine transmission electron microscopy. Cells of proximal convoluted tubules from treated animals were found to contain focal aggregates of smooth endoplasmic reticulum. Such aggregates were not normally present in cells of control animals. The smooth membranes of these aggregates bear some resemblance to phenobarbital‐induced proliferations of smooth endoplasmic reticulum described in liver cells by many previous investigators, and the suggestion is made that the aggregates described here may reflect a vinblastine‐induced increase within proximal tubule cells of enzymes which function in drug metabolism. That molecules of vinblastine actually entered proximal tubule cells was evidenced by the fact that cytoplasmic microtubules were greatly reduced in number and paracrystals of microtubular protein were occasionally observed.
An ultrastructural comparison of the uptake and transport of horseradish peroxidase by the rat visceral yolk‐sac placenta during mid‐ and late gestation
Authors: Seibel Werner
Published: February 2005

Horseradish peroxidase was used to explore electron microscopically the uptake and transport of protein by the rat visceral yolk sac at 2 minutes, 6 hours, and 12 hours following a single intravenous injection into pregnant rats on day 12 and day 21.5 of gestation.

On both days, the visceral endoderm absorbed peroxidase via micropinocytosis at 2 min postinjection, but not at the 6 and 12 hr intervals. At the latter two postinjection intervals on day 12, peroxidase was localized mainly at two sites, i.e., within intraepithelial supranuclear storage vacuoles, and within the vitelline endothelium deep to the visceral endoderm. On day 21.5 at 6 and 12 hr postinjection, peroxidase was localized in supranuclear storage vacuoles, though most of it was within tubular structures and small vacuoles in the paranuclear and infranuclear cytoplasm of the endoderm. Many dense vacuoles were in close anatomical relationship with the basal cell membrane. Deep to the endoderm a few macrophages were actively engulfing peroxidase, but reaction product was rarely found in the fenestrated vitelline endothelium.

The results presented differ from the previous physiological and anatomical transport studies of the visceral yolk sac in that protein (peroxidase) transport was observed deep to the endoderm during both mid‐ and late gestation.
Hydrolytic enzyme activity during endochondral ossification of secondary cartilage
Authors: Silbermann Michael , Frommer Jack
Published: February 2005

Reactions for hydrolytic enzymes such as aminopeptidase, β‐glucuronidase, N‐acetyl‐β‐glucosaminidase, arylsulfatase and non‐specific esterases indicated various degrees of activity within the chondrocytes of the young mandibular condyle. Most of the reaction products of the above enzymes appeared as discrete granules, which might indicate a lysosomal origin. The most intense activity of these enzymes was observed within chondroblasts and premineralizing hypertrophic chondrocytes. However, chondrocytes within the mineralizing zone also appeared synthetically active. The latter cells, as well as those at the adjacent ossification front, revealed some activity by a majority of the enzymes tested. This could indicate that some metabolic functions, although reduced in degree, continue in the cells of these mineralizing zones of endochondral ossification.

Matrical reactions, with the exception of arylsulfatase and aminopeptidase, were essentially negative. The positive reactions for the latter enzymes might be an indication of their involvement in the process of extracellular mineralization.
The double hemidesmosome: A new intercellular junction
Authors: Listgarten Max A.
Published: February 2005

A new type of intercellular junction was observed between adjacent gingival epithelial cells. The junction appears to be composed of two hemidesmosomes facing one another, with the intervening space occupied by basement lamina material. It is distinctly different from desmosomes or any other intercellular junction described thus far. It is perhaps significant that the combination of two hemidesmosomes into a junction may not result in the creation of a desmosome, but of a rather distinct anatomical structure.
Postnatal growth of the extra‐ and intrafusal fibers in the soleus and medial gastrocnemius muscles of the cat
Authors: Maier Alfred , Eldred Earl
Published: February 2005

Development of intrafusal and extrafusal fibers in the soleus and medial gastrocnemius muscles in kittens was studied in sections stained by van Gieson or histochemical procedures. Cross‐sectional areas of intrafusal and extrafusal fibers overlapped extensively in the two weeks following birth, with the means for intrafusal fibers in the medial gastrocnemius muscle being larger than those for the extrafusal fibers. A definite increase in extrafusal fiber size was seen at 20 days and in intrafusal fibers at 29 days. In the one mother cat studied, mean areas for soleus and medial gastrocnemius fibers were 12 and 59 times larger than those for a kitten sacrificed the day after birth, while the intrafusal fiber areas were 3.0 and 4.8 times greater. The equatorial region in nuclear bag fibers showed no significant growth in cross‐sectional area, but almost doubled in length. In a newborn kitten, all extrafusal fibers in the soleus and medial gastrocnemius demonstrated a high level of nicotinamide adenine dinucleotide diaphorase activity, but with the adenosine triphosphatase reaction, fibers had either low or high activity. After one month, soleus fibers with high adenosine triphosphatase activity were scarce, whereas in the medial gastrocnemius fibers with both low and high levels of activity were present. The intrafusal fibers at birth were already morphologically and histochemically differentiated into nuclear chain and bag fibers, and two varieties of the latter could be recognized in slides treated for adenosine triphosphatase activity.
Experimental evidence indicating that the penis of the rat is innervated by short adrenergic neurons
Authors: Dail William G. , Evan Andrew P.
Published: February 2005

To determine if the penis of the rat is supplied by long or short adrenergic neurons, hypogastric and perivascular neurectomies were performed. Reserpine, a drug which depletes the store of norepinephrine from long adrenergic nerves more rapidly than from short adrenergic neurons, has also been used to aid in characterizing this innervation. Hypogastric neurectomy, with or without denervation of the common iliac vessels, had no effect on the density or fluorescence intensity of adrenergic fibers in the rat penis. The long adrenergic fibers to the atria did not fluoresce in reserpine‐treated rats; however, fluorescent adrenergic fibers in the penis and vas deferens remained visible. Reserpine depressed atrial levels of norepinephrine by 75%, while norepinephrine in the penis and vas deferens was reduced only by 32% and 29%, respectively. The absence of any effect of hypogastric neurectomy on the adrenergic fibers of the penis indicates that such fibers arise from neurons distal to the site of lesion of the hypogastric nerves. This result and the similar response of the vas deferens and penis to reserpine strongly suggest that the penis of the rat is supplied by short adrenergic neurons.
Early hypophysial developmental in the chick embryo
Authors: Hammond Warner S.
Published: February 2005

The purpose of this study was to determine the developmental interrelationships existing between the lobes of the hypophysis and the prechordal mesoderm in the chick embryo.

Using glass needles, operations were performed in ovo on embryos of three to 13 somites. The operative series involved extirpations of the prospective area or precursors of: (1) anterior lobe alone; (2) posterior lobe alone; (3) posterior lobe and the prechordal mesoderm together; and (4) anterior and posterior lobe precursors and the intervening mesoderm.

The results of these experiments indicate that there is a mesodermal‐neural sequence in the inductive process which leads to the development of the anterior lobe. Prechordal mesoderm induces the formation of Rathke's pouch. The latter is then influenced to differentiate through a vascular supply arising from the pial plexus of the infundibular region. Contact of the epithelial and neural rudiments of the hypophysis is not necessary.
The differentiation of white pulp and red pulp in the spleen of human fetuses (72–145 mm crown‐rump length)
Authors: Weiss Leon , Chen Li‐Tsun
Published: February 2005

The development of the white and red pulp in spleen from thirteen human fetuses measuring from 72 mm to 145 mm in crown‐rump length (CRL) was studied using the electron microscope. This period follows the development of the primary vascular reticulum (Weiss, '73).

The white pulp appears first as a periarterial sheath with variable numbers of large and medium‐sized lymphocytes, monocytes, macrophages, and some granulocytes and erythrocytes. It is always rich in macrophages. At 90 to 100 mm CRL, reticular cells closely associated with collagen and having a distinctive dark hyaloplasm appeared first in the endothelium and close about blood vessels and then out in the pulp. In the white pulp they became circumferentially arranged about the central artery while in the red pulp they formed a branching reticulum. Small lymphocytes were present in increasing number in the periarterial lymphatic sheath after the development of the circumferential reticulum. The venous sinuses developed and the marginal zone stood out as an erythrocyte‐rich and macrophage‐rich shell of reticulum surrounding the periarterial sheath.
An improved fixation procedure for microtubules and microfilaments in cells of the anterior pituitary gland
Authors: Warchol Jerzy B. , Herbert Damon C. , Rennels Edward G.
Published: February 2005

A fixation procedure for the preservation of microtubules and microfilaments in anterior pituitary cells is presented. Small pieces of tissue were fixed at room temperature in a glutaraldehyde solution. The temperature was gradually reduced to 4–5°C before the tissue was post fixed. Post fixation was carried out using several changes of a mixture of cold glutaraldehyde and osmium tetroxide and then osmium tetroxide alone. The osmolarity of both fixing solutions was 400 milliosmoles. The procedure permits a clear visualization of both microtubules and microfilaments within anterior pituitary cells, particularly in regions where they are not ordinarily seen such as within the Golgi apparatus.
An ultrastructural study of normal human mammary epithelial cells in culture
Authors: Russo Jose , Furmanski Philip , Rich Marvin A.
Published: February 2005

The ultrastructure of normal human mammary cells cultured from post‐weaning breast fluids is described. Cells from confluent monolayers in two week old cultures were studied. The epithelial nature of these cells was established by the demonstration of a well developed system of cell‐to‐cell interdigitation and numerous desmosomes. These cells also share with breast epithelial cells in vivo, polarity, with blunt short microvilli on the apical surface and an oriented arrangement of organelles in the basal and apical portions of the cells. The Golgi apparatus, which is the most highly developed organelle, is localized in the apical pole and contains substantial quantities of secretory material in the cisternae and vesicles. A variegated palisade of finely granular material mixed with tonofilaments is seen in the basal portion of the cells; many of these tonofilaments end in the terminal web of the desmosomes.

The regular occurrence of these cells in breast fluids during the terminal phases of lactation suggests that their separation is a part of normal breast involution.
Permeability of ovarian follicles and capillaries in mice
Authors: Payer Andrew F.
Published: February 2005

The permeability of ovarian capillaries and follicles in prepubertal and sexually mature (proestrus and metestrus) randomly bred Swiss Albino female mice (SCH:ARS HA ICR strain) was studied by intravenous injection of either ferritin or horseradish peroxidase (HRP), followed by examination with light and electron microscopes. The study revealed that capillaries in the interstitial and perifollicular regions were provided with a continuous endothelium that had constant permeability characteristics irrespective of sexual maturity or phase of the estrous cycle. Horseradish peroxidase left the capillaries primarily through interendothelial cell junctions and was present in all follicles within 30 seconds after administration of the tracer. Ferritin, on the other hand, was absent from endothelial cell junctions, and left the capillaries, at a slower rate than HRP, via cytoplasmic vesicular transport. Both tracers were found in the granulosa cells but rarely in the oocytes. The tracers reached the oocyte through the intercellular spaces between granulosa cells.

These findings demonstrate that the follicular apparatus of the mouse is permeable to ferritin and HRP, and that follicular regions such as the basal lamina of the follicle and the zona pellucida do not stop or retard the passage of either tracer.
Cytopathological effects of estradiol on the arcuate nucleus of the female rat. A possible mechanism for pituitary tumorigenesis
Authors: Brawer James R. , Sonnenschein Carlos
Published: February 2005

Large subcutaneous doses (2 mg/21 days) of estradiol valerate (EV) given over several months will induce a prolactin and growth hormone‐secreting pituitary tumor in female rats. The medial basal hypothalami (MBHs) of such EV‐treated animals were examined at different time intervals with light and electron microscopes to determine whether EV affects the MBH and to relate any observed effects to the process of tumorigenesis.

The MBHs of extensively treated rats exhibited profound glial and neuronal changes. The filament content of astrocytes was greatly increased and large dense pleomorphic inclusions filled both astrocytic perikarya and processes. Degenerating neuronal elements have been observed in the neuropil of extensively treated animals. Dark cells identified as M cells were seen to engage in phagocytosis and were loaded with dense inclusions. Some neurons in MBH contained large quantities of lipofuscin that was different in appearance from that of normal females of the same age. The glial reaction developed gradually. At earlier stages of EV treatment there were fewer reactive glia and these contained fewer inclusions. Myelin figures often occurred in these early inclusions. Reactive glia in EV‐treated rats did not appear in the preoptic area, dorsomedial nucleus or lateral hypothalamus but were found in ventromedial nucleus. Retired breeders and starvation‐stressed rats resembled normal controls.

These pathological changes in MBH may result from a direct effect of EV on the hypothalamus. It is possible that, in addition to its effects on the hypophysis, EV suppresses or injures hypophysiotropic cells in MBH, thus releasing pituitary chromophobes from inhibitory hypothalamic influences. This could result in hypersecretion and neoplasia.
The origin of the follicular capillaries in the human spleen
Authors: Snook Theodore
Published: February 2005

The major arteries which supply the follicular capillaries in the human spleen do not arise as they do in most mammals as lateral or radial branches from the central artery but come from penicillar arteries which penetrate the marginal zone and enter the follicle at various points around its circumference. Such arteries may have a very short course through the red pulp or they may pursue very long courses.

Upon entering the follicle, these arteries branch a number of times, the branches remaining together in a tight array of parallel arterioles along with capillaries formed from them, the whole bundle being enveloped by a reticular fiber sheath. There is thus formed an arteriolar‐capillary bundle. The whole bundle may branch. From the sides, especially from its central end, arterioles and capillaries radiate out to all parts of the follicle to terminate in the marginal zone or in the follicle itself.
A morphological and histochemical study of the developing tongue musculature in the mouse: Its relationship to palatal closure
Authors: Holt Thomas M.
Published: February 2005

Some question exists concerning the ability of the embryonic tongue to undergo reflex movements at the time of palatal closure (15.5 days of development). Functional motor endplates are prerequisite for such movements to occur. Light and ultrastructural cytochemical methods were employed to elucidate the morphology of neuromuscular relationships in the developing mouse tongue. The A/Jax mice used in the experiments demonstrated a 12–20% incidence (seasonal variation) of spontaneous cleft palate, allowing a correlation between normal and teratological processes. Organized myofibrils were first seen in tongues of normal and spontaneous cleft lip‐cleft palate (SCL‐CP) specimens at 14.5 days of development. The thiocholine technique of Karnovsky and Roots was used to demonstrate acetylcholinesterase (AChE) activity at the light microscope level. The Lewis and Schute method was used for ultrastructural localization of this enzyme. Tissues from normal and SCL‐CP specimens from 12.5 to 20.5 days of gestation failed to show differences in amounts or distribution of AChE activity. AChE activity was seen as early as 14 day's gestation. Electron microscopic studies demonstrated reaction product in the endoplasmic reticulum and nuclear envelope of developing myoblasts. AChE activity at the developing neuromuscular junction and the occurrence of myofilaments preceded palatal closure by several days.

Based on these morphological and histochemical findings the tongue of normal and SCL‐CP embryos appears capable of responding to a neurogenic stimulus at the time of palatal closure. The findings suggest that the tongue of animals exhibiting a spontaneous cleft palate is not actively involved in the etiology of this condition.
Capillary innervation in the mammalian central nervous system: An electron microscopic demonstration
Authors: Rennels Marshall L. , Nelson Erland
Published: February 2005

Capillaries in the cat hypothalamus receive axon terminals which are comparable to neurovascular junctions in cerebral and systemic arteries and arterioles. The innervation of capillaries in the central nervous system may be derived from central neurons, in contrast to cerebral arterial vessels, which are supplied by the peripheral autonomic nervous system.
A light and electron microscopic study on the embryonic development of the rat carotid body
Authors: Kondo Hisatake
Published: February 2005

The embryonic development of the rat carotid body was studied with electron microscopy. In the 11 mm embryo a cell aggregation consisting of undifferentiated cells and unmyelinated nerve fibers appears on the anterior wall of the third branchial artery. Granule‐containing cells appear in the 12 mm embryo and continue to increase in number as the cellular aggregation increases in size and becomes separated from the wall of the third branchial artery. Synapse formation and the appearance of fenestrated capillaries occur almost simultaneously at the 17 mm stage. There are two types of synapses, one with membrane densification and vesicles clustered inside the nerve endings, the other with dense material and vesicles inside the granule‐containing cells. At the 20 mm stage the undifferentiated cells send enveloping cytoplasmic processes toward adjacent granule‐containing cells and the carotid body anlage displays rudimentary lobules.
Scanning electron microscopy of normal rat liver: The surface structure of its cells and tissue components
Authors: Grisham J. W. , Nopanitaya W. , Compagno J. , Nägel A. E. H.
Published: February 2005

Scanning electron microscopy (SEM) allows the surface ultrastructure of intrahepatic cells and other tissue components of liver to be delineated. Excellent depth of focus of the SEM makes it possible to visualize surfaces of intact cells in their native configurations. This report details the surface characteristics and inter‐relationships of hepatocytes and hepatic plates, sinusoidal endothelial cells and sinusoids, presumed Kupffer cells, vessels, bile ducts, connective tissue, and the capsule of rat liver. Hepatocytes present three structurally distinctive faces – the intercellular face containing flat surfaces and bile canaliculus, the sinusoidal face, and the connective tissue face which abuts portal tracts and hepatic veins. Sinusoidal endothelium is penetrated by large (1 to 3 μm) and small (0.1 μm) fenestrae, the latter occurring in clusters of up to 50. The width of bile canaliculi and distribution of large fenestrae vary proximodistally along hepatic plate or sinusoid. The cells of portal bile ductules contain microvilli located in linear rows and sparse cilia. Endothelium of hepatic artery and of portal vein is sparsely fenestrated.
Periodic fibrillar material in intracellular vesicles and in electron‐dense bodies in chondrocytes of rat costal and tracheal cartilage at various ages
Authors: Dearden L. C.
Published: February 2005

The occurrence of intracellular fibrillar material (frequently banded) has been studied in normal costal and tracheal chondrocytes of rats at various ages ranging from 1 to 90 days. The study methods have included digestion with collagenase, electron histochemical techniques and routine electron microscopy.

Banded fibrillar material has been observed intracellularly in vesicles or in electron‐dense bodies in perichondrial and subperichondrial chondrocytes from rats of all ages. These fibrils and extracellular collagen fibrils are partially and equally degradable by collagenase, they are positive after staining with phosphotungstic acid or with silver nitrate methenamine, and their lucency corresponds with that of collagen when they are stained only with lead citrate.

They have not been observed in intracellular clefts. They, therefore, seem to be formed intracellularly and to be exocytosed subsequently.

Large vesicles and electron‐dense bodies seem to be derived from Golgi saccules. A mechanism whereby banded intracellular fibrils could be formed from tropocollagen molecules is postulated. The frequency of occurrence and the diameter of intracellular fibrils seems to increase with increasing age.
Morphological diversity of oocytes released from the adult mouse ovary
Authors: Swartz William J. , Schuetz Allen W.
Published: February 2005

This study was designed to classify and differentiate the population of oocytes released from the mouse ovary by mechanical means. Liberated oocytes were classified on the basis of their number, size and by the nature of the attachment of follicle cells to these oocytes. Microscopical examination of oocytes mechanically released from the ovaries revealed three distinct morphological classifications of oocytes: (1) those completely devoid of follicle cells, (2) those encased in follicle cells and (3) those in the process of degeneration. Oocytes ranged in size from approximately 30μ to 119μ. Those oocytes surrounded by follicle cells could be further subdivided into two groups depending on whether the follicle cells could be mechanically removed from the oocyte. These data demonstrate that the adult ovary contains a variety of classes of oocytes which differ in size and in the extent to which the follicle cells are attached to the oocytes. It is suggested that the metabolic activities and meiotic potentials of the various oocyte populations differ and as a result, care should be employed to insure a uniform population of oocytes when conducting further studies with mechanically liberated oocytes.
The cytochemical localization of adenyl cyclase activity in rat sublingual gland
Authors: Kim S. K. , Han S. S.
Published: February 2005

Adenyl cyclase activity in mucous acinar cells and serous demilune cells of the rat sublingual gland was localized cytochemically. After incubation with adenylyl‐imidodiphosphate (AMP‐PNP) as substrate, deposits of reaction product are found along the cell membranes bordering the secretory surfaces of serous demilune cells. These are the membranes which participate directly in secretion by fusing with the granule membranes. The granule membranes of the demilune cells do not reveal reaction product, but the membranes of the granules which are fused with and become part of the cell membrane do show deposits. Thus, it appears that the cell membranes which fuse with granule membranes during secretion are associated with a high level of adenyl cyclase activity. In support of this, the luminal membranes of the mucous acinar cells which do not fuse with granule membranes during secretion are not associated with detectable amounts of adenyl cyclase activity.
The programming of canalization in fetal lungs of man and monkey
Authors: Boyden Edward A.
Published: February 2005

In the monkey lung (Macacus nemestrina) canalization of all bronchopulmonary segments begins simultaneously at the peripheral future‐alveolar‐duct portions of each segment and then continues progressively centralwards. Its simultaneous appearance in all segments of a human lung of the 17th postovulatory week (19th postmenstrual week) has now been confirmed (cf. Boyden, '74). The mode of canalization, as seen under the light microscope, is here demonstrated.