bluuebunny/crossref_metadata_2025 huggingface dataset:
A degeneration study of efferent connections of the habenular complex in the opossum
Authors: Way John S. , Kaelber William W.
Published: February 2005

Parts of the medial and lateral habenular nuclei were removed unilaterally in each of thirteen opossums and the brains were studied for fiber degeneration by a modified Nauta method. Degeneration was seen in the ipsilateral, but not the contralateral, habenulopeduncular tract, which at the level of the interpeduncular nucleus underwent a partial decussation over it, whereas there were almost no degenerating fibers in the nucleus itself. Caudal to the nucleus extensive degeneration was present bilaterally among nuclei of the raphé and this extended into the predorsal fasciculus. Many terminals were observed in the nuclei of the raphé and within the deep tegmental nucleus. Although degenerating fibers were seen in the region of the dorsal tegmental nucleus, no terminals could be identified with certainty. Degeneration was also present in the superior colliculus.

Bilateral degeneration occurred in the stria medullaris and extended to the preoptic area and the olfactory tubercle. In the dorsal preoptic area a small, but quite definite fiber bundle, separated from the posterior surface of the stria medullaris, traversed the lateral hypothalamus and passed dorsal to the mammillary bodies into the midbrain tegmentum, where it became intermingled with fibers of the habenulopeduncular tract just ventral to the red nucleus.

Findings appear to indicate that in the opossum relatively few, if any, fibers of habenular origin terminate in the interpeduncular nucleus. In addition, fairly substantial evidence has been obtained to show that there are a number of efferent fibers within the stria medullaris.
The fine structure of granular cells in the uterine endometrium of the rhesus monkey (Macaca mulatta) with a discussion of the possible function of these cells in relaxin secretion
Authors: Cardell Robert R. , Hisaw Frederick L. , Dawson Alden B.
Published: February 2005

This report describes in detail the fine structure of a unique granular cell, termed “granulocyte,” which populates the endometrium of the monkey uterus under certain physiological conditions. Morphological evidence is presented which establishes that this cell is similar, if not identical, to granular cells found in the uteri of a wide variety of vertebrate species, including the human. Evidence supporting the hypothesis that these cells secrete relaxin is reviewed.

The granulocyte is nearly spherical, approximately 10 μ in diameter, and contains an eccentrically located, kidney‐shaped nucleus approximately 6 μ × 8 μ in size. Opposite the concave surface of the nucleus is located a cluster of specific granules. The granules vary in diameter, but they rarely exceed 0.5 μ. Each granule is surrounded by a unit membrane, and often a space is present between the enveloping membrane and the granule proper. Smaller vesicles and dense bodies (approximately 0.1 μ in diameter) are found within this space. The morphology of these small vesicles and dense bodies suggests that they have their origin in the Golgi complex and are involved in transporting some material to the specific granules.

Similarities of the granulocyte to other cells types found in uterine endometrium, particularly eosinophilic leucocytes, are pointed out, but it is argued that the fine structure of the granulocyte provides good evidence that this is a distinct uterine cell type.
Cephalometric growth analyses of the human upper face region during the last two trimesters of gestation
Authors: Burdi Alphonse R.
Published: February 2005

This study was designed to demonstrate quantitative growth trends in the human upper face region before birth. Photographs of 68 sagittally sectioned fetal heads were measured using a series of linear and angular measurements for changing height, length and shape. Cross‐sectional types of data were treated with a statistical model which tested for linearity of the data, correlation between growth changes and increasing fetal age, significance of the differences between rates of change in related upper face regions and the general significance of the trends shown in the study.

Pooled data for the second and third trimesters suggested three distinct growth trends. Linear measurements of the cranial base, nasal area, and plate correlated significantly with increasing crown‐rump length. Finally, a composite upper face profile for the sample suggested a relative migratio of the region downward and forward away from the anterior cranial base and the hypophyseal fossa. These three trends collectively demonstrated that the pattern of upper facial growth before birth involves progressive enlargement of a relatively static profile. It should be understood that this pattern is a group trend as shown by cross‐sectional sampling of many individuals over a period of time with no individual being measured more than once. Conversely, variabilities in a specific individual's growth are most appropriately demonstrated by measuring that individual several times throughout some time span, i.e., by longitudinal sampling. Studies of the human fetus are restricted generally to the cross‐sectional sampling technique.

The close similarly of these prenatal trends with those reported for postnatal craniofacial growth suggests that certain patterns of facial growth in childhood can be seen as early as the beginning of the fetal period and emphasizes the continuum of human development.
An electron microscopic study of initial intramembranous osteogenesis
Authors: Bernard George W. , Pease Daniel C.
Published: February 2005

Calvariae of fetal mice were investigated with electron microscopy in order to demonstrate initial stages of immature, membrane bone calcification. As a consequence, nucleation sites for initial calcification of hydroxyapatite crystals in woven bone were found in extrusions from osteoblasts within the osteoid. Growth of the crystals epitaxially from these initial calcification loci into the surrounding collagen was spherulitic, forming discrete spheres referred to as “bone nodules”. These nodules, when coalesced, formed seams of bone. Decalcified, the organic substructure of the bone nodules was revealed. It contained a centrally disposed initial calcification locus, a peripheral zone of decomplexing collagen and an intermediate zone of altered collagen. Fully formed collagen fibrils remained interposed between most of the coalesced nodules. Polysaccharides were localized within the initial calcification locus and in the peripheral zone of the bone nodules where collagen was shown to be decomplexing.
The innervation of the umbilical vein in human embryos and fetuses
Authors: Pearson Anthony A. , Sauter Ronald W.
Published: February 2005

In human embryos and fetuses, a small bundle of nerve fibers from the anterior and posterior vagal trunks descends between the layers of the hepatogastric ligament. These fibers pass to the region of the junction of the umbilical vein with the ductus venosus. At this junction, there is a slight thickening of the muscular wall. Nerve fibers pass to this junction and the proximal portion of the umbilical vein.

Fibers from the posterior vagal trunk follow the left gastric artery to the celiac plexus. Fibers from this plexus follow the hepatic artery into the lesser omentum and along the portal vein to the liver. Continuing along the left branch of the portal vein, fibers reach the proximal portion of the umbilical vein and its junction with the ductus venosus.

Ganglion cells were observed along the course of vagus nerve fibers to the umbilical vein. In embryos these cells were observed on the lower end of the anterior vagal trunk near the attachment of the upper end of the lesser omentum to the lower end of the esophagus. In older fetuses they were found in a small ganglion in the connective tissue surrouding the distal end of the ductus venosus.
The pattern of the terminal air spaces in a premature infant of 30–32 weeks that lived nineteen and a quarter hours
Authors: Boyden Edward A.
Published: February 2005

The availability of a perfectly preserved lung from a premature infant of 30–32 weeks that lived nineteen and a quarter hours has made possible the first wax reconstructions of the terminal air spaces in the canalicular period of fetal growth. Here, as in the newborn, the most distal respiratory bronchioles give rise to two pairs of clusters of saccules, but with this difference: each saccule (lined by flat epithelium) is separated from others by a spongy, vascular, connective tissue matrix. By reconstructing just the cavities of the saccules one can study the bizarre shapes presented by the saccules. In pattern the latter closely resemble peripheral alveolar saccules of the child lung modelled by the writer. Seemingly, therefore, this fetal period is the one in which the terminal generations of branches are being elongated and their shapes determined by invading capillaries and connective tissues. Clinically, one may conclude that peripheral diffusion of gases (in the infant or adult lung) does not follow any such simple dichotomous pattern of flow as has been hitherto assumed.
Light and electron microscopy of diet‐induced atrial thrombosis in TS mice. I. Primary changes in the endocardium
Authors: Lockwood W. R. , Clower Ben R. , Hetherington Frances
Published: February 2005

Light and electron microscopic studies were made of atria of mice (TS stock) fed either a normal diet or one high in fat (28% lard), low in protein (8% casein) and hypolipotropic. After four weeks on the high fat diet there was a pronounced thickening and splitting of the endocardial basement membrane into several layers. Concurrently the basal surface of atrial endothelium became indented and irregular. By 5–6 weeks numerous villous projections were present on the luminal surface of endothelial cells at sites other than at cell junctions, and vacuolization of endothelial cells had developed. Vacuole formation began on the basal surface of atrial endothelial cells. Closure of the indentations on the basal surface of endothelial cells seemed to produce the vacuoles. At seven weeks there was degeneration of the endothelial cells and atrial myocardium, with severe swelling of the mitochondria adjacent to unorganized thrombi. After 8–9 weeks small organizing atrial mural thrombi were observed attached to the atrial wall. Growth and organization of the lesion eventually filled the entire atrial lumen. After 20 weeks on the fat diet, 92% of the mice had large atrial thrombi. Control mice did not develop the above changes.
Studies of Brunner's glands in the opossum. II. Postnatal development
Authors: Krause William J. , Leeson C. Roland
Published: February 2005

The postnatal development of Brunner's glands in the opossum has been traced, using 170 specimens divided into 21 groups according to snout‐rump length. The newborn opossum has a well developed small intestine, possessing villi and a differentiated intestinal epithelium with concentrations of PAS‐positive material in the apical cytoplasm. The ducts of the glands begin to develop within 24 hours after birth and, as they proliferate, two cell types appear. A tall, columnar cell type lines the excretory duct whereas the intralobular duct system is lined by pyramidal cells. Intralobular ducts undergo differentiation by the 50 mm stage and, after this event, secretory units appear as outgrowths from the intralobular duct system. Development continues into early adulthood.

Duodenal glands appear to evaginate simultaneously at localized foci, resulting in the formation of a duodenal sinus between glandular elements. The glands evaginate from the mucosa in the most proximal portion of the duodenum, involving both intestinal and gastric mucosal elements. That portion of mucosa lying between the forming glands is submerged and forms the floor of the duodenal sinus. Excretory duct epithelium often lines the sinus in part. The development of Brunner's glands in the opossum is completely independent both of pyloric and intestinal glands.
Factors influencing villus size in the small intestine of adult rats as revealed by transposition of intestinal segments
Authors: Altmann Gabriel G. , Leblond C. P.
Published: February 2005

As an index of villus size, the number of epithelial cells per representative villus section was counted in longitudinal sections of the rat small intestine. Villus size was found to decrease gradually along the length of the small intestine, with villi being nearly three times as large in upper duodcnum as in terminal ileum. The influence of various surgical operations on villus size was then examined.

In ileal segments inserted into the jejunum, villi enlarged to the size of local jejunal villi. In jejunal segments inserted into the ileum, villi decreased almost to the size of local ileal villi. Thus, villus size was influenced by the environment, that is, most probably by the different types of chyme in jejunum and ileum.

In duodenal segments inserted into the ileum, villi did not decrease in size, and distally located ileal villi enlarged. This and other experiments indicated that the duodenum produced secretions which not only neutralized the villus‐reducing effect of the ileal environment, but also exerted a potent villus‐enlarging effect. Pyloric secretions had a similar villus‐enlarging effect.

Segments of intestine were made into blind sacs by closing their proximal end and joining their distal end to the colon, so as to remove the influence of the chyme. Villus size decreased in sacs of jejunum and lower duodenum (without the duodenal papilla), but increased in sacs of ileum. Thus in the three types of sacs, there was a tendency for villi to acquire an intermediate size.

In conclusion, an intermediate villus size, which is postulated to exist in chyme‐free, non‐functional intestine, would normally be modified by two types of factors: villusenlarging factors present mainly in pyloric and duodenal secretions, and villus‐reducting factors present in the ileal chyme. Interaction between these factors would result in the gradient of villus size along the small intestine.
The morphological effects of parathyroid extract upon the developing skeleton of the embryonic chick
Authors: Jones Helena S.
Published: February 2005

The in vivo effects of parathyroid extract (PTE) on the formation of the embryonic chick humerus and femur were examined. PTE had a considerable effect on mortality (increased) and ossification (inhibited). Group I embryos were injected with 0.1 ml PTE on day 4 of incubation; their survival rate was 71% which encompassed the experimental period through day 15. Group II embryos were injected with 0.1 ml PTE on day 6; only 32% survived through day 7 and none were alive after day 9. Until the effects of PTE were overcome as seen in Group I nine‐day embryos, PTE (1) inhibited ossification, (2) retarded development of the cartilage model and (3) caused chondrolysis of the capsular matrix in the zone of cellular hyperthrophy. PTE did not appear to cause (1) increased formation of osteoclasts, (2) formation of fibrous connective tissue instead of osteoid or (3) reversion of bone cells to a more primitive or multipotential bone type. It is suggested that the toxic effect of PTE on Group II embryos relates to its application at a critical stage of development.
Cytology of the pars anterior of the bovine adenohypophysis
Authors: Heath Everett
Published: February 2005

Selected samples from the pars anterior of 2 lactating cows, 2 normal calves, 3 thyroidectomized calves, and 12 heifers at different stages of the estrous cycle or in early pregnancy were examined by electron microscopy. Adjacent thick sections were differentially stained and routinely examined by light microscopy.

Two acidophilic cell types were distinguished. One had granules with maximum diameters between 350 and 500 mμ. The other, containing granules with maximum diameters between 550 and 750 mμ, was frequently seen in lactating cows and midcycle or pregnant heifers.

Basophilic cell types were not so clearly distinguishable. PAS‐positive, Alcian bluenegative basophils were most frequently seen in proestrous heifers, but basophils with Alcian blue, PAS‐positive granules were also present, and in some of these the granules were morphologically similar to those of the PAS‐positive cell type. Globular bodies, morphologically similar to those reported in amphibia but negative for acid phosphatase, were routinely observed in some of the Alcian blue, PAS‐positive basophils.

The most significant change in estrous heifers and thyroidectomized calves was the development of large chromophobes with an extensive dilated rough endoplasmic reticulum. It was not possible clearly to relate these chromophobes individual basophilic cell types.
The trigeminal mesencephalic nucleus. II. Electron microscopy
Authors: Hinrichsen Colin F. L. , Larramendi Luis M. H.
Published: February 2005

The fine structure of cells in the trigeminal mesencephalic nucleus was examined in adult mouse and cat. Cell surfaces were studed with small spinous processes which were free of synaptic contacts. Some cells in soma‐soma and axosomatic contact were joined by maculae and membrane fusions resembling in cross section the zonula adherens and macula occludens of epithelial cells. Synapses containing three distinct morphological types of vesicles contacted the cell soma. The possible functions of synapses and membrane fusions were discussed.
The small pyramidal neuron of the rat cerebral cortex. The perikaryon, dendrites and spines
Authors: Peters Alan , Kaiserman‐Abramof Ita R.
Published: February 2005

The small pyramidal neurons of layers II and III of the rat parietal cortex have been examined with both Golgi staining and electron microscopy. The cell body contains a large nucleus and only a thin rim of cytoplasm in which the Nissl substance is not well developed. A cap of Nissl substance occurs at the base of the apical dendrite, however, and a number of cisternae of the Golgi apparatus occur in this same location. A centriole is often found here too, so that this region of the neuron represents the cell center. Little Nissl substance occurs in the dendrites, which mainly contain well‐ordered arrays of microtubules.

Projecting from the stem of the apical dendrite and from the secondary dendrites are spines. Basically, the spines are of three types. The most common ones have long, thin stalks and small end bulbs. The least common ones are mushroom‐shaped and have thick stalks ending in large bulbs. The other spines are short and stubby, and have no well‐defined stalk. The distribution of these three types of spines has been determined. Although they are rare, spines may also project from the cell body, which has very few synapses on its surface.
Ultrastructure of the amnion and amniotic plaques of the white‐tailed deer
Authors: Sinha Akhouri A. , Seal Ulysses S. , Erickson Albert W.
Published: February 2005

The ultrastructure of the aminon and aminotic plaques of the white‐tailed deer was studied throughout pregnancy. The single layered amniotic epithelium had short, blunt, club‐shaped microvilli, tortuously folded lateral plasma membranes enclosing an intercellular space, and basal foot‐procsses. Wherever lateral plasma membrane processes abutted, desmosomes occurred. Hemidesmosomes were observed only in association with the foot‐processes. The epithelium contained granular endoplasmic reticulum, rod‐shaped mitochondria, free ribosomes, Golgi complexes, tonofibrils, tonofilaments and glycogen granules. The epithelium was supporte by a basal lamina. The subjacent connective tissue layer contained mesenchymal cells, fibroblasts and collagenous fibers.

The amniotic plaques varied in size from microscopic to 4 mm in diameter. The small plaques were formed by mitotic activity of the aminion cells. their sites of formation appeared randomly distributed. Each microscopic plaque had one to three layers of basal columnar to cuboidal cells, and a single layer of covering cells next to the amniotic cavity. Further mitotic activity of basal columnar cells led to the formation and differentiation of large plaques which contained over 15 cell layers. The main mass of a large plaque showed four zones: stratum basale, stratum spinosum, stratum granulosum and stratum corneum. Cytoplasmic organelles were plentiful in the basal and spinous cells, but were sparse in the granular and cornified layers. Keratohyalin granules and dense tonofibrils were usually found in the granular cells, but only occasionally in cornified cells. Each plaque contained varying amounts of PAS‐positive glyucogen granules. The tortuously folded lateral plasma membranes enclosed intercellular spaces which extended from basal to cornified layers. Small portions of amniotic cells and layers of cornified cells sloughed throughout pregnancy and thus contributed to the composition of amniotic fluid. The homology of the plaques with mammalian skin and their distribution in the eutherian mammals is discussed.
Experimental studies on the dorsal nerve of the penis of the rat
Authors: Calaresu Franco R.
Published: February 2005

Dorsal nerves of the rat penis were studied in osmium tetroxide‐treated sections for number and diameter distribution of myelinated fibers. The mean count in four nerves was 1423 fibers. The percentage distribution of diameters was unimodal with the peak at 5‐6 μ. Counts taken at different levels of the nerve showed a proximo‐distal decrease in the number of fibers but no difference in the percentage a distribution of fiber diameters. The compound action potential of the dorsal nerve exhibited potential waves with conduction velocities between 62 and 10 meters/second, which correlates well with the histological data. Counts of myelinated fibers in the dorsal nerve of four animals 14, 26, 38 and 70 days after section of the ipsilateral pudendal nerve revealed complete degeneration at 14 days, progressive regeneration at 26 and 38 days, and complete recovery at 70 days. The percentage distribution of diameters in the nerves at different stages of regeneration was essentially the same. The rate of regeneration expressed as percentage of the total number of fibers from day 14 to day 36 was approximately 1.2% day and from day 36 to day 70 approximately 2.2% /day.
Regeneration of the rat gastrocnemius muscle from sibling and non‐sibling muscle fragments
Authors: Carlson Bruce M.
Published: February 2005

Regeneration of the gastrocnemius muscle from minced transplanted muscle fragments was studied in 46 rats. The jumping complex of muscles (gastrocnemius, soleus and plantaris) was removed from the donor and minced into 1 mm3 fragments. In one experimental series minced muscle was orthotopically implanted into sibling animals, and in the other series minced muscle was implanted into non‐sibling animals of the same strain. During the first week after implantation, regenerative activity in the homotransplanted muscle fragments was intense and did not differ histologically from that occurring in autotransplanted muscle. Staritng in the second week, areas of regenerating homotransplanted muscle fibers became infiltrated with small lymphocytes. Despite relatively massive cellular rejection in the regenerates, individual skeletal muscle fibers regenerated to maturity. Regenerates from homotransplanted muscles often attained the same gross from as regenerates from auto‐transplanted material, but in no case was the amount of muscle fibers in homografted regenerates greater than 50% of that seen in regenerates arising from autografted muscle fragments. About half of the advanced regenerates were reduced to broad bands of connective tissue containing no muscle fibers.
Electron‐dense material within sarcoplasmic reticulum apposed to transverse tubules and to the sarcolemma in dog papillary muscle fibers
Authors: Walker S. M. , Schrodt G. R. , Edge M. B.
Published: February 2005

The space between the sarcoplasmic reticulum (SR) apposed to the transverse (T) tubules and the sarcolemma in dog papillary muscle fibers is traversed by structures of varying densities. The distance between apposed membranes is about 70 Å at the level of densities and about 100 Å at the level of less dense areas that alternate with the densities. The apposed SR shows a marked increase in electrondense material when comparison is made with the SR not apposed. The electron‐dense material is located in a dense layer parallel to and about midway between the membranes of the apposed SR and in numerous projections from the inside surface of the membranes. With appropriate staining procedures the central dense layer and the projections are as thick as membranes and they frequently show paired densities separated by a distance about equal to the distance between the outer dense layers of trilaminar membranes. The paired densities in the central dense layer and in the projections indicate that the electron‐dense material within apposed SR has structure. The projections are frequently in register with scallops or serrations in the SR membranes and they also appear to contribute to a waviness in the central dense layer. The serrations and waviness are interpreted as evidence that the projections exert a holding force because they project from the SR membranes and connect with the central dense layer.
Human choroid plexus: Morphologic and histochemical alterations with age
Authors: Shuangshoti Samruay , Netsky Martin G.
Published: February 2005

The choroid plexus was studied in 217 necropsy specimens from human beings two months to 94 years of age. With advancing age, the height of the cuboidal epithelial cell gradually decreases, many becoming squamous. Cytoplasmic vacuoles increase in number. Focal stratification is not an artefact, and is evidence of proliferation. The proliferated cells eventually desquamate, becoming round, large and foamy as they accumulate intracytoplasmic lipid and degenerate. The findings indicate that cellular desquamation occurs during life. Filaments of mucopolysac‐charides are common in the choroid plexus of old people. Stromal alterations associated with increased age consist of a gradual increase in the amount of connective tissue, in number of meningocytes and psammoma bodies, and in severity of hyalinization, fibrosis, fragmentation of connective tissue fibers and calcification. Most psammoma bodies are found in the glomus choroideum. Non‐lamellar calcific foci occur mainly in the matrix of the choroidal villi and fronds. Formation of psammoma bodies is associated closely with the meningocytic whorls. Lipids, mucopolysaccharides and mucins are identified in both epithelial and stromal components of the choroid plexus. Lipids appear in the stroma later in life. It is suggested that lipid in the cytoplasm of desquamated choroidal eipthelial cells is one source of lipids in the cerebrospinal fluid.
Morphogenetic studies of the rabbit XLI. Gradients of correlation in the architecture of morphology
Authors: Sawin P. B. , Fox R. R. , Latimer H. B.
Published: February 2005

Significant sex and strain differences in correlation of bone, body and skeletal weights show significant localized effects of sex and strain and a combination of both. Individually they seem to lack biological meaning. However, when considered in relation to the ponderal correlations, of which they are a part, they fall into place at the distal ends of a graded linear correlation series, both within and between limbs; and similarly between mandible and sacrum, respectively, with each bone of both limbs. The pattern of these gradients reveals a linear decline in correlation of bones with distance (rule of neighborhood, Karl Pearson) in most cases, but the exceptions are such as can be related to the functions in which they cooperate. In this way they demonstrate at least two major unifying genetic influences. One associates sex and strain with locomotion and the other with the incipient upright investigative posture of the Lagomorphs (including the rabbit). The expected effect of sex on the pelvis is apparently not expressed by these ponderal measurements. The manner in which this correlation approach, based on well established genetic growth differences, converges with the phylogenetic and ontogenetic concepts of normal and abnormal growth of bone in limbs and cranio‐facial development suggests that a combination of correlation and epigenetic analysis would be helpful in establishing a sound genetic background for the newer biomechanic, functional matrix and architectonic approaches.
Afferent nerve endings in the urinary bladder of the cat
Authors: Fletcher Thomas F. , Bradley William E.
Published: February 2005

In five cats, sacral dorsal rhizotomies were performed, alone or in conjunction with sympathetic nerve transections. Urinary bladders, collected 7, 10, or 30 days following the nerve transections, were sectioned and stained by the Holmes silver nitrate and the Nauta and Gygax methods and examined under the light microscope. Degenerative changes occurred in bladders of all the cats permitting an assessment of the appearance and distribution of vesical sensory endings. Degenerated myelinated axons and nerve terminals were found bilaterally in bladders, although they were more numerous ipsilateral to the transections. Within the muscle coat, degenerated endings were found in the perifascicular connective tissue, and less frequently, on the surface of muscle fascicles; endings were not seen among the muscle cells within a fascicle. Sensory endings were identified in the subserosa and lamina propria but not in transitional epithelium. Except for an occasional Paccinian corpuscle, encapsulated endings were not found. Afferent endings in the bladder appeared to be non‐encapsulated and without terminal fiber modifications.
The litter effect as a variable in teratologic studies of the albino rat
Authors: Jensh Ronald P. , Brent Robert L. , Barr Mason
Published: February 2005

This study was conducted to determine if there is a greater variation in fetal weight and/or placental weight among litters of rat fetuses than within a single litter. Three hundred and twenty‐seven litters comprising 1,979 fetal and placental weights were analyzed using analysis of variance within versus among litters. There was a definite litter effect, i.e., variation in fetal and placental weight was greater (p < 0.05) among litters than within litters. The variation in fetal and placental weights between litters became greater with increasing litter size. Experimentally limiting the litter size early in gestation does not reduce or eliminate the litter effect. This litter effect means that individual fetuses from several rat pregnancies cannot be considered to have come from a common universe and, therefore, the number of litters and their mean growth data are much more meaningful than the number of embryos in an experiment. When designing research programs in which embryonic and placental growth in rats are to be evaluated, it is more important to establish the experimental goal on the basis of the total number of litters rather than the total number of embryos per experimental or control group.
Histology of the subauricular and rump glands of the pronghorn (Antilocapra americana ord)
Authors: Moy Randall Frank
Published: February 2005

Subauricular and rump glands of pronghorns (Antilocapra americana) collected during every month of the year, were examined histologically. In early spring the apocrine and sebaceous zones of the paired subauricular glands, which are found only in males, proliferate abruptly. These zones continue to enlarge and become highly secretory during the summer; they regress during the fall and are quiescent in December. During the peak of activity large sebaceous storage vesicles are present and copious amounts of secretory material occupy the apocrine lumina. Irregular clumps of cells that are associated with the apocrine tubules are numerous in summer and appear to be associated with apocrine secretory activity. The subauricular glands of castrated bucks are small and inactive compared to normal glands. Annual proliferation and regression of the subauricular glands follows similar activities of the testes. Thus, the cycle of activity in these glands is apparently controlled by gonadal hormones. Odors from the subauricular glands may serve for sex recognition, stimulation, and marking of territories. The paired rump glands consist of lobulated sebaceous units and coiled apocrine tubules that maintain limited secretory activity throughout the year. Contraction of large arrector pili muscles associated with hairs in the glands may cause accelerated secretion. The rump glands of normal males, females, and castrated males, are similar in all respects. Apparently these glands are not sexually influenced. The rump glands may serve for olfactory warnings in conjunction with the visual warnings of the white rump patch.
The prenatal development of the human femur
Authors: Gardner Ernest , Gray D. J.
Published: February 2005

The study reported here is the result of a detailed investigation of the changes in shape of the femur with growth and torsion, the type, rate and character of ossification, and the onset, subsequent course, and general features of remodeling.

Forty pairs of femurs, from a series of embryos and fetuses ranging from 26 to 342 mm in crown‐rump length, were measured, radiographed, and sectioned for microscopic study.

A primary bony collar was present before the end of the embryonic period, and in a 27 mm embryo it extended for about one‐fifth of the length of the femur. Erosion of the collar was evident at 34 mm. and invasion and destruction of calcified cartilage were occurring by 37 mm. Cartilage canals first appeared in the proximal epiphysis at 57 mm and in the distal epiphysis at 61 mm.

Along with the progression of endochondral ossification proximally and distally and the establishment of growth zones, periosteal bone formation also proceeded in both directions, and, until 275 mm, extended about 1 mm beyond the zones of cartilage destruction. After 275 mm, the extents of periosteal and endochondral ossification were the same and at term occupied almost four‐fifths of the length of the femur.

Trabeculation of the bony collar was first noted at 37 mm. Fusion of endochondral trabeculae with the inner aspect of the periosteal shell began by 61 mm. A central marrow cavity free of trabeculae was present at 86 mm and thereafter. Evidence of reconstruction appeared in both proximal and distal ends by 92 mm, and was consistently present in both ends in all specimens of 111 mm and larger.
Electron microscopic changes following canine cardiac allografts: The effects of irradiation
Authors: Weymouth Richard J. , Seibel Hugo R. , Craig Shirley S. , Graham Walter H. , Lower Richard R.
Published: February 2005

Orthotopic cardiac allotransplantation was performed on ten adult mongrel dogs. At the time of acute rejection (decline in QRS voltage to at least onehalf of the post‐operative level) a cardiac biopsy was removed from the left ventricle of each dog and followed by 300 r of local x‐irradiation on five consecutive days. After a full course of x‐irradiation (1500r) to each dog a second biopsy was removed from the left ventricle. In this way, each dog acted as its own control in order to determine the effects of x‐irradiation on cardiac transplants and the rejection phenomenon. The electron microscopic findings at the time of acute rejection involved primarily the myocytes and their cellular organelles in that the A, I, and Z bands were less distinct and there was significant enlargement and cytological distortion of the mitochondria, endoplasmic reticulum and T tubules. Endothelial hyperplasia of the smaller blood vessels was also more apparent in the pre‐irradiation biopsies. Following irradiation the ultrastructural changes appeared to be reversed in six of the ten dogs; mitochondria and other organelles of the myocytes were more normal and the banding of the fibers was more distinct. Vascular alterations were less and the tissue approached normal cytological architecture. Pre‐ and post‐irradiated cardiac tissues were not different in two animals and in two other animals the post‐irradiated tissues appeared more abnormal than those showing acute rejection. Local irradiation as a method of immunosuppression in cardiac transplants is discussed.
Repair of the external granular layer after postnatal treatment with 5‐fluorodeoxyuridine
Authors: Shimada Morimi , Langman Jan
Published: February 2005

Repair of the external granular layer, damaged by prenatal treatment with methylazoxymethanol, has in previous experiments been shown to be successful; by postnatal day 20 little difference in cerebellar architecture could be detected between treated and control animals. In the present experiments repair of the external granular layer was studied after postnatal treatment with 5‐fluorodeoxyuridine (FUdR), a drug known to interfere with DNA synthesis. Two‐day‐old mice were injected with various doses of this compound and sacrificed at successive time intervals after treatment.

A striking difference in response to the treatment was noted between the anterior, intermediate and posterior lobes of the cerebellum. In the anterior lobes 5‐FUdR caused almost complete destruction of the external granular layer and few if any surviving cells were noted. During subsequent days repair of the layer was minimal and a grossly abnormal cytoarchitecture resulted. The Purkinje cells were dispersed throughout the molecular layer and the (internal) granular layer contained only a few cells. In the posterior lobes (particularly in the uvula) 5‐FUdR destroyed many external granular cells but the surviving cells reconstituted a new layer and the normal architecture was temporarily reestablished. Many cells of this new layer migrated centrally to become neurons, but others stopped in their migration halfway through the molecular zone, forming a heterotopic granule cell layer. In the intermediate lobes a thin molecular layer was present, but the Purkinje cells were widely dispersed and separated from each other by light and dark nucleated cells. It is thus concluded that repair of the external granular layer after postnatal damage is minimal in the anterior lobes and most advanced in the posterior lobes; in the intermediate lobes repair was seen but the cytoarchitecture was abnormal.
On the histogenesis of the ovarian interstitial gland in rabbits. I. Primary interstitial gland
Authors: Mori Hiroshi , Matsumoto Keishi
Published: February 2005

Ovaries from rabbits one to three months old were examined to demonstrate the histogenesis of ovarian interstitial cells.

Electron micrographs showed that “primary interstitial gland cells” with abundant agranular endoplasmic reticulum were present prior to appearance of follicular atresia and that extensive development of the agranular endoplasmic reticulum and accumulation of lipid droplets occurred in the epithelial cells of medullary cords and granulosal cell nests. Therefore, it was concluded that the “primary interstitial gland” of juvenile rabbit ovaries is of epithelial origin, derived from the medullary cords and the granulosal nests, although the “secondary interstitial gland” is considered to arise from the theca interna of atretic follicles.

This conclusion was confirmed by biochemical and histochemical demonstration of 3β‐hydroxysteroid dehydrogenase, an enzyme system necessary for steroid biosynthesis. The activity of 3β‐hydroxysteroid dehydrogenase increased significantly at two months when the agranular reticulum began to devlop in epithelial cells. Histochemical findings showed that the cells having the enzyme activity were consistent with the cells containing a large quantity of lipid.
Ultrastructure of the bone marrow of the frog
Authors: Campbell Ferrell R.
Published: February 2005

The structure of hematopoietic marrow of the frog, Rana pipiens, was studied by electron microscopy. Lining cells of the sinus wall lack a basal lamina and are not phagocytic. Phagocytic cells of the marrow are found free in the lumina of sinuses and in the extravascular tissue. Heterophil leucocytes, during their differentiation, possess a single population of granules; mature granules are elongate bodies having a crystalline content. Eosinophil leucocytes also have a single population of granules; the granules are round and have a homogeneous content.
Secretory processes in follicular cells of the bat thyroid. I. Ultrastructural changes during the preearly and mid‐hibernation periods with some comments on the origin of autophagic vacuoles
Authors: Nunez Eladio A. , Becker David V.
Published: February 2005

Ultrastructural changes which occur in bat thyroid follicular cells between late August and early January are discussed. During the first half of this period the principle changes are proliferation of the granular endoplasmic reticulum, an increase in size of the Golgi apparatus and an increase in the number of apical vesicles. These changes are followed by a gradual reduction in the amount of endoplasmic reticulum and in the size of the Golgi complex. During the expansion phase of the granular endoplasmic reticulum, large numbers of dense granules, and “light” and “dark” multivesicular bodies are present throughout the cytoplasm of the follicular cells. An unusual finding is that in the bat, the thyroid follicular cells also contain many autophagic vacuoles at this time. The role of the dense granules in the formation of autophagic vacuoles is discussed and evidence for the transformation of multivesicular bodies into dense granules is presented. Autophagic vacuoles were not found during the phase when the granular endoplasmic reticulum underwent a marked regression. At this time, follicular cells contained prominent complex dense bodies which resemble the “phagolysosomes” of other mammalian follicular cells. These observations are discussed in relation to the changes which occur in thyroid function of hibernators during the period studied.
Myoid elements in the mammalian nephron and their relationship to other specializations in the basal part of kidney tubule cells
Authors: Ross Michael H. , Reith Edward J.
Published: February 2005

The basal region of proximal convoluted tubule cells from mouse kidney was studied with the electron microscope. Particular attention was given to grazing sections, i.e., sections whose plane was approximately parallel to that of the basement lamina. The findings indicate that many of the “basal compartments” of the proximal convoluted cells are elongate parallel structures which contain aggregations of filaments resembling those of smooth muscle. These elongate structures, referred to as myoid bands, react positively with dyes which are selective for muscle tissue. Close membrane appositions are also seen in grazing sections, apparently related to the myoid bands, at least by virtue of location.

In addition, the basal region of the proximal convoluted tubule cells possesses branching microvillous processes. Because of their arrangement, the basal extracellular space associated with the microvillous processes appears as a maze‐like network of channels. The microvillous processes and the associated extracellular space are at a level just slightly higher than the level of the myoid bands. This space appears to be distinct from the basal labyrinth inasmuch as the latter extends well into the mitochondrial region of the cell, whereas the basal extracellular space does not. In places, the microvillous processes extend to the basement lamina between the myoid bands.

It is postulated that the microvillous processes and the related extracellular space are associated with fluid transport and that the myoid bands may constitute a regulatory device related to the control of fluid movement.
Electron microscope studies of frozen‐substituted marine eggs. III. Structure of the mitotic apparatus of the first meiotic division
Authors: Rebhun L. I. , Sander G.
Published: February 2005

Eggs of the clam Spisula solidissima were studied by freeze‐substitution techniques at the time of the first meiotic division. The mitotic apparatus is organized into regions containing microtubules, endoplasmic reticulum, ribosomes and mitochondria which surround densely stained amorphous regions. The amorphous regions, which appear to be channels running through the mitotic apparatus, are radially arranged in the asters and are parallel to the spindle axis. Microtubule‐associated particles, each about 250 Å in diameter, are arranged in crystalline arrays around the microtubules of the mitotic apparatus. After a period of time in hypertonic sea water the mitotic apparatus disappears and the microtubule‐associated particles remain aggregated in hexagonally packed crystals. Histochemical tests suggest that the particles are composed of polysaccharide material. Other particles and inclusions show orientation relative to the mitotic apparatus axis or show non‐uniform localization in the egg. The possible meaning of such localization and orientation in the physiology of the egg is discussed.
The opisthonephric kidney of the sea lamprey of the great lakes, Petromyzon marinus L. IV. Intermediate, distal, and collecting segments of the adult
Authors: Youson John H. , McMillan Donald B.
Published: February 2005

Both short and long intermediate segments are found in the opisthonephric kidney of the adult sea lamprey and they possess morphologically distinct cell types. Wide lateral intercellular spaces appear between both the cuboidal cells of short segments and the squamous cells of long segments. Periodically the epithelium of the long segment is reduced in thickness providing for a close relationship between the interstitium and the tubular fluid. These features indicate that the segment may be involved in urine formation.

The distal segment is divisible into two distinct portions: a straight pars recta and a twisted pars convoluta. The cuboidal cells of the pars recta and the columnar cells of the pars convoluta are characterized by abundant smooth endoplasmic reticulum and mitochondria, features reminiscent of cells involved in ion transport. Multivesicular bodies, coated vesicles, and dense apical tubules suggest that cells of both regions may also be involved in endocytosis.

The cells of the collecting segment have few organelles but they possess a cytoskeleton of coarse filaments and wide intercellular spaces.

The parallel arrangement of the intermediate, distal, and collecting segments and of the blood vessels within the adult kidney is suggestive of a functional unit similar to that found in the medulla of the mammalian kidney.
Organization and histology of the pineal region in the hyrax (Procavia capensis)
Authors: Quay W. B. , Millar R.
Published: February 2005

The pineal region of four adult male Procavia capensis from South Africa was studied in serial sections of median portions of entire brains. A consistent and unique pineal morphology was found in all specimens, in contrast with previous reports based on specimens of Procavia from diverse and distant populations or species. A principal pineal tissue mass bounds the pineal recess anterodorsally and makes contact with the subcommissural organ at the apex of the recess. A dorsal or accessory pineal tissue mass occurring on the opposite (anterior or dorsal) side of the habenular commissure forms part of the basal wall of the dorsal sac. Both pineal parts are penetrated throughout by nerve fibers, of which at least the great majority belong to the habenular commissure system. Tissue zonation, rich and distinctive vascularization, abundant pinealocytes in lobules, and parenchymal follicles are also characteristic. The dorsal sac and pineal recess are unusually large in this species. Additional features of the pineal body, dorsal sac and subcommissural organ are described.