bluuebunny/crossref_metadata_2025 huggingface dataset:
Placentation of the sea otter
Authors: Sinha Akhouri A. , Mossman H. W.
Published: February 2005

Development of the sea otter placenta is described from implantation to term. It is a typical carnivore placenta, labyrinthine, endotheliochorial, and zonary (sometimes incomplete mesometrially). The annulus has 4 to 8 lobes and is widest antimesometrially. Maternal capillaries of the labyrinth have very thick almost columnar endothelium, and thick diastase resistant, heavily PAS positive basement membranes. They are surrounded by syntrophoblast and a few cytotrophoblast cells. Instances of intratrophoblastic fetal capillaries increase with age; thus maternal and fetal blood are in greater proximity in late gestation. The hematome arises during the limb‐bud period at the center of the antimesometrial portion of the developing chorio‐allantoic placenta as small isolated pouches of vascular chorio‐allantoic membrane filled with maternal blood. Each pouch is lined by columnar cytotrophoblast which phagocytoses maternal erythrocytes, and no doubt also absorbs histiotrophic products of the endometrial glands at its base. These early pouches grow and coalesce to form larger ones. The definitive hematome consists of one large, often bilobed sac (diam. 5 to 7 cm) surrounded at the base of its stalk by several smaller sacs. Elaborate villous folds subdivide the sacs and stalk. The whole hematomic mass invaginates the allantoic vesicle, the endoderm of which thus becomes its outer covering. The hematome remains very large to term. The uterine glands of the placental base are highly active throughout gestation.
The production of congenital malformations using tissue antisera. IV. Evaluation of the mechanism of teratogenesis by varying the route and time of administration of anti‐rat‐kidney antiserum
Authors: Brent Robert L.
Published: February 2005

Sheep anti‐rat‐kidney serum and rabbit anti‐rat‐kidney serum were utilized in a number of biological studies in order to clarify some of the qualitative and quantitative effects of this antiserum. The teratogenic factor or factors present in these antisera can be characterized as follows: The antiserum is (1) ineffective when administered by the oral route; (2) the antiserum is teratogenic when administered by the intravenous, intraperitoneal, subcutaneous or intrauterine route; (3) more effective by the intravenous and intraperitoneal route than by the subcutaneous route and (4) no more effective when injected into the uterine lumen of a pregnant rat than when given intravenously; (5) uterine vascular clamping experiments and injection of the antiserum during the preimplantation period indicate that the teratogenic milieu persists for days following the administration of the antiserum; (6) the antiserum can be considered a classical teratogenic agent because it produces a different spectrum of malformations on different days of gestation and concomitant fetal mortality and growth retardation; although stage specificity is not as dramatic with the antiserum as with irradiation; (7) although the exact mechanism of teratogenesis is not understood, it was pointed out that fluorescent localization data and the experiments reported herein indicate a similarity between teratogenic antiserum and trypan blue; (8) the importance of yolk sac pathology during the period of differentiation is discussed as it pertains to normal embryology, teratogenesis and the utilization of animals in drug testing programs for the evaluation of teratogenic effects.
Circadian rhythms in blood glucose and the effect of different lighting schedules, hypophysectomy, adrenal medullectomy and starvation
Authors: Pauly John E. , Scheving Lawrence E.
Published: February 2005

With other environmental factors rigidly standardized, normal Sprague‐Dawley rats were maintained under the following lighting schedules: (1) LD 12:12, artificial light from 6:00 A.M. to 6:00 P.M. alternating with 12 hours of darkness; (2) DL 12:12, reversal of the first schedule; (3) DD, constant darkness; and (4) LL. constant illumination.

During each lighting regimen, blood glucose levels were determined on separate subgroups of 11 to 18 animals at bi‐hourly intervals during a 24‐hour period. Significant circadian fluctuations or rhythms under all lighting conditions were found when the mean blood glucose values for each bi‐hourly group were plotted as a function of time. Rats maintained under LD 12:12 conditions showed approximately a 25% difference between the maximum and minimum values. When the phasing of the peaks and troughs of blood glucose rhythm in Sprague‐Dawley rats was compared with that of a separate colony of Wistar rats, it was noted that they were similar. Starvation of the LD rats for 66 hours did not abolish the characteristic rhythm, although a lower level of blood glucose resulted. The LD 12:12 blood glucose pattern was reversed by reversing the LD cycle 180 degrees. Under LL and DD the troughs and crests seen in the glucose curves were out of phase with those of LD and with each other; this suggested that under LL or DD the rhythm had become free‐running because of the absence of the light‐dark synchronizer.

Hypophysectomy modified the phasing of the normal LD pattern but did not abolish its fluctuating nature; this suggested that the LD cycle of light no longer was an effective entraining agent. Adrenal medullectomy caused an overall 13% decrease in the 24‐hour mean but did not alter the phasing of the LD pattern. The significance of periodicity analysis in relation to bioassay is discussed.
Effect of hypophysectomy and gonadotropin treatment on follicular development and ovulation in the hamster
Authors: Moore Pamela J. , Greenwald Gilbert S.
Published: February 2005

In hamsters hypophysectomized on day 1 of the cycle (morning of ovulation) on days 1–28 post‐hypophysectomy 99% of follicular development is limited to small and medium sized follicles with no more than five layers of granulosal cells. Since the largest preantral follicles on day 1 of the cycle have 10–12 layers of granulosal cells, it is evident that follicles become dependent on gonadotropins at an early stage of their maturation.

The daily injection of 200 μg ovine follicle stimulating hormone (FSH) on days 8–11 post‐hypophysectomy results in large antral follicles; when 10 μg ovine luteinizing hormone (LH) is then injected the animals ovulate 32 eggs. When 200 μg FSH on day 8 post‐hypophysectomy is followed by 50 μg FSH on days 9–11, injecting LH results in the ovulation of nine eggs — comparable to the ovulation rate of intact hamsters. These experiments indicate that superovulation depends on sustained high levels of FSH whereas the ovulation of a normal number of eggs requires an initially high level of FSH and then much lower maintenance levels.

When replacement therapy with 200 μg FSH for four days is started on the day of hypophysectomy (day 1) or day 2, follicles fail to develop past the six‐seven granulosal layer stage. However, deferring the initial injection of FSH until day 3 results in antral follicles that are ovulated by LH (ovulation = 36 eggs). This suggests that functional corpora lutea inhibit the effects of FSH on follicular growth. Progesterone administered to hypophysectomized hamsters (days 8–11 post‐hypophysectomy) increases the percentage of medium follicles at the expense of smaller stages. Progesterone injected daily along with FSH also prevents follicular development past the six‐seven granulosal layer stage in 14 of 24 hypophysectomized animals.
Action of metabolic hormones on the fine structure of liver cells. II. Effects of hypophysectomy and chronic administration of somatotropin
Authors: Cardell Robert R.
Published: February 2005

Electron microscopic studies of hepatocytes from sham‐operated, hypophysectomized, and hypophysectomized rats treated with somatotropin were undertaken in order to obtain morphological information on the mechanism of hormone action at the cellular level. Fed and fasted animals from each of the above groups were studied. Hepatocytes from fed rats of the three groups showed similar characteristics: periportal cells contained large dense masses of glycogen throughout the cytosome with relatively little smooth endoplasmic reticulum; mid‐lobular cells displayed small dense masses of glycogen with few associated elements of smooth endoplasmic reticulum; centrilobular hepatocytes showed dispersed glycogen and abundant smooth endoplasmic reticulum. Hepatocytes from hypophysectomized rats fasted fifteen hours showed significant alterations in structure when compared with liver cells from sham‐operated animals. Differences noted were: decrease in mid‐lobular cell size and amount of smooth endoplasmic reticulum; decrease in glycogen, number of ribosomes and polysomes per hepatocyte; disorganization of the rough endoplasmic reticulum; and swelling of mitochondria and increase in number per cytoplsmic volume. Periportal hepatocytes from fasted hypophysectomized rats treated with somatotropin for ten days contain numerous small masses of glycogen with elements of smooth endoplasmic reticulum at the periphery of the glycogen masses. Mid‐lobular and centrilobular hepatocytes contain masses of dispersed glycogen with an abundance of smooth endoplasmic reticulum associated with the glycogen particles.
Pineal canaliculi: Demonstration, twenty‐four‐hour rhythmicity and experimental modification
Authors: Quay W. B.
Published: February 2005

Parenchymal perfusions of rat pineal glands with India ink solutions reveal an extravascular and intercellular system of continuous microscopic channels containing ink perfusate. This system has two, apparently interconnecting, components: pericapillary sleeves or networks, and intralobular canaliculi 0.2–0.4 μ in diameter and enmeshing the pinealocytes individually.

Perfusion of the canaliculi was reduced or inhibited by either partial dehydration or exposure to hypertonic solutions, and was blocked when the perfusate contained either CaCl2 or trypsin. Hyaluronidase was without effect. The extent to which the canaliculi could be perfused followed a 24‐hour‐rhythm with a peak (mean maximal canalicular perfusion distance = 95 μ) near the end of the daily environmental light phase, and a trough (mean maximal canalicular perfusion distance = 13 μ) during the dark phase. This rhythm resembles that in rat pineal content of 5‐hydroxytryptamine. Dark‐phase perfusion distances equivalent to those of the light‐phase were obtained when 5‐hydroxytryptamine (5 × 10−3 M) was present in the perfusate. In similar circumstances norepinephrine, heparin and melatonin were without effect.

It is suggested that this system of canaliculi may be significant for transport activities between pinealocytes and capillaries and that its circadian and local patency may be regulated in part by release of 5‐hydroxytryptamine by the pinealocytes, and in part by calcium ions.
DNA replication in the epithelium of rat vagina and lower cervix following estrogen‐progesterone treatment
Authors: Krueger Wayne A. , Bo Walter J. , Garrison Benjamin M.
Published: February 2005

The purpose of this study was to ascertain the effects of different amounts of progesterone on estrogen‐induced DNA synthesis in the vaginal and lower cervical epithelia of the rat. Ovariectomized rats were injected subcutaneously with 1 μg of estradiol‐17β dipropionate or with estradiol and 1, 5, 10 or 15 mg of progesterone for three days; control rats received oil. Tritiated thymidine was injected one hour prior to necropsy; the tissues were processed for autoradiographic study and the percentages of labeled nuclei in the basal layer from the lower half of both the vagina and cervix were determined. In the group of rats given estradiol and 1 mg of progesterone the thymidine uptake in the vagina was significantly increased over that of rats given only estrogen. However, in the rats treated with estradiol and 5, 10 or 15 mg of progesterone, the extent of DNA replication in the basal epithelial nuclei was similar to the estrogen group. These responses were compared with those of the basal epithelium from the lower half of the cervix. None of the estrogen‐progesterone treatments increased the thymidine index in the cervical epithelium above that of estrogen alone; additionally, 5, 10 or 15 mg of progesterone given with estrogen suppressed DNA replication. These data indicate that stratified epithelia of these two portions of the reproductive tract respond differently to exogenous ovarian hormones.
Paracrystalline aggregates of microtubules in the anterior pituitary cells of the chinchilla (Chinchilla laniger)
Authors: Shiino Masataka , Rennels Edward G.
Published: February 2005

Paracrystalline aggregates of microtubules were observed by electron microscopy in some cells of the anterior pituitary glands from ten untreated chinchillas (Chinchilla laniger). Longitudinal section of the paracrystals revealed regular arrays of electron‐opaque lines parallel to the long axis of the microtubules and in transverse sections the paracrystals showed an unusual checkerboard pattern of closely packed microtubules. However, the inner wall of each subunit was hexagonal in shape.
Regional differences in the contractile apparatus of intrafusal muscle fibers
Authors: Yellin Herbert
Published: February 2005

In spindles of rat muscles, the particular class of intrafusal fiber that is unreactive over its entire striated length when incubated for alkali‐stable “myofibrillar” ATPase, exhibits pronounced regional differences in staining following incubation for acid‐stable ATPase. This variation along the contractile polar regions of the fiber can easily lead to misinterpretations of intrafusal fiber type, as well as the erroneous suggestion of two distinct populations of muscle spindles. Furthermore, such regional staining differences are strongly suggestive of variations in the contractile apparatus along certain intrafusal muscle fibers.
Adrenergic innervation of the mammalian choroid plexus
Authors: Edvinsson L. , Nielsen K. C. , Owman Ch. , West K. A.
Published: February 2005

Choroid plexuses from the four cerebral ventricles of mice, rats, guinea‐pigs, rabbits, cats, cows, and monkeys were either sectioned after freeze‐drying or stretched on microscope slides for subsequent exposure to formaldehyde gas to demonstrate fluorescent adrenergic nerves. All plexuses received a substantial amount of noradrenaline‐containing axons which originated in the superior cervical sympathetic ganglia. The nerve terminals enclosed both arterial and venous vessels. Some of the terminals in the tufts of the choroid plexus ran between the base of the epithelial cells and the underlying vascular wall. Thus, there are structural possibilities for a sympathetic innervation of the plexus epithelium, the plexus blood vessels, or both.
The morphology of the kidney of the atlantic hagfish, Myxine glutinosa (L.)
Authors: Heath‐Eves Michael J. , McMillan Donald B.
Published: February 2005

The kidney of the Atlantic hagfish, Myxine glutinosa, consists of large, paired, segmentally arranged renal corpuscles connected to the archinephric ducts by short tubules. The blood supply to the kidneys is arterial in origin; there is no renal portal system. Each renal corpuscle is supplied by one afferent arteriole and drained by several efferent vessels which in turn supply the tubules and archinephric ducts. Irregularly spaced renal veins drain blood from the ducts into the posterior cardinal veins.

The capillaries of the multilobed glomeruli are lined by thick endothelial cells which are rarely fenestrated. These are coated by the short pedicels of the podocytes of the visceral layer of Bowman's capsule. The mesangium is well developed between the endothelium and the glomerular basal lamina.

The epithelial cells of all regions of the tubules and archinephric ducts are characterized by a brush border, a complex system of lateral interdigitations, and a paucity of basal infoldings. Pits, vesicles, large vacuoles, and single membrane‐limited inclusion bodies (lysosomes?) are abundant in the apical cytoplasm. It is suggested that these cells are specialized for the reabsorption of materials.
Intravascular macrophages in normal calf lung. An electron microscopic study
Authors: Rybicka Krystyna , Daly Benedict D. T. , Migliore Joseph J. , Norman John C.
Published: February 2005

Intravascular macrophages were found commonly in sections of calf lung capillaries. These cells were large with many pseudopodia of various sizes. The cell membrane was covered with an electron‐opaque coat which remains between adjacent pseudopodial walls and results in structures suggesting “micropinocytosis vermiformis.” The cytoplasm of the macrophage was electron‐lucent and contained endoplasmic reticulum, numerous mitochondria, free ribosomes, Golgi zones, dense bodies and vesicles of many sizes. These macrophages showed phagocytic activity. During erythrophagocytosis, a dense layer initially appeared at the red blood cell periphery. This layer moved toward the center together with the erythrocyte membrane as phagocytosis progressed. Simultaneously, the electron opacity of the red blood cell decreased until the cell was completely dispersed within the macrophage. This erythrophagocytosis occurred relatively seldom. The possibility that intravascular macrophages are the pre‐cursors of alveolar macrophages is discussed.
A morphological and histochemical study of sertoli cells in normal and XX sex‐reversed mice
Authors: Chung Kyung Won
Published: February 2005

Morphological and histochemical studies on the testes of mice with XX sex‐reversal demonstrates several profound differences in the ultracytology and oxidative enzyme activity of Sertoli cells as compared to the normal. Membranous structures, cytoplasmic inclusions, and certain dehydrogenases in Sertoli cells of normal mice are described in relation to a possible role in steroid synthesis. In XX sex‐reversed mice, two types of Sertoli cells are observed in the seminiferous tubules which are devoid of germ cells. One type is the randomly dispersed cells, which reveal the following ultrastructural alterations when compared with the normal cells: large spherical nuclei with prominent nucleoli, reduced smooth endoplasmic reticulum, pleomorphic mitochondria with no apparent cristae, and decreased lipid droplets. The other type is clustered cells which appear similar to immature Sertoli cells. These cells have small nuclei with poorly developed nucleoli, small profiles of rough endoplasmic reticulum, pleomorphic mitochondria, decreased lipid droplets, and an absence of specialized inter‐Sertoli cell junctions.

The results of this study suggest that functional and ultrastructural alterations of Sertoli cells in XX sex‐reversed mice may result from degeneration or absence of germinal cells, and that steroidogenesis by Sertoli cells in mice may be associated with the development of germinal cells. It is also suggested that Sertoli cells may secrete a steroid which controls follicle‐stimulating hormone secretion.
Distribution of lumbar afferent axons in muscle coat of cat urinary bladder
Authors: Uemura Etsuro , Fletcher Thomas F. , Bradley William E.
Published: February 2005

Lumbar spinal ganglia, L2,3,4 were ablated in four cats to determine the distribution of degenerating lumbar afferents in the urinary bladder. Bladders were collected at 7, 14, 21 and 35 days following ganglionectomy. Six regions of the urinary bladder were sampled bilaterally and examined ultrastructurally in each cat. Overall, 3,033 terminal axons were counted, of which 2.6% were degenerating; of these, 9% had synaptic vesicles and were interpreted as efferent axons of postganglionic neurons with cell bodies in spinal ganglia. Lumbar afferents were most numerous in the trigone region, followed next by the ventral neck region; regions cranial to the ureters had similar small populations of lumbar afferents. A similar distribution pattern was observed for terminal axons containing granular synaptic vesicles. The relative concentration of lumbar innervation caudal to the ureters seems to account for the increased density of terminal axons observed in this region. Lumbar afferents were distributed bilaterally to the bladder and were numerically similar within and outside muscle fascicles. Ultrastructural evidence supports the position that bladder receptors are free nerve endings except for sparse Pacinian corpuscles.
A scanning electron microscopic study of the extrapulmonary respiratory tract
Authors: Andrews Peter M.
Published: February 2005

Scanning electron microscopy, sometimes supplemented with transmission electron microscopy, was used to study the ultrastructural morphology of the extrapulmonary respiratory tract. Material for observation was taken from male rat respiratory tracts which were fixed in situ and critical point‐dried. Goblet cells, brush cells, potential ciliated cells, ciliated cells, cornified vestibule cells and the olfactory mucosa could be distinguished by their characteristic surface morphologies. The distribution of these various cell types throughout the extrapulmonary respiratory tract is described. Transmission electron microscopy of material treated with ruthenium red reveals that a polyanionic surface layer coats all cilia, microvilli and the intervening cell surfaces on all cell types found in the nasal cavities, trachea and extrapulmonary bronchi.
Circadian rhythm of glycogen in the immature rat uterus: Effects of estrogen administration
Authors: Hoopes Phillip C. , Bo Walter J. , Krueger Wayne A.
Published: February 2005

The glycogen concentration in the immature rat uterus was investigated at three‐hour intervals over a 24‐hour period. Control animals received injections of 0.1 ml of oil while 0.06 μg of 17β‐estradiol was administered to experimental rats; the animals were sacrificed 24 hours later. Peak concentrations were observed at 9 a.m. for both control and experimental groups. The low value for controls appeared at 12 p.m. and for experimentals at 3 a.m. The difference between low and high points represented a 102% increase for controls and 59% for estradiol‐treated rats. These data show that a circadian rhythm is present in the rat uterus and that the uterus of the immature rat responds differently to estrogen stimulation according to the time of day the hormone is given.
The anatomy and innervation of the sphincter of oddi in the dog and cat
Authors: Kyösola Kimmo , Rechardt Leena
Published: February 2005

The fine morphology of the choledocho‐duodenal junctions of dogs and cats was studied by means of microdissection, classical histological staining techniques and by demonstrating in serial sections non‐specific cholinesterases, which stain the smooth muscle components excellently. The inbuilt cholinergic nervous apparatus was studied in serial sections by demonstrating acetylcholinesterase. By combining these methods, the three‐dimensional structural arrangement of the intrinsic cholinergic innervation system, with reference to the various substructures to be innervated, could be studied and mapped in detail.

The most important features in the morphology, with respect to the function, were the tapering of the terminal ductus choledochus into a nozzle, the existence of concentric retrograde saccules around the ampulla and the intramural part of the bile duct, and the complex construction of the sphincters. Normally such a structure makes possible an active suction‐pressure pumping for evacuation of bile and pancreatic juice, being at the same time effective in preventing regurgitation of the duodenal fluid. On the contrary, if the orificium of the ampulla is obstructed, this structural arrangement probably facilitates regurgitation, especially into the pancreatic duct.

The intrinsic cholinergic nervous apparatus of the choledocho‐duodenal junction was extremely rich, especially if compared with the cholinergic innervation of the muscular layer of the gut wall. This can probably be considered as an indication of complex motor (and possibly associated sensory) functions of the sphincters, in contrast to only slow gross contractions of the gut.

To summarize: both morphological and neuroanatomical bases seem to be provided for rhythmic suction‐pressure pumping as well as for sensitive protective reflex functions in the choledocho‐duodenal junctions of the dog and cat. The finely graded complex interactions of the various muscle components are regulated by connecting and integrating neural elements between the individual smooth muscle units.
Effects of cytochalasin B on the fine structure of organized endodermal cells of the early chick embryo
Authors: Stagno Paul A. , Low Frank N.
Published: February 2005

Fresh pullet eggs (White Leghorn) were incubated for 36 to 48 hours. The blastoderms were exposed to cytochalasin B (CB), 10 or 40 μg/ml, for 2, 5, and 15 minutes prior to fixation by immersion in buffered chick Ringers solution containing CB, previously dissolved in dimethysulfoxide (DMSO), or by sub‐blastodermic injection. Controls fixed in ovo possess relatively flat surfaces with bulges due to uptake of yolk. Numerous microappendages (blebs, microvilli and ruffles) are present, especially at cell margins. DMSO‐controls present a similar cell surface except that small blebs are more prominent. The plasmalemmas of CB‐treated endodermal cells possess numerous large blebs (2‐10 μm in diameter), smaller blebs (0.2 μm) and microvilli. Cell dissociation occurs in selected areas resulting in rounded cells, devoid of microappendages, with peripheral processes. Transmission electron microscopic preparations of tissues similar to those used for scanning electron microscopy reveal that large blebs are filled with membranous material. Microfilaments are present but lack their normal subplasmalemmal arrangement. Microtubules and other cell organelles are apparently unaffected by CB. Evidence in this study supports the concept that cytochalasin B exerts its influence through alteration of the plasmalemma.
Evolution of the endoplasmic reticulum during rat spermiogenesis
Authors: Clermont Yves , Rambourg Alain
Published: February 2005

The endoplasmic reticulum (ER) was stained selectively by a sequence of uranyl acetate, lead and copper citrate, according to the method of Thiéry and Rambourg ('76), and then investigated in 0.5 to 2.0‐μm‐thick sections with the transmission electron microscope. Examination of photographic stereopairs allowed a three‐dimensional visualization of the ER at various steps of spermiogenesis.

During the Golgi and cap phases of spermiogenesis (steps 1–7, classification of Leblond and Clermont, '52a), the ER is distributed throughout the cytoplasm as a three‐dimensional network of spherical and tubular cisternae connected by narrow tubules. In addition, a close network of tubular cisternae is located along the convex surface of the Golgi apparatus and lines the plasma membrane. Where the cell membrane joins that of another spermatid to form an intercellular bridge, this network extends across the bridge.

During the acrosome phase (steps 8–14), the cytoplasm contains an abundant ER that shows the following modifications: (A) Along the inside and outside of the caudal tube the cisternae form long tubes or plates which run adjacent and parallel to the microtubules. These cisternae are connected by delicate lateral anastomoses; (B) Along the flagellum the ER forms a “fenestrated sleeve” made up of a close network of tubular cisternae; (C) Similar networks are organized as “fenestrated spherules” enclosing large vesicles seen throughout the cytoplasm; (D) At a short distance from the flagellum, the ER cisternae are continuous with a stack of annulate lamellae and an aggregate of radially arranged collapsed cisternae called the “radial body”.

During the last or maturation phase (steps 15–19), the ER regresses. Thus, during the final steps in the formation of the flagellum, the ER network fragments and then most of the cisternae disappear from the cytoplasm. The “radial body” is the last element of the ER to be dissolved. Thus the ER undergoes extensive structural modifications during spermiogenesis, suggesting an active contribution of this organelle to the differentiation of the spermatid into a spermatozoon.
Qualitative and quantitative morphologic study of peyer's patches of the mouse after neonatal thymectomy and hydrocortisone injection
Authors: Abe Kazuhiro , Ito Takashi
Published: February 2005

Peyer's patches in normal adult mice, neonatally thymectomized mice and mice injected with hydrocortisone were studied qualitatively and quantitatively by light microscopy. The patch was divided into germinal center, follicular area, parafollicular area and dome area. In normal mice, the volumetric ratio of the germinal center to the entire patch was 30.9%; that of the follicular area, 33.3%; that of the parafollicular area, 27.7%; and that of the dome area, 8.2%. Thymus‐dependent small lymphocytes were 40% of small lymphocytes in the patch. Out of the total thymus‐dependent small lymphocytes in the patch, 13% were included in the germinal center; 19%, in the follicular area; 62%, in the parafollicular area; and 6%, in the dome area. Hydrocortisone‐sensitive small lymphocytes were 65% of the total small lymphocytes in the patch, the germinal center contained 9%; the follicular area, 84%; the parafollicular area, 2%; and the dome area, 5%. The epithelium over the dome area was invaded by numerous small lymphocytes. Forty‐eight percent of lymphocytes within the epithelium over the dome were thymus‐dependent and 67% were hydrocortisone‐sensitive.

It is concluded that Peyer's patch may be considered as a peripheral lymphatic tissue, functionally as well as morphologically.
The spiral constrictor of the gastroesophageal junction
Authors: Jackson Arthur J.
Published: February 2005

The gastroesophageal region was reconstructed from the histological analyses of five human newborn infants. In addition, the musculature of eight (3 newborn and 5 adult) human stomachs obtained from autopsies, with the lower one‐third of the esophagus attached, was dissected with the aid of a binocular dissecting microscope.

The muscularis mucosae, in the region of the gastroesophageal junction, exhibited no increase in thickness, nor was there any indication of special mucosal folds. In addition, the gastroesophageal junction contained no morphologic evidence that would support the existence of an anatomic sphincter (a localized thickening of circular muscle fibers). However, the obliquely arranged inner circular muscle fibers of the esophagus separated into fascicular bundles below the esophageal opening. Some of the fasciculi, as they descended, again became circular in shape and continued into the stomach, forming the middle circular muscle layer, while other fasciculi maintained their oblique course toward the left surface of the esophagus. These fasciculi, coursing on the anterior and posterior surfaces of the esophagus, crossed and interdigitated along the left surface of the esophagus in the region of the incisura cardiaca. After crossing, the oblique fasciculi descended into the stomach forming the inner oblique muscle layer. Based upon this description of crossing and interdigitating fasciculi, it is suggested that closure of the gastroesophageal junction may be due to contraction of spirally arranged muscle. Since the term “sphincter” generally implies a circular structure, it is proposed that the term “spiral constrictor” be considered in naming this anatomical arrangement.
Effects of therapeutic radiation on microstructure of the human mandible
Authors: Savostin‐Asling Irene , Silverman Sol
Published: February 2005

Mandibular bone from eight patients who had received therapeutic radiation (6,000–7,200 rads) for intra‐oral cancer was obtained at surgery (1 month to 9 years after radiation) and compared histologically with non‐irradiated mandibular bone from five subjects. Measurements made on the nternal remodeling process of cortical bone included the extent of internal surface and the fraction indicating resorption, and the proportions of osteones which were incomplete (less than 3/4 filled with matrix), complete, and plugged. Appreciable differences were observed in all parameters except plugged osteones. The findings suggested early cessation of osteogenesis, and somewhat later cessation of resorption, without subsequent resumption of either process. The histologic appearance of the osteoblasts, osteoclasts, and osteones was in accord. Microfractures found in the irradiated bone were not seen to have healed. Radiation damage to the osteoprogenitor cells is postulated.
The luminal surface of thyroid cysts in sem
Authors: Zelander Tor , Kirkeby Svend
Published: February 2005

Four of the five kinds of cells constituting the walls of thyroid cysts can be identified in the SEM. These are cuboidal cells, mucous cells, cells with large granules and ciliated cells. A correlation between SEM and TEM observations is attempted.
Elimination of multiple innervation in the developing avian superior oblique muscle
Authors: Holt R. K. , Sohal G. S.
Published: February 2005

Motor endplates in the developing avian superior oblique muscle first appear on day 18 of incubation. Most of the endplates from this time through hatching (day 27) are innervated by multiple fibers. Each endplate in the post‐hatching period is innervated by only one fiber. Time of elimination of multineuronal innervation does not correlate with the time of trochlear neuron loss; the former occurs much later in development. Removal of multiple innervation is therefore, not the cause of the naturally occurring neuron loss.
Ultrastructure of Merkel corpuscles and so‐called “transitional” cells in the white leghorn chicken
Authors: Saxod Raymond
Published: February 2005

In the chicken Merkel corpuscles are located in the dermis and consist of specialized Merkel cells, discoid nerve endings and lamellar cells. Merkel cells contain characteristic membrane‐bound dense‐core granules and bundles of microfilaments. Asymmetric junctions, synapse like, with thickened membranes and clusters of dense‐core vesicles were observed between the Merkel cells and the nerve endings. The nerve ending is derived from myelinated nerves and sometimes contains clusters of clear vesicles. A laminar system formed by lamellar cells of the Schwann cell type encloses the Merkel cells and the nerve endings. So called “transitional” cells, showing some of the morphological features of both keratinocytes and Merkel cells, were observed in the basal layer of the epidermis. One was located partly in the epidermis and partly in the dermis. The structure of Merkel corpuscles is compared with that of Merkel cells in other tetrapods. The developmental significance of “transitional” cells and the origin of Merkel cells are discussed.
Development of the diarthrodial joints in the rat embryo
Authors: Mitrovic D.
Published: February 2005

The development of appendicular synovial joints of both legs was studied with histological and histochemical techniques in 43 rat embryos aged 12 to 21 days. From this and previous studies, it appears that joints develop by a sequence of cellular events leading to a full expression of the phenotypic characteristics. The classically described stages: cell condensation, three layered mesenchyme, vascular invasion and joint clefting, were chronologically recorded in all joints. The observations relevant to the intra‐articular structures, such as joint capsule, menisci and ligaments, were also presented. Previously unreported, cellular aspects were described during joint morphogenesis and their biological significance was discussed. Among these cellular aspects, of particular interest are: a. an early wave of cell necrosis occurring immediately after differentiation of the interzone. Disappearance of necrotic cells is thought to prevent chondrification of this tissue by clearing up the cells with chondroblastic potentialities; and b. a morphologically peculiar type of cells that differentiate alongside, and by the time of, clefting and seem to be related to this process. Thus, the joint clefting appears also to result from a cell‐tissue related phenomenon, acting in conjunction with the joint motion, the importance of which has been previously demonstrated.
Glucocorticoid‐induced alterations in collagen of neonatal mouse condylar cartilage
Authors: Lewinson Dina , Silbermann Michael
Published: February 2005

Neonatal mice were treated with a single dose of triamcinolone hexacetonide, a long‐acting synthetic analogue of cortisol, and their mandibular condyles were studied ultrastructurally ten days thereafter. A pronounced decrease in the number and size of matrix granules (proteoglycans) was found in the cartilaginous matrix of triamcinolone‐treated condyles. In contrast, a marked increase concomitant with significant structural changes was noted in collagen fibrils. An obvious enhancement of collagen fibrillogenesis was noticed in the pre‐mineralizing extracellular matrix. Atypical, wider than normal, banded collagen fibrils were found to form dense meshworks which appeared to lack any specific orientation or organization. It is proposed that glucocorticoid hormones, given systemically to neonatal mice, interfere with regulatory mechanisms involved with the biosynthesis of cartilaginous matrical macromolecules, i.e., proteoglycans and collagen and thereby promote certain aging processes within active growth centers.
Postnatal development of the granule cell in the kitten cerebellum
Authors: Smith Diane E. , Downs Irene
Published: February 2005

Newborn to 9‐week‐old kittens were anesthetized and then sacrificed by inserting a scalpel into the thoracic cavity and severing the descending aorta. The cerebella were removed and processed according to Golgi‐Cox and rapid Golgi modifications. The results indicate that the dendritic processes of the granule cells undergo a marked postnatal maturation even though there is little postmigratory change in the size and shape of the cell body. A clubshaped swelling of the distal portions of the dendrites is observed by the end of the first week; this “claw” becomes multilobated by three weeks and displays elaborate digitiform projections by nine weeks. The sequence of postnatal development in the kitten appears to follow a time course similar to that observed in other species. A possible correlation between the postnatal development of the granule cell and the postnatal development of the spincocerebellar system is discussed.
Scanning electron microscopy of epidermal cell migration in wound healing during limb regeneration in the adult newt, Notophthalmus viridescens
Authors: Repesh Lillian A. , Oberpriller Jean C.
Published: February 2005

The epidermal cells which migrate over the wound surface of the amputated limb of the adult newt were examined using the scanning electron microscope. Specimens were prepared routinely for scanning electron microscopy or were embedded in Epon 812 for light microscopic observations. A cuff of epidermal cells was seen at the edge of the wound, from which cells appeared to migrate over the wound surface. As early as five hours after transection of the limb, the basal layers of this cuff appeared to send out pseudopodial projections. These seemed to establish a physical contact with a fibrin‐like substratum, which apparently served as a means of support for the migrating cells. Subsequently, the epidermal cells became elongate and had the appearance of streaming toward the center of the wound. Between 10 and 13 hours post‐amputation, the cells in the central region of the stump were rounded up and some possessed microappendages resembling microplicae and microvilli. Throughout the entire period of wound coverage, the cells seemed to maintain contact with the fibrin network, which appeared to be the first structural element of wound architecture. As a result of these observations, the mechanism by which the epidermal cells migrate has been clarified.
Permeability of the diaphragmatic mesothelium: The ultrastructural basis for “stomata”
Authors: Leak Lee V. , Rahil K.
Published: February 2005

The topography and organization of cells lining the peritoneal surface of the diaphragm in normal and intraperitoneally injected mice have been studied by transmission and scanning electron microscopy and freeze‐fracture replication techniques. The mesothelial cells of the peritoneal surface of the diaphragm are organized into two discrete populations. A population of cuboidal cells are found in areas over the lymphatic lacuna (roof covering submesothelial lymphatic vessels) while the remaining areas (not covering lymphatic lacunae) of the diaphragm are lined by extremely flattened cells. The apical surfaces of both cuboidal and flattened mesothelial cells are covered with numerous microvilli. The lateral borders of the cuboidal cells are characterized by the presence of numerous filamentous processes which interlace with similar structures from adjacent cells to form intercellular gaps which overlie a thin layer of connective tissue. In addition to the intercellular gaps, special circular pores are found between the margins of several neighboring cells. The observations suggest that these circular pores are formed when cell margins of several lymphatic endothelial cells span the submesothelial connective tissue to form intercellular junctions with cell margins of several neighboring mesothelial cells lining the peritoneal surface of the diaphragm. The intimate intercellular contact between these two different cell types provides an open channel between the peritoneal cavity and the lumen of the diaphragmatic lymphatic vessels (lymphatic lacunae). It is suggested that these circular pores correspond to the “stomata” of von Reckling‐hausen. Intraperitoneally injected colloidal particles (biological carbon) and red blood cells are rapidly removed from the peritoneal cavity via the circular pores (stomata).
Insemination‐induced histolysis of the flight musculature in fire ants (solenopsis, spp.): An ultrastructural study
Authors: Jones Ruth G. , Davis Walter L. , Hung Akey C. F. , Vinson S. Bradleigh
Published: February 2005

The fine structure of the insemination‐induced flight muscle degeneration (histolysis) in the queen fire ant (Solenopsis spp.) has been investigated. Within 2 hours post‐insemination, degenerative changes are detectable in the most peripheral fasciculi of the fibrillar flight muscle. Histolysis proceeds internally with time. Myofibril (sarcomere) dissolution begins with myofilament breakdown and continues until only free Z‐line material remains. The latter subsequently disappears leaving, at the terminal stages, only nuclei, lamellar bodies (myelin figures), and tracheoles as residual myoid elements. Lysosomes and/or phagocytes do not appear to play a primary role in the initiation and continuance of this process.
Functional interpretations of the radiographic anatomy of the femora of Myotis iucifugus, Pipistrellus subflavus, and Blarina brevicauda
Authors: Dawson David L.
Published: February 2005

Radiographs of right femora from 29 shrews (Blarina brevicauda) and 51 bats (27 Myotis lucifugus, 14 Pipistrellus subflavus) were analyzed to determine if bone in these small mammals conformed to Bassett's (′68) revision of Wolff's Law. Five external and four cortical dimensions were made on enlargements of radiographs of each femur. Comparative descriptions of the spongiosa are given.

External dimensions appear to be determined genetically, and, in bats, are closely related to functional demands. Shrew femora retain a primitive mammalian morphology.

No apparent relationship exists between animal weight and mid‐diaphyseal cortical thickness. Although differences in cortical thickness in bats suggest a possible relation between bone and pressure, no relationship is apparent in shrews; further, the comparative magnitude of these dimensions is similar in all three species, indicating genetic control mechanisms. Computations of maximal loading suggest that loading is so slight, that the inherent strength of bone tissue is adequate to resist mechanical deformation. However, there is evidence of cortical bone response to physiological demands.

Inspection of the spongiosa also fails to provide evidence of conformity to Wolff's Law. Instead, the trabeculae appear to be related to physiologic factors, animal age, and inherited disposition patterns.

Thus, there is no evidence that bone in these diminutive mammals responds to mechanical forces, and the applicability of Wolff's Law is not indicated. It is hypothesized that, as the mechanical forces are so minimal, intrinsic tissue strength is sufficient to resist mechanical deformation, and femoral anatomy in these species is dictated by genetic and inherent physiologic conditions.
The axial musculature of Pontoporia blainvillei, with comments on the organization of this system and its effect on fluke‐stroke dynamics in the cetacea
Authors: Strickler Timothy L.
Published: February 2005

The axial muscular system of Pontoporia blainvillei is described and compared with published reports of this system in other cetaceans. A comprehensive system for classification of axial muscles is presented, based on the studies of Slijper. A discrete obliquus capitis inferior is described for the first time in cetacea, and it is suggested that its absence in previous descriptions may have been due partly to dissection error. The major axial muscle‐masses are organized in a similar way in most cetaceans, comprising a set of tail elevators and depressors, and a set of tendons with similar actions on the flukes. The anatomy of the axial musculature does not support the idea that the upstroke is the main propulsive stroke in cetaceans, but suggests similar roles of the upstroke and downstroke in propulsion.
Scanning microdensitometry of glycogen zonation in the livers of rats adapted to a controlled feeding schedule and to 30, 60, or 90% casein diets
Authors: Richards William L. , van Potter R.
Published: February 2005

The effect of diet composition on diurnal changes in glycogen zonation patterns in rat liver was investigated in individually‐caged male Sprague‐Dawley rats adapted to the 2 + 22 controlled feeding and lighting schedule and to diets containing 30% casein/55% carbohydrates, 60% casein/25% carbohydrates, or 90% casein (30 rats/dietary group). Three rats from each dietary group were killed at the following times relative to the onset of feeding (0 min):−60, −30, 0, 15, 30, 45, 60, 90, 120, and 180 min. Glycogen in cryostat sections from the median and right lateral lobes of the liver was fixed and stained by standard techniques. The optical density of glycogen at points along the path between the central and portal veins of a given lobule was determined, and lobular glycogen gradients of replicate animals were integrated to form a composite lobular glycogen distribution profile. In the period from −60 to 0 min, liver glycogen levels were similar for rats on any of the diets, and the glycogen concentration was similar in periportal (P), midlobular (M), and centrilobular (C) hepatocytes. During the 0‐ to 45‐min period, diet‐related glycogen depletion occurred (90 > 60 ≫ 30% casein) by asymmetrical glycogen loss (P > M ≫ C hepatocytes) from the liver lobules. Similar food intake curves occurred for all diets. During the 45‐ to 180‐min period, asymmetrical glycogen accumulation began in lobular parenchymal cells (P > M ≫ C hepatocytes), and the rate of accumulation was related to dietary composition (30 > 60 ≫ 90% casein). The differential responses of parenchymal cells within liver lobules to physiological stimuli resulted in glycogen distributional changes that were rapid and of large magnitude. Our results are consistent with the hypothesis that periportal and midlobular hepatocytes are more metabolically responsive and active than centrilobular hepatocytes.