bluuebunny/crossref_metadata_2025 huggingface dataset:
Holocrine cell Lysis in the rat preputial sebaceous gland. Evidence of autophagocytosis during cell involution
Authors: Mesquita‐Guimarãtes José , Coimbra Antonio
Published: February 2005

The fine morphological and cytochemical (acid phosphatase) changes occurring during holocrine cell lysis in the sebaceous preputial gland of the adult rat were investigated. When cells reach full differentiation cisternae of the widespread rough endoplasmic reticulum show invaginations of the wall. Cytoplasmi areas comprising such altered cisternae, normal RER and some mitochondria, are later sequestered into autophagic vacuoles, either surrounded by a single membrane (type I‐bodies), or by a thick wall formed by concentric membranes (type II‐bodies). Other vacuoles with similarly stratified wall and containing debris and acid phosphatase appear in cells at the next stage of involution. These autophagic vacuoles (type III‐bodies) are probably derived from type II‐bodies, and become gradually transformed into residual bodies rich in myelin figures, while the cell membrane and the nuclear envelope rupture. These findings show that prior to cell disintegration most of the cell cytoplasm, with the exception of the lipid and proteinaceous secretion granules and some mitochondria, is focally degraded within autophagic bodies.
Analysis of cell populations of normal and injured mouse lens epithelium. II. Contribution of local and migrating cells to wound healing
Authors: Rafferty Nancy S.
Published: February 2005

The contribution of progenitor cells in the normal peripheral region of mouse lens epithelium to healing of a centrally located wound was studied using an autoradiographic technique designed to follow migrating 3H‐thymidine labeled cells. It was found that few progenitor cells labeled before or at the time of injury migrate toward the wound and hence contribute little to the repair of the wound. Moreover, the central injury did not delay or reverse the normal migration of the labeled peripheral cells in the opposite direction into the bow. It is concluded from this and other studies that a central injury to the mouse lens is healed mainly by numerous local cells which are stimulated for the most part to traverse one replicative cycle of normal duration, and that the injury does not affect formation of new lens fibers. These findings are thought to be related to the observed low incidence of traumatic cataract in the mouse.
Ultrastructural arrangement and distribution of smooth muscle and striated muscle fibers in the cremaster of the guinea‐pig
Authors: Ninomiya Jesus G. , Merchant Horacio , Alonso‐Deflorida Francisco
Published: February 2005

Besides the well‐known striated muscle fibers, the cremaster muscle of the guinea‐pig contains smooth muscle fibers, which appear either as isolated elements or as networks. These smooth muscle fibers are embedded within a matrix of the compact fibrous coat of collagenous connective tissue which covers the vaginal surface of the striated muscle layer. Presumably the smooth muscle fibers maintain the initial, fast contraction produced by the striated muscle fibers, thus attaining an economical, tonic elevation of the testicle.
Logarithmic growth of the hominoid mandible
Authors: Hildyard L. T. , Moore W. J. , Corbett M. Elisabeth
Published: February 2005

The growth of the basal unit of the mandible was studied by plotting the position, relative to the median plane, of the oval, mandibular and mental foramina in immature and adult skulls of Man, chimpanzee and gorilla. In Man, the basal unit was found to grow out along a constant logarithmic spiral. In the apes, the basal unit grew along a progressively unfolding logarithmic spiral, the amount of unfolding being greater in the gorilla than in the chimpanzee. It is argued that the mode of growth seen in the apes evolved, as these forms became more prognathous, because it requires less compensatory rotation of the mandible, while the mode seen in Man is probably closer to that which occurred in the common ancestral form.
Urogenital anomalies in fetal rats produced by the anticancer agent 4(5)‐(3,3‐dimethyl‐1‐triazeno) imidazole‐4‐carboxamide
Authors: Chaube Shakuntala , Swinyard Chester A.
Published: February 2005

Pregnant Wistar rats injected intraperitoneally on gestational day 12 with single doses (100–1,000 mg/kg) or 600 mg/kg of 4(5)–(3,3‐dimethyl‐1‐triazeno)imidazole‐4‐carboxamide (DIC) were autopsied on day 21 (100–1,000 mg/kg) or at 24‐hour intervals on days 13–20 (600 mg/kg). Controls received CMC on the same schedule. All fetuses were weighed and examined for urogenital system (UGS) malformations. Those given 600 mg/kg were also studied histologically.

DIC produced significant growth retardation at all doses on day 21 (18–72%). UGS malformations occurred in 27–67% of the fetuses at 200–400 mg/kg and in 100% of those given 600 mg/kg or more of DIC. Abnormalities included renal growth inhibition, fusion, ectopia, and ureteropelvic dilatation. At 600 mg/kg renal and body weights were reduced 40 and 55%, respectively. Ureteropelvic dilatation was common, and cortical glomeruli, nephric collecting tubules, and papillae were retarded in development. The juxtamedullary glomeruli were well developed. Proximal nephric tubular mitotic activity was 85% greater than in control animals (day 17).

On the basis of pertinent morphological and physiological data, it is postulated that the dilated upper urinary tracts represent functional hydronephrosis incident to severe renal retardation and its resultant compensatory response.
DNA synthesis in the oocyte of the mature mouse: A radioautographic study
Authors: Hoage Terrell R. , Cameron Ivan L.
Published: February 2005

Mice were injected three times over an 8‐hour period with a total of 48 m̈ci 3H‐T/gm of body weight and were sacrificed 1, 3, 5, 9 and 17 days afterwards. Radioautographs of the ovaries showed significantly higher grain counts in oocytes of follicles that are in the antrum formation stage. The radioautographic visualization of DNase digestible 3H‐thymidine incorporation into the juxtanucleolar region in oocytes of mature mice occurs in association with oocyte growth in follicles that are in the antrum formation stage.

The scheduled disappearance of this juxtanucleolar oocyte DNA and its label during later oocyte growth suggests a degradation or dispersion of this labeled DNA prior to ovulation.
An electron microscopic study of the spleen of the rat in an acute myelogenous leukemia
Authors: Chen Li‐Tsun , Handler Evelyn E.
Published: February 2005

The spleens of rats were studied by light and electron microscopy during the course of an acute myelogenous leukemia, with special reference to infiltration of leukemic myeloblasts in the spleens and to the correlation of leukemic cell infiltration with splenic hematopoiesis and splenomegaly. Leukemic myelo‐blasts infiltrated the cordal space of the red pulp. Many of them appeared in groups. Even in spleens which were heavily infiltrated, leukemic myeloblasts did not penetrate the white pulp. Massive infiltration and proliferation of the leukemic myeloblasts in the red pulp resulted in splenomegaly. The spleen increased its he‐matopoietic activity, while the medullary hematopoiesis diminished due to the invasion of leukemic myeloblasts in the bone marrow. Compensatory splenic hemato‐poiesis occurred in most of the leukemic spleens, but diminished in spleens which were very heavily infiltrated with leukemic myeloblasts. Thus, the degree of splenomegaly and splenic hematopoiesis did not necessarily correspond to the percentage of leukemic myeloblasts in the bone marrow, but rather related to the number of leukemic myeloblasts present in the spleen. A possible role for the splenic sinus walls in promoting compensatory hematopoiesis in the spleen is discussed. A consistent association of type “C” virus particles with leukemic myeloblasts was observed.
Intracellular collagen in the nonpregnant and IUD‐containing rat uterus
Authors: Dyer Robert F. , Peppler Richard D.
Published: February 2005

An experiment designed to study the effects of the copper IUD on the virgin rat uterus has revealed the presence of intracellular collagen fibrils in control uteri and in uteri that have contained a copper IUD for three months. The cells containing the collagen are found in the stroma in close proximity to the uterine epithelium. The collagen is found within membrane‐bound cytoplasmic vacuoles that vary in morphology. In some cases the fibrils are tightly packed and linear, with no other material evident in the vacuole. In other examples, the fibrils are randomly arranged and the vacuoles contain a punctate material which is characteristic of phagolysosomes. Finally, cytoplasmic vacuoles are seen which contain ill‐defined debris and poorly‐visualized structures that exhibit a periodicity, suggesting a terminal phase of fibril breakdown. All animals were sacrificed in metestrus, and the results indicate that intracellular collagen is present in the nulliparous rat uterus at this stage of the cycle. In addition, this phenomenon does not appear to be influenced by the presence of a copper IUD over a period of three months.
Myelinated granule cell bodies in the cerebellum of the monkey (Saimiri sciureus)
Authors: Cooper Margaret H. , Beal John A.
Published: February 2005

Electronmicrographs of both the vermis and hemisphere of the cerebellum of the squirrel monkey (Saimiri sciureus) show numerous granule cell bodies partially or completely surrounded by myelin. The myelin is of the compact type and consists of 1 to 13 lamellae. In several cases of partially ensheathed cells the myelin is clearly derived from extensions of myelin sheaths that surround small caliber axons. Either all or only the outer lamellae surrounding the axon contribute to the extensions. In the first instance the myelin buckles at its mesaxon pole and the resulting doubled flap extends for a variable distance along the cell surface.
Stimulation of cell division in ectopic kidney grafts following unilateral removal of the lung
Authors: Simnett John , Walton John , Oates Christine
Published: February 2005

Small fragments of kidney tissue were grafted into the right lung (Xenopus laevis) and the left lung was subsequently removed. This stimulated compensatory hyperplasia (increased mitotic rate) in alveolar tissue of the right lung and in the kidney graft. This suggests that the stimulus to compensatory hyperplasia is location‐specific rather than tissue‐ or organ‐specific. After implantation into the lung the kidney grafts are revascularized by the surrounding pulmonary supply. Damage or functional impairment of an organ usually produces a localized increase in the rate of blood flow and we therefore propose that this may lead to an increased rate of cell division in one of two ways: by permitting an increased functional capacity in the tissue concerned, or by causing a more rapid local clearance of mitotic control factors.
Enamel rod formation in the monkey observed by scanning electron microscopy
Authors: Skobe Ziedonis
Published: February 2005

Scanning electron microscopy of permanent tooth buds of the monkey confirmed that mineralizing interrod enamel surrounds Tomes' processes on three sides, forming pits that restrict enamel rod formation. The forming face of the enamel rod, which is the floor of the pit, angled toward the tooth surface at the apical edge of the pit, the side nearest the cervical region of the tooth. Consequently, the apical edge of each pit was the only site where both rod and interrod enamel were formed at the nascent tooth surface.

The ameloblasts had two secretory surfaces. One was the microvillous surface of the short Tomes' process abutting the forming face of the enamel rod. The other surface, closer to the ameloblast, was between Tomes' processes, abutting the crests of interrod enamel which formed the pits. At each site forming enamel crystallites had specific orientations.

Due to the angle of the forming face of the rod and the short Tomes' process, crystallites with both rod and interrod orientation form at the same time and the same plane within the apical (cervical) margin of each rod. It is hypothesized that indistinct boundaries between rod and interrod enamel at the apical margin of each rod are due to both secretory surfaces of ameloblasts secreting at the same time and at the same site.
Regional variation in the surface morphology of the epithelium of the rat ductuli efferentes, ductus epididymidis and vas deferens
Authors: Hamilton David W. , Olson Gary E. , Cooper Trevor G.
Published: February 2005

The luminal surface ofepithelial cells lining the ductuli efferentes, ductus epididymidis and first portion of the vas deferens were studied with the scanning electron microscope. In ductuli efferentes obvious ciliated cells are identified and it is shown that on non‐ciliated cells the short microvilli adhere to one another to form clumps of microvilli. In the epididymis two cell types are described and can be identified as principal cells and clear cells based on the presence or absence of microvilli. Clear cells vary in number along the duct, being most numerous distally. Their surface morphology is also most variable distally. In the vas deferens, principal cells with surface microvilli are easily identified; but in addition, a second cell type is seen, the identity of which is not known.
Cell kinetics in the small intestine of suckling rats I. Influence of hypophysectomy
Authors: Yeh Kwo‐Yih
Published: February 2005

Cell kinetics have been examined in the duodena of intact rats at 6, 16, and 22 days of age, and of hypophysectomized rats at 22 days. In intact rats the crypt population per villus increases more than 10‐fold, the greater part of the increase occurring late in the third week. The labelling index does not differ between 6 (28.3%) and 16 (27.6%) days, but increases to 37.8% at 22 days. Generation time also does not differ between 6 (18.0 hours) and 16 (17.7 hours) days, but falls to 10.8 hours at 22 days by shortening of both the presynthetic and synthetic phases. Acceleration of cell migration rate between 18 and19 days of age results in shortening of cell transit time from seven days in rats younger than 18 days to two days in those older than 18 days.

When rats are hypophysectomized at six days, the duodenal crypt population per villus at 22 days is comparable to that of intact rats at 16 days. The labelling index at 22 days is 19% below that of intact rats at six days. Generation time at 22 days is slightly shortened by a decrease of the presynthetic phase, but the duration of 15.5 hours is 43% longer than in intact rats at the same age. Despite the small crypt population and the low cell production rate, the cell‐transit time in 22‐day‐old hypophysectomized animals is only three days.
A comparison of the protein synthetic activity of presecretory and secretory ameloblasts in rat incisors
Authors: Warshawsky H. , Vugman I.
Published: February 2005

Presecretory ameloblasts were compared morphologically and functionally to secretory ameloblasts in the rat incisor. Structurally, the cell types are similar except for the absence of a Tomes' process at the presecretory stage. The developmental changes at the apical end of the ameloblast were described and correlated sequentially with the onset of extracellular events. First, a layer a amorphous dense material appeared at the dentinal surface adjacent to the ameloblasts. Second, the initial layer of enamel began to develop. Third, inner enamel secretion began with the appearance of interrod enamel. This occurred concomitantly with the appearance of the interdigitating portions of Tomes' processes.

Functionally, the protein synthetic activity of presecretory ameloblasts was compared to secretory ameloblasts. Light microscopic radioautography of 1‐m̈m thick Epon sections was used to localize 3H‐proline and 3H‐tyrosine at various times after injection. At time intervals up to 20 minutes the two presursors were localized as a band of labeled protein in the supranuclear cytoplasm of both presecretory and secretory ameloblasts. At 30 minutes an additional band of radioactivity was localized within the apices of both types of ameloblasts. In presecretory cells the apical reaction band was over the proximal portion of Tomes' processes which border on the dentin. In the secretory cells, the apical reaction band was over both proximal and interdigitating portions of Tomes' processes and over the enamel. Grain counts over the secretory ameloblasts showed that the incorporation of tyrosine increased by 7.5% as opposed to a 63% increase with proline when compared to the values in presecretory cells. The different increases with the two precursors were in keeping with the different amounts of the two amino acids reported to be present in enamel protein.

It was concluded that while the secretory ameloblasts synthesize and secrete enamel protein, both presecretory and secretory cell types produce another category of protein which is involved in the apical reaction band. It was proposed that this material is structural protein being contributed to the continuously lengthening Tomes' process which is speculated to occur during formation of enamel.
Intraperitoneal transplants of taste buds in the newt
Authors: Poritsky Raphael , Singer Marcus
Published: February 2005

Autografts of tongue onto the liver contained taste buds without nerves for up to 30 days. However, these denervated taste buds were generally smaller than normal and distorted in structure. Nerve fibers invaded the graft from the liver and after 30 days normal appearing taste buds were found only in implants of tongue which contained extensive nerve fibers. Thus it appears that certain visceral nerves can maintain and possibly induce taste bud formation in implants of tongue. This is interpreted as additional evidence for the trophic influence of nerves upon taste buds. Moreover, this ability to maintain taste buds is not restricted to gustatory nerves in the newt.
The embryonic development of the proctodeal gland of Coturnix coturnix japonica (Aves)
Authors: Schafersman Lynn R. , Klemm Robert D.
Published: February 2005

The embryogenesis of the proctodeal gland and development of the connective tissue of the associated lamina propria in the dorsal wall of the proctodeum of Common Coturnix (Coturnix c. japonica) were studied on embryos collected at 12‐hour intervals from day 7 of incubation through hatching. Gland development began at 9.5 days from ectodermal‐derived epithelial buds developing in the craniolateral region of the dorsal proctodeal epithelium. At 11 days, the epithelial buds had become solid convoluted epithelial cords which, by 11.5 days branched to form solid individual glandular units. Lumina of the unit were formed by degeneration and vacuolization of the central cells of these solid units. Squamous epithelial caps, several layers thick, separated the vacuolizing units from the proctodeal cavity at day 13; these caps subsequently thinned, bulged into the proctodeal cavity and, by day 16, began to disappear opening the lumen of the units to the proctodeal cavity.

Sequential formation of epithelial buds, by region, was: craniolateral at 9.5 days, craniomedial expansion at 10.5 days followed, beginning at 11 days, by cau‐dal expansion along entire dorsal proctodeal wall. Sequence of appearance of gland‐associated connective tissue fibers was: 9.5 days, reticular fibers already present; 11 days, collagen fibers; 11.5 days elastic fibers.

Serially reconstructed models of an individual glandular unit at hatching enabled classification of the unit as a simple branched alveolar gland.
Cytodifferentiation of pituitary primordia transplanted to the kidney capsule of adult hosts
Authors: Gash Don , Ahmad Nazir , Schechter Joel
Published: February 2005

This study demonstrates the ability of pituitary anlagen from 12‐ and 15‐day embryonic rats to undergo cytodifferentiation in a site distant from that of its normal juxtaposition with the hypothalamus.

Pituitary anlagen (PA) were isografted from 12‐ and 15‐day‐old embryonic donors to under the kidney capsule of intact adult female rats. Seventeen days later the grafts were recovered and processed for light and electron microscopy (LM and EM). Four of six 12‐day and all five 15‐day PA grafts developed into adenohypophyseal‐like tissues. At the light as well as EM level, no consistent quantifiable differences could be detected between the glandular tissues that developed from the two different donor groups. While most of the cells within anterior pituitary‐like tissue were chromophobic at the LM level, some cells were stained positive with periodic acid‐Schiff and Orange G. Examination by EM revealed that most cells within the glandular portions of the grafts were granular and that these cells could be grouped into three general categories based on their secretory granule morphology. The sizes of the secretory granules ranged from 150‐550 nm in diameter. Clear examples of exocytosis of the granules were evident in grafts of both 12‐ and 15‐day PA, usually in areas of the graft that were more vascularized. In some cells exocytosis was extensive. Agranular cells in the graft parenchyma included follicular and undifferentiated cells.

The results of this investigation suggest that kidney capsule grafts may prove useful in elucidating the factors that influence pituitary development.
The aberrant course of the cutaneous component of the ilioinguinal nerve
Authors: Oelrich Thomas M. , Moosman Darvan A.
Published: February 2005

The ilioinguinal nerve was dissected in 196 adult human cadavers. A normal pattern of distribution, consistent with modern textual descriptions, was defied in 60% of in guinal regions. In 35% of the inguinal regions a previously undescribed aberrant course for the cutaneous component of the ilioinguinal nerve was observed in which it is incorporated within the genitofemoral nerve, entered the inguinal canal at the deep inguinal ring, coursed within the cremasteric layer and emerged into the subcutaneous tissue at the superficial inguinal ring on the dorsal side of the spermatic cord or the round ligament of the uterus. The cutaneous component of the ilioinguinal nerve is most frequently found on the ventral surface of the spermatic cord or round ligament during inguinal hernia operations thus an unrecognized aberrant course of this nerve within the spermatic cord is particularly susceptible to accidental trauma.
Embryonic and fetal hemopoiesis in the mongolian gerbil (Meriones unguiculatus)
Authors: Smith Richard A. , Glomski Chester A.
Published: February 2005

A study of the development of hemopoiesis in the Mongolian gerbil (Meriones unguiculatus) was conducted in order to determine the temporal sequence, the organs involved and the cytology of blood cell formation in this species. Hemopoiesis in the intrauterine life of the gerbil can be divided into four phases based on the site of blood cell formation: (1) the vitelline phase, (2) the hepatic phase, including thymic histogenesis, (3) the splenic phase and (4) the medullary phase, with the development of secondary lymphoid tissues. At the onset of each of these phases a blast‐like cell was identifiable in each hemopoietic organ which, because of its morphology and its presumed multipo‐tentiality was classified as a “lymphoid cell.” In the yolk sac phase (gestational day 12) two generations of erythrocytes, a primitive and a definitive, are formed. The liver is by day 15 erythropoietic and megakaryopoietic, but later, a few gran‐ulocytes are also found in its extravascular compartment. The thymus is exclusively lymphopoietic from the appearance of its earliest cells on day 15. Splenic hemopoiesis is initiated with the presence of lymphoid cells (day 20) followed later by the appearance of morphologically identifiable blood cell lines. Early normoblastic and granulocytic activity begins in the marrow cavities on day 23, though the marrow is not considered to be a source of circulating blood cells during fetal life. Lymph node histogenesis occurs during the last four days of gestation, first in the cervical region and then in other parts of the body. The finding of undifferentiated lymphoid cells in all organs at the initiation of hemopoiesis and in the peripheral blood throughout gestation is discussed in light of the migratory theory of hemopoiesis.
Response of the adult newt, Notophthalmus viridescens to partial or complete gonadectomy
Authors: Scadding Steven R.
Published: February 2005

Following partial castration of the newt, the remaining testis hypertrophies until it reaches the normal testis mass for the current season of the year. The effect of seasonal changes in testis growth and morphology on the hypertrophy of the testis are discussed. Following partial ovariectomy of the newt, there is no regenerative response. The remaining ovarian fragment remains the same size or partially degenerates. No evidence could be found for regeneration of the gonad from non‐gonadal tissue following total gonadectomy.
Autoradiographic analysis of altered glycosaminoglycan synthesis in the epiphyseal cartilage of neonatal brachymorphic mice
Authors: Greene Robert M. , Brown Kenneth S. , Pratt Robert M.
Published: February 2005

Brachymorphic (bm/bm) mice are disproportionately short in stature. Past biochemical studies on neonatal mice (Orkin et al., '76) demonstrated that epiphyseal cartilage from these mutants synthesizes glycosamino‐glycans (GAG) that are undersulfated. In this study, synthesis of GAG, as determined autoradiographically with Na2 35SO4 and 3H‐glucosamine was reduced in all areas of bm/bm epiphyses both in vivo and in vitro as compared to normal C57BL/6J mice. Incorporation of both isotopic precursors into GAG of the brachymorphic proliferative zone was reduced to a greater extent than in the reserve zone. In addition, incorporation of these precursors into GAG of epiphyseal cartilages in vitro, as determined biochemically, was reduced by 40%. In contrast, the incorporation of 3H‐leucine and 3H‐proline into protein did not show differences between mutant and normal epiphyses. These results suggest that alterations in GAG synthesis in bm/bm epiphyseal growth plates are not exclusive to any one zone, but do appear to be most pronounced in the proliferative zone.
A study of the structure of the papilla neglecta in the lizard, Anolis carolinensis
Authors: Baird Irwin L. , Lowman Gerald F.
Published: February 2005

Scanning and transmission electron microscopy have been used to investigate the structure of the papilla neglecta in the lizard, Anolis carolinensis.Situated in the posterior part of the utricle, the receptor is innervated by a branch of the posterior ampullary nerve and is covered by an extracellular membrane that exhibits a tapering extension into the orifice of the utriculo‐saccular duct. The neuroepithelium contains two populations of sensory cells within a matrix of sustentacular cells; one population (non‐calyceal hair cells) is supplied primarily by boutons and clublike terminals, while the other (calyceal hair cells) is served by calycine terminals that invest from one to five sensory cells. The apices of calyceal hair cells bulge into the utricular lumen and have larger diameters and ciliary counts than non‐calyceal cells, but other differences are not marked. Although the bases of calyceal hair cells are deeply indented by calyceal processes, both types show similar afferent synaptic structures confined to the nuclear and infranuclear regions. Efferent terminals synapse on afferent endings and hair cells in both cases; synapses directly on calyceal hair cells lie above the calyx, just beneath the apicolateral junctional complexes. Those complexes are basically similar throughout the receptor, except that a hemispheroidal gap junction between a supporting cell and adjacent hair cell was noted in several instances. Arrays of endoplasmic reticulum and specialized mitochondria occur adjacent to aggregations of afferent synaptic vesicles in both types of sensory cell; it is suggreted that such arrays may participate in the production of the vesicles in a process involving membrane recycling similar to that at the neuromuscular junction. Differences between calycine units and the type I hair cell of mammals are discussed, and evidence that suggests an equilibratory function for the lacertilian papilla neglecta is presented.
Embryologic origin of the various epithelial cell types in the second kind of thyroid follicle in the C3H mouse
Authors: Wollman Seymour H. , Hilfer S. Robert
Published: February 2005

The thyroid gland of the C3H mouse is composed largely of the usual follicle but it also contains a second kind of follicle. To ascertain the embryologic origin of the cell types in each of these follicles, ventral pharyngeal outpocketings and ultimobranchial outpocketings were isolated (before they fused to form the thyroid gland) from the 12‐day‐old fetus of the C3H mouse. The outpocketings were implanted into different kidney capsules of adult C3H mice and were allowed to grow for several months. Transplants were then excised and examined by electron microscopy.

The ventral contribution formed large aggregates of follicles and was recognized as a distinct bump on the surface of the kidney. It formed only typical thyroid epithelium arranged in follicles containing colloid. On the other hand, the ultimobranchial contribution usually formed only a small number of follicles, generally of small size. It was readily located because the follicles occurred next to a white plaque of bone or cartilage at the site of implantation. The ulti‐mobranchial contribution formed follicles containing four cell types: a ciliated cell, a cell with abundant agranular reticulum, a cell with many free ribosomes and fiber and occasional hemidesmosomes, and the C cell which was the most frequent cell type. No typical thyroid epithelium was observed in the ultimobran‐chial transplant.

These observations suggest that the C cell in the usual follicle is derived from the ultimobranchial contribution, and that the second kind of follicle is largely an ultimobranchial contribution but the typical thyroid epithelium in it is largely or entirely a ventral contribution.
Progenitor cells of erythroblasts: An in vitro investigation of erythropoietin‐responsive cells of guinea pig bone marrow
Authors: Rosse Cornelius , Beaufait David W.
Published: February 2005

The experiments were designed to test whether or not erythroblast progenitor cell function could be demonstrated in a morphological cell type designated as “transitional cells.” Two cell fractions, were obtained from the bone marrow of normal and polycythemic guinea pigs. One fraction (F1) was enriched in transitional cells and contained few, if any, other cell types which could be considered as candidates for erythropoietin responsive cells (ERC). The other fraction (F2) contained undifferentiated blast cells as well as transitional cells. The effect of human urinary erythropoiesis stimulating factors (ESF) on heme synthesis was compared in these two fractions by measuring 59Fe incorporation into heme. ESF was more effective in stimulating heme synthesis in guinea pig bone marrow cells than homologous sera obtained from anemic or hypoxic animals. The majority of ERC sedimented in F2, but the stimulation index was comparable in the two fractions. It was confirmed by radioautography that the ESF reesponse in F1 was due to the generation of proerythroblasts and basophilic erythroblasts that incorporated 55Fe. The generation of these cells in F1 was dependent on the addition of ESF to the cultures, whereas 55Fe‐labeled erythroblasts were recovered from cultures of F2 not supplemented with ESF. ESF induced a proportion of transitional cells to incorporate 55Fe in both F1 and F2. Transitional cells were the only cell type in which heme synthesis was dependent on ESF. In other cells of clearly non‐erythroid morphology (mononuclear phagocytes and reticular cells), 55Fe incorporation occurred independent of ESF.

Although the fractionation procedure employed is unsuitable for the separation of ERC from bone marrow, it permitted the enrichment of transitional cells, a cell type defined by morphology. Radioautography with 55Fe identified a proportion of these cells as ERC in both F1 and F2 fractions of bone marrow obtained from normal and polycythemic guinea pigs. Although there may be other cell types in F2 capable of responding to ESF, the present studies show that some transitional cells function as progenitors of erythroblasts because they respond to ESF by initiation of heme synthesis and by transformation into the earliest recognizable erythroid cells.
Sympathetic connections to the fifth and sixth cranial nerves
Authors: Parkinson Dwight , Johnston Jane , Chaudhuri Anup
Published: February 2005

Thirty additional parasellar gross dissections and light microscopic examinations have been carried out, confirming a previous observation that the sympathetic nerve or nerves running with the carotid artery gives off a multitude of fine branches at irregular intervals on the way up, but the largest residual component joins the sixth cranial nerve and leaves to join the first division of the fifth cranial nerve. No similar fibers can be found by us to join the third or fourth cranial nerve. Based on the observations that section of the sympathetic in the neck results in a Horner's syndrome and that section of the ophthalmic artery at its point of departure from the carotid does not result in any part of Horner's syndrome nor does section of the external, internal or common carotid in the neck, it is assumed that these fibers process the functions the absence of which result in Horner's syndrome.
Erythropoietic response of hypertransfused neonatal rats suckled by anemic mothers
Authors: Carmichael Robert D. , Gordon Albert S. , Lobue Joseph
Published: February 2005

Twelve‐day‐old hypertransfused neonatal rats nursed for four days by a twice‐bled mother exhibited higher 48‐hour RBC‐59Fe incorporation than control neonates nursed by a normal mother. Erythropoietin (Ep) in plasma of 12‐day‐old hypertransfused neonates suckled for four days by twice‐bled mothers was initially equivalent to approximately 0.5 IU/day. This calculation was based on the observation that reticulocytosis induced in these animals was similar to that produced in neonates of the same age injected intra‐peritoneally with 0.5 IU Ep for four days while nursing from normal mothers. The reticulocyte maturation curve was shifted to the left in 12‐day‐old hy‐pertransfused neonates suckled by anemic mothers, and in 12‐day‐old normal neonates rendered anemic by bleeding, while nursing from normal mothers. This left‐shift of the reticulocyte maturation curve was also evident in 12‐day‐old hypertrans fused neonates injected with Ep.

Decreases in relative percentages of nucleated RBC was evident in spleens of 12‐day‐old neonates nursed by anemic mothers and spleens of 12‐day‐olds injected with Ep. Significant reduction in nucleated RBC were noted in both spleen and marrow of 12‐day‐old anemic neonates.

These results suggest: (1) Ep, present in increased amounts in the anemic mother, is transmitted through milk to nursing neonates thereby stimulating erythropoiesis in these animals; (2) Ep may not stimulate stem cell differentiation towards the erythroid compartment but rather acts on already differentiated erythroid cells by influencing their rate of maturation.
Scanning electron microscope study of the developing trout pelvic fin bud
Authors: Geraudie Jacqueline
Published: February 2005

The growth of the pelvic fin bud has been studied with the SEM along with the characteristics of the pseudoapical epidermal ridge which occupies the free margin of the bud. SEM revealed fluffy protuberances in many of the epidermal cells, distinguishing the fin bud territory from adjacent areas. When the pseudoapical ridge appears, all the cells show this feature but their relative number decreases and these cells, termed the “tassel cells,” are finally restricted to the base of the fin bud. This particular surface structure of the superficial cells may be unique to the fish, since it has not been heretofore reported in SEM studies of tetrapod limb bud.
Circadian variation in cell division of the mouse alimentary tract, bone marrow and corneal epithelium
Authors: Scheving Lawrence E. , Burns E. Robert , Pauly John E. , Tsai Tien‐Hu
Published: February 2005

Circadian rhythms in DNA synthesis are described for the tongue epithelium, five different regions of the alimentary canal (gut) –esophagus, stomach, duodenum, jejunum and rectum– and bone marrow in a group of BDF1 male mice. A circadian rhythm is also described for the mitotic index in the corneal epithelium in the same mice. The data document for the first time in the same animals the dramatic variation in cell division encountered from one region of the gut to another. This variation is seen in the amplitudes of the rhythms as well as in the over‐all 24‐hour means. On the contrary, the phasings of the rhythms in the different regions of the gut are remarkably similar. In this study, where the mice were standardized to 12 hours of light (0600‐1800) alternating with 12 hours of darkness, the peak of the DNA‐synthesis rhythm occurred around the time of transition from dark to light, and the trough around the time of transition from light to dark. The implications of these findings, and those of others, to the study of cell kinetics and to cancer chemotherapy are discussed.
The merkel cell in the labial ridge epidermis of anuran tadpole. I. Fine structure, distribution and cytochemical studies
Authors: Tachibana Tamiko
Published: February 2005

The labial ridge epidermis of the anuran tadpole, which is the formative site of horny teeth, was studied with the electron microscope. The triangular epidermis covering the apex of the labial ridge was composed of horny teeth cells arranged in a columnar shape, keratinocytes, secretory epidermal cells, two kinds of non‐epidermal cells and Merkel cells. Individual non‐epider‐mal cells were identified as neutrophils and macrophages respectively.

In addition, the fine structure, distribution and cytochemistry of the Merkel cell were studied. The fine structure of Merkel cells in the labial ridge epidermis was not so different from those of other vertebrates reported previously by other workers, except for the presence of numerous glycogen particles. The presence of Merkel cells in the labial ridge epidermis was very frequent, and they were arranged in a line at a uniform level of the triangular epidermis. They were usually located in the third cell layer from the base of the epidermis.

PAS and azure A stains were used on semithin epoxy sections to reveal the Merkel cells, and both stained them intensely. On the other hand, though glutaraldehyde‐silver techniques and permanganate fixation were used to detect monoamines in the Merkel cells ultracytochemically, a positive reaction was observed on the pigment granules.
Regional differentiation of cell junctions in the excurrent duct epithelium of the rat testis as revealed by freeze‐fracture
Authors: Suzuki Fumie , Nagano Toshio
Published: February 2005

Intercellular junctions of the excurrent duct system of the adult rat testis were studied by freeze‐fracture. In the terminal segment of the seminiferous tubule, where there are no spermatogenic cells, the tight junctions of Sertoli cells consist of many parallel strands of particles. The particles of the junctions predominantly appear on the E face instead of the P face, similar to those of the seminiferous tubules reported previously. From the rete testis to the ductus deferens, the tight junctional particles or smooth strands are mainly found on the P face, and the tight junctions show anastomosing networks. In the ductuli efferentes, whose epithelial lining consists of ciliated and nonciliated cells, the tight junctions between two adjacent nonciliated cells and between nonciliated and ciliated cells are poorly developed. In the former, belt‐like gap junctions are often associated with segmented tight junctions. In such area, there are tiny regions, where no junctional elements are observed. Between two ciliated cells, several strands of the tight junctions can be seen. The result of the tracer experiment suggests that the barrier of the ductuli efferentes is weak. In the epididymis, the tight junctions are well developed throughout the duct. Corresponding with the regional variation of the epi‐didymal epithelium, the geometrical organization of the tight junction networks varies along the duct. In the ductus deferens, many strands of the tight junctions are scattered throughout the lateral cell surface in addition to the belt‐like network of the tight junction in the adluminal area.

The number of the tight junctional strands is presented graphically in the various segments of the excurrent duct of the testis.
Morphological observations on the normal human cardiac glands
Authors: Krause William J. , Ivey Kevin J. , Baskin William N. , Mackercher Peter A.
Published: February 2005

The majority of human cardiac glands that lie immediately distal to the termination of esophageal epithelium are compound or branched tubular glands. They empty into overlying gastric pits. The glands of this region are often organized into lobule‐like complexes by the surrounding connective tissue of the lamina propria. The secretory tubules contain mucous cells, parie‐tal cells and endocrine cells. The mucous cell is the most common cell type observed and appears to comprise two populations. The majority are pyramidal in shape and show numerous spherical, electron‐dense secretory granules. Profiles of rough endoplasmic reticulum are observed scattered throughout the cytoplasm and Golgi complexes occupy a supranuclear position in relation to forming secretory granules. Morphologically this cell type appears similar to the mucous neck cell of the fundus. Secretory granules of a second mucous cell type are mottled in appearance and show an area of increased electron density near the limiting membrane. Parietal cells are observed and appear identical to those in the fundus. The large number of endocrine cells present raises questions concerning the traditional concept of the function of these particular glands.
Alterations in hepatic fine structure after chronic exposure of rats to dexamethasone
Authors: Garfield Sanford A. , Scott Alexis C. , Cardell Robert R.
Published: February 2005

The objective of this study was to determine the effects of chronic dexamethasone (DEX) administration on hepatic ultrastructure and to correlate these changes with plasma lipoprotein levels. Electron microscopic studies were made of hepatocytes from male rats killed 1, 3 and 5 days after DEX (2 mg, twice per day) administration. Three days after treatment plasma lipoprotein levels were highest and hepatocytes contained regions of the cytosome rich in elements of the smooth endoplasmic reticulum (SER). Osmiophilic particles were present in the tubules and vesicles of the SER, in the saccules and vacuoles of the Golgi complex, in secretory vesicles near the cell surface and in the space of Disse. DEX treatments also caused hepatocytes to accumulate tightly packed masses of β‐particles of glycogen in some regions of the cell while other areas displayed dispersed glycogen particles that were associated with the SER. These observations are consistent with the hypothesis that glucocorticoids 1. cause an elevation of plasma lipoprotein levels by in creasing hepatic synthesis and secretion of VLDL, which involves the sequential participation of the ER, the Golgi complex and exocytosis of VLDL‐containing vacuoles into the space of Disse, and 2. produce a change in the nature of the association of glycogen particles with the SER membranes in response to the physiological state of the animal.
Rod‐shaped particles in the plasma membrane of the mitochondria‐rich cell of amphibian epidermis
Authors: Brown D. , Ilic V. , Orci L.
Published: February 2005

A freeze‐fracture study has revealed rod‐shaped intramembra‐nous particles on the plasma membrane P‐face (cytoplasmic leaflet) of the mi‐tochondria‐rich cell (or flask cell) of Xenopus laevis and Rana ridibunda epidermis. Such particles have previously been found in all other mitochondria rich cells examined by this technique, namely, the MR‐cell of toad bladder epi‐thelium, the dark cèll of rat kidney collecting tubule, and the flask cell of Xenopus kidney collecting tubule. These particles are assumed, therefore, to be closely connected with the function of this cell type.
A quantitative analysis of hepatic ultrastructure in rats during enhanced bile secretion
Authors: Jones Albert L. , Schmucker Douglas L. , Mooney Jill S. , Adler Ronald D. , Ockner Robert K.
Published: February 2005

The ultrastructural changes in hepatocytes of rats subjected to selective biliary obstruction (SBO), wherein the biliary system draining approximately two‐thirds of the liver is obstructed, were evaluated by quantitative electron microscopy or stereology. The remaining unobstructed portion of the organ compensates for this loss of bile secretion by functioning in a hyper‐secretory mode. This animal model permits the comparison of hepatocellular fine structure associated with the conditions of nonsecretion and hypersecre‐tion of bile with that found in normal secreting sham‐operated rats. Since recent evidence suggests the presence of lobular gradients in hepatic structure and function, both centrolobular and periportal hepatocytes were examined. The low incidence of Golgi membrane profiles in high magnification electron micrographs results in a low confidence level of sampling and, thus, necessitates the application of a novel parameter for estimating the amount of Golgi complex, i.e., the Golgi‐rich area.

For the most part, the lobular variation in hepatic fine structure in the sham‐operated animals was similar to that described by Loud ('68). However, the periportal parenchyma contained approximately twice the volume of Golgi‐rich area as the centrolobular tissue. The amount of cytoplasmic lipid increased significantly in the SBO unobstructed lobes, although there were few or no changes in the other intracellular organelles or inclusions except those related to the Golgi complex. The volume of Golgi‐rich area increased significantly in the centrolobular tissue of the SBO unobstructed (hypersecretory) lobes to the extent that both intralobular zones contained similar amounts of this component. These data suggest that the Golgi complex is a dynamic unit which responds to changes in hepatocellular activity and may be involved in bile secretion.
Orthogonal arrays of particles in plasma membranes of the gastric parietal cell
Authors: Bordi Cesare , Perrelet Alain
Published: February 2005

Freeze‐fracture of rat gastric mucosa revealed a specific set of intramembranous particles in the plasma membrane of the parietal cells. The particles were small and of square shape and formed orthogonal arrays in the P‐face with corresponding orthogonal arrays of pits in the E‐face. Arrays, scattered among usual globular particles, were particularly numerous at the basal pole of the cell and less concentrated on the lateral side. They were not present in the apical microvillar membrane nor in the membranes of intracellular tubulovesicles. As in other cell types in which similar arrays were described previously (e.g., astrocytes, “light” cells of the kidney collecting tubule), their presence in parietal cell membranes suggest some specialized function of these membranes not shared by plasma membranes showing only a population of globular particles. This function has yet to be identified.