bluuebunny/crossref_metadata_2025 huggingface dataset:
Morphometric study of the prepubertal rabbit testis: Germ cell numbers and seminiferous tubule dimensions
Authors: Iczkowski Kenneth A. , Sun Eric L. , Gondos Bernard
Published: February 2005

Testes from rabbits aged 1–9 weeks were examined by light microscopy. Changes in seminiferous tubule dimensions, testicular volume, and volume fraction of tubules were assessed. Germ cells and Sertoli cells were counted in round tubular cross sections and total germ cell number in each testis was estimated. Mitotic, meiotic, and degenerative activities of germ cells as well as their basal or central positions within tubules were quantified. A marked, steady increase in testis volume and in tubular length and volume occurred over the prepubertal period; but diameter underwent no significant increase and in fact decreased until week 4. Overall, tubules lengthened 40‐fold and testis volume increased 25‐fold; the percentage volume of the testis occupied by tubules rose from one‐third neonatally to three‐fifths at the onset of spermatogenesis. The ratio of germ cells to total tubular (germ and Sertoli) cells was lowest at 3 weeks. However, the total number of germ cells increased little until 3 weeks, after which it rose at a sharp rate commensurate with testis volume. Percentage of germ cells in mitosis peaked sharply at 3 weeks, dropped in subsequent weeks, and then rose at 7 weeks at the initiation of spermatogenesis. Importantly, the surge in mitosis at 3 weeks was followed by a redistribution of germ cells to a predominantly basal location from 3 to 7 weeks. Meiotic activity was sparse at 7 weeks and became abundant by 9 weeks. Germ cell degeneration remained relatively constant during weeks 1 through 6, with an increase at 7 weeks.
Distribution of cytochrome P‐450 monoxygenase enzymes in the nasal mucosa of hamster and rat
Authors: Adams Donald R. , Jones Alisa M. , Plopper Charles G. , Serabjit‐Singh Cosette J. , Philpot Richard M.
Published: February 2005

Deposition of inhaled particulates onto the respiratory mucosa is relatively great in that portion of the nasal cavity unprotected by ciliated, goblet, or keratinized superficial cells. The cytochrome P‐450 system is an important enzyme system involved in the biotransformation of xenobiotics into metabolites that are more readily absorbed. To examine the transitional region caudal to the nasal vestibule, nasal tissues of hamster and rat were prepared for immunocytochemistry. Blocks of tissue representing four levels along the axis of the nasal cavity were examined. Paraffin sections were processed through the avidin‐biotin peroxidase procedure, with diaminobenzidine tetrahydrochloride as the chromagen. Enzyme localization was accomplished through the use of antibodies for three rabbit cytochrome P‐450 isozymes; 2, 5, and 6 (subfamilies IIB, IVB, and IA, respectively); and for rabbit NADPH‐cytochrome P‐450 reductase. Enzyme distribution was similar in both hamster and rat nasal tissues except in cells of striated and intercalated ducts of nasal glands and in cells of the nasolacrimal duct where immunoreactivity for reductase and isozyme 2 was intense in nonciliated cells lining the nonolfactory epithelium, in sustentacular cells of the olfactory epithelium, and acinar cells of olfactory glands. Distribution of reaction products to isozyme 5 and 6 were similar to but not so intense as those of reductase an isozyme 2. Reaction products for reductase and isozyme 2 occurred generally in the same cellular and intracellular regions with the following exceptions: isozyme 2 was more concentrated in cells of striated ducts and of the nasolacrimal duct, and reductase was more abundant in intercalated ducts of nasal glands. Ciliated and goblet cells in epithelia lining much of the nasal cavity evidenced little reactivity; those ciliated cells adjacent to olfactory mucosa contained reaction product. It is concluded that the nonciliated epithelium adjacent to the internal ostium of the nose contains enzymes essential for biotransforming extrinsic particles that impinge on it from inhaled air currents.
Spontaneous decidual reactions and menstruation in the black mastiff bat, Molossus ater
Authors: Rasweiler John J.
Published: February 2005

Uterine function was assessed histologically in nonpregnant Molossus ater removed from a laboratory breeding colony. During the luteal phase of the cycle, bilateral decidual reactions were found to develop spontaneously in the absence of either embryos or experimental manipulation of the uterus. These included the formation of early decidual giant cells, closure of the uterine lumina, and morphological changes in the endometrial blood vessels. Some endothelial cell hypertrophy was noted in much of the decidua, but this was most pronounced in vessels associated with an unusual vascular tuft that formed in the endometrium surrounding the cranial end of the uterine lumen. These latter vessels also developed very prominent basal laminae. In pregnant bats, this tuft played a central role in the morphogenesis of the definitive discoidal chorioallantoic placenta. At the end of nonpregnant cycles, the decidua became necrotic and was sloughed off with associated bleeding. As in menstruating catarrhine primates, the endometrium of M. ater is vascularized by spiral arterioles and populated by distincitve granulocytes containing large, acidophilic granules. Increased coiling of these arterioles did not appear to be an essential element in the mechanism of menstruation in this species. M. ater is a monotocous, seasonal breeder, with a relatively long gestation period. Although it has a bicornuate uterus, ovulation and implantation appear to occur only on the right side of the tract. The ability to menstruate probably affords this bat an efficient mechanism for eliminating a highly differentiated endometrium from the usual implantation site in the event of a reproductive failure. In the wild, this may provide M. ater with another chance to establish a pregnancy at a still opportune time during the same breeding season.
Development of Sertoli cell junctional specializations and the distribution of the tight‐junction‐associated protein ZO‐1 in the mouse testis
Authors: Byers Stephen , Graham Robert , Dai Hai Ning , Hoxter Becky
Published: February 2005

Basally located tight junctions between Sertoli cells in the postpubertal testis are the largest and most complex junctional complexes known. They form at puberty and are thought to be the major structural component of the “blood–testis” barrier. We have now examined the development of these structures in the immature mouse testis in conjunction with immunolocalization of the tight‐junction‐associated proteins ZO‐1 (zonula occludens 1). In testes from 5‐day‐old mice, tight junctional complexes are absent and ZO‐1 is distributed generally over the apicolateral, but not basal, Sertoli cell membrane. As cytoskeletal and reticular elements characteristic of the mature junction are recruited to the developing junctions, between 7 and 14 days. ZO‐1 becomes progressively restricted to tight junctional regions. Immunogold labeling of ZO‐1 on Sertoli cell plasma membrane preparations revealed specific localization to the cytoplasmic surface of tight junctional regions. In the mature animal, ZO‐1 is similarly associated with tight junctional complexes in the basal aspects of the epithelium. In addition, it is also localized to Sertoli cell ectoplasmic specializations adjacent to early elongating, but not late, spermatids just prior to sperm release. Although these structures are not tight junctions, they do have a similar cytoskeletal arrangement, suggesting that ZO‐1 interacts with the submembrane cytoskeleton. These results show that, in the immature mouse testis, ZO‐1 is present on the Sertoli cell plasma membrane in the absence of recognizable tight junctions. In the presence of tight junctions however, ZO‐1 is found only at the sites of junctional specializations associated with tight junctions and with elongating spermatids.
Proximal skeletal muscle alterations in streptozotocin‐diabetic rats: A histochemical and morphometric analysis
Authors: Medina‐Sanchez Maria , Rodriguez‐Sanchez Carmen , Vega‐Alvarez Jose Antonio , Menendez‐Pelaez Armando , Perez‐Casas Antonio
Published: February 2005

The response of rat quadriceps muscle fibers to chronic streptozotocin (STZ) diabetes was studied. Transverse sections of rectus femoris muscle from diabetic and weight‐matched control rats were assayed for myofibrilar adenosine triphophatase (ATPase) and nicotinamide adenine dinucleotide‐tetrazolium reductase (NADH‐TR). A quantitative analysis was carried out by an automatic interactive analysis system focused on the fiber type size and distribution. STZ‐induced diabetes caused important effects in this muscle, with changes in the distribution of oxidative enzyme reactions, type I fiber hypertrophy, and type II fiber atrophy, which was greater in type IIB than in type IIA. It is concluded that hypoinsulinism produces morphological alterations in proximal skeletal muscle fibers that are similar to those of neurogenic myopathy. Thus the pathological changes in these mammalian muscle fibers could explain the clinical syndrome seen in diabetic patients called “diabetic symmetrical proximal motor neuropathy”, perhaps the least understood of the major neuropathic complications of diabetes.
Effects of early partial decapitation on the ontogenic development of chicken lymphoid organs. I. Thymus
Authors: Herradón P. G. , Razquin B. , Zapata A. G.
Published: February 2005

For the present study we used the classic model of early partial decapitation (DCx) of chicken embryos (Fugo, J. Exp. Zool., 85:271–298, 1940; Betz, Gen. Comp. Endocrinol., 9:172–186, 1967) in an attempt to analyze the neuroendocrine immune relationships during ontogeny. The elimination of the prosencephalon in chickens at 33–38 hr of incubation induced profound structural, histochemical, and morphometric changes in the embryonic development of the thymus gland. These included a greater development of the cortex than of the medulla, an increased mitotic index, high numbers of pyknotic cells, and enlarged connective tissue trabeculae containing numerous large lymophoid cells; hypertrophied reticular‐epithelial cells; delayed appearance of medullary epithelial cysts; and intrathymic granulopoiesis. Furthermore, preliminary radioimmunoassays revealed a sharp increase in the values of circulating thymic hormones, mainly thymosin β4 in 17‐day‐old embryos. The results are discussed with regard to the possible role of prolactin, thyroxine, testosterone, and thymic hormones in the ontogenic development of the chicken thymus.
Interodontoblastic collagen (von Korff fibers) and circumpulpal dentin formation: An Ultrathin serial section study in the cat
Authors: Bishop M. A. , Malhotra M. , Yoshida S.
Published: February 2005

The collagenous fibers of von Korff pass from the dentin matrix between the odontoblasts into the dental pulp. Although collagen fibrils are known to be present between odontoblasts, the existence of von Korff fibers has remained controversial. This may be because their continuity between the dentin matrix and the pulp has not been demonstrated ultrastructurally.

In this study we have examined the odontoblast layer in the middle to apical regions of perfusionfixed permanent canine teeth of cats by using transmission electron microscopy. Ultrathin sections of demineralized specimens revealed frequent bundles of collagen fibrils (1) entering the odontoblast layer from the predentin, (2) present between odontoblst cell bodies, and (3) passing form between the odontoblasts into the pulp.

The question of continuity of these bundles from the predentin, across the odontoblast layer into the pulp was examined in ultrathin serial sections. Unbroken continuity of a collagen bundle from the predentin between the odontoblasts into the pulp was established in a reconstruction of one series of 22 serial sections and was very strongly suggested by a number of other series in which the numbers of available sections restricted their full visibility.

This investigation has shown, therefore, that classical von Korff fibers are present and that these fibers are present in fully erupted teeth with closed apices, i.e., at a time when secondary circumpulpal dentinogenesis is in progress.

The findings call for a reexamination of the question of von Korff fibers during mantle dentinogenesis and primary circumpulpal dentinogenesis. Resolution of their existence at the earlier stages of dentinogenesis should be possible by using the ultrathin serial‐sectioning technique.
Tandem Scanning Confocal Microscopy (TSCM) of normal and ischemic living kidneys
Authors: Andrews Peter M. , Petroll W. Matthew , Cavanagh H. Dwight , Jester James V.
Published: February 2005

Tandem Scanning Confocal Microscopy (TSCM) allows one to section optically into and record real‐time images of living organs and tissues in a noninvasive fashion. In this paper, we will present some initial TSCM observations of subcapsular nephrons in the living, intact kidneys of Munich‐Wistar rats and evaluate the nephron's responses to temporary ischemia and to intravenous infusion of mannitol. The rats were anesthetized with Inactin and a laparotomy performed to expose the kidneys. Using a TSCM equipped with a 20× water‐immersion objective, we optically sectioned through the intact kidney capsule and recorded real‐time images of living subcapsular glomeruli and uriniferous tubules. The proximal tubule brush border was highly reflective and allowed us to distinguish between the first and second segments of the proximal tubules as well as the distal tubules. Cellular elements of the blood could be seen passing repidly through peritubular capillaries and individual glomerular capillary loops. With fluorescent filters in place, intravenously injected carboxyfluorescein was seen to pass through the glomerular capillary loops and then progressively through the different segments of the uriniferous tubules. Ligation of the renal artery resulted in rapid swelling of proximal tubule cells into the tubular lumens, loss of reflectiveness of the microvillous brush broders, and closure of the peritubular capillary spaces. Upon relases of the ligature, the proximal tubule lumens again became patent, often opening up abruptly and in a zipper‐like fashion down the length of the tubules. Increasing the glomerular filtration rate by intravenous infusion of mannitol resulted in increases in tubular luminal and perimeter dimensions. Mannitol also acted as an effective impermeant osmotic agent and prevented most of the cellular swelling which was otherwise seen in response to renal ischemia.
Liver units in three dimensions: I. organization of argyrophilic connective tissue skeleton in porcine Liver with particular reference to the “compound hepatic lobule”
Authors: Ekataksin Wichai , Wake Kenjiro
Published: February 2005

Liver units were investigated in pig livers by means of histologic serial tracing, physical model building, and computer‐aided three‐dimensional imaging. Observations of the argyrophilic connective tissue skeleton were based mainly on the celloidin‐embedded serial sections treated with silver impregnation. The parenchymal mass that clothed the initial segments of hepatic venous radicles was demarcated by fibrous septa which formed isolable units with two basic patterns: the simple hepatic lobule (SHL) and the compound hepatic lobule (CHL). Both lobule types presented regular limiting structures circumscribing each unit. Three‐dimensional studies revealed that 25% of the lobules in a section belonged to the SHL type and 75% to the CHL type, the latter being predominant among the surface lobules. When considered in only two dimensions, however, the SHL‐like lobules constituted the majority. Polygonal analysis disclosed that the pentagonal lobule was the most typical, instead of the “hexagonal” or “classic” lobule. The CHLs represented a multiaxial unit containing a system of venous tributaries in accordance with intralobular septation, whereas the SHLs were found with one axial vessel having a dendritic tendency at the incipient end; some SHLs were drained eccentrically by separate vessels into a sublobular vein. It was observed that, in dividing CHLs, whereas particular sinosoids were transformed into portal twigs, other sinusoids were changed into central venous tributaries. Fibrous deposition occurred along the septal‐line sinusoids, bringing into view the septum‐initiating plane. Fibroconnective tissue was supplied from the portal area and central (sublobular) adventitia, where portal triad structures and adventitial arterioles, respectively, were included. The findings of the present study facilitate the understanding of several characters of the lobules that have been reported previously, or occasionally postulated, such as the portal‐central bridging tendency, the intralobular arterioles or ductules, the translobular artery or portal vein, the “portal‐portal” or “portal‐central” anastomoses, and the apposition of pericentral zone close to periportal zone. Based on differences in argyrophilia of sinusoidal reticulum, in proportion of lobule types, and in vasculature, the anatomic heterogeneity of liver unity was demonstrable in zonality, regionality, and locality. © 1991 WILEY‐LISS, INC.
Distribution of five peptides, three general neuroendocrine markers, and two synaptic‐vesicle‐associated proteins in the spinal cord and dorsal root ganglia of the adult and newborn dog: An immunocytochemical study
Authors: Bonfanti Luca , Bellardi Sergio , Ghidella Silvana , Gobetto Armando , Polak Julia M. , Merighi Adalberto
Published: February 2005

This study describes the immunocytochemical distribution of five neuropeptides (calcitonin gene‐related peptide [CGRP], enkephalin, galanin, somatostatin, and substance P), three neuronal markers (neurofilament triplet proteins, neuron‐specific enolase [NSE], and protein gene product 9.5), and two synaptic‐vesicle‐associated proteins (synapsin I and synaptophysin) in the spinal cord and dorsal root ganglia of adult and newborn dogs. CGRP and substance P were the only peptides detectable at birth in the spinal cord; they were present within a small number of immunoreactive fibers concentrated in laminae I–II. CGRP immunoreactivity was also observed in motoneurons and in dorsal root ganglion cells. In adult animals, all peptides under study were localized to varicose fibers forming rich plexuses within laminae I–III and, to a lesser extent, lamina X and the intermediolateral cell columns. Some dorsal root ganglion neurons were CGRP‐ and/or substance P‐immunoreactive.

The other antigens were present in the spinal cord and dorsal root ganglia of both adult and newborn animals, with the exception of NSE, which, at birth, was not detectable in spinal cord neurons. Moreover, synapsin I/synaptophysin immunoreactivity, at birth, was restricted to laminae I–II, while in adult dogs, immunostaining was observed in terminal‐like elements throughout the spinal neuropil.

These results suggest that in the dog spinal cord and dorsal root ganglia, peptide‐containing pathways complete their development during postnatal life, together with the full expression of NSE and synapsin I/synaptophysin immunoreactivities. In adulthood, peptide distribution is similar to that described in other mammals, although a relative absence of immunoreactive cell bodies was observed in the spinal cord.
Accumulation and localization of two adult acinar cell secretory proteins during development of the rat submandibular gland
Authors: Moreira Jorge E. , Ball William D. , Mirels Lily , Hand Arthur R.
Published: February 2005

The seromucous acinar cells of the adult rat submandibular gland secrete a characteristic mucin glycoprotein and a family of unusual glutamine/glutamic acid‐rich proteins (GRP). Monoclonal antibodies to the mucin and GRP localized in a very few Type III cells in glands of newborn and 1 day‐old rats, using light and electron microscopic immunocytochemistry. Both mucin and GRP reactivities were present in the polymorphic Type IIIP granules during the 1st postnatal week. By 9 days after birth, the granules contained both mucin and GRP and were mucous‐like in appearance. At earlier stages, however, cells containing only GRP or mucin could be found, indicating that the initiation of GRP and mucin biosynthesis may not be coordinately regulated. No reactivity was seen in the neonatal Type I cells or in duct cells at any age. Northern and Western blot analysis showed GRP mRNA and protein levels to be barely detectable at birth, with marked increases during the first 2 postnatal weeks. In contrast, Western blots of B1‐immunoreactive proteins (B1‐IP) showed levels highest in the 1st week and markedly decreased in the adult. Immunocytochemical colocalization, using gold particles of different sizes, showed that the B1‐IP, mucin, and GRP colocalized in the granules. These results strengthen the hypothesis that the adult acinar cells develop from the neonatal Type III cells. No evidence was obtained for the involvement of Type I cells in the pathway of acinar cell development.
Development of the discodial hemochorial placenta in the black mastiff bat, Molossus ater: Evidence for a role of maternal endothelial cells in the control of trophoblastic growth
Authors: Rasweiler John J.
Published: February 2005

In an effort to define further the factors that can influence trophoblastic growth, development of the discoidal chorioallantoic placenta was examined histologically in laboratorybred black mastiff bats, Molossus ater. This placenta normally forms only at the cranial end of the right uterine horn. Its positioning was found to be related to the development of an unusual vascular tuft in the endometrium at this site following ovulation. When a decidual reaction occurred, the endothelial cells of the tuft vessels hypertrophied and their basal laminae became more prominent in sections stained for glycoproteins. Cytotrophoblast then proliferated preferentially around the tuft in the right horn and its vessels became surrounded by trophoblastic cuffs. A functional placenta was formed when trophoblastic tubules grew out from these cuffs, became interconnected, developed lumina, and began to carry maternal blood. Maternal endothelial cells generally persisted only in portions of the larger vascular tubules.

These observations suggest that the endothelial cells of the tuft vessels may be secreting factors that influence early trophoblastic growth and are at least partially incorporated into the basal laminae of the endothelial cells. Evidence is reviewed which raises the possibility that endometrial endothelial cells might have a similar morphogenetic role in many other mammals with invasive trophoblast.

Mitotic activity in the trophoblastic tubules of M. ater ceased when the tubules became patent and began to carry blood. Further growth was then accomplished by hypertrophy of the existing cytotrophoblast cells. Electron microscopic examination of near‐term placentas confirmed that the interhemal barrier was hemomonochorial and lacked a continous layer of syncytiotrophoblast.
Changes in ultrastructure of transport systems and in rates of progestin secretion in the corpus luteum during late pregnancy in the rat
Authors: Dharmarajan A. M. , Bruce Neville W. , Waddell Brendan J.
Published: February 2005

Morphometric studies have confirmed that the corpus leteum (CL) of the pregnant rat contains luteal cells with numerous microvilli which directly face an extensive network of sinusoidal capillaries. From this it has been suggested that extensive development of transport structures is necessary to support progesterone synthesis and secretion. The present study was carried out to determine whether these transport structures could be related quantitatively to different rates of total progestin (progesterone plus 20 α‐hydroxypregn‐4‐en‐3‐one) secretion reported to be 32, 10, and 23 μg/hr per ovary on day 16 and the morning (AM) and afternoon (PM) of day 22, respectively.

Histological analysis was carried out on two CL, fixed by immersion, from each of five rats, at each stage of gestation. The important findings to emerge were that when the progestin secretion rate was greater, there was a significant increase in surface specializations on the lutelal cell and a thickening of the capillary walls. There was also a greater volume of interstitial space between luteal cells and capillaries. However, due to the development of microvilli and unevenness in the capillary wall, the physiological diffusion distance (harmonic distance) between luteal cell cytoplasm and blood was not increased. Collectively, these results show that changes in the rate of progestin secretion are accompanied by significant, although disproportionate, changes in transport structures and suggest that the latter are important in supporting luteal function.
Initial migration and distribution of the cardiac neural crest in the avian embryo: An introduction to the concept of the circumpharyngeal crest
Authors: Kuratani Shigeru C. , Kirby Margaret L.
Published: February 2005

The distribution and migration of the cardiac neural crest was studied in chick embryos from stages 11 to 17 that were immunochemically stained in whole‐mount and sectioned specimens with a monoclonal antibody, HNK‐1. The following results were obtained: (1) The first phase of the migration in the cardiac crest follows the dorsolateral pathway beneath the ectoderm. (2) In the first site of arrest, the cardiac crest forms a longitudinal mass of neural‐crest cells, called in the present study, the circumpharyngeal crest; this mass is located dorsolateral to the dorsal edge of the pericardium (pericardial dorsal horn) where splanchic and somatic lateral mesoderm meet. (3) A distinctive strand of neural‐crest cells, called the anterior tract, arises from the mid‐otic level and ends in the circumpharyngeal crest. (4) By stage 16, after the degeneration of the first somite, another strand of neural‐crest cells, called the posterior tract, appears dorsal to the circumpharyngeal crest. It forms an arch‐like pathway along the anterior border of the second somite. (5) The seeding of the pharyngeal ectomesenchyme takes place before the formation of pharyngeal arches in the postotic area, i.e., the crest cells are seeded into the lateral body wall ventrally from the circumpharyngeal crest; and, by the ventralward regression of the pericardial dorsal horn, lateral expansion of pharyngeal pouch, and caudal regression of the pericardium, the crest cell population is pushed away by the pharyngeal pouch. Thus the pharyngeal arch ectomesenchyme is segregated. (6) By stage 14, at the occipital somite level, ventrolateral migration of the neural crest is observed within the anterior half of each somite. Some of these crest cells are continuos with the caudal portion of the circumpharyngeal crest. An early contribution to the enteric neuroblasts is apparent in this area.
Ultrastructural localization of Tartrate‐resistant acid phosphatase (purple acid phosphatase) activity in chicken cartilage and bone
Authors: Fukushima Osamu , Bekker Petrus J. , Gay Carol V.
Published: February 2005

Tartrate‐resistant acid adenosine triphosphatase activity at pH 6.5, using a lead‐salt method, was localized at light and electron microscopic levels in cartilage and bone matrices, osteocalsts, and chondrocalsts. Cartilage matrix staining occurred after vascular invasion of the growth plate. In osteoclasts, activity was present in lysosomes, extracellular ruffled border channels, and the underlying cartilage and bone matrices. Staining artifacts occurred at lower pH levels (pH 5.4, 5.0).

Adenosine diphosphate, p‐nitrophenylphosphate, thiamine pyrophosphate, and α‐naphthylphosphate also acted as substrates; but no activity was observed when adenosine monophosphate, adenylate‐(β,γ‐methylene) diphosphate, and β‐glycerophosphate were used. The activity was inhibited by NaF, dithionite, and a high concentration of p‐chloromercuribenzoic acid, and activated by simultaneous addition of FeCl2 and ascorbic acid, as has been shown in biochemical studies. These histochemical results support the view that the adenosine triphosphate hydrolyzing activity at pH 6.5 is due to tartrate‐resistant acid phosphatase (TRAP).

There were some differences in ultrastructural localization between TRAP and tartrate‐sensitive acid phosphatase (TSAP) activities in osteoclasts: TSAP activity was more intense in lysosomes and Golgi complexes and TRAP was stronger in the cartilage and bone matrices. It is suggested, therefore, that most of TRAP is in an inactive form in cells and is activated when secreted.
Ontogeny of reticular cells in the ileal Peyer's patch of sheep and goats
Authors: Nicander L. , Halleraker M. , Landsverk T.
Published: February 2005

The ontogeny of reticular cells in the ileal Peyer's patch of sheep from 70 days gestational age was studied by light and electron microscopy and by enzyme histochemistry. Small to medium‐sized lymphocytes were seen in the lamina propria at 97 days, when the stroma was essentially still mesenchymal. By 110 days, the stromal cells in the dome/follicle primordia had differentiated into reticular fibroblasts, whose processes and fibers were seen to surround groups of lymphocytes. With advancing age the number and size of primordia increased, and proliferation was obvious among the lymphocytes. Processes of reticular cells increased in number and penetrated between individual lymphocytes of the groups. Coarser desmosome‐like contacts were seen between the reticular cells from 115 days onwards. A central light area in the follicle was apparent from 130 days onwards. The fine structure of the stromal cells in this light follicle center developed towards but never became similar to that of follicular dendritic cells in a typical germinal center. The fine interdigitating end branches of the stromal cells were less numerous, and the dense homogeneous material present in between the end branches was not observed in the ileal Peyer's patch follicle. Instead, small particles and vesicles were seen between the various cell types of the light center and were not restricted to the intercellular spaces between the stromal cells. In the dark peripheral zone of the follicle, the stromal cells retained more immature features. The follicle became bordered by a capsule at an early stage. This capsule was formed by multiple layers of flattened fibroblasts separated by small amounts of intercellular material only. The alkaline phosphatase, Mg2+‐dependent adenosine triphosphatase and 5′nucleotidase reactivities of the follicular dendritic cells in the ileal Peyer's patch were similar to those of early prenatal primary follicles of sheep lymph nodes. This study indicates that the stromal cells of the ileal Peyer's patch are mesenchymal in nature and different from those of germinal centers and the epithelial stromal cells of bursa Fabricii of birds. © 1991 Wiley‐Liss, INC.
Organization of tubules in the human caput epididymidis and the ultrastructure of their epithelia
Authors: Yeung C. H. , Cooper T. G. , Bergmann M. , Schulze H.
Published: February 2005

The structure of the human caput epididymidis was examined by gross morphological and light and electron microscopic techniques. There were at least seven types of tubules, each characterized by a different epithelium. These tubules were connected with one another by at least eight types of junctions to form a network. Most of the caput epididymidis was composed of efferent ducts. Within these, five types of tubules, each with a different ciliated epithelium, were found in different regions; and four types of junctions between the efferent ducts and the epididymal tubule were observed. The efferent ducts left the testis, initially as parallel straight tubules containing both ciliated and non‐ciliated cells in an epithelium of irregular height. Each efferent duct then coiled tortuously into lobules that folded over one another. These efferent ducts then branched out as thin tubules to join a network of dark tubules which were lined by a regular epithelium containing prominently vacuolated, nonciliated cells. These tubules anastomosed via common cavities characterized by a ciliated cuboidal epithelium and sometimes joined tubules exhibiting a non‐vacuolated ciliated epithelium. The latter, as well as typical efferent ducts, made connection with the epididymis proper in both end‐to‐end and end‐to‐side junctions. In the more distal junctions with the epididymis, the efferent ducts joined to a transitional epididymal ductule before joining to the side of the epididymis proper. Post‐junctional epithelia in the beginning of the epididymis occasionally contained patches of cells characteristic of efferent ducts. Tall cells with long stereocilia constituted a discontinuous “initial segment”‐like region of the epididymis. This is the most detailed study so far of the epithelia and the tubule organization in the caput epididymidis of any species, and most of the results are reported for the first time for the human. Although the pattern of the tubule network resembles that of some domestic species, the rich variety of epithelia has not been appreciated before.
Spatial and temporal patterns of muscle cleavage in the chick thigh and their value as criteria for homology
Authors: Schroeter Sally , Tosney Kathryn W.
Published: February 2005

Regions of lower cell density, called cleavage zones, emerge within the dorsal and ventral muscle masses in the vertebrate limb to separate distinct muscles. In the chick thigh, the stereotyped patterns of separation have been broadly outlined, but differences in interpretation exist because no criteria for separation have been defined, and the tissues of the limb are indistinct early in development. We have examined the cleavage process using modern applications of light microscopy and immunocytochemistry to completely detail the spatial and temporal progression of cleavage in stage 27–32 embryos. We find that each muscle has a complex but characteristic pattern of separation along the proximodistal axis. The complex pattern of separation is not related to the positions of muscles within the thigh, locations of blood vessels, activity patterns of muscles, or innervation patterns. The initial separation patterns are more straightforward than later separations and may be of value in determining the phylogenetic history of limb muscles since the same patterns are common to many tetrapods. Our detailed documentation clarifies the ontogeny of the thigh musculature and reveals more complex separation patterns between muscles than previously described.
An immunocytochemical study of cutaneous innervation and the distribution of neuropeptides and protein gene product 9.5 in man and commonly employed laboratory animals
Authors: Karanth S. S. , Springall D. R. , Kuhn D. M. , Levene M. M. , Polak J. M.
Published: February 2005

The cutaneous nerves of rat, cat, guinea pig, pig, and man were studied by immunocytochemistry to compare the staining potency of general neural markers and to investigate the density of nerves containing peptides. Antiserum to protein gene product 9.5 (PGP 9.5) stained more nerves than antisera to neurofilaments, neuronspecific enolase (NSE), and synaptophysin or histochemistry for acetylcholinesterase (AChE). Peptidergic axons showed species variation in density of distribution and were most abundant in pig and fewest in man. However, the specific peptides in nerves innervating the various structures were consistent between species. Nerve fibers immunoreactive for calcitonin gene‐related peptide (CGRP) and/or vasoactive intestinal polypeptide (VIP) predominated in all the species; those immunoreactive to tachykinins (substance P and neurokinin A [NKA]) and neuropeptide tyrosine (NPY) were less abundant. Neonatal capsaicin, at the doses employed in this study, destroyed approximately 70% of CGRP‐ and tachykinin‐immunoreactive sensory axons; whereas 6‐hydroxydopamine (6‐OHDA) at the doses employed resulted in a complete loss of NPY and tyrosine hydroxylase (TH) immunoreactivity without affecting VIP, CGRP, and tachykinins.

Thus, this study confirms that antiserum to PGP 9.5 is the most suitable and practical marker for the demonstration of cutaneous nerves. Species differences exist in the density of peptidergic innervation, but apparently not for specific peptides. Not all sensory axons immunoreactive for CGRP and substance P/NKA are capsaicin‐sensitive. However, all sympathetic TH‐ and NPY‐ immunoreactive axons are totally responsive to 6‐OHDA; but no change was seen in VIP‐immunoreactive axons, suggesting some demarcation of cutaneous adrenergic and cholinergic sympathetic fibers.
Histometry of normal thyroid glands in neonatal and adult rats
Authors: Conde E. , Martin‐Lacave I. , Gonzalez‐Campora R. , Galera‐Davidson H.
Published: February 2005

The present histometric study is on thyroid glands of Wistar rats ranging in age from 0 to 120 days. The mean volume of one lobe of the thyroid in 4‐month‐old animals was some 22‐, 10‐, 5‐, and 3‐fold greater, respectively, than the volumes in the newborn, 5‐, 10‐, and 30‐day‐old rats. At 4 months of age the mean length of the lobe was 3 times greater than at birth. The volumetric fractions (Vv) of the different histological components (follicular cells, C‐cells, colloid, and interstitial tissue) changed considerably in the course of development. The Vv of follicular cells diminished from 61.4% at birth to 37.2% at 4 months. C‐cells increased from 2.9% in the newborn to 4% at 15 days, with no further significant change at 4 months. Colloid and stroma together represented 35.7% at birth, increasing to 58.5% at 120 days. In the course of the first 4 months of life, the absolute volumes occupied by follicular cells, C‐cells, colloid, and stroma increased 13.25, 30.75, 38.6, and 33.7 times, respectively; these changes reflect the variations that occur in the volume of the gland and the Vv throughout postnatal development.
Comparative morphology and morphometry of alveolar macrophages from six species
Authors: Haley P. J. , Muggenburg B. A. , Weissman D. N. , Bice D. E.
Published: February 2005

Pulmonary alveolar macrophages (PAM) were collected from normal, healthy mice, rats, dogs, cynomolgus monkeys, chimpanzees, and humans and evaluated for morphologic and morphometric characteristics. The PAM of mice, rats, and dogs were morphologically similar and had statistically similar frequency distributions for size. The cell size distribution or these three species was relatively homogeneous. The PAM of nonhuman primates and humans were morphologically heterogenous with sometimes prominent cytoplasmic vacuolation, irregular cell outlines, and increased numbers of multinucleated cells as compared to the PAM of rodents and dogs. The mean size of human PAM was statistically greater than that for all other species evaluated, including nonhuman primates. These data indicate that significant differences in PAM morphology and size exist among species.
A quantitative evaluation of Fourier components in transparent and opaque calf cornea
Authors: Gisselberg Margo , Clark John I. , Vaezy Shahram , Osgood Thomas B.
Published: February 2005

Fourier transform methods were applied to STEM (scanning transmission electron microscopy) images to detect and quantify the subtle differences between the structure of normal transparent calf cornea and opaque calf cornea. In order for a tissue to be transparent, it can scatter or absorb only a small amount of light. Light scattering is minimized when the principal Fourier components of the spatial fluctuations in the index of refraction have wavelengths which are small relative to the wavelength of light (Benedek, 1971). Corneal opacity was produced as a result of high intraocular pressure (100–150 mmHg) when liquid was injected into calf eyes (0–2 weeks old). Pressurization created large structural defects and slight disruptions in the organization of the collagen fibers. Although the fiber organization appeared similar in the micrographs of both opaque and transparent corneas, Fourier analysis of STEM images collected at 50K magnification identified statistically significant differences. Far fewer Fourier components with wavelengths in the light scattering range (200–1100 nm) were observed in the transparent corneas than in the pressurized corneas as predicted by Benedek's theory. It was of interest that corneas treated with 100% glycerol prior to pressurization remained transparent at high intraocular pressures, possibly because glycerol stabilized the structure of the corneas and maintained a uniform index of refraction across the corneal stroma. The results demonstrate the effectiveness of Fourier analysis in detection and quantification of slight changes in structure at the electron microscopic level.
Epidermal ridge formation in the human fetus: A correlation to the appearance of basal cell heterogeneity and the expression of epidermal growth factor receptor and cytokeratin polypeptides in the epidermis
Authors: Misumi Yuko , Akiyoshi Toshio
Published: February 2005

This paper aims to clarify an expression of epidermal growth factor receptor (EGFR) and cytokeratin 10 and/or 11 in relation to primary and secondary epidermal ridge formation of the human fetus.

Firstly, scanning electron microscopy revealed heterogeneity in basal cell morphology during epidermal ridge formation. Basal cells had a uniform, smooth, and polygonal dermal surface until formation of the primary epidermal ridges. Thereafter, the dermal surface became ruffled and elliptic except at the primary epidermal ridges.

Secondly, EGFR was detected by monoclonal antibody and autoradiography using 125I‐EGF. The antibody reacted with primary epidermal ridge, stratum basale, stratum intermedium, and outer layer of sweat duct. The reactivity became stronger at the primary epidermal ridge than at the secondary one. The binding of 125I‐EGF was concentrated in the primary epidermal ridge and sweat duct.

Thirdly, cytokeratin 10 and/or 11, a maturation marker of keratinocytes, was detected by monoclonal antibody. The antibody reacted only with the stratum intermedium before secondary epidermal ridge formation. Afterward, it also reacted with the stratum basale of the secondary epidermal ridge but never reacted with that of primary epidermal ridge.

The results indicate that basal cells of the secondary epidermal ridge enter the maturation process and suggest a localization of epidermal stem cells on the primary epidermal ridges. Concerning epidermal ridge formation, we suppose that the formation of the primary epidermal ridge causes the segregation of the epidermal stem cells, and that the increased density of the basal cells between the two primary epidermal ridges brings about the change in their dermal surface shape and the formation of the secondary epidermal ridge.
Voltage‐dependent ‐L‐type Ca2+ channels participate in regulating neural crest migration and differentiation
Authors: Moran Denis
Published: February 2005

General models of cell activation implicate Ca2+ conductance as pivotal in conveying transmembrane signals. During embryonic development, both cell migration and differentiation are influenced by changes in Ca2+; and, as a consequence, the modulation of Ca2+ is important in the control of many morphogenetic processes. Because Ca2+ conductance may be regulated at voltage‐dependent Ca2+ channels (VDCCs), we investigated whether neural crest cells develop VDCCs and, if so, whether they function in regulating migration and establishing cytomorphology. Autoradiography indicates that neural crest cells in vitro develop‐L‐type Ca2+ channels during migration and differentiation. Blockage of these channels by verapamil, both in vivo and in vitro, leads to a dramatic and reversible inhibition of neural crest migration. Alterations are manifest in vitro in cell‐to‐cell and cell‐to‐substratum contact and in the organization of the actin cytoskeleton. In whole embryos, verapamil or nifedipine inhibits pigment pattern formation. Moreover. blockage of the ‐L‐type Ca2+ channels in whole embryos or cultures, after cells have already migrated and differentiated, results in a significant change in individual cell shape and in the overall pigment cell pattern, suggesting further that maintenance of the differentiated state also requires regulation at the ‐L‐type Ca2+ channel. Since certain aspects of neural crest adhesion and cytoskeletal function are dependent on Ca2+, it is suggested that interactions that regulate the availability of Ca2+ through the VDCC may provide coordinate control of motile and adhesive interactions at the cell‐substratum interface.
Generation of color composites for enhanced tissue differentiation in magnetic resonance imaging of the brain
Authors: Brown H. Keith , Hazelton Todd R. , Silbiger Martin L.
Published: February 2005

Currently, the diagnostic interpretation of magnetic resonance (MR) images requires that radiologists integrate specific tissue contrast information from several different images obtained at the same anatomic slice position. Each of these images has its own unique tissue contrast patterns which are based on the image acquisition parameters (pulse sequence) selected. The complex contrast patterns observable in these images reflect the inherent biophysical characteristics of the tissues and fluids present in the imaged section. In an effort to increase the diagnostic accuracy and efficiency of MR image interpretation, we have generated color composite images from quantitatively analyzed achromatic MR images of the brain, obtained while utilizing different pulse sequences. By using a DEC Micro VAX II computer with Interactive Digital Language (IDL), this color display method has been applied to images obtained from General Electric Signa and Siemens Magnatom imagers. For this study, our image sets included T1‐weighted, T2‐weighted, and proton density spin echo sequences as well as both high and low flip angle gradient echo sequences. Advantages of our color composite methods, in contrast to many other image processing techniques that have been described, are that minimal information is lost, computer misclassification of tissues is avoided, and the conspicuity of specific tissues is enhanced. Furthermore, with this method it is possible to produce composite images whose color renditions approach a natural anatomic tissue appearance. Availability of these color composites to radiologists may improve the efficiency and accuracy of the diagnostic interpretation of MR images.