bluuebunny/crossref_metadata_2025 huggingface dataset:
Functional organization of the oculomotor nucleus in the baboon
Authors: Augustine James R. , Deschamps Edgar G. , Ferguson James G.
Published: February 2005

The functional organization of the oculomotor nucleus was investigated using horseradish peroxidase (HRP) histochemistry. In a series of baboons, injections of HRP were made into the skeletal muscles supplied by the oculomotor nerve (medial rectus, superior rectus, inferior rectus, inferior oblique, and the levator palpebrae superioris). After a 48‐hour survival time the animals were sacrificed via perfusion‐fixation and the brains treated according to the tetramethylbenzidine (TMB)‐HRP method of Mesulam (1978).

The inferior oblique, inferior rectus, medial rectus, and levator palpebrae superioris muscles are supplied by cells located primarily in the homolateral oculomotor nucleus. Some fibers to the levator palpebrae superioris arise from cells in both caudal central nuclei. The superior rectus muscle receives fibers from cells in the contralateral oculomotor nucleus. The results were complied using a Lucite‐plate reconstruction method that permits visualization of the three‐dimensional configuration of the neuronal populations within the oculomotor nucleus.

Oculomotor neurons are organized in a vertical column that may be anatomically divided into rostral, middle, and caudal thirds. A section through any of these levels may be further subdivided into dorsal, intermediate, and ventral zones. Each of the oculomotor skeletal muscles was found to have cells at almost all levels of the nucleus and in certain zones at each level. These functional cell groups intermingle with one another in the baboon and do not remain segregated into distinct subnuclei or subdivisions. Much overlap was evident between cells innervating the homolateral inferior rectus, homolateral inferior oblique, and the contralateral superior rectus muscles. There was also overlap between those cells supplying the homolateral levator palpebrae superioris and the homolateral medial rectus muscles.
Influences of age and vasopressin on the uptake capacity of fluorescent granular perithelial cells (FGP) of small cerebral vessels of the rat
Authors: Mato Masao , Ookawara Shigeo
Published: February 2005

Fluorescent granular perithelial cells (FGP) were found in the perivascular space around fine cerebral blood vessels. Their profiles and intracellular inclusions varied with the age of the animals. The FGP are able to take up exogenous substances administered intraventricularly.

With light and electron microscopy, the relation between the uptake capacity of FGP and the aging of animals was studied using horseradish peroxidase (HRP). The effects of vasopressin on the uptake of HRP also were examined. The results can be summarized as follows: (1) The uptake capacity of FGP diminished with aging, that is, the reaction product of administered HRP was found abundantly in FGP in young rats, while it was sparse in the FGP of old rats; and (2) vasopressin increased the incorporation of HRP into the FGP of both young and old rats. The possible role of vasopressin in modulating the uptake capacity of FGP is considered, and the differences between FGP and other perivascular cells are discussed.
Nerve endings in human sympathetic ganglia
Authors: Helén Pauli , Hervonen Antti
Published: February 2005

Forty‐eight human sympathetic ganglia from 22 sympathectomies were examined ultrastructurally after one of three different fixations: (1) glutaraldehyde + osmium tetroxide, (2) glutaraldehyde + potassium dichromate + osmium tetroxide, or (3) potassium permanganate.

Three different kinds of synapsing nerve ending could be identified after all fixation schedules. Type 1: “Cholinergic,” containing small, agranular vesicles 40–60 nm in diameter (75% of all vesicles) and some large granular vesicles (100 nm in diameter). The number of type 1 profiles decreased with increasing age. Type 2: “Adrenergic,” containing small granular vesicles 40–70 nm in diameter (over 90% of the vesicles). Type 3: “Nonadrenergic, noncholinergic,” characterized by large opaque vesicles 80–160 nm in diameter (over 50% of all vesicles). The frequencies of the types were counted after potassium permanganate fixation: type 1–71%, type 2–23%, and type 3–6%.

In addition, at least two types of nerve profiles were observed which did not form synapses: (1) profiles entirely filled with mitochondria (mitochondrial accumulation), and (2) large nerve profiles full of different kinds of vesicles, myelin figures, and mitochondria (axonal dilatation).

It is concluded that the sympathetic ganglion cells receive cholinergic and adrenergic innervation and also a third type of innervation, the possible peptidergic nature of which is discussed.
Morphological and histochemical observations on the duodenal glands of eight wild ungulate species native to North America
Authors: Krause W. J.
Published: February 2005

The duodenal glands of the species examined (Alces alces, Ovis canadensis, Cervus canadensis, Oreamnos americanus, Bison bison, Antilocapra americana, Odocoileus virginianas, Odocoileus heminous) are confined primarily to the submucosa of the small intestine. In one species, the moose, a significant population of secretory tubules also is observed in the mucosa. The ducts of the duodenal glands pierce the overlying muscularis mucosae to empty most often independently into the intestinal lumen. Those of the bison, unlike the other species examined, drain into intestinal glands. The duodenal glands consist primarily of a simple columnar epithelium, the cells of which contain basally positioned round or oval nuclei. The lumina of scattered duodenal glands in the pronghorn and to some extent those of the moose, white‐tailed deer, and mule deer may be extremely dilated, and the surrounding epithelium thin and attenuated. Component cells of the duodenal glands of all the species examined show remarkably similar ultrastructural features. They exhibit scattered profiles of rough endoplasmic reticulum, dilated cisternae of which contain an electrondense, amorphous material. Numberous well‐developed Golgi complexes occupy the supranuclear region together with transport vesicles and forming secretory granules. Electron‐dense, membrane‐bound secretory granules generally are concentrated in the apical cytoplasm immediately subjacent to the cell membrane. The apical cell membrane exhibits short, scattered microvilli; and the basal cell membrane is smooth without apparent specialization.

Histochemically, the duodenal glands of most species examined in this study consist of a heterogeneous population. The majority of the glands of the moose, elk, mountain goat, bison, pronghorn, and white‐tailed deer elaborate a neutral mucin, whereas scattered individual glands, tubules or cells also produce acid mucins. Cells near the terminations of the ducts of the bighorn sheep are the only elements to produce acid mucins in the duodenal glands of this species. The duodenal glands of the bison are unusual in that only the peripheral portions of individual glands produce acid mucins. The remainder of the glands elaborate neutral mucins. Morphological differences between the two regions were not observed. The duodenal glands of the mule deer secrete both acid and neutral mucins. The structural and histochemical observations appear unrelated to the diet of individual species.
The development of the lung in mammals: An analysis of concepts and findings
Authors: Ten Have‐Opbroek Antonia A. W.
Published: February 2005

To evaluate one model of mammalian‐lung development, i.e., division into periods, pre‐ and postnatal lung development in the CPB‐S mouse strain was divided into the currently distinguished periods: the pseudoglandular period, covering establishment of the air‐conducting portion; and the canalicular, terminal‐sac, and alveolar or postnatal periods, in which the respiratory portion develops. The last three periods would each cover the formation of a different component of the respiratory unit or pulmonary acinus (acinus pulmonaris) (nonalveolated respiratory bronchiole, nonalveolated duct and sac, and alveolar pouch). However, determination of the nature of the relevant structures on the basis of recent findings concerning the epithelia showed that these hypotheses are not tenable. Since the tubule with cuboidal epithelium (appearing in the pseudoglandular and following periods) is the basic structure in the genesis of the pulmonary acinus, the development of the respiratory portion must start in the pseudoglandular period. Likewise, since the definitive components of the acinus are derived from this acinar tubule, their establishment may not be restricted to one of the other periods.

Because other postulated divisions of mammalian‐lung development were based on similar histological interpretations, they cannot reflect the course of mouse‐lung development either. Therefore, a developmental scheme based on the recent findings concerning the epithelia is given as well as a tentative scheme for the human lung.

The respiratory portion proved to develop by budding of acinar tubules, the mode of budding being not restricted to any particular pattern.
Microcirculation of the rat adrenal gland: A scanning electron microscope study of vascular casts
Authors: Kikuta Akio , Murakami Takuro
Published: February 2005

Blood vascular beds of the rat adrenal gland were filled with methacrylate resin and observed with a scanning electron microscope. The classical findings on mammalian adrenal glands of Flint (1900), Bennett and Kilham (1940), and Gersh and Grollman (1941) were confirmed. The cortical capillaries arise from the cortical arteries and converge at the corticomedullary junction into the peripheral venous radicles which flow into the tributaries of the central vein. The medullary capillaries originate from the medullary arteries and drain through the deep venous radicles into the tributaries of the central vein. No direct connection between the cortical and medullary capillaries was noted except for rare communications via the peripheral venous radicles. These findings show that most of the cortical blood, rich in glucocorticoids, flows in the medulla, not through the medullary capillary plexus but exclusively through the radicles of the central vein. Evidence for adrenal portal vessels could not be found.
Anatomy and innervation patterns of cat lateral gastrocnemius and plantaris muscles
Authors: English Arthur W. , Letbetter William D.
Published: February 2005

The anatomy, fiber architecture, and innervation patterns of cat lateral gastrocnemius (LG) and plantaris (P) muscles are described. The plantaris is a simple unipennate muscle arising from an aponeurosis in common with LG and inserting primarily into the tendon of m. flexor digitorum brevis, but with ligamentous connections to the calcaneus. The lateral gastrocnemius is more complex and contains three distinctly identifiable heads, each of which is a unipennate band of fibers coursing between a proximally attached aponeurosis of origin and a distal aponeurosis of insertion that gives rise to the tendocalcaneus. Following microdissection of the LG and P nerves, and using glycogen depletion of the primary muscle nerve branches, discrete motor subvolumes are demonstrated in both muscles. Despite large specific differences in fiber architecture between the LG and P muscles, their organization into compartments about primary muscle nerve branches is fundamentally similar. This principle of organization may be a basis for the observed functional and structural properties of other vertebrate muscles. It may thus constitute a unifying concept in the organization of motor control mechanisms.
Morphological studies on long‐term culture of marrow cells: Characterization of the adherent stromal cells and their interactions in maintaining the proliferation of hemopoietic stem cells
Authors: Tavassoli Mehdi , Takahashi Kiyoshi
Published: February 2005

In long‐term cultures of bone marrow, the adherent stromal cells provide support for the proliferation and maintenance of hemopoietic stem cells. These stromal cells and their interactions were characterized by means of scanning (SEM) and transmission (TEM) electron microscopy in correlation with functional studies. Cultures were initiated by establishing the adherent stromal layer as a “soil” which was then “seeded” after 3 weeks by the addition of another marrow‐cell suspension. Clonal assay of the supernatant demonstrated the continuous proliferation of the hemopoietic stem cell. The stroma essentially consisted of two cell types, macrophages and epithelioid cells. Macrophages were smaller, 10–15 μm, phagocytosed latex and carbon particles, and contained lysosomes. Their surface did not stain with polycationic ferritin (PCF). Epithelioid cells were much larger, more than 100 μm; contained numerous thin, elongated mitochondria; did not phagocytose latex particles; but did display strong surface staining with PCF. The appearance of epithelioid cells in TEM depended on their state of development and whether the section was parallel or perpendicular to the substratum. Epithelioid cells displayed a maturational spectrum, at two ends of which were synthetic and storage phases. In the synthetic phase, the cell contained numerous profiles of rough endoplasmic reticulum, and in the storage phase, numerous storage granules. These two phases were best appreciated in sections perpendicular to the substratum, demonstrating synthetic cells on top settling over the substratum upon maturation into the storage cells.

Both macrophages and epithelioid cells contained fat globules which increased in number and size with the addition of hydrocortisone to the culture medium. A distinct fat‐cell type, as has been claimed, was not found in this study. Granulopoiesis was observed in the culture system in the absence of colony‐stimulating activity in the supernatant, suggesting direct cellular interaction or short‐range factors in the induction of granulopoiesis. Widespread cellular interactions were noted between macrophages and epithelioid cells, the latter often completely embracing the former and both extending cytoplasmic processes toward each other. This is reminiscent of the cooperative interaction of endoderm and meso‐derm in chick embryo hemopoiesis and may be necessary for the maintenance of stem cells in these cultures.
Quantitative autoradiography, electron microscopy, and granulometry of endocrine cells in the rabbit colon
Authors: Lefranc G. , Barriere P. , Chung Y. T. , Pradal G.
Published: February 2005

A high‐resolution autoradiographic study was conducted on 268 thin sections of endocrine cells in the rabbit colon following injection of (3H) Ldopa. Using quantitative autoradiography, silver‐proteinate impregnation, granulometry, and statistical analysis of cell populations by the Falck procedure, three cell types were identified‐EC, L; and H‐as well as a single cell with distinct ultrastructural characteristics. For the first time, a fine quantitative estimation of the handling ability of amine precursor related to the cross‐sectional areas of each cell type was obtained, using a Kontron Digiplan image analyzer. All cells studied showed the ability to take up the precursor. Labeling indices were 6.63, 2.15, and 2.14 for EC, L, and H, respectively. These data and silver‐proteinate impregnations provide good criteria for differentiating EC from H cells despite morphological similarities. After critical analysis of granule diameters, L cells were considered to be pluripotential in secretory activity.
Morphometric studies on rat seminiferous tubules
Authors: Wing Tung‐Yang , Christensen A. Kent
Published: February 2005

The goal of this morphometric study was to obtain quantitative information on the seminiferous tubules of Sprague‐Dawley rats, including changes seen at various stages of the cycle of the seminiferous epithelium. Tissue from perfusion‐fixed testes was embedded in Epon‐Araldite; and sections were subjected to morphometric measurements at the light microscopic level, using point counting for volume densities and the Floderus equation for numerical densities.

Changes occur in the diameter of the seminiferous tubule, as well as in the volume of the seminiferous epithelium and tubule lumen, from stage to stage during the cycle. A significant constriction of the seminiferous tubule accompanies spermiation. The volume of the seminiferous epithelium per unit length of the tubule begins to increase after stage XIV, and peaks at stage V of the next cycle. The tubule lumen increases dramatically from stages V to VII, at the expense of the epithelium.

The number of Sertoli cells is constant per unit length of the seminiferous tubule at all stages of the cycle. This is also true for primary spermatocytes of various developmental phases and for round spermatids from step 1 through step 10 of spermiogenesis. The average number of younger (preleptotene, leptotene, zytgotene) primary spermatocytes per Sertoli cell is 2.34 ± 0.082 (SEM), the number of older (pachytene, diplotene) primary spermatocytes per Sertoli cell is 2.37 ± 0.064, and the ratio of step 1–10 spermatids to Sertoli cells is 7.89 ± 0.27. By studying tangential views of serially sectioned seminiferous tubules at stage V, it is shown that the number of step‐17 spermatids associated with each Sertoli cell averages 8.35 ± 0.128, although the counts ranged from 6 to 11. The only appreciable occurrence of cell death after the last spermatogonial mitosis appears to be a 15% loss during the first meiotic division. From our morphometric results, corrected for volume changes during preparation for microscopy, there are 15.7 million (± 0.99 million) Sertoli cells per gram of fresh rat testis. The length of seminiferous tubule per gram of testis is estimated to be 12.4 ± 0.56 meters, and the tubule surface area per gram testis is 119.7 ± 2.57 cm2. The daily production of mature spermatids is 9.61 million (± 0.615 million) per gram of testis.
Appearance and disappearance of tubular paracrystalline structures in somatotrophs and lactotrophs during the annual life cycle of the bat (Myotis lucifugus)
Authors: Nunez Eladio A. , Gershon Michael D.
Published: February 2005

The fine structure of the endocrine (granulated) cells of the adenohypophysis of the bat was examined at different periods of the annual life cycle. During the active homeothermic period (early spring until late summer) the endocrine cells were heavily granulated, and evidence of granule release was commonly seen. At this time, but not at other times (hibernation and arousal), prominent paracrystalline structures were numerous and transiently appeared in the cytoplasm of acidophils (apparently both lactotrophs and somatotrophs) but not in the cytoplasm of basophils. These paracrystalline bodies were composed of densely packed, parallel arrays of tubules. The paracrystalline structures in lactotrophs differed in size, shape, and the pattern of arrangement of component tubules from those of somatotrophs. During hibernation no evidence of exocytosis was seen, and secretory granules accumulated in the cytoplasm. Prior to arousal, secretory granules were removed by autophagy.
Kinetics of fibrous sheath formation in the rat spermatid
Authors: Irons Margaret J. , Clermont Yves
Published: February 2005

The morphogenesis of the fibrous sheath in the rat spermatid has been studied by electron microscopy and by EM radioautogaphy following injection of 3H‐proline. The appearance of the developing fibrous sheath from the distal to proximal end of the principal piece has been examined in spermatids in each of the 19 steps of spermiogenesis. The precise timing of the various steps of its formation has been established and related to radioautographic observations on the synthesis and incorporation of proteins into the developing fibrous sheath. The longitudinal columns form slowly over a period of 15 days, appearing first at the distal end of the principal piece in step 2 and gradually extending in a proximal direction, ending at the level of the annulus in step 17. Throughout this 15‐day period, proline‐containing proteins are synthesized and incorporated into the growing columns.

All of the ribs, on the other hand, arise from anlagen which are assembled along the length of the principal piece during a much shorter (4.5‐day) period between steps 11 and 15 of spermiogenesis. New rib anlagen seemingly originate from bundles of proteinaceous filamentous material which are synthesized in the cytoplasm of step 11–15 spermatids and become aligned along the plasma membrane of the principal piece, starting at the distal end. These observations suggest that the two components of the fibrous sheath are assembled by means of two independent mechanisms that proceed asynchronously except during an overlap period of 2.5 days between steps 12 and 14.
Culture of A‐431 human epidermoid carcinoma cells in serum‐free medium: Effect of culture conditions on the binding of [125I]‐epidermal growth factor
Authors: Barka Tibor , Van Der Noen Hendrika
Published: February 2005

Serum‐free culture conditions that permit the continuous growth of A‐431 human epidermoid carcinoma cells were developed. In Dulbecco's modified Eagle's synthetic nutritional medium (DME) supplemented with fetuin, insulin, transferrin, biotin, and oleic acid‐fatty acid‐free bovine serum albumin complex A‐431 cells grew at a rate comparable to that observed in the presence of calf or fetal calf serum. Of the factors tested, oleic acid had the most pronounced stimulatory effect on the growth and [3H]‐thymidine incorporation of A‐431 cells in serum‐free medium. A‐431 cells have a high number of receptors for epidermal growth factor (EGF); they bind and rapidly internalize EGF. Nevertheless, EGF did not stimulate either the growth or the [3H]‐thymidine incorporation of these cells. Analyses of [125I]‐EGF binding data indicated that A‐431 cells grown in the presence of calf serum had about 3.2–3.9 × 106 specific, saturable EGF receptor sites on their surface. Linear Scatchard plots indicated a single class of noninteracting receptors with an apparent equilibrium dissociation constant of about 2.8 × 10−9 M. The average number of receptors of A‐431 cells maintained in DME supplemented with only fetuin, insulin, and transferrin for several months was significantly less, 1.54 × 106, than that of A‐431 stock cells cultured in the same medium for 2 days only (2.68 × 106). The apparent dissociation constants for the same cell populations were, however, similar, 4.5 × 10−9 M and 4.1 × 10−9 M, respectively. Stimulation of growth by oleic acid resulted in about 20% decrease in the average number of receptor sites, with an increase in the apparent equilibrium dissociation constant.
The contribution of the mesonephros to the development of the sheep fetal testis
Authors: Zamboni Luciano , Upadhyay Shakti
Published: February 2005

In this study, which was performed on 52 sheep fetuses aged 24 to 85 days, we examined the relationship between testicular development and the “giant” mesonephric nephron, a peculiar structure consisting of a large glomerulus and multiple tubules. The development of the testis occurred in two phases. The preparatory phase began at day 24 of gestation, evolved simultaneously with the involution of the glomerulus of the giant nephron, and was characterized by mobilization of the glomerular cells and by their colonization of the genital ridge. By day 31, a prominent mass of migrating mesonephric cells had developed; it extended uninterrupted from the giant glomerulus into the gonad where the mesonephric cells associated with the germinal cells forming the cellular template from which the testicular cords later became assembled. At complete involution of the glomerulus (day 52), the migratory mass implanted on the tubules of the giant nephron, which thus became continuous with the gonad. During the organizational phase, which began at day 29 with the formation of the tunica albuginea, the various components of this continuum became progressively organized along a testis‐to‐mesonephros direction into seminiferous cords, tubuli recti, the cords of the rete testis, and the ductules efferentes. These observations show that, in the sheep, the precursors of the Sertoli cells are mesonephric in origin, and that the genital tract proximal to the epididymis differentiates from a single mesonephric nephron.
Vasculature of the mouse, rat, and rabbit testis‐epididymis
Authors: Chubb Curtis , Desjardins Claude
Published: February 2005

The arrangement of blood vessels serving the testis‐epididymis was investigated microscopically in the mouse, rat, and rabbit. Blood vessels were visualized by infusing liquid silicone rubber into the vessels and subsequently clearing the surrounding tissue. Comprehensive illustrations of the vasculature were prepared from three‐dimensional examinations.

Arterial and venous vessels serving the testis‐epididymis follow similar routes in all three species. However, the arrangements and characteristics of the blood vessels demonstrate dramatic species differences. For example, arteries within the testes have tight coils in the mouse and artery‐artery anastomoses in the rat. Veins form vascular pathways that connect the testis and efferent ductules in all three species but also form a connection between the testis and cauda epididymidis in the rabbit only.

Testosterone concentrations were determined in blood obtained by micropuncture of selected testis‐epididymal veins. The measurements establish that the highest levels of testosterone are found in testicular surface veins. Also, vas deferential veins of the rabbit had significant amounts of testosterone. Studies of the blood‐vessel volumes suggested that the volumes of arteries and veins in the testis are similar, whereas venous volumes exceed arterial volumes in all of the other organs examined.

The studies provide comprehensive information about the architecture and physiology of blood vessels serving the testis‐epididymis in the mouse, rat, and rabbit. Each species exhibits diversity in the vasculature and testosterone content of the veins. Veins connecting the testis to the efferent ductules and cauda epididymidis may provide for the preferential delivery of testicular secretions to androgen‐dependent organs before the secretions are metabolized or diluted in the systemic blood.
Secretory cells of the oviduct of the pig‐tailed monkey, Macaca nemestrina, during the menstrual cycle and after estrogen treatment
Authors: Odor D. Louise , Gaddum‐Rosse Penelope , Rumery Ruth E.
Published: February 2005

The secretory cells of the oviductal epithelium in the pig‐tailed monkey, Macaca nemestrina, have been studied by light and electron microscopy. Changes during the menstrual cycle and after ovariectomy, with and without subsequent estrogen treatment, have been documented. During the early follicular phase the epithelium is recovering from deciliation and secretory cell atrophy that occur in the late luteal phase. A few fimbrial and a moderate number of ampullar and isthmic cells contain a few electron‐dense, homogeneous secretory granules in their apical cytoplasm. During the late preovulatory and early postovulatory periods, secretory cell structure varies considerably. Fimbrial cells typically display apical protrusions that contain no or a few small, mainly homogeneous, secretory granules. The cytoplasm is crowded with elements of the Golgi complex, with granular endoplasmic reticulum profiles often intimately associated with mitochondria, and with variable numbers of polysomes and glycogen granules. In ampullar and isthmic cells secretory granules are more abundant than in fimbrial cells, and electron‐lucent vacuoles appear. The granules are of two types: (1) those having an electron‐dense, homogeneous matrix, and (2) those possessing lamellar structures within moderately dense matrices. The lamellae of the second type course in parallel arrays separated by a distance of approximately 15.5 nm and exhibit a periodicity of approximately 11.3 nm. Possible transitional stages between the lamellar granules and the vacuoles containing lamellar fragments are observed. Secretion occurs by exocytosis. During the late luteal phase no fimbrial cells have secretory granules. In the ampulla many of the cells have poor development of the organelles involved in secretory activity and have few or no secretory granules. In others, a moderate number of secretory granules are present; in one animal, exocytosis is observed. In the untreated ovariectomized animal no secretory granules occur, and the organelle content is much less than in the cycling and the estrogen‐treated monkeys. In ovariectomized, estradiol‐treated monkeys, some areas of all three oviductal segments are well stimulated whereas others display little or no secretory activity.
Effect of ovariectomy on the hypothalamic content of immunoreactive gonadotropin‐releasing hormone in the female mouse as revealed by quantitative immunocytochemistry and radioimmunoassay
Authors: Briski Karen P. , Baker Burton L. , Christensen A. Kent
Published: February 2005

Our radioimmunoassay data reveal that ovariectomy for either one or two months resulted in a significant decrease in the GnRH content of the mouse basal hypothalamus, while in mice ovariectomized for two weeks the GnRH levels did not differ significantly from controls. Parallel immunocytochemical analyses gave similar results. Tissue sections from specific regions of the median eminence in intact and ovariectomized mice were immunolabeled for GnRH with the peroxidase‐antiperoxidase procedure of Sternberger. Differences in area and average unit density of the reaction product were measured with a Quantiment 720 image analyzer. At two weeks after ovariectomy, a majority of matched sections from intact and ovariectomized animals, taken in each sampled region of the median eminence, showed no visually apparent difference in GnRH immunoreactivity. Quantitative image analysis of these preparations revealed no statistically significant difference in either the area of neural tissue covered by deposit or the average unit density of this material in any given region. In contrast, in mice ovariectomized for either one or two months, immunolabeled GnRH was decreased throughout the cephalo‐caudal extent of the median eminence. In each region, a reduction in reaction deposit was observed over most of the area in which GnRH is localized, especially in the medial aspects of this distribution. Image analysis of these preparations revealed a significant reduction of both specimen area immunolabeled for GnRH and the average unit density of reaction product in each region of the median eminence. While the decrease in density was uniform throughout the median eminence, the greatest reduction in area covered by deposit occurred in the infundibular region.

The demonstration of a decrease in basal hypothalamic GnRH in the chronically ovariectomized mouse suggests that GnRH neurosecretion is increased in response to the absence of the ovaries and supports the premise that tonic secretion of this neurohormone, in the mouse, may be subject to regulation by the gonads. At two weeks after ovariectomy, it is possible that changes in GnRH secretion occur without a concomitant alteration in hypothalamic hormone content. In addition, the quantitative immunocytochemical data suggest that GnRH neurons responsive to ovariectomy terminate throughout the rostro‐caudal extent of the mouse median eminence, especially in the medial sites of localization. A proportionally greater number of these endings appear to be present within the infundibular region of the median eminence, relative to the other regions sampled.
Role of the vagus nerve and its recurrent laryngeal branch in the development of the human ductus arteriosus
Authors: Leonard Michael E. , Hutchins Grover M. , Moore G. William
Published: February 2005

The reason that the normal ductus arteriosus has a muscular media, contrasting with the elastic lamellar structure of the adjacent great arteries, is unknown. We examined the hypothesis that the anatomic relationship of the ductus arteriosus to the vagus and recurrent laryngeal nerves during early development might be of importance in influencing ductal morphology. Normal human embryos from the Carnegie Embryological Collection and embryos and fetuses from the Hopkins Pathology Collection were studied microscopically, by reconstructions made from serial histologic sections, or by gross dissection. At Carnegie stage 16 the recurrent laryngeal nerves pass medially from the vagus nerve to the laryngeal area and are caudal to the bilaterally symmetric sixth aortic arches. By stage 18 the right sixth aortic arch has disappeared and the left sixth aortic arch is in a more caudal position relative to the larynx. The left vagus nerve and its recurrent laryngeal branch form a sling supporting the distal (or ductus arteriosus component) of the left sixth aortic arch. In subsequent development there is greater relative separation of the larynx and ductus arteriosus. The media of the ductus arteriosus beneath the supporting nerves is thinner and has less elastic fiber formation than the elastic lamellar media of the adjacent aortic arches. The study shows that the vagus and recurrent laryngeal nerves are in a position to provide mechanical support to the ductus arteriosus during its development and that the morphology of the media of the supported ductus arteriosus differs from that of the adjacent unsupported aortic arches. It is suggested that this local mechanical support may be the reason that the normal ductus arteriosus differentiates as a muscular artery and is therefore able to obliterate its lumen in postnatal life. Without such support the ductal media could develop the abundant elastic fibers characteristic of the normal unsupported aorta and pulmonary trunk and become an abnormal, persistently patent ductus arteriosus.
The cytology of the dental follicle and adjacent alveolar bone during tooth eruption in the dog
Authors: Marks Sandy C. , Cahill Donald R. , Wise Gary E.
Published: February 2005

Previous studies from our laboratories have shown that premolar eruption in dogs depends upon the presence of the dental follicle and is independent of root or crown growth or attachment to the oral epithelium. The present study is an analysis of the cellular composition of the dental follicle and the cellular investment of the adjacent walls of the bony crypt before and during eruption of the third and fourth mandibular permanent premolars in young beagle dogs. Four premolar follicles and their adjacent bony crypts were examined at 2‐week intervals over 12 weeks before and during eruption of these teeth. Tissues were removed, fixed, processed, and oriented so that each follicle and the adjacent crypt wall could be reproducibly examined in vertical and horizontal planes. Mononuclear cells with abundant cytoplasm, euchromatic nuclei, and prominent nucleoli were present in juxtavascular location in the coronal part of the dental follicle; and these cells increased in number immediately preceding and during tooth eruption in parallel with an increase in osteoclasts on the adjacent crypt wall. These data are interpreted to mean that the coronal part of the dental follicle may coordinate the alveolar bone resorption required for tooth eruption by attracting and directing to the crypt wall a population of mononuclear cells, which either become osteoclasts and/or direct osteoclastic activity during tooth eruption.
Organogenesis of the pituitary, adrenal, and lung at birth in the wallaby, Macropus rufogriseus
Authors: Walker M. T. , Gemmell R. T.
Published: February 2005

The ultrastructure of the pituitary, the adrenal, and the lung was examined in the newborn wallaby, Macropus rufogriseus. Tissue from six wallaby neonates (less than 8 hr of age), two near‐term fetuses (26 days after removal of suckling pouch young [RPY]), and a two‐day‐old pouch young was examined; and tissue levels of cortisol in the adrenal glands of five neonates and a near‐term fetus (26 days) were measured by radioimmunoassay.

At birth the adenohypophysis comprised the bulk of the pituitary gland. The pars distalis was well vascularized and many cells contained electron‐dense, membrane‐bound granules. The adrenal glands lacked specific zones but comprised two distinct populations of cells. The cytoplasm of one cell type contained electron‐dense, membrane‐bound granules, similar to those observed inside catecholamine‐secreting cells of the adrenal medulla; the other cell type possessed large amounts of smooth endoplasmic reticulum and mitochondria with tubulo‐vesicular cristae. These features are characteristic of cells which are actively synthesizing steroid hormones. The concentration of cortisol was 0.58 ng/adrenal in the wallaby at birth. The fetal lungs near term were at the glandular stage of development, and epithelial differentiation of type I and type II pneumocytes was imminent although attenuation was not evident. The canalicular neonatal lung did not contain true alveoli, but type II pneumocytes contained osmiophilic lamellar inclusions of surfactant.

The fetal pituitary and adrenal are functional at birth and are thus capable of initiating parturition and of influencing lung maturation in the fetus.
Histochemical evaluation of mouse and rat kidneys with lectin‐horseradish peroxidase conjugates
Authors: Schulte B. A. , Spicer S. S.
Published: February 2005

Paraffin sections of mouse and rat kidney were stained with a battery of ten lectin‐horseradish peroxidase conjugates and lectin binding was correlated with the ultrastructural distribution of periodate‐reactive sugar residues as determined by the periodic acid‐thiocarbohydrazide‐silver proteinate technique. Various segments of the uriniferous tubule in both species showed differential affinity for labelled lectins. Significant differences were also evident between comparable tubular segments in mouse and rat kidneys. Neutral glycoconjugates containing terminal β‐galactose and terminal α‐N‐acetylgalactosamine were prevalent on the luminal surface of the proximal convoluted tubule in the rat, but α‐N‐acetylgalactosamine was absent in this site in the mouse. In both species, terminal N‐acetylglucosamine was abundant in the brush border of proximal straight tubules but absent in proximal convolutions. Fucose was demonstrated in both proximal and distal segments of mouse kidney tubules but only in the distal nephron and collecting ducts in the rat. Lectin staining revealed striking heterogeneity in the structure and distribution of cellular glycoconjugates. Such cellular heterogeneity was previously unrecognizable with earlier histochemical methods. The marked cellular heterogeneity observed with several lectin‐conjugates in distal convoluted tubules and collecting ducts of both species raises a prospect that lectins can provide specific markers for intercalated and principal cells in the mammalian kidney. Glycoconjugates containing terminal sialic acid and penultimate β‐galactose were present on vascular endothelium in both rodent kidneys, as were terminal α‐galactose residues; but both species lacked reactivity for Ulex europeus I lectin in contrast to human vascular endothelial cells. The constant binding pattern of lectin conjugates allows convenient and precise differentiation of renal tubular segments and should prove valuable in the study of changes in kidney morphology promoted by experimental manipulation or pathologic changes.
Electron microscopic analysis of the effect of progesterone upon the hormone‐sensitive solitary cilia and centriolar complexes in the luminal epithelial cells of the uterus of the ovariectomized‐adrenalectomized rat
Authors: Tachi Sumie
Published: February 2005

The time course of the hormonally controlled deciliation cycles of the centriolar complexes in the cells of the luminal epithelium of the uterus of the ovariectomized and adrenalectomized rat was analyzed at ultrastructural levels. The results were expressed quantitatively. The half‐life of the solitary cilia after progesterone administration in the cell population was 14.6 hr, longer approximately by 1 hr than that previously reported for the estrogen‐induced deciliation of the same cells.

The time course of the progesterone‐induced loss of solitary cilia strongly suggested that the phenomenon is biphasic. After the initial loss of 50%, the process progressed slowly. Twenty‐four hours after the injection of the hormone, 35% of the cilia remained; after 60 hours, 4% were still present. This is in striking contrast to the effect of estrogen, which causes almost complete deciliation within 24 hr after the injection of the hormone. Prolonged exposure of the deciliated luminal epithelial cells to progesterone leads to disarrangement of the diplosome relationship. The phenomenon might be causally correlated with the block of estrogen‐induced mitoses by this hormone; this view, however, needs further experimental corroboration.
A quantitative study of pituitary colloid in the batMyotis lucifugus lucifugusin relation to age, sex, and season
Authors: Anthony Edythe L. P. , Gustafson Alvar W.
Published: February 2005

Extracellular colloid accumulations were examined in pituitary glands of adult and juvenile, male and female, little brown bats,Myotis lucifugus lucifugus(Chiroptera: Vespertilionidae), collected at various times during the annual reproductive cycle. Round or ovoid periodic acid‐Schiffreactive accumulations of colloid were scattered throughout the pars distalis, pars intermedia, and pars tuberalis. These accumulations were surrounded by processes of agranular “follicular” cells. The proportion of the volume of the pars distalis occupied by colloid (volume fraction) exhibited considerable variation among animals, ranging from 0.00 to 3.18% in the total sample of bats. Pituitaries of juvenile males, yearling males, and nonparous females contained significantly less colloid than those of parous females and adult males. The mean volume fraction for each of these groups suggested that colloid content increased progressively from birth through sexual maturity in this animal. In addition, the frequency distribution of colloid content measurements made in parous females and adult males provided indirect evidence that colloid continues to accumulate throughout life. No sexual dimorphism in colloid content was observed before or after sexual maturity, and colloid content did not fluctuate in relation to the annual reproductive cycle of either males or females.
The fine structure of the placenta and chorionic vesicles of the bush baby, Galago crassicaudata
Authors: King Barry F.
Published: February 2005

The fine structure of the placental villi and the chorionic vesicles of the bush baby, Galago crassicaudata, were examined. The placenta was of the diffuse epitheliochorial type. The trophoblastic epithelium of the placental villi consisted of cells joined by tight junctions and desmosomes. The apical borders of these cells interdigitated with corresponding processes on the uterine epithelial cells. The fetal capillaries indented the trophoblastic cells later in gestation, and the trophoblast over the capillaries was correspondingly thinner with advancing gestation. The trophoblast of the villi was characterized by numerous lipid droplets and moderate amounts of granular endoplasmic reticulum (ER). The apical cytoplasm often had many mitochondria as well as small electron‐dense vesicles and tubules. Uterine epithelial cells contained agranular ER and a well‐developed Golgi apparatus. The apical cytoplasm contained numerous granules often with an electron‐dense content. The uterine epithelial cells appeared to be secretory, contributing to the electron‐dense material found between the fetal and maternal cells. Fetal capillaries were of the continuous type, whereas occasional fenestrae were observed in maternal capillaries. Recesses in the trophoblastic epithelium occurred at the tips, sides, and bases of the villi. These areas had taller trophoblastic cells that appeared to be more active in phagocytosing uterine content. The chorionic vesicles are invaginations of the chorion opposite the mouths of uterine glands. A layer of columnar trophoblastic cells covered the villi of the vesicles. These cells had abundant vacuoles and coated pits and vesicles. The mesodermal component of the chorionic vesicles included a capillary network and a layer of smooth muscle cells in the wall of the vesicle. It was concluded that the trophoblast of the placental villi is engaged in both hemotrophic and histotrophic nourishment of the embryo. The specialized chorionic vesicles are particularly important in providing histotrophic nutrients to the embryo, especially the secretions of the uterine glands. The similarity of the chorionic vesicles to the areolae of other species suggests they may be the pathway by which iron is transported from mother to fetus, perhaps by receptor‐mediated endocytosis of macromolecules derived from uterine gland secretions.
The effects of insulin replacement and withdrawal on hepatic ultrastructure and biochemistry
Authors: Garfield Sanford A. , Mohamed Shadia A. , Cardell Robert R.
Published: February 2005

This study examines the early hepatic biochemical and ultra‐structural responses to insulin replacement in streptozotocin‐diabetic rats and insulin withdrawal from insulin‐maintained diabetic rats. Insulin administration rapidly lowered plasma glucose and the elevated glucose‐6‐phosphatase (G‐6‐Pase) specific activity of the diabetic rats. However, hepatic glycogen did not increase until after 3 hr of insulin treatment. Hepatic ultrastructure responded to insulin replacement after the decline in glucose and G‐6‐Pase. This was seen in periportal hepatocytes as a reduction in the close association between smooth endoplasmic reticulum (SER) and glycogen particles in the diabetic animals. The treated rats showed hepatic SER restricted to the periphery of glycogen masses, as is characteristic of these cells from normal rats, in many cells by 6 hr and all cells by 18 hr. Insulin withdrawal from insulin‐treated diabetic rats elicited nearly a total reversal of the above events. Plasma insulin declined to a value half that of the normal rats by 6 hr after withdrawal; concurrently, plasma glucose rose sharply to hyperglycemic values as hepatic glycogen content dropped. Following the rise in plasma glucose and fall in glycogen content, G‐6‐Pase specific activity increased and by 16 hr reached the high values characteristic of the diabetic animal. Hepatic ultra‐structure was also changed as evidenced by an intrusion of elements of the SER into the dense glycogen masses; the result was dispersed glycogen closely associated with SER as seen in the diabetic animal. It is concluded that the hepatic response to insulin replacement in diabetic animals and diabetic onset in insulin‐withdrawn animals is rapid and occurs through defined stages.