bluuebunny/crossref_metadata_2025 huggingface dataset:
Fine structure of an end organ in the periodontal ligament of the mouse incisor
Authors: Everts V. , Beertsen W. , van den Hooff A.
Published: February 2005

Nerve endings were observed between collagen fiber bundles in the alveolar compartment of the periodontal ligament. In close relation to these endings, cells were observed with a rounded cell body from which cytoplasmic extensions protruded, each forming part of a sheath around the terminal region of a small nerve fiber. The nuclei of these cells occupied an eccentric position in the cytoplasm and were characterized by a typical kidney shape. In the cell's center a prominent Golgi complex was present. In the peripheral cytoplasm ladder‐like structures with a periodicity of 160 nm were occasionally observed. The cell bodies were surrounded by a basal lamina, while the cytoplasmic extensions investing the nerve endings were surrounded by an envelope consisting of alternating electron dense and electron translucent layers containing material that stained with PAS and Alcian Blue. Where these envelopes bordered on the connective tissue, areas of filamentous material with a periodicity of 100–150 nm were occasionally found. The end organs may be considered to form part of a receptor system.
Regional specialization of the hair cell plasmalemma in the organ of corti
Authors: Gulley R. L. , Reese T. S.
Published: February 2005

Nonjunctional and nonsynaptic membranes of hair cells in the chinchilla organ of Corti were examined using the freeze‐fracture technique. Cy‐toplasmic leaflets of the apical membranes of hair cells have particles, 6–12 nm in diameter, but many more particles are found on apical membranes of outer hair cells than on inner hair cells. Cytoplasmic leaflets of the lateral membranes of outer hair cells are covered with large particles, but the corresponding regions of the inner hair cell membrane have fewer particles and these are small or medium‐sized. Two types of particle aggregate also distinguish this region of the inner hair cell. The first consists of patches of particles closely spaced in rec tilinear arrays. The second consists of parallel strands of widely spaced large particles similar in size, but not in distribution, to the large particles on the lateral membranes of the outer hair cells. The basal membrane of outer hair cells is distinguished from that of inner hair cells by plaques consisting of cross‐hatched in‐cisures in the external membrane leaflet. While the significance of these anatomical features is not yet apparent, they give the hair cell plasmalemma a richness of regional specialization found in few other cells and suggest that there are important functional differences between inner and outer hair cells.
Differentiation of olfactory receptor cells in organ culture
Authors: Farbman Albert I.
Published: February 2005

Presumptive olfactory mucosa was excised from the heads of rat fetuses in the eleventh and twelfth days of gestation and explanted in organ cultures. At the time of explantation, the presumptive olfactory cells were recognizable by their long narrow apical processes and basally located nuclei. However at this stage they were in an early phase of differentiation as indicated by the large numbers of free ribosomes and virtual absence of microtubules and cilia in the apical cytoplasm. After three to eight days in culture, there was a progressive increase in the total number of cells in the epithelium. Differentiation in olfactory receptor cells was detectable by the appearance in the apical processes of axially oriented microtubules and centrioles or basal bodies. Some of which generated cilia. At their basal ends, the cytoplasm narrowed into axons and bundles of these axons, arranged in the unique manner of olfactory nerve axons, entered the connective tissue. Olfactory receptor cells, as defined by morphological criteria, differentiated under suitable organ culture conditions in the absence of any tissue from the central nervous system.
Ultrastructural observations on cytoplasmic lamellar inclusions in oocytes of the rodent, Thomomys
Authors: King Barry F. , Tibbitts F. Donald
Published: February 2005

The object of the present study was to examine ovarian oocytes of the sciuromorph rodent. Thomomys townsendii, to determine if they contained cytoplasmic inclusions similar to those reported in myomorph rodents. Our observations indicated the presence of cytoplasmic lamellar inclusions of oocytes of primary, secondary and large vesicular follicles of Thomomys. Small primary oocytes contained numerous cytoplasmic lamellae which appeared as spirals or concentric rings in cross‐section. Longitudinal sections suggested the inclusions were arranged as concentric cylindrical sheets of material. Secondary and vesicular oocytes had morphologically similar inclusions, but, in addition, often had a tubular element of the endoplasmic reticulum associated with the core of the lamellae. Tangential sections through the lamellae revealed a crystalline substructure, regardless of the age of the oocyte. Our results indicate that cytoplasmic lamellar inclusions are not restricted to myomorph rodents, but may well be present in other species. The lamellar inclusions are three‐dimensionally most similar in structure to those described in the hamster, but several fine structural differences exist even between these species. Thomomys is the only species to date in which a close topographical association develops between the lamellar inclusions and elements of the endoplasmic reticulum. Since the lamellae‐endoplasmic reticulum association was not observed in the youngest oocytes examined, it is unlikely the endoplasmic reticulum is involved in synthesis of the lamellae, but it may, nonetheless, be metabolically related to the lamellae.
The dorsal motor nucleus of the vagus nerve of the cat: Localization of preganglionic neurons by quantitative histological methods
Authors: Smolen Arnold J. , Truex Raymond C.
Published: February 2005

The dorsal motor nucleus of the vagus nerve (DMX) of adult cats and young kittens was studied by quantitative light microscopic methods. In normal animals, the DMX was found to contain no distinct subgroupings of neurons, based on somatic volume or Nissl pattern. Retrograde perikaryal responses to axotomy of neurons in the DMX were found to be of a more subtle nature than those seen in other types of neurons. Quantitative methodology applied to the DMX after cervical vagotomy permitted a better understanding of the results of axotomy than could be obtained by routine microscopic observations. Changes which occurred included a slight chromatolytic reaction, and a decrease in the volume of the nucleus followed by an increase in somatic volume. These morphological alterations were affected by the factors of age of the animal, time after axotomy, and length of the intact proximal axon stump. More pronounced perikaryal changes occurred when the vagus nerve was recut at a more proximal level five days after the first vagotomy. Interpretation of the data yielded the conclusion that most if not all neurons of the ipsilateral DMX contribute axons to the cervical vagus nerge. In addition, at least 10% of the neurons on the side contralateral to vagotomy showed signs of retrograde reaction. It was therefore concluded that there exists in the vagus nerve a population of axons with cell bodies located in the contralateral DMX.
Autoradiographic demonstration of the pattern of 3H‐estradiol concentrating cells in the brain of a carnivore, the mink, Mustela vison
Authors: Morrell J. I. , Ballin A. , Pfaff D. W.
Published: February 2005

The purpose of this study was to examine the neuroanatomical pattern of cells which concentrate 3H‐estradiol in the brain and pituitary of a carnivore, the mink, Mustela vison. In addition, since the mink has one breeding season a year it was possible to compare the pattern and number of estradiol concentrating cells in the brains of estrous versus anestrous animals. Five female mink (three estrous; two anestrous) were ovariectomized, and one week later administered 3H‐estradiol. The animals were sacrificed, and autoradiograms were prepared with the method for steroid autoradiography used routinely in this laboratory (Pfaff and Keiner, '73). The entire brain was sampled and subsequently analyzed with the aid of a light microscope.

The majority of estradiol concentrating cells were found in the hypothalamus and limbic system, although a small number were seen in other structures. Specifically, structures containing a large number of estradiol concentrating cells were: the ventral lateral septum, the bed nucleus of the stria terminalis, the medial preoptic area, medial anterior hypothalamus, the ventromedial and arcuate nuclei of the hypothalamus, the medial and cortical nuclei of the amygdala, and the anterior pituitary. Structures containing a small number of estradiol concentrating cells were also seen in the telencephalon and diencephalon. The most posterior population of estradiol concentrating cells was in the central grey of the mesencephalon. No difference in the neuroanatomical pattern or number of estradiol concentrating cells was seen when the autoradiograms from estrous animals were compared to those from anestrous animals.
Ultrastructural study of the nerve plexus accompanying the ovarian artery and vein in the rat
Authors: Payer Andrew F.
Published: February 2005

The ultrastructural characteristics of the nerve plexus that accompanies the ovarian vessels of the rat were studied. The nerve fibers were primarily unmyelinated with less than 5% myelinated. Two types of neuronal cell bodies were found along these nerves. They were located at variable distances along the nerve bundle. The first and more numerous was a larger cell type similar to the autonomic postganglionic neuron. The second and smaller cell type had granulated vesicles throughout the cytoplasm. Synapses of the axodendritic type and synapses between the neuronal cell bodies were found. Most of the synapses possessed agranular vesicles. The presence of neuronal cell bodies is an important characteristic to consider in evaluating denervation of the ovary by interruption of this nerve plexus.
Immunocytochemical and histochemical studies on intestinal epithelial cells producing both lysozyme and mucosubstance
Authors: Montero Claudio , Erlandsen Stanley L.
Published: February 2005

The simultaneous demonstration of lysozyme using the unlabelled antibody enzyme method and mucosubstances by staining with the periodic acid‐Schiff (PAS) and Alcian Blue pH 2.5 techniques has led to the identification of a new subpopulation of mucus‐producing cells containing lysozyme in small intestinal specimens from normal rats and from patients with inflammatory bowel diseases. These cells, containing both mucosubstances and lysozyme, are located in the lateral walls of the crypts of Lieberkuhn, but can occasionally be found also in or near the tips of the villi. The specific staining for lysozyme was observed in the apical and/or basal cytoplasm of these mucus‐producing cells and was readily detected in sections counterstained for mucosub‐stances with Alcian Blue. The localization of these mucus‐producing cells was similar both in the normal rat and in the pathological human specimens. Absorption controls and controls where a non‐immune serum was substituted for the specific antilysozyme serum confirmed the specificity of the lysozyme localization.
Fenestrae in the rough endoplasmic reticulum of Xenopus laevis hepatocytes
Authors: Brown Dennis
Published: February 2005

The rough endoplasmic reticulum (RER) of Xenopus laevis hepatocytes was examined by freeze‐fracture and by conventional thin section electron microscopy. Much of the RER was present as stacks of cisternae at the cell periphery but, in addition, large whorls of cisternae were seen in the cytoplasm in most sections. Freeze‐fracture replicas revealed fenestrae in both stacked and whorled cisternae, although the fenestrae were more numerous in the whorls. The role of these fenestrae is unknown, but such structures would facilitate access of precursors to the protein synthetic machinery in this highly metabolically active cell type. This would be particularly important in RER whorls, where the innermost cisternae would otherwise be isolated from the rest of the cytoplasm.
Arteriovenous anastomoses in the skin of seals. I. The Weddell seal Leptonychotes weddelli and the elephant seal Mirounga leonina (Pinnipedia: Phocidae)
Authors: Molyneux G. S. , Bryden M. M.
Published: February 2005

The structure, distribution, density and innervation of arteri‐ovenous anastomoses (AVAs) have been compared in the skin of Weddell and elephant seals, as part of a study of the structure and function of arteriovenous anastomoses in mammals.

In both genera AVAs were coiled vessels with the segmental structure typical of “epithelioid” anastomoses and possessed a dense peripheral adrenergic innervation.

In both Weddell and elephant seals there was no statistically significant difference between the mean density of AVAs in body skin and flipper skin. The majority, approximately 71% of AVAs occurred superficially in the dermis, fewer (23%) occurred in the deeper dermis, and 6% were present in the thick hypodermis (blubber). The density of AVAs in Weddell and elephant seals is approximately eight times greater than that reported in other animals and the superficial position of anastomoses over the whole of the body surface is characteristic of phocid seals.

When open, AVAs in Weddell and elephant seals allow maximal heat loss from the skin surface by passing large volumes of blood into the superficial veins. AVAs in seals are important in dissipation of body heat, particularly when the animals are out of the water, and the entire surface area is thermo‐regulatory rather than specific regions such as the flippers.
Spermiogenesis in Nautilus pompilius. II. Sertoli cell‐spermatid junctional complexes
Authors: Arnold John M.
Published: February 2005

A “ball and socket‐like” junction between branches of the Sertoli cells and the developing spermatids is described. A cytoplasmic extension of the Sertoli cell fits into a pocket in the spermatid and has a constricted neck region. Frequently there are large multivesiculate bodies in the Sertoli cell extension and small vesicles frequently appear in the spermatid cytoplasm, in the area of the “ball and socket‐like” junction. This suggests the possibility that there may be communication of materials between the two cells. The possible function of the junctions is discussed and it is concluded that they more likely have a role in nutrition than in coordination.
Pelvic and perineal anatomy of the male Gorilla: Selected observations
Authors: Oelrich Thomas M.
Published: February 2005

The anatomy of parts of the pelvic outlet and perineum is described in an adult male gorilla. Two previously undescribed muscles are presented: (1) The puborectalis muscle, completely separated from the levator ani, arises from the region of the symphysis and forms a sling for the rectum while it also substitutes for the perineal membrane. (2) The puboampullaris muscle, a paired smooth muscle, arises from the pubis and inserts into the rectum to elevate the rectum while additionally providing support for the urogenital viscera. The levator ani muscle is recounted to point out its lack of attachment to the pelvic viscera while allowing a hiatus in which the rectum is exposed within the perineum. The sphincter urethrae muscle is presented emphasizing its true sphincteric characteristics, its absence of lateral attachments and its similarity to man. Other muscles of the pelvis and perineum as well as urogenital viscera are described or modified where necessary. The manner in which these structures enter into the support of the pelvic viscera is considered.
Development of the embryonic chick otic placode. II. Electron microscopic analysis
Authors: Meier Stephen
Published: February 2005

The otic placode takes its origin from surface ectoderm. Prior to the arrival of neural crest cells, surface epithelial cells adjacent to the neural folds are squamous in shape and synthesize primarily interstitial bodies. However, by 26 hours of development, neural crest cells, using the undersurface of the epithelium as a substratum, migrate away from the neural tube. Cells of surface epithelium above the neural crest cells assume a columnar shape, and the amount of intercellular space between adjacent epithelial cells is consequently reduced. Placode cells show extensive interdigitation apically as they pseudostratify and invaginate, while it appears that many of the basal cells contribute components to the underlying extracellular matrix. This extracellular matrix interface between surface epithelium and neural crest cells is distinctly fibrillar and less granular than that found between ordinary head ectoderm and primary mesenchymal cells. Just prior to complete invagination as an otocyst, otic placode cells in a region near the ventrolateral wall of the hindbrain extend cell processes through discontinuities in the basal lamina and leave the otocyst. These are likely to be the cells which contribute to the formation of the acoustico‐facialis ganglion. These observations support the hypothesis that the development of the otic placode is the result of a tissue interaction between surface epithelium and neural crest cells.
A morphological study of early cellular changes in the closure of the rabbit ductus arteriosus
Authors: Yoder Monroe J. , Baumann F. Gregory , Grover‐Johnson N. M. , Brick Irving , Imparato Anthony M.
Published: February 2005

A light and transmission electron microscopic study was performed on 67 ductus arteriosus (DA) specimens from rabbits (31 days normal gestation period) ranging in age from 21 days of gestation to 4 days after birth. Some fetuses were permitted to breath before sampling, while others were not. The aorta and pulmonary trunk served as controls. The objectives of the study were to identify the earliest cellular alterations leading to closure of the DA, to study in detail the sequence of cellular changes in closure of the DA, and to correlate these observations with what is known about the physiological factors involved in closure of the DA. Changes in the architecture of the DA wall were seen as early as on the twenty‐sixth day of gestation and involved the appearance of increased numbers of radially or longitudinally reoriented smooth muscle cells in the intima and fragmentation of the internal elastic lamina. The progress of these changes continued and intensified until the end of gestation. At that stage the inner one‐half of the medial smooth muscle cells was reoriented, and the lumen was significantly reduced by a greatly expanded intima which often contained many intercellular “ghost bodies.” Very few mitoses were seen during DA closure, especially during 29 to 31 days of gestation. It is concluded that cellular changes involved in closure of the DA of the rabbit fetus begin far in advance of birth and breathing. These cellular changes are highly analogous to those which occur in the early pathogenesis of arterial intimal fibromuscular lesions. Closure of the DA, therefore, seems to afford an excellent, natural model for study of key cellular events involved in the production of arterial fibromuscular lesions.
Changes in length of sarcomeres following tenotomy of the rat soleus muscle
Authors: Baker James H. , Hall‐Craggs E. C. B.
Published: February 2005

Tenotomy of the proximal and distal tendons of the soleus muscle of female Wistar rats was performed and sarcomeric length and muscle fascicle length measured. On the first postoperative day muscle bellies were found shortened and their sarcomeric length considerably reduced. Four weeks following tenotomy, although the muscle bellies remained shortened, sar‐comeric length was comparable with that of control muscles. Measurement of muscle fascicle lengths at this time showed that those of experimental muscles were nearly 50% less than those of control muscles. It was concluded from these experiments that a reduction of the number of sarcomeres in series had occurred, thus compensating for the reduced length of the muscle belly.
A histochemical study of the microvasculature in the left and right cardiac ventricles of the dog
Authors: Cannon M. Samuel , Jones Carl E. , Cannon Anita M. , Schultz Lucille H.
Published: February 2005

Subepicardial and subendocardial arteries and arterioles in both the left and right normal canine ventricle were examined histochemically to determine their metabolic profiles. Aerobic metabolic capacity was assessed by determining the reactivities of the enzymes cytochrome oxidase, succinate dehydrogenase and NAD‐isocitrate dehydrogenase. Glucose‐6‐phosphate dehy‐drogenase was examin̈ed to assess activity of the hexose‐monophosphate‐shunt. The substrate glycogen was determined as an evaluation of anaerobic metabolic capacity, while the amounts of deoxyribonucleic and ribonucleic acid were assessed as an indication of protein synthesis. Results of the present investigation indicate that despite known hemodynamic differences, the metabolic profile of the coronary vasculature is similar in all regions of ventricular myocar‐dium. Reactivities of the enzymes succinate and NAD‐isocitrate dehydrogenase and cytochrome oxidase are greater in smooth muscle of arterioles than in arteries. This suggests that arteriolar smooth muscle has a higher capacity for aerobic metabolism than does arterial smooth muscle. The greater reactivity of glycogen in arterial, than in arteriolar smooth muscle, suggests that arterial muscle is more adapted for anaerobic metabolism. Deoxyribonucleic and ribonu‐cleic acids demonstrate a low reactivity in both arteries and arterioles from all regions of ventricular myocardium which conforms to the opinion that under normal conditions, coronary vasculature is quite stable with little cell proliferation. Glucose‐6‐phosphate dehydrogenase shows little reactivity in all myocar‐dial vessels which implies a low capacity for nucleic acid and protein synthesis.
Histochemical study of ovarian hydroxysteroid dehydrogenase activity during normal pseudopregnancy in the rat
Authors: Kovarik Frances A. , Velardo Joseph T.
Published: February 2005

3β‐Hydroxysteroid dehydrogenase activity was localized in ovaries removed from rats during normal pseudopregnancy. Ovarian sections were incubated in media containing either pregnenolone (P‐one) or dehydroepiandrosterone (DHA). P‐one‐3β‐HSD activity appeared strongest on day 6 whereas DHA‐3β‐HSD was highest on day 13. NADH2 diaphorase activity was localized and observed to be greater than 3β‐HSD.

Both P‐one‐ and DHA‐3β‐HSD activities were localized in primary‐, secondary‐ and tertiary follicles; granulosa and theca interna cells have a variable potential for steroidogenesis. Mature tertiary follicles appear most responsive of the follicular population in steroidogenic potential. In atretic follicles, theca interna cells showed a marked ability for potential steroid production and may be one of the more stable sites of steroidogenesis. Interstitial tissue is a major site for potential estrogenic and progestational biosynthesis during the functional life of the ovary. Luteal cells exhibited strong ability for DHA‐3β‐HSD activity during the ongoing process of pseudopregnancy while P‐one‐3β‐HSD activity declined in these cells as pseudopregnancy progressed. In summary, at the onset of pseudopregnancy, it appears that ovarian P‐one‐3β‐HSD activity is greater than DHA‐3β‐HSD activity. Near the termination of this condition, DHA‐3β‐HSD activity is greater than P‐one‐3β‐HSD activity in the rat.
Ultrastructure of the hepatic perisinusoidal cells in man and other mammalian species
Authors: Bartók I. , Tóth Jeannette , Remenár Éva , Virágh Sz.
Published: February 2005

Perisinusoidal (P.S.) cells occurring in the spaces of Disse in the livers of normal cats, dogs, miniature pigs, albino rats, human adults and children were examined by electron microscopy. The ultrastructural details of the P.S. cells and their topographic relationships with hepatocytes, sinusoidal lining cells and reticulum fibers are described. Species differences between P.S. cells were primarily a dissimilarity in lipid content: the main ultrastructural features were the same in all species studied. The P.S. cells of the rat liver displayed only low endocytotic activity, and no phagosome formation following intravenous administration of horseradish peroxidase. The close topographic relationship of the P.S. cells with the intralobular reticulum fibers was reminiscent of the intimate connection between fibroblasts and collagen fibers, or, in cat liver, of the reticulum cell ‐ reticulum fiber association seen in lymphoid organs. Fibroblasts were not found inside the hepatic lobules. These findings support the conclusion that, the reticulum fibers of hepatic lobules are produced by perisinusoidal cells which, however, display also other functions.
Sites of lipoprotein production in the small intestine of the unsuckled and suckled newborn rat
Authors: Berendsen Peter B.
Published: February 2005

The size and distribution of lipoprotein particles in the intestinal epithelium were determined before and after the start of suckling by infant rats. Prior to suckling very low density lipoprotein particles were within the smooth endoplasmic reticulum (SER), rough endoplasmic reticulum (RER), Golgi apparatus and interepithelial cell spaces of duodenal villus tip cells. Chylomicrons were produced in the SER, RER and Golgi apparatus of duodenal epithelial cells after the commencement of suckling.

Ileal epithelial cells did not contain particles of VLDL dimensions prior to suckling. Ileal cells of rats suckled for 24 hours after birth had VLDL particles in the SER, RER and Golgi apparatus above and at the sides of the large supranuclear vacuole in each cell. Ileal cells at 10 and 15 days of age had fewer and smaller particles. These particles were also present in the interepithelial cell spaces and lacteals.

It is suggested that VLDL particles are produced by duodenal cells prior to suckling when only endogenous lipid is available. The ingestion of exogenous lipids in milk is associated with the production of chylomicrons by duodenal epithelial cells and VLDL particles by ileal epithelial cells. VLDL particles within ileal cells become smaller and less numerous as suckling continues, possibly due to increased pancreatic lipase. This is interpreted as evidence that chylomicrons and intestinal VLDL particles are related.
Corpus luteum growth and plasma progesterone levels in unilaterally ovariectomized pregnant rats
Authors: Meyer Geoffrey T. , Bruce Neville W.
Published: February 2005

Unilateral ovariectomy (ULO) was carried out on rats at Day 8 of gestation: term is Day 23. The effect on peripheral plasma progesterone levels at Day 16 and on growth and cellular changes in the remaining corpora lutea (CL) at Day 17 was determined by comparison with results from control and sham‐operated rats. ULO increased the volume of remaining CL by 18% at Day 17. At Day 16 this effect was only apparent in rats with three or fewer CL remaining. CL hypertrophy was due to an increase in the volume of individual luteal cells and not to cell hyperplasia. Luteal cell nuclear volume also increased as did the number of endothelial cells per corpus luteum. The proportion of the corpus luteum occupied by vascular space did not alter.

ULO had little effect on mean plasma progesterone levels at Day 16 (92 ± 7 ng/mltreated; 86 ± 11 ng/ml controls). In rats with three or fewer CL remaining, however, progeserone levels were low (51 ± 7 ng/ml).

It was concluded that ULO can enhance the growth of corpora lutea and perhaps increase their rate of progesterone production.
Correlation of early cytodifferentiation of the human fetal prostate and leydig cells
Authors: Kellokumpu‐Lehtinen P. , Santti R. , Pelliniemi L. J.
Published: February 2005

The ultrastructural differentiation of the human prostatic epithelium and mesenchyme was studied in early developing glands and correlated with the differentiation of the Leydig cells of the same individuals during the tenth to sixteenth weeks.

After initial folding of the basal lamina, the epithelial cells began to migrate into the differentiated, condensed mesenchyme at the end of the 10th week, and in the 11th week some of the prostatic outgrowths acquired a lumen. The acinar and tubular epithelium in the fetal prostate remained stratified, and adult type simple epithelium was not seen during the period between the 10th and 16th weeks. As a sign of incipient secretory activity, a few epithelial cells became polarized, and secretion granules with flocculent or dense content appeared in the Golgi area and in the apical parts of the cells in the 13th week. Occasional direct epitheliomesenchymal cell contacts were visible in association with the appearance of the secretory activity. Two cell types, not seen in the normal adult prostate, appeared in the epithelium of the primitive glands. Their nature and role in the glandular morphogenesis are not clear.

During this time, the ultrastructural differentiation of the Leydig cells continued and their size and number increased. They occupied almost the whole in terstitium by the time secretion granules appeared in the prostatic cells. These findings support the current notion that androgens secreted by Leydig cells are the major regulators of prostatic development in man.
The effects of desiccated thyroid on the rat lung
Authors: Callas G. , Adkisson V. T.
Published: February 2005

Pressure‐volume characteristics of whole lungs were measured in euthyroid rats and in rats fed 0.4% desiccated thyroid for eight weeks. The lungs were degassed by incising the diaphragm after the animals had breathed 100% oxygen for ten minutes. The pressure‐volume characteristics were measured by inflating and deflating the lungs at a rate of 3.5 cc/min. Total lung capacity (TLC) was considered to be that volume of air required to produce a transpulmonary pressure of 30 cm H2O. At TLC there was 35% greater lung volume in the thyroid‐treated animals than in their littermate controls. Similar results were observed in saline‐filled lungs. Alveolar surface area (Sa) increased from 0.28m2 in the lungs of control animals to 0.75m2 in lungs of thyroid‐treated animals. There was an 85% increase in the alveolar surface density (Sva) in the thyroid‐treated animals. These results, obtained by morphometric analysis, suggest that greater lung volume in the thyroid‐treated animals resulted from alveolar hyperplasia or „partitioning”︁.
Growth patterns and hormonal profile of male rats with protein‐calorie malnutrition
Authors: Herbert Damon C.
Published: February 2005

A condition of protein‐calorie malnutrition was precipitated in young Sprague‐Dawley male rats at 20 days of age using an 8% low protein diet (LPD). At five‐day intervals for up to 50 days of age, the rats were studied to determine the effect of an LPD on the reproductive axis of the endocrine system. Daily monitoring of the body weight, as well as the consumption of food, kilocalories, and protein was conducted. The same parameters were followed over the identical time peroid in a group of animals designated as controls which were fed a standard laboratory diet (SLD) containing 27% protein. The controls showed a linear growth rate over the 30‐day experimental period. In comparison, the malnourished rats grew more slowly so that by 50 days of age, their mean body weight was 68.9 ± 3.1 g as compared to 249.1 ± 6.1 g for the controls. The daily food, kilocalorie, and protein intake by the experimental animals were also appreciably less. The pituitary gland, ventral prostate gland, testes and liver were smaller in the animals fed the LPD. This was observed as early as five days after initiating the dietary regimes and remained a consistent observation until the end of the experiment. In general, the absolute weights of these organs in the 50 day‐old malnourished rats were similar to those found in 25 to 26 day‐old animals fed the SLD. The relative weights of the pituitary gland and liver remained similar between the two animal groups. The testes and ventral prostate gland, however, were relatively smaller in the malnourished animals at nearly every time interval studied. On light microscopic examination of the testes, it was found that normal maturation of the germ cells failed to occur in all but one of the experimental animals, whereas maturation proceeded normally in the rats fed the SLD. Serum luteinizing hormone (LH), follicle stimulating hormone (FSH), prolactin (PRL), and testosterone were lower in the malnourished animals at all ages studied. These hormones did not exhibit the fluctuations that were seen in the controls and are typical in rats that are becoming sexually mature. The effect of protein deficiency on the concentration of the pituitary gonadotrophins was more varied. FSH concentrations were consistently lower, PRL was moderately affected, and LH remained essentially unchanged. Hypothalamic LH‐releasing hormone was measured and found to be significantly less in the rats fed the LPD at most of the time intervals examined. These results indicate that the hypothalamo‐hypophyseal‐gonadal axis is impaired when the consumption of proteins and calories is decreased. The possible involvement of extrahypothalamic centers in the control of hormone secretion in the protein‐deficient rat is discussed.
Incidence and morphology of equine and murine chondrocytic cilia
Authors: Wilsman Norman J. , Farnum Cornelia E. , Reed‐Aksamit Debra K.
Published: February 2005

The incidence and structure of equine and murine chondrocytic cilia were studied using serial sections and transmission electron microscopy. Overall, 96% of all equine chondrocytes and 100% of all murine chondrocytes had one cilium. The structure of these cilia included rootlets, basal feet, alar sheets, and an axoneme of nine peripheral doublets which progressively bent and terminated as they coursed towards the tip of the ciliary shaft. Together with the previous studies on neonatal and adult canine chondrocytic cilia, we conclude that the structure and incidence of chondrocytic cilia does not vary among species, regions within a joint, cell types, or age groups.
Critique of “an electron microscope study of crystal calcium carbonate formation in the mouse otolith”
Authors: Peacor Donald R. , Rouse Roland C. , Ross Muriel D.
Published: February 2005

Electron micrographs of otoconia of fetal mice, as obtained by Nakahara and Bevelander, provide morphological evidence that the otoconia consist of both organic material and calcium carbonate (calcite), contrary to their own conclusions. Calcite is an integral component of otoconia, apparently from their inception. The concept of mineralization by calcite of an already developed organic template (“preotolith”) is shown to be in error.
The myelinated fibers of the deep branch of the ulnar nerve at the wrist in bonnet monkeys (Macaca radiata) and of some of its branches to the hand
Authors: Devanandan M. S. , Ghosh S. , Simoes E. A. F.
Published: February 2005

In order to estimate the peripheral nervous correlates concerning the motor performance of the hand, the myelinated fibers of the deep ulnar nerve and some of its branches to the intrinsic muscles of the monkey (Macaca radiata) hand have been enumerated and their caliber spectra plotted. The content of the myelinated sensory fibers in the deep ulnar nerve was found to be 70% of the total. This high figure is attributable to the fact that 25‐50% of the myelinated fibers in the deep ulnar nerve are destined to innervate the joints of the hand. Approximately 50% of the myelinated fibers in nerves to the intrinsic muscles of the hand were sensory.
Changes in intramembranous particle distribution in the plasma membrane of didelphis virginiana spermatozoa during maturation in the epididymis
Authors: Olson Gary E.
Published: February 2005

Structural specializations in the plasma membrane of opossum spermatozoa obtained from different levels of the epididymis have been analyzed in thin sections and freeze‐fracture replicas. The maturation process was accompanied by a redistribution of intramembranous particles in the flagellar midpiece region. Caput epididymal spermatozoa are immotile, and freeze‐fracture replicas of the midpiece plasma membrane reveal a random arrangement of intramembranous particles. As spermatozoa transit the corpus epididymis, the intramembranous particles in the midpiece plasma membrane are redistributed from a random arrangement to an organized packing pattern. This redistribution apparently involves the formation of chains of intramembranous particles which gradually increase in length, orient parallel to the flagellar long axis, and ultimately form numerous parallel rows, each three to five particles wide. In cauda epididymal spermatozoa the intramembranous particles within the rows are packed in an organized manner, and few free intramembranous particles are noted between rows. Analysis of thin sections revealed that the reorganization of intramembranous particles is accompanied by the deposition of a mat of amorphous material at the cytoplasmic face of the membrane. No striking changes in intramembranous particle distribution during epididymal maturation were found in other flagellar segments or in the plasma membrane overlying the sperm head.
Histology of the canine urethra. I. Morphometry of the female urethra
Authors: Cullen W. Craig , Fletcher Thomas F. , Bradley William E.
Published: February 2005

Urinary bladders and urethrae were collected from six adult and two juvenile female dogs. Five urethral regions and the neck and body of the bladder were sampled. Volume fractions for connective tissue including elastic fibers, smooth and striated muscle, and epithelium were obtained by projecting section images onto an array of points and computing the number of points overlying a tissue constituent per total points overlying the tissue section.

Smooth muscle occupied approximately half the volume of the bladder wall, one‐third the volume of the vesical neck, and one‐fourth the volume of the proximal urethra. Striated muscle was present in the distal half of the urethra, where the total muscle coat occupied about one‐third of the urethral wall volume. Smooth muscle was practically absent in the terminal urethra, where the striated urethralis muscle encircles urethra and vagina in common. Epithelial area and lumen perimeter were not significantly different along the length of the urethra except that urethral epithelium was significantly thicker adjacent to the vesical neck. In terms of histological proportions, the vesical neck was intermediate between the body of the bladder and the proximal urethra.
Developmental changes in the fine structure of the chorion laeve (Smooth chorion) of the rhesus monkey placenta
Authors: King Barry F.
Published: February 2005

Developmental changes in the fine structure of the chorion laeve (smooth chorion) of the rhesus monkey were studied at two time periods during gestation: (1) Early (19–60 days of gestation), before the chorionic epithelium fuses with the parietal decidua, and (2) near term, when the fused chorioamnion has also fused with the parietal decidua. Early in gestation the chorionic epithelium consisted of columnar and cuboidal cells one or two layers thick. The apical border of the cells had microvilli and coated pits, and adjacent cells were joined by tight junctions and desmosomes. The chorionic epithelial cells during this early period contained numerous large vesicles and vacuoles of varying electron‐density. The apical cytoplasm contained various small coated vesicles and tubules. Taken together these observations were interpreted as indicating a possible role for these cells in endocytosis or phagocytosis of substances from the uterine lumen; i.e., a potential role in histiotrophic nutrition during this early period. Late in gestation the trophoblastic cells were more irregular in shape. The cells contained abundant granular endoplasmic reticulum (ER) and mitochondria, and a well‐developed Golgi complex, suggesting the cells were actively synthetic late in gestation. The numerous cytoplasmic vacuoles characteristic of the trophoblastic cells of early gestation were absent near term. Glycogen deposits and lipid droplets were moderately well‐developed near term. Most of the cells were joined by desmosomes but wide intercellular spaces, unobstructed by any cell junctions, were frequently observed. This observation provides at least one explanation for the increase in permeability of the chorion laeve later in gestation. Cells of the parietal decidua associated with the chorion laeve were also examined. These cells generally had a well‐developed granular ER and Golgi apparatus, and numerous mitochondria. Limited numbers of membrane‐bounded secretory bodies, similar to those in human decidual cells, were also present.
Stereotaxic placement of cannulae in cerebral ventricles of the pig
Authors: Poceta J. Steven , Hamlin Michael N. , Haack David W. , Bohr David F.
Published: February 2005

We have developed and employed a stereotaxic coordinate system for the pig brain based on external skull landmarks. Sagittal, coronal, and horizontal planes were defined. Based on histological maps and ventricular casts, the coordinates for locating the lateral ventricles were described. Guide tubes leading to the lateral ventricles have been chronically implanted. This access route to the ventricular system has been used for stimulation of the dipsogenic response with angiotensin and for withdrawal of cerebrospinal fluid. Solved and unsolved problems arising with these procedures have been defined.
Cytoplasmic granules in luteal cells of pregnant and non‐pregnant guinea pigs. A cytochemical study
Authors: Paavola Laurie G. , Boyd Charles O.
Published: February 2005

Secretory granules, which are released by exocytosis and are speculated to contain progesterone, have been described in luteal cells of sheep and other large domestic animals. These granules are small and densely staining. Gemmell and Stacy ('79) suggested that luteal cells of guinea pigs also contain secretory granules, although they could not document exocytosis of granule content at the fine structural level. For the present study, quantitative methods were used to reexamine the possibility that luteal cells of guinea pigs possess secretory granules. Ovaries of guinea pigs were fixed in situ by vascular perfusion at the time of maximum progesterone secretion, when such granules would be most abundant, as well as at other stages. Two types of granules that might be confused with secretory granules are microperoxisomes and lysosomes. Therefore, slices of perfusion‐fixed corpora lutea were incubated for the fine structural localization of a peroximomal enzyme, catalase, or for the lysosomal enzymes, acid phosphatase (ACPase) and arylsulfatase. Other tissue was prepared for conventional electron microscopy. Granule types were classified on the basis of size, morphology, and enzyme content. Quantitation of granule types was carried out on both cytochemically reacted and conventionally prepared luteal tissue. More than 5500 microperoxisomes, 2800 lysosomes, and 1100 multivesicular bodies (MVBs) were tabulated. The results indicate that luteal cells of guinea pigs have three main types of granules: (1) Microperoxisomes, about 0.2μm in diameter and containing catalase; (2) lysosomes, about 0.5μm in diameter and positive for ACPase and arylsulfatase; and (3) MVBs, about 0.4μm in diameter and containing small vesicles. At the time of peak steroid secretion during pregnancy and the estrous cycle, the granule population in luteal cells of guinea pigs consists of 73–80% microperoxisomes, 13–17% lysosomes, and 7–l9% MVBs. These proportions are similar in tissue reacted for cytochemistry and tissue prepared by conventional means. Greater than 99% of the small 0.2–0.3μm diameter granules in guinea pig luteal cells are catalase reactive. This finding eliminates from further consideration most of the prime candidates for secretory granules in these cells. Finally, neither a sequential appearance of granules nor exocytosis of secretory product was detected. Our data thus argue against the suggestion that luteal cells of guinea pigs have secretory granules of the type observed in corpora lutea of large domestic animals.
The effect of buffer molarity on axonal exposure and axoaxonal apposition in the rat molar pulp
Authors: Holland G. R.
Published: February 2005

Axons in the rat molar pulp have been examined morphometrically to determine axonal size and the degree of axonal exposure and axoaxonal apposition in tissue fixed by perfusion using 2% glutaraldehyde in cacodylate buffers ranging in molarity from 0.025 M to 0.4 M. Between 31.2% and 45.0% of the axons were incompletely ensheathed. This proportion of axons exposed was linearly related to the buffer molarity (P < 0.05) and was approximately double that found in more central axons. Between 32.3% and 45.0% of the axons were in contact with other axons. This proportion was not linearly related to buffer molarity but was at least ten times higher than that observed in more centrally positioned nerve fibers in the inferior alveolar nerves. Increasing buffer molarity reduced the size of the axons, a relationship not found in the more central axons. It is suggested that axonal exposure and axoaxonal apposition are constant, significant features of pulpal nerve fibers that may be related to the onset and spread of nociceptive activity. The permeability properties of pulpal axons may differ from those of more centrally placed axons.
Membrane specialization in the rat epididymis. II. The clear cell
Authors: Brown Dennis , Montesano Roberto
Published: February 2005

The clear cell is a characteristic cell type, particularly frequent in the epididymal tail, which has many small vesicles and larger vacuoles in the apical cytoplasm. In freeze‐fracture replicas of adult rat epididymis, we found that the limiting membrane (P‐face) of these vesicles and vacuoles, as well as the luminal plasma membrane (but not the basolateral membrane) contain a high density of prominent intramembrane particles. In contrast, the apical vesicles of the most common cell type, the principal cell, have a much lower density of particles, which are also of smaller size. The unique organization of these membranes in clear cells suggests that this cell type has a special role in epididymal function.
Studies on zonation in the epididymis of the guinea pig. I. Ultrastructural and biochemical analysis of the zone rich in large lipid droplets (zone II)
Authors: Hoffer Anita P. , Karnovsky Manfred L.
Published: February 2005

In the epididymis of the guinea pig, zone II exhibits striking histological features that distinguish it readily from the other six regions of the epididymis. At the light microscope level, the pseudostratified epithelium of zone II is characterized by tall principal cells that are densely packed with large, intensely staining granules or droplets ranging up to 8μ in diameter. At the electron microscope level, the principal cells exhibit numerous large lipid droplets and abundant agranular endoplasmic reticulum, which is frequently arranged in concentric whorls around one or more of the droplets. Quantitative biochemical studies comparing zone II with zones I and III show that zone II contains 2.5–3‐fold more cholesterol and a significantly greater amount of cholesterol ester than the other two zones. These data indicate that the epididymal duct of the guinea pig includes a clearly defined region of epithelial cells possessing ultrastructural and biochemical characteristics consistent with steroidogenic activity. The potential significance of these observations to the epididymal physiology of the guinea pig and epididymal physiology in general is discussed.