bluuebunny/crossref_metadata_2025 huggingface dataset:
Differentiation of the Leydig cell of the mouse testis during the fetal period — an ultrastructural study
Authors: Russo Jose , de Rosas Juan C.
Published: February 2005

Differentiation of the Leydig cell in the fetal mouse as studied by light and electron microscopy was divided into three phases. During phase 1 (day 12 to day 15) the spindle‐shaped cell becomes an immature Leydig cell which contains numerous free ribosomes and some polysomes. Phase 2 (day 16 to day 19) is marked by a considerable development of smooth endoplasmic reticulum and by an equally important decrease in ribosomal population. Mitochondria are increased in number 100%. Phase 3 (day 19 to birth) is characterized by maximal lipid and glycogen content. Close to the time of birth, smooth endoplasmic reticulum decreases in extent and becomes vesicular.

The peak in prenatal Leydig cell differentiation as judged by development of the endoplasmic reticulum occurs during phase 2. These findings are discussed in the light of data derived from study of other species and an attempt is made to correlate morphological features with available information concerning the control of differentiation by gonadotropins.
Cholinesterase‐positive and catecholamine‐containing nerves in the guinea‐pig pericardium
Authors: Ellison Jeffrey P.
Published: February 2005

The functions of the pericardium are traditionally defined in terms of lubrication and support. However, its complement of autonomic nerve fibers, shown by physiologc experimnts to be sensory, suggests that the pericardium may also serve as a mechanoreceptor site. In this study acetycholinesterase‐positive, and catecholamine‐containing elements of the pericardial plexus of the guinea‐pig were visualized, using thiocholine and fluorescence techniques, respectively. A cholinesterase‐positive nerve net, containing the preterminal segments of unmyelinated fibers and simple nerve endings, extended over the entire parietal pericardium. Some of the cholinesterase‐positive endings, apparently separate from effector structures were assumed to be sensory. A few heavily myelinated fibers were contributed by the phrenic nerve. The parietal pericardium covering the atria contained many adrenergic nerves and endings. Not all pericardial adrenergic endings were linked to effector structures, such as blood vessels. Some fibers ended freely. It is suggested that liberation of catecholamines from “unattached terminals” may serve to lower the threshold, and prolong the adaptation of adjacent cholinesterase‐positive mechanoreceptor terminals.
Placentation in the American beaver (Castor canadensis)
Authors: Fischer Theodore V.
Published: February 2005

Implantation in the beaver is superficial and antimesometrial. The embryonic disc occupies one side of the flattened mesometrial hemisphere of the large blastocyst. An endometrial papilla, unique to the beaver, forms on the mesometrial uterine wall just prior to chorioallantoic contact. The reniform placenta then develops around this papilla. Amniogenesis is by folding. A transient choriovitelline placenta develops very early. Yolk sac inversion is late, and the bilaminar omphalopleure is partially retained throughout gestation. The chorion persists until term as two paraplacental membranes. A large permanent allantoic vesicle is present. The labyrinthine placenta has a lobulate architecture. It possesses a hemodichorial barrier, the inner layer being syncytial and the outer cellular. Maternal blood is supplied by two arterial channels which do not penetrate the labyrinth, and is drained by a single, central venous channel. A large basal subplacenta develops by trophoblastic invasion of the endometrial papilla, and becomes quite massive at term. Its function is unknown. Except for this specialized subplacenta, all the fetal membrane characteristics are typical of the primitive sciuromorph group, to which the Castoridae seem to be closely related.
Argentaffin and other “endocrine” cells of the small intestine in the adult mouse. I. Ultrastructure and classification
Authors: Ferreira M. N.
Published: February 2005

Electron microscopic examination of the epithelium of crypts and villi in the jejunum of the adult mouse revealed the existence of three main types of cells which may be classified within the group of argentaffin and other “endocrine” cells of the gastrointestinal tract.

Sixty per cent of the cells are characterized by the presence of biconcave granules. They are referred to as biconcave granule cells (Type EC). While most granules are biconcave, some of them are spherical and may show a particulate structure. Those cells with 95% or more biconcave granules predominate in the crypt, while those with 50–75% predominate in villi. The cells of this type are considered by some authors to be true argentaffin or enterochromaffin cells.

Thirty‐seven per cent of the cells have spherical dense granules, a few of which look like empty vesicles. However, because of the marked differences between the sizes of the granules, these cells are classified into two categories. Those with granules averaging 360 mμ in diameter are referred to as large spherical granule cells (Type L, 13%), while those with granules averaging 250 mμ in diameter, are referred to as small spherical granule cells (Type S, 24%). Both types are found in crypts and villi.

Three per cent of the cells do not fit into these categories. All these uncommon cells contain spherical granules; and, in addition, some have oval ones; others show large halos; and still others include granules of different sizes and densities.

The existence of several “endocrine” cell types suggests that they play different roles in the jejunum of the mouse.
The indifferent fiber plexus and its relationship to principal fibers of the periodontium
Authors: Shackleford John M.
Published: February 2005

Scanning electron micrographs demonstrate the presence of an indifferent fiber plexus as an integral part of periodontia in the rat, dog, armadillo and man. Individual fibers measure 1400 Å in diameter in scanning electron micrographs. The indifferent fibers course in every direction throughout the area between bone and cementum without particular orientation. They anastomose extensively with the principal fibers to form a continuous fibrous matrix. Anastomoses with principal fibers begin adjacent to bone or cementum and increase until the indifferent fiber plexus reaches maximum density a short distance from the mineralized matrix. At this point a principal fiber may lose its structural identity as it blends with the profusion of indifferent fibers. This phenomenon occurs in all species studied but is more evident in the relatively unstressed teeth of armadillos. In the dog, principal fibers may extend from cementum to bone as highly compact structures. Anastomoses between principal and indifferent fibers often occur via fibers of intermediate size. The latter fibers become more oriented as their fiber diameters increase. Gingival fibers of the rat, in contrast to principal fibers of the alveolodental ligament, rarely consist of compact fiber bundles. Instead, fibers of indifferent and intermediate size aggregate to form gingival cords in which component fibers are readily distinguishable.
Tubal surgery in the rabbit: Fertilization and polyspermy after resection of the isthmus
Authors: Hunter R. H. F. , Léglise P. C.
Published: February 2005

Transport and capacitation of spermatozoa, and the normality of the process of fertilization, were examined after unilateral resection of the isthmus and end‐to‐end anastomosis of the remaining portions of the Fallopian tube. The operation was performed in eighteen rabbits, in each of which the contralateral tube remained intact to serve as a control.

Recent ovulations were present in fourteen animals at autopsy, although in only eleven were ovulations detectable on the side of the anastomosis. Thirteen animals yielded a total of 89 eggs, the proportion recovered from the control tube (79.3%) being significantly higher than that from the anastomosed tube (57.2%). Six of nine anastomosed tubes yielding eggs were patent to sperm passage, and 67% of the eggs recovered from this side were fertilized compared with 91% from the control tubes. Three eggs recovered from the anastomosed tube of three animals were dispermic. It is concluded that normal fertilization and early cleavage of rabbit eggs can take place in the absence of the isthmus, and that the rate of cleavage is not retarded under such conditions. An increased number of spermatozoa on the eggs from the anastomosed tube, together with the incidence of dispermic eggs, indicates that the isthmus exerts considerable control over sperm transport to the site of fertilization.
Osmiophilia of the saturated phospholipid, dipalmitoyl lecithin, and its relationship to the alveolar lining layer of the mammalian lung
Authors: Kaibara Manabu , Kikkawa Yutaka
Published: February 2005

The appearance and the osmiophilic properties of synthetic dipalmitoyl lecithin (DPL) were characterized under various conditions. It was shown that DPL appeared as 50 Å round to oval dots and lamellae of 50 Å periodicity when negatively stained with phosphotungstate. Osmium‐vapor treatment of a DPL suspension produced negatively outlined DPL, similar to the images obtained with negative staining with phosphotungstate. A mixture of ethanol, osmium and DPL showed the heavily osmiophilic lamellae of DPL in thin sections. The periodicity measures 42 Å. These results are the first in the literature to reveal the osmiophilic nature of saturated dipalmitoyl lecithin.

Prolonged washing after both glutaraldehyde and osmium fixation of lung tissue, thus eliminating the chance for interaction among osmium tetroxide, ethanol and saturated phospholipid, resulted in a loss of the heavily osmiophilic surface film that has been reported to be present after routine tissue processing. Secondary osmication of the washed lung with a mixture of osmium tetroxide and ethanol solution brought about striking osmiophilia of the surface film, which was lamellar and was identical to synthetic DPL in its periodicity.

It is suggested that the osmiophilic line observed after routine tissue processing is saturated phospholipid that binds osmium during the process of ethanol dehydration immediately following osmium fixation.
Protein synthesis in vivo by preimplantation hamster embryos
Authors: Weitlauf Harry M.
Published: February 2005

The level of protein synthesis by hamster embryos in vivo, as inferred from the incorporation of 35S methionine, was determined for the four days of the preimplantation period by radioautography. The embryos incorporated 35S methionine throughout the preimplantation period. Furthermore, the hamster eggs continued to incorporate 35S methionine following ovariectomy. Therefore, the pattern of protein synthesis in hamster eggs differs from the mouse with its low levels in cleaving eggs and in blastocysts following ovariectomy and high levels in blastocysts influenced by estrogen and progesterone.

This finding is of interest because unimplanted mouse embryos remain viable in ovariectomized females for many days, whereas hamster embryos rapidly degenerate. It is suggested that the inability of hamster eggs to reduce the level of protein synthesis and become “dormant” may prevent their survival if implantation is blocked by ovariectomy.
Sites of protein synthesis in the cells of the zona fasciculata of the young rat adrenal, as shown by electron microscope radioautography
Authors: Magalhãtes Maria C. , Magalhãtes M. M. , Coimbra Antonio
Published: February 2005

Young rats received 1 mCi of leucine‐H3 or tyrosine‐H3 intraperitoneally and adrenals were fixed in glutaraldehyde‐osmium after 10, 60 and 240 minutes. Epon ultrathin sections were coated with Ilford L4 nuclear emulsion for radioautography. Ten minutes after injection of both tritiated amino acids, labeling indicating the sites of protein synthesis was found principally over the endoplasmic reticulum (∼ 57% of the silver grains) and mitochondria (∼ 32%). Distances of silver grain centers to the nearest interface between these two organelles were plotted; the results seemed to confirm that protein synthesis occurred in the endoplasmic reticulum and mitochondria but was more active in the endoplasmic reticulum. Values remained the same at the other time intervals examined, suggesting the formation of sedentary protein. However, values for the Golgi apparatus were low at ten minutes, fairly high at 60 minutes and low again at 240 minutes, suggesting migration of a small fraction of the newly‐formed protein through the Golgi apparatus and subsequent discharge. The possibility is raised of this being an exportable protein.
The development of pigment cells in the eyes of rhesus monkeys
Authors: Hu Funan , Montagna William
Published: February 2005

The eyes of rhesus monkeys possess two lines of pigmented cells: those of the pigmented retinal epithelium and those of the uveal tract, also known as stromal pigmented cells. The cells of the pigmented epithelium differentiate first and are fully functional in 65‐day old fetuses. By contrast, stromal pigmented cells do not become recognizable until late gestation (140 days). The differences in development and structure of these cells may reflect a different and perhaps distinct function.
Differentiation of granulated metrial cells in the uterus of the pregnant rat: An electron microscopic study
Authors: Larkin Lynn H. , Cardell Robert R.
Published: February 2005

The fine structure of the granular metrial gland cell of the pregnant rat was studied during early stages of differentiation. “Precursor cells” were identified with the electron microscope that exhibited characteristic features of the mature cell as well as many cytoplasmic ribosomes. Notable features of differentiation were: a great increase in cell size, decrease in overall electron density, formation of a large centrosphere surrounding the centrioles, and accumulation of granules. The first sign of granule formation was the appearance of dense‐core vesicles in the Golgi complex. Subsequently, larger granules appeared which had small vesicles between a dense core and the limiting membrane. Finally, multilaminated myelin figures were noted in the mature granule in addition to the core material and vesicles. The possible role of coated vesicles in granule formation is discussed.
The fine structure of the Necturus (Amphibia) heart
Authors: Hirakow Reiji
Published: February 2005

The fiber diameter in the heart of Necturus maculosus is not significantly different from that of other amphibian myocardial cells, averaging approximately 5 μ over most of its length and about 10 μ in the nuclear region. No transverse (T) tubular system was found. Instead, there were shallow invaginations of the sarcolemma and many pinocytotic vesicles at the periphery of the myocytes. Other intracellular membrane systems such as the Golgi apparatus and sarcoplasmic reticulum were also sparse and poorly organized. However, subsarcolemmal cisterns, specialized segments of the sarcoplasmic reticulum in close apposition with the sarcolemma, were clearly demonstrated. Nexal junctions were recognized at points of contact between myocytes, although they occupied smaller areas than those of mammalian myocardial cells. Mitochondria were small and few. Light cells with few organelles or myofibrils, which resembled Purkinje fibers of mammalian and avian hearts, were often observed. A nerve ending in close contact with muscle cells was described.
Effects of unilateral ovariectomy on follicular development and ovulation in cycling, aged rats
Authors: Peppler Richard D.
Published: February 2005

Cyclic rats were unilaterally ovariectomized at random stages of the cycle between 66 to 72 days of age and killed on day 2 (metestrus) of the estrous cycle after three cycles, and after 3, 6 or 12 months. Control (intact) rats were also killed at these time periods.

Counts of tubal ova revealed that intact rats ovulated an average of 5.3 eggs per ovary after three cycles (N = 7); 4.8 after three months (N = 12); 4.2 after six months (N =12) and 3.5 after 12 months (N = 2). Following unilateral ovariectomy, compensatory ovulation (11 eggs) occurred in all rats after three cycles (N = 10) and at three months (N = 11). Only four to five eggs were ovulated at six (N = 13) and 12 months (N = 4) after hemicastration. The remaining ovary in rats unilaterally ovariectomized after three cycles, or 3, 6 and 12 months hypertrophied 38%, 64%, 55% and 118%, respectively.

Follicular development on the second day of the cycle was the same in intact and hemicastrated rats. The total number of follicles larger than 352 μ in diameter did not differ between three cycles and three months. By six months a 50% reduction occurred and the number of follicles remained the same after 12 months. This decrease in follicular development supports the finding of an absence of compensatory ovulation in the hemicastrated rat after 6 or 12 months.
Regional differentiation in the heads of spermatozoa of rabbit, man and bull
Authors: Bernstein Maurice H. , Teichman Robert J.
Published: February 2005

The heads of the spermatozoa of rabbit, man, and bull are flattened in the dorsoventral plane and exhibit three distinct regions in the head coverings. The anterior one‐half to two‐thirds of the nucleus is covered by the acrosome, the middle of the nucleus by the thinned equatorial segment of the acrosome and the remainder of the head is covered by the postacrosomal segment. Species variation is evident in the head coverings; most prominent are the equatorial bands of the rabbit spermatozoon. The bands are subacrosomal bulges curving around the head; the arms of each band are displaced in the anteroposterior axis and do not cross the midline axis. The equatorial bands are visible in scanning electron micrographs, which also show a serrated junction between the equatorial segment and the postacrosomal region.
The secretory granules of the acinar cells of the mouse submaxillary gland
Authors: Martinez‐Hernandez Antonio , Nakane Paul K. , Pierce G. Barry
Published: February 2005

Absence of membranes from the secretion granules of the acinar cells of the submaxillary gland of the mouse had led to speculation concerning mechanisms of secretion of these cells. By means of rapid perfusion fixation, smooth membranes have been identified around the secretion granules, and the mode of secretion proves to be similar to that of the other exocrine glands. The evidence suggests that potent membranolytic agents of unknown nature, capable of rapidly destroying the membranes are present in these secretory granules.
Light and electron microscopic radioautography of glucose‐6‐H3 incorporation in the retina of the adult newt, Triturus viridescens dorsalis
Authors: Dickson D. H. , Hollenberg M. J.
Published: February 2005

Tritiated glucose was administered to fasted newts to study glucose incorporation in the retina and particularly the photoreceptor cells. Incorporation of glucose into glycogen throughout the retina commenced at 30 minutes after injection. The first silver grain concentrations were observed over the photoreceptor myoid at two hours. Incorporation of glucose into glycogen reached a maximum at six hours with grains concentrated over photoreceptor paraboloids, the apices of Müller cells and the inner and outer plexiform layers. By 24 hours there was a reduction of the label in glycogen but silver grains were now visible over mitochondria in the photoreceptor ellipsoids and in increased amounts in the outer and inner plexiform layers and the nerve fiber layer. After three weeks, most radioactive material was observed over the photoreceptor cell outer segments. These results suggest that glycogen is added at the inner aspect of the photoreceptor paraboloid and then moves outward in a scleral direction, where it is metabolized by the ellipsoidal mitochondria.
An electron microscopic study of intimal cushions in intracranial arteries of the cat
Authors: Takayanagi Tetsuya , Rennels Marshall L. , Nelson Erland
Published: February 2005

Subendothelial protuberances associated with the tunica intima have been described by light microscopy at branching sites of arteries in various animal species. These structures are termed intimal cushions or intimal pads. Some investigators regard them as being pathologic, preceding the appearance of atherosclerosis in the vessel wall. This fine structural study was done because of the possible role of intimal cushions in the regulation of cerebral blood flow at branching sites of intracranial arteries. The internal elastic lamina is split at the margins of a cushion to enclose irregularly arranged bundles of smooth muscle cells and collagenous fibrils. These smooth muscle cells are generally arranged at a right angle to smooth muscle cells in the underlying media. The outermost layer of the internal elastic lamina forms a boundary between the body of the cushion and the media; however, areas of discontinuity cause this border to be poorly defined in some instances. Perivascular autonomic nerves do not extend into either media or intimal cushions. Intercellular contacts between smooth muscle cells are observed within cushions as well as in the media, suggesting that cushions may be contractile and capable of modifying cerebral blood flow.
Placental development in the mongolian gerbil (Meriones unguiculatus). II. From the establishment of the labyrinth to term
Authors: Fischer Theodore V. , Floyd Alton D.
Published: February 2005

Placental development was studied in 24 gerbils from day 13 to term. Allantoic mesoderm contacts and vascularizes the chorionic‐trager plate of germinal cytotrophoblast on day 13. Soon villous extensions penetrate the plate, carrying with them a covering of three layers of trophoblast derived from it. As the villi elongate, clumps of germinal cytotrophoblast are carried peripherally by them. Further development of each villus results in a cylindrical mesenchymal core with a central arteriole, and radially arranged branching lamellar extensions carrying capillaries derived from the villus arteriole. Germinal cytotrophblast clusters disappear near term, but some indication always remains of the trilaminar covering of the villus and its lamellae. A typical countercurrent blood flow pattern occurs. The trophospongium is derived from the ectoplacental cone and the mesometrial surface of the germinal cytotrophoblastic plate. Although a few clusters of small cells occur, it is essentially a giant cell trophospongium and never contains cells resembling the clear cells of the rat. Late in pregnancy it becomes much reduced in thickness. The unique subplacental gland begins to degenerate soon after placental establishment and is gone by the last half of pregnancy. The metrial gland begins development at midterm and becomes a solid mass of cells filling the perivascular space of the mesometrial triangle at term.
Ultrastructural and fluorescence histochemical studies of developing sympathetic ganglia in the rabbit
Authors: Papka Raymond E.
Published: February 2005

The development of thoracic sympathetic ganglia was studied in rabbit fetuses at 14 to 30 days of gestation by light, electron, and fluorescence microscopy. Changes that occurred during the development of sympathetic neurons, supporting cells, and granule‐containing cells are described and the following conclusions drawn. (1) Sympathetic neurons and granule‐containing cells arise from a common “indifferent cell” precursor. (2) Monoamine fluorescence (a manifestation of the presence of catecholamines) appears early in the development of sympathetic neuroblasts. (3) The development of neuroblasts in a sympathetic ganglion is asynchronous; i.e., each neuroblast develops at its own rate, irrespective of the rate of development of its sister cells. (4) Granule‐containing and catecholamine‐storing cells develop rapidly and probably become potentially functional early in the life of the fetus, as inferred from the abundance of dense‐core vesicles and intense monoamine fluorescence. (5) The derivation of supporting cells (“satellite” and Schwann cells) could not be determined. They had differentiated into an easily recognizable cell form in the youngest specimens studied, and appeared to be enveloping cell bodies (as satellite cells) or axons (as Schwann cells) in all specimens.
The structure of compressed lungs in congenital diaphragmatic hernia
Authors: Boyden Edward A.
Published: February 2005

The case of a full term, stillborn infant with herniation of the viscera through a so‐called left Bochdalek foramen is analyzed. Graphic and wax reconstructions of the uninflated left lung record the degree of differentiation and the histologic appearance of the atelectatic parenchyma. To this is appended a discussion of the probable sequence of events during gestation; and an explanation of why such hernias usually protrude into the left, and not the right pleural cavity.
The effects of acute starvation on parotid acinar cells. Ultrastructural and cytochemical observations on Ad Libitum‐fed and starved rats
Authors: Hand Arthur R.
Published: February 2005

Parotid acinar cells from ad libitum‐fed and starved rats were studied using electron microscopic and cytochemical techniques. Lysosomes containing acid phosphatase and non‐specific esterase activity were present in cells of both ad libitum‐fed and starved rats. They included lipofuscin‐like bodies, smaller round or irregularly‐shaped bodies, multivesicular bodies, and coated vesicles. After 16–24 hours of starvation, lipid droplets had accumulated in the basal cytoplasm, and secretory granules showed evidence of degeneration. These altered granules consisted of irregular clumps of dense material in a less dense matrix. After 48–72 hours of starvation, the altered granules increased in number and fused to form large aggregates. Some of the aggregates also contained vesicles, membranous material, and lysosomal residues. The altered granules and aggregates were reactive for acid phosphatase and non‐specific esterase. The formation of the altered granules appeared to occur by spontaneous degeneration of the secretory granules, with secondary fusion with pre‐existing lysosomes and other altered granules. The results suggest that the lysosomal system of the parotid acinar cell functions to segregate and digest secretory granules during periods of reduced secretory stimulation.
Steroid‐protein interactions. XXV. Binding of progesterone and cortisol in pregnancy sera; progesterone‐binding globulin and uterine cytosol receptor in the pregnant guinea pig
Authors: MacLaughlin David T. , Harding George B. , Westphal Ulrich
Published: February 2005

The question of the identity of the high‐affinity binding sites for progesterone with those of the corticosteroid‐binding globulin (CBG) was investigated in pregnancy serum of man, rabbit, rat and mouse. Chromatographic techniques failed to separate a potential progesterone‐binding macromolecule from CBG in any of the sera. Competition studies with enriched fractions containing added [3H] progesterone and [14C] cortisol strongly bound to protein showed displacement of [3H] progesterone by an excess of unlabeled cortisol, and vice versa. It is concluded that CBG is the principal progesterone binder in the pregnancy sera investigated and that no other protein with high affinity for progesterone is present in significant quantity.

In contrast, the progesterone‐binding globulin (PBG) in the serum of the pregnant guinea pig is distinct from CBG and has been separated from it. The PBG differed from the uterine cytosol receptor for progesterone in its sedimentation coefficient (sucrose gradient centrifugation) and its molecular size (gel filtration). With both the uterine receptor and PBG, norethynodrel displaced radiolabeled progesterone from the specific binding sites. This is in contrast to analogous binding systems involving other steroid hormones and other species, where the synthetic hormonal agent interacts strongly with the receptor protein of the target tissue, but not with the high‐affinity binder in the serum.
Ultrastructural changes in renal Glomeruli of rats during experimentally induced hypertension and uremia
Authors: Lee M. L. , Purkerson M. L. , Agate F. J. , Dempsey E. W.
Published: February 2005

Internal vascular ultrastructural detail of renal microcirculation observed by a combination of latex injection/corrosion/scanning electron microscopy techniques can be correlated with structures visible in transmission electron micrographs. Glomeruli of normal and hypertensive rats have been examined using both techniques. In the casts, indentations occur which are comparable in size, shape and frequency to nuclei of endothelial cells; and other irregular indentations may be correlated with the occurrence of platelet thrombi and endothelial cell proliferation. From these observations we conclude that ultrastructurally accurate casts of blood may be visualized by scanning electron microscopy. Such visualization offers much promise for the study of microcirculatory structures in states of disease and altered function.
The utility of antiserums to subunits of TSH and LH for immunochemical staining of the rat hypophysis
Authors: Baker Burton L. , Pierce John G. , Cornell James S.
Published: February 2005

The objective was to assess the effectiveness of antiserums to the β‐subunit of bovine TSH (thyrotropin) and α‐ and β‐subunits of LH (luteinizing hormone) for immunochemical staining of rat pituitary cells and in so doing to acquire more information about the properties of the subunits. For the following reasons it was concluded that antiserum to TSH‐β is specific for demonstration of TSH‐cells. The morphology and distribution of the presumptive TSH‐cells so revealed conform to the descriptions presented by other investigators who have used histological techniques. When pituitary TSH content was reduced by thyroidectomy or administration of propylthiouracil or thyroxine, the stainability of TSH‐cells was reduced; it was increased with elevation of TSH content during rebound after cessation of propylthiouracil treatment. The effectiveness of anti‐TSH‐β was lost after absorption with bovine TSH.

The specificity of antiserum of LH‐β for demonstration of LH‐cells was indicated since the cells demonstrated with it correspond to the gonadotropic cells described by others with respect to morphology, distribution and response to gonadectomy. Antiserum to LH‐α, the nonspecific subunit of LH, permitted staining of both TSH‐ and LH‐cells. The individuality of TSH‐ and LH‐cells, as revealed immunochemically with antiserums to the respective specific β‐subunits, was demonstrated by double staining and by comparison of adjacent sections stained with one of the two antiserums.
Sexual dimorphism of the miniature pig submandibular glands
Authors: Pinkstaff Carlin A.
Published: February 2005

The submandibular salivary glands of 14 Pitman‐Moore miniature pigs were examined to determine whether they exhibit sexual dimorphism. Sections of the glands from seven male and seven female animals were stained by several histochemical methods. No morphological sex differences were noted in hematoxylin and eosin‐stained sections but differences were found with all of the histochemical methods utilized. Most noticeable was the higher concentration of sialic acid‐containing mucosubstances in mucous acini of the female submandibular gland sections when they were stained with either the Alcian blue (pH 2.5), Alcian blue (pH 2.5)‐periodic acid‐Schiff or periodic acid‐phenyl‐hydrazine‐Schiff methods. Unlike mucous acini, demilunes of the male submandibular gland possessed a higher concentration of sialic acid‐containing mucosubstance than did those of the female. The miniature pig, unlike other animal orders studied, possesses sexual dimorphism at three weeks of age, thus differing markedly from other animals in which sexual dimorphism of the salivary glands does not occur until after the onset of puberty.
Relationship between the cell cycle and cell localization in crypts of the guinea‐pig ascending colon
Authors: Rowiński J. , Sawicki W.
Published: February 2005

Guinea‐pigs were injected with either 3H‐thymidine or colchicine and killed at various time intervals after the injections. Duration of the over‐all cell cycle and of the G1, S and G2 phases was determined with autoradiography for cells in the short, medium and long crypts of the colon as well as for the lower, middle and upper segments of the crypt.

The duration of mitosis estimated with the colchicine method increased from the mouth of the crypt downward to the bottom, from about one to three hours. The cells located in the crypt between the mouth and approximately the twentieth cell position have a cell cycle of about 15 hours whereas those located in the crypt section between the twentieth cell position and the bottom have a cell cycle of about 25 hours. This difference is due mainly to a change in the G1 phase. The results of planimetry for the first and second waves of labeled mitoses suggest that in the lower segment of medium and long crypts, cells in the G0 phase occur. It is concluded that the factor(s) controlling cell cycle duration in the colon crypt appears either at the crypt mouth or nearby.
Effects of embryonic overgrowth on the avian optic tectum
Authors: Wilson Doris Burda
Published: February 2005

The effects of embryonic overgrowth on the avian optic tectum were determined during late developmental stages in 121 chick embryos in which overgrowth was induced surgically. The embryos ranged in incubation age from seven days through 21 days and showed a variety of gross brain defects, including fused optic lobes, fusion of one or both optic lobes with a cerebral hemisphere or with the cerebellum, absence or reduction of one optic lobe, convolutions of the tectal wall, and hydrocephalus. At seven days to 11 days of incubation, histological defects of the tectum included irregularities in the migration patterns of neuroblasts and abnormal stratification among the migrated neuroblasts. The most severe defects in the 12‐day through 21‐day tectum were in the stratification of the outer region which corresponds to the adult stratum griseum and fibrosum superficiale, whereas deeper areas of the tectum underwent relatively normal histodifferentiation. Epithelial rosettes were common until the sixteenth day, after which they disappeared almost entirely except for a few occasional ones near the ventricular zone. Preliminary behavioral observations of the defective embryos revealed random motility similar to that in the control embryos, but a failure to achieve the proper hatching position. Of 61 operated embryos maintained until hatching, only one was capable of emerging from the shell.
Fine structure of the atrioventricular node as viewed in serial sections
Authors: Thaemert J. C.
Published: February 2005

Atrioventricular nodal tissue obtained from a two‐week‐old mouse heart was fixed in osmium tetroxide, embedded in Epon 812, and serially sectioned for electron microscopy. From the study of electron micrographic montages of the first 620 serial sections of the posterior‐inferior (tail) portion of the node, it was determined that many of the nodal cells are spindle‐shaped and each has a single, centrally‐placed, ellipsoidal nucleus. Other cells exhibit irregular surfaces with protrusions of variable dimensions and some are flattened. Most of the flattened cells are located in the peripheral borders of the posterior and lateral portions; irregularly‐shaped cells occupy deeper positions in the tail of the node. Two cells, which are different from all others, reside in the peripheral border of the medial portion. They are contiguous with one another and globular in shape, each containing a single, centrally‐placed, spherical nucleus. These two cells are sparsely endowed with myofilaments but contain many mitochondria. They may be pacemaker cells. Intercellular relationships among nodal cells exhibit a wide variety of complicated contact areas in addition to some rather simple contiguities of the lateral aspects of adjacent cells. No typical intercalated discs are present; however, junctional specializations between interdigitating protrusions of contiguous nodal cells do occur. Intimate contact between vesiculated nerve processes and nodal cells varies in extent from a profuse innervation in the posterior and lateral portions of the tail of the node to lack of contact with many of the cells in the medial and anterior portions. This pattern of innervation, in conjunction with the absence of maculae occludentes between cells of the posterior and lateral portions of the tail of the node but present between cells of the other portions, suggests that the medial and anterior areas are conductive and the posterior and lateral areas are regulative.
Blood supply of the human fetal mandible
Authors: Hamparian Arthur M.
Published: February 2005

Gross anatomic and radiologic studies of the blood supply to the human mandible of the full‐term fetus and newborn infant were performed on 22 specimens ranging from 320–538 mm crown‐heel length and 1,192–4,108 gm in weight. Ten specimens were injected with red‐lead and liquid soap to demonstrate the arteries radiographically. Twelve other specimens were injected with Castolite with a sprinkling of red‐lead and yellow dye. The best side of each specimen was studied by radiography and dissection. This study demonstrated: (1) a masseteric arterial plexus supplying the coronoid process and the lateral wall of the ramus with contributions from the facial, masseter, transverse facial and external carotid arteries or combinations thereof; (2) a mental arterial plexus anastomosing with the mental, submental and inferior labial arteries; (3) an inferior alveolar artery supplying most of the body of the mandible with a majority of its branches passing in an upward direction; and (4) periosteal vessels supplying the lower border of the mandible and receiving their blood supply from the blood vessels supplying the muscles attaching to these areas and the periosteum. Supplemental to the above findings were anastomoses between the submental, mylohyoid and sublingual arteries along the medial border of the mandible. Also a significant variation not previously recorded was noted in one specimen in which the sublingual artery originated from the facial artery rather than the lingual.
Lobular structure of hemochorial primate placentas, and its relation to maternal vessels
Authors: Gruenwald Peter
Published: February 2005

Structure of the placental lobule and its topographic relation to the ostia of maternal vessels were studied in primates with hemochorial placentas. The lobule contains most of the terminal villi, whereas stems predominate in interlobular areas. The placenta of Tarsiidae consists of one lobule supplied by one maternal artery. Ceboidea (New World Monkeys) have multilobular placentas. In both forms arteries reach the intervillous space below the center of a lobule, and then continue into the lobule as perforated, branched channels which lose their maternal vessel wall. In Cercopithecoidea (Old World Monkeys) each maternal artery has a convolution in the decidua below an interlobular area, then continues straight to a point below the center of a lobule, and opens there. Hominoid (ape and human) placentas are supplied by much larger numbers of arterial convolutions at interlobular areas, with interlobular openings close to anchoring points of villous stems. Venous drainage is at the periphery in Tarsius and interlobular in all other forms. The interlobular intervillous space may have more or less specialized portions emptying into maternal veins. Circulation in the intervillous space must be directed from the center toward the periphery of the lobule in Tarsiidae and Ceboidea. In Cercopithecoidea and Hominoidea the path of maternal blood issuing from arteries is not known. It is suggested that arterial blood irrigates first the periphery, and that this is the cause of dense proliferation of villi there.
The relationship between jaw, arm and leg size in three ethnic groups
Authors: Lavelle Christopher L. B.
Published: February 2005

Overall height, arm length, leg length and mandibular size were measured in 800 male subjects from three ethnic groups aged three months to 20 years. Mandibular size or limb size showed a linear relationship when plotted against overall body height for each ethnic group and emphasized that different relationships exist between the size of a region and that of the body as a whole in caucasoids, negroids and mongoloids.
Distribution of sacral afferent axons in cat urinary bladder
Authors: Uemura Etsuro , Fletcher Thomas F. , Dirks Victor A. , Bradley William E.
Published: February 2005

Terminal axon density was examined in five selected regions of the urinary bladder in five cats. The trigone region had more terminal axons than other bladder regions. Extra‐terminal axons in the trigone were outside muscle fascicles and thought to be afferent axons related to the hypogastric nerve.

In four of the cats, afferent axons of the pelvic nerve were identified by degeneration following sacral spinal ganglionectomy. The afferent axons were distributed equally to all regions of the bladder, implying that micturition sensitivity is not preferentially organized in the bladder. One‐third of the sacral afferent axons crossed to the contralateral side of the bladder. This bilateral redundancy constitutes a safety feature. Afferent terminal axons were more numerous outside than inside muscle fascicles. Morphologically, afferent terminations outside muscle fascicles appeared to be tension receptors, while terminations inside the fascicles are candidates for volume receptors. The greatest number of degenerating terminal axons was found 14 days after ganglionectomy. Thirteen percent of degenerating axons contained agranular vesicles, and these were presumed to be autonomic postganglionic neurons with cell bodies in spinal ganglia.
Heart development in the mexican salamander, Ambystoma mexicanum. II. Ultrastructure
Authors: Lemanski Larry F.
Published: February 2005

Heart development in the Mexican axolotl, Ambystoma mexicanum, from early embryonic stages to the adult was studied by electron microscopy. During early development, myocardial cells exhibit scanty cytoplasmic matrixes which contain numerous large yolk platelets and lipid droplets. As development progresses the yolk and lipid materials become reduced; the cytoplasmic matrixes increase in glycogen content and membranous organelles. Degradation of yolk platelets appears to take place by an “unraveling” process. The Golgi complex becomes well‐developed just prior to the first heart beats and its many associated vesicles are suggestive of secretory activity. Degeneration and death of certain myocardial cells are evident at the onset of trabeculation. Several mechanisms for myofibrillogenesis appear to operate both simultaneously and at different developmental stages. Pre‐heart‐beat myocardial cells display ribosome‐containing amorphous masses and unorganized 60 Å and 140 Å filaments in their cytoplasm. They also have electron‐opaque plaques on their plasma membranes. Sarcomeric myofibrils first appear parallel to and immediately beneath the sarcolemma. This occurs at stage 34, the heart‐beat initiation stage (6 days). During later development “isolated” Z band‐myofilament complexes, numerous loosely‐organized 60 Å filaments and a few 140 Å filaments are observable in the cell matrixes. This suggests that Z bands may form centers for myofibril organization at these stages. Also at later stages, polysomes are parallel to the already‐formed myofibrils. These polysomes are possibly synthesizing contractile proteins “in situ” and may represent a mechanism for myofibril diameter growth. In late embryonic and juvenile stages 100 Å—110 Å filaments appear to be continuous between Z bands of adjacent myofibrils. It is possible that such filaments of intermediate size are involved in aligning myofibrils into register during advanced developmental stages.
The relationship of organ weight, body weight and age in mice
Authors: Simpson L. O. , Spears G. F.
Published: February 2005

A method is described which permits the examination of the influences of increasing age and body weight on organ weights. Polynomial multivariate analysis is performed by computer, and the predicted organ weight values permit the construction of three dimensional graphs which show the influence on organ weight of all combinations of age and body weight. The application of the method will allow the physical biology of organisms to be determined with considerable precision over their life span.
Cytological aspects of pineal development in rats and hamsters
Authors: Clabough Jeanne W.
Published: February 2005

Evidence has been accumulating which supports the hypothesis that through phylogenetic evolution, the mammalian pinealocyte has evolved from the pineal photoreceptor‐cell which is characteristic of certain lower vertebrates. In the present study, developing pineal glands in fetal rats and hamsters were studied at light and electron microscopic levels to determine whether or not the ontogenetic development of pineal cells affords clues to their phylogenetic origin. Pineal development in fetal rats occurs during the last eight days of gestation (14–22) and in fetal hamsters, during the last five days of gestation (11–16). The pineal gland exhibits many similarities in the two species as it develops from a tubular evagination of the diencephalic roof into a compact cellular mass. Different cellular types could not be readily distinguished in fetal material from either species. In both animals, as long as lumina persist, cells bordering on these lumina exhibit surface modifications reminiscent of developing photoreceptor‐cells, i.e., an “ellipsoid‐like” apical cytoplasmic bulge which often contains one or two centrioles and bears a ciliary derivative exhibiting a 9 + 0 tubular configuration. As pineal tissue proliferates, the lumina and cilium‐like structures disappear. The findings, when considered with phylogenetic studies, strengthen the hypothesis that the mammalian pineal gland contains cells derived from the photoreceptor‐cell line.
The postnatal development of the respiratory system of the opossum. I. Light and scanning electron microscopy
Authors: Krause William J. , Leeson C. Roland
Published: February 2005

The postnatal development of the respiratory system in the opossum has been traced, using 102 specimens divided into 11 groups according to snout‐rump length. At birth, the lung is markedly underdeveloped and is represented by a pumitive system of branching airways that end in a number of terminal chambers or sacs. The airways, constituting the conducting portion of the lung, are lined by columnar epithelium that is devoid of cilia and goblet cells. The terminal air chambers contain an extensive capillary bed and are surfaced by squamous epithelium interspersed with scattered cuboidal cells. By the 3 cm stage, bands of smooth muscle have differentiated in relation to the bronchial epithelium and scattered cilia are present in the epithelium of the trachea and bronchi. Air chambers immediately adjecent to established bronchi differentiate further and become incorporated into the bronchial tree and new air chambers develop at the most distal extent of the bronchial system up to the 15.5 cm stage. Numerous spaces lined by squamous epithelium, which represent the first appearance of the arbor alveolaris, appear within the cellular stroma of the lung of the 7 cm opossum. By the 20 cm (juvenile) stage, mature alveoli, containing many vacuolated cells, are present and a thick collagenous lamina has developed between the pleura and the lung parenchyma.