bluuebunny/crossref_metadata_2025 huggingface dataset:
The postnatal growth of the rat lung II. Autoradiography
Authors: Kauffman Shirley L. , Burri Peter H. , Weibel Ewald R.
Published: February 2005

Combined morphometric and autoradiographic methods were used to analyze the postnatal growth of rat lung from 1–21 days after birth. Each cell population had distinct growth patterns with an increase in the number of fibroblasts and capillary endothelial cells largely determining the increase in interstitial volume and capillary surface, respectively. The height of proliferation activity in mesodermally‐derived cells was concurrent with the outgrowth of secondary alveolar septa (between days 4 and 13). Analysis of the location of labeled cells on day 7 showed that the higher labeling index on septal crests could be ascribed to the proliferative activity of fibroblasts and endothelial cells.

Within the alveolar epithelium only the type II alveolar cells had a detectable labeling index. Over the first week, the number of type I epithelial cells steadily increased while the number of type II cells remained constant. Subsequently the number of type II cells increased rapidly, reached a peak on day 13 and then decreased, whereas type I cells continued to increase in number. These facts led us to consider that type II epithelial cells may represent the stem cell population of alveolar epithelium. The height of proliferative activity of type II cells on day 7 coincided with the outgrowth of septal crests and was followed by the steepest increase in number of type I and II cells.

Between the 10th and 21st day labeling indices rapidly declined, cell production became undetectable after day 13. Increase in alveolar and capillary surface area however continued, resulting in a thinning of the interstitial layer and of the epithelial and endothelial sheets.
Synthesis, intracellular transport, and release of secretory protein in the seminal vesicle of the rat, as studied by electron microscope radioautography
Authors: Flickinger Charles J.
Published: February 2005

The seminal vesicle secretes a variety of substances into semen, ranging from small molecules to enzymes. The formation of protein components of the seminal vesicle secretion was studied in male rats following an injection of leucine‐3H. Samples of seminal vesicle were fixed and prepared for light and electron microscope radioautography at intervals ranging between four minutes and two hours after the injection. In specimens prepared four minutes after administration of the precursor, the majority of silver grains overlay the rough endoplasmic reticulum. At subsequent intervals, the proportion of grains over the endoplasmic reticulum declined, and peaks of labeling were observed sequentially over the Golgi apparatus and over secretory vacuoles. The maximal labeling of the Golgi apparatus was attained between 10 and 30 minutes after the injection. Secretory vacuoles acquired their greatest radioactivity 30 minutes following administration of the leucine‐3H. Labeled secretions began to appear in the lumen 30 minutes after the injection, and they became heavily labeled by one hour. The results suggest that secretory proteins are synthesized in the rough endoplasmic reticulum and transported rapidly to the Golgi apparatus where secretory vacuoles are formed. The secretory vacuoles migrate to the apical ends of the cells and discharge their contents into the lumen. The transport and release of secretory proteins in the seminal vesicle is unusually rapid and exceeds the rate in many other protein secreting cells, including that of the ventral prostate.
Chromatoid bodies in somatic cells of the planarian: Observations on their behavior during mitosis
Authors: Coward Stuart J.
Published: February 2005

The behavior of somatic cell chromatoid bodies in the planarian Dugesia dorotocephala during mitosis has been studied by electron microscopy. The relatively undifferentiated beta (progenitor) cells are the only somatic cells containing chromatoid bodies and also are the only dividing somatic cells. Somatic cell chromatoid bodies are known to disappear as differentiation takes place and reappear when dedifferentiation occurs. Interphase and prophase beta cells have juxtanuclear and peripheral cytoplasmic chromatoid bodies. There is no ultrastructural evidence to suggest they are derived from formed nuclear material. During metaphase and anaphase, the chromatoid bodies are segregated from the chromosomes and adjacent cytoplasm by cups of double membranes. By the completion of telophase, the chromatoid body size and number immediately adjacent to the nucleus is markedly decreased and extremely large chromatoid bodies may be found further out in the cytoplasm. These findings are compared to the behavior of germ cell chromatoid bodies and discussed in terms of their possible significance and function.
Proliferation of non‐neuronal cells in spinal cords of irradiated, immature rats following transection of the sciatic nerve
Authors: Gilmore Shirley Ann
Published: February 2005

Transection of a peripheral nerve not only elicits changes in the injured neurons but also results in an increase in non‐neuronal cells, considered by most workers to be neuroglia, in the region of these neurons. Since studies in this laboratory have shown that the neuroglial population of spinal cords of immature rats can be reduced markedly by ionizing radiation, the present investigation was undertaken to determine if this reaction would occur in the irradiated spinal cord following transection of the sciatic nerve. In order to answer this question the sciatic nerve was sectioned unilaterally at 17 days of age (14 days post‐irradiation). Sham‐irradiated littermates served as controls. Light microscopic examination showed an increase in non‐neuronal cells throughout the gray matter on the side of axotomy in spite of a decreased neuroglial population in the 2,000 R and 3,000 R groups. These cells were scattered in the neuropil or were adjacent to injured neuronal perikarya in the anterior horn. Qualitatively similar reactions occurred in the 500 R and 1,000 R groups and in shamirradiated controls. Whether the magnitude of response is the same in all groups is currently under investigation, as are questions dealing with the origins of the reactive cells.
Mitochondrial pleiomorphism in sustentacular cells of Xenopus laevis
Authors: Kalt Marvin R.
Published: February 2005

The mitochondrial population of sustentacular cells in the testis of the amphibian, Xenopus laevis, has been examined by electron microscopy. Three distinct types of mitochondria have been observed. The first and most common mitochondrial type is a “typical” organelle with a rod‐like profile containing tubular to plate‐like cristae. The second mitochondrial form is characterized externally by irregular bulbous protrusions and internally by increased numbers of tubular cristae. The third mitochondrial type, which is usually ovoid in profile, has the most unusual internal membrane configuration, consisting of pleated folds pierced by regular rows of fenestrations. Mitochondrial type one is found in all sustentacular stages, mitochondrial type two first appears in sustentacular cells surrounding early spermatids, and mitochondrial type three is observed only in sustentacular cells surrounding spermatozoa. These observations indicate that discrete subclasses of mitochondria are present in sustentacular cells of Xenopus.
Specialized contacts of astrocytes with astrocytes and with other cell types in the spinal cord of the cat
Authors: Morales Ricardo , Duncan Donald
Published: February 2005

Adult and half grown healthy male and female cats were used in this study. The white and gray matter of the dorsolateral region in the upper lumbar levels of the spinal cord were examined by electron microscopy after fixation by aldehyde perfusion and commonly used methods of embedding, sectioning and staining. The report is limited to description and illustration of specialized junctions of astrocytes. In addition to previously described astrocyte‐astrocyte gap junctions, astrocytes are connected by gap junctions to oligodendroglia cells and to neurons. Astrocytes also are connected with each other and with neurons by junctions characterized by wide (250 Å) gaps containing opaque gap material and by dense material adhering to the inner surfaces of the plasma membranes. The results suggest a morphological basis for adhesion and intercommunication between all adult derivatives of the embryonic neural tube.
Fine structure of the myotendinous junction and “terminal coupling” in the skeletal muscle of the lamprey, Lampetra japonica
Authors: Nakao Taisuke
Published: February 2005

The myotendinous junction in the skeletal muscle of adult lamprey Lampetra japonica was studied with an electron microscope. Numerous finger‐like sarcolemmal invaginations were present at the ends of muscle fibers to form the myotendinous junction. Parietal fibers of each muscle unit showed more closely distributed sarcolemmal invaginations than central fibers. Features of the myotendinous junction. Parietal fibers of each muscle unit showed more closely distributed sarcolemmal invaginations than central fibers. Features of the myotendinous junction generally conform to the accounts in the literature. The sarcolemmal invagination was covered on its sarcoplasmic aspect by the connecting filament layer and the dense amorphous attachment layer, and on the extracellular aspect by the intermediary layer and the external lamina with collagen fibrils arising from the myosepta. Sarcolemmal invaginations were sometimes seen to consist of a pair of sarcolemmas of adjacent muscle fibers within a muscle unit, which is characteristic to the myotendinous junction of lamprey. It is noteworthy that the connecting filament layer is much thinner than that, e.g., in the tadpole tail muscles (Nakao, '74). Furthermore, it is much thicker in the parietal fibers than in the central fibers. The sarcolemma of the terminal segment of the invagination frequently showed specific coupling with cisterns of the sarcoplasmic reticulum (terminal coupling). The external lamina is partially or completely deficient in the terminal segment of sarcolemmal invaginations which form terminal couplings so that collagen fibrils contained in the invagination appear to be in direct contact with the sarcolemma; however, definite relationships of collagen fibrils with the sarcolemma and the external lamina in the terminal segment of invagination still remain obscure. This type of coupling is considered to play a role in the coupling of excitation to contraction of muscle fibers as triads and diads.
Acute effects of ACTH on dissociated adrenocortical cells: Quantitative changes in mitochondria and lipid droplets
Authors: Zoller Lawrence C. , Malamed Sasha
Published: February 2005

To study the role of certain organelles in steroidogenesis, dissociated rat adrenocortical cells were incubated for two hours with ACTH at a concentration that induces a high level of steroid production. Sections of ACTH treated and untreated cells were photographed in the electron microscope, and morphometric analysis was undertaken to assess possible ACTH‐induced changes in total cell volume, volume density and numerical density of lipid droplets and mitochondria.

There was no change in total cell volume. Lipid droplet volume density and numerical density decreased. Mitochondrial volume density did not change, but numerical density increased.

The decrease in lipid droplet volume density indicates a rapid depletion of cholesterol for steroid production. This depletion is almost entirely due to the disappearance of lipid droplets, rather than to an overall diminution in their size, as shown by the decrease in lipid droplet numerical density. The mitochondrial data suggest that the adrenocortical cell has an adequate mitochondrial apparatus to respond to acute ACTH stimulation with increased steroid output without an increase in mitochondrial volume.
Cellular renewal in the enamel organ and the odontoblast layer of the rat incisor as followed by radioautography using 3H‐thymidine
Authors: Smith C. E. , Warshawsky H.
Published: February 2005

Renewal of the cell populations of the incisor was studied in 100 gm male rats injected with a single dose of 3H‐thymidine and sacrificed at various times from one hour to 32 days after injection. Radioautographs showed that a cohort of labeled cells within the enamel organ, odontoblast layer, and pulp was carried passively with the erupting incisor from the apical end toward the gingival margin where the life cycle of these cells was terminated. Labeled cells in the upper and lower incisor, although traversing different absolute lengths, were found in approximately the same functional stage of their life cycle at similar times after the injection. Thus, by one and one‐half days labeled ameloblasts began inner enamel secretion. By 32 days labeled ameloblasts had traversed the entire maturation zone and were located at the gingival margin. Labeled odontoblasts followed closely the movement of labeled ameloblast. The mean rate of ameloblast migration was 567 μm/day on the upper incisor and 651 μm/day on the lower. For the odontoblasts this rate was 500 μm/day (upper) and 631 μm/day (lower). Finally, it was found that as the rat aged, the duration of the life cycle for epithelial and pulp cell populations of the incisor increased because of growth within the longitudinal axis of the tooth. It was concluded that the apical end of the incisor literally “grows backward” in the bony socket, and hence, the duration of the life cycle becomes greater simply because it takes cells longer to physically reach the gingival margin.
Distribution of lumbar and sacral afferent axons in submucosa of cat urinary bladder
Authors: Uemura Etsuro , Fletcher Thomas F. , Bradley William E.
Published: February 2005

Lumbar and sacral afferent axons in the submucosa of the urinary bladder were recognized by degeneration in seven cats subjected to spinal ganglionectomies. Of 2,935 observed terminating axon profiles, 145 were found degenerating. Lumbar afferent axons were 3.7 times more numerous than sacral afferent axons in the submucosa, a reversal of the ratio reported for the muscle coat of the bladder. Sacral afferent axons were evenly distributed to different regions of the bladder, but lumbar afferents were concentrated in the bladder neck. Apparent endings in the submucosa of the urinary bladder were principally free nerve endings. Synaptic vesicles were found in 57% of observed terminating axon profiles. The bladder neck had more terminating axon profiles of all kinds than other regions of the urinary bladder.
Anatomical data on the intracranial venous drainage of the tufted capuchin, Cebus apella linnaeus, 1758
Authors: Madeira Miguel C. , Watanabe Ii‐Sei
Published: February 2005

The venous channels responsible for the intracranial drainage were dissected in a series of 25 male and female adult tufted or brown capuchin monkeys (Cebus apella).

It was found that Cebus have a venous arrangements fundamentally the same as in man, differing only in that: 1. the monkey has no inferior sagittal sinus, sphenoparietal sinus, and emissary parietal and condylar veins; 2. the occipital sinus is not in connection with other sinuses; 3. there are a sphenopetrosal sinus, a petrosquamous sinus, and an unpaired inferior cerebellar vein; 4. besides the internal jugular vein, there is additional intracranial drainage through the petrosquamous sinus and the postglenoid vein; 5. the superficial middle cerebral vein opens into the petrosquamous sinus; 6. the lingual and facial veins are not tributaries of the internal jugular vein; 7. there is a bilateral uniform division of the superior sagittal sinus at the confluence of the sinuses to drain equally into both transverse sinuses; 8. the vascular pattern appears to be quite stable; anatomical variations appear to be few and unimportant.
The growth of the chick retina after hatching
Authors: Morris Valerie B. , Wylie C. C. , Miles V. J.
Published: February 2005

In autoradiographs of the retina from two‐week old chicks injected with tritiated thymidine during the first week after hatching, the labelled cells were found mainly in the extreme periphery of the retina and the ciliary epithelium of the pars plana. The pattern of labelling in the extreme periphery resembles that observed (Fujita and Horii, 1963) in retinae exposed to tritiated thymidine during embryonic development. The mechanisms underlying the histogenesis of retinal cells during growth at the extreme periphery in young stages may be the same as those which operate during embryonic development.
Studies of the hemopoietic microenvironment. VIII andrenergic and cholinergic innervation of the murine spleen
Authors: Reilly Frank D. , McCuskey Robert S. , Meineke Howard A.
Published: February 2005

Neurohistochemical techniques were used to confirm morphologically the distribution of adrenergic and cholinergic nerves to the splenic microvasculature. The results form the basis of this report.

Using these methods, adrenergic innervation was observed only in the adventitia of arteries and arterioles. No cholinergic innervation was found in this site. No adrenergic or cholinergic innervation could be demonstrated to the channels of the red pulp, venules or veins. These data provided morphological evidence that in the murine spleen only splenic arteries and arterioles are innervated; and these have only an adrenergic innervation.
A proposed function for microridges on epithelial cells
Authors: Sperry David G. , Wassersug Richard J.
Published: February 2005

Microridges (MR), also called microvillar ridges, microplicae and cytoplasmic folds, have been noted on many epithelial surfaces. Several functions have been proposed for these structures. In the present study we examine the mechanical role that microridges may play in holding mucus to the lumenal surface of the esophagus in the trout Salmo gairdneri. Our findings support the hypothesis that the microridges help hold a protective coat of mucus to the epithelium. In addition, the complex curved or whorled arrangement of microridges appears to facilitate the spread of mucus away from goblet cells.
Anchoring device between Sertoli cells and late spermatids in rat seminiferous tubules
Authors: Russell L. , Clermont Y.
Published: February 2005

Near the end of spermiogenesis, the late spermatids remain attached to the superficial layer of the seminiferous epithelium for an appreciable period of time (i.e., 3 to 4 days). The sickle‐shaped heads of the spermatids are embedded in an apical process of Sertoli cell cytoplasm which is connected to the rest of the cell by a narrow stalk. In the concavity of the head several long (2–3 μm) and very narrow (50 nm) tubular projections of the spermatid's plasma membrane invaginate the Sertoli cell cytoplasm. These tubular processes terminate by a bulbous swelling which may measure up to 1 μm in diameter. Along the process the plasma membrane of the Sertoli cell is closely apposed to the spermatid's membrane, the intercellular space being only 6–8 nm wide. In the Sertoli cytoplasm immediately surrounding the tubular portion of the structure there is an accumulation of filamentous material, while next to the bulbous extremity there are, at a short distance, smooth surfaced cisternae of endoplasmic reticulum. The whole structure was referred to as a tubulobulbar complex. These complexes, of which there are up to 24 per spermatid, appear as these cells complete their migration toward the apex of the Sertoli cells. They disappear just before the release of the spermatids in the lumen of the seminiferous tubule as a result of the fragmentation of the spermatid's plasma membrane followed by a resorption of the Sertoli plasma membrane. Morphological evidence suggests that the tubulobulbar complexes serve as anchoring devices that retain the spermatids at the surface of the seminiferous epithelium while their dissolution contributes in part to the process of spermiation. Similar tubulobulbar complexes were also formed by the plasma membranes of two adjacent Sertoli cells close to the Sertoli‐Sertoli tight junctions near the tubular limiting membrane.
The early stages of wallerian degeneration in the severed optic nerve of the newt (Triturus viridescens)
Authors: Turner James E. , Glaze Kathleen A.
Published: February 2005

The initiation of Wallerian degeneration in the severed optic nerve of the newt (Triturus viridescens) was very rapid and intense. Significant degeneration of nonmyelinated axons was observed as early as six hours after lesion (h.a.l.) and was almost complete by 48 h.a.l. Initial degeneration of non‐myelinated axons began in “extracellular digestion chambers” formed between burgeoning ependymoglial processes. The remaining fragments and debris were later phagocytized by surrounding ependymoglial processes.

Many axons of myelinated fibers have degenerated as early as 6 h.a.l. However, the overall population of myelinated axons degenerates at a much slower rate than nonmyelinated ones, for many of them appear intact as late as 48 h.a.l.

Some myelin sheaths show significant signs of degeneration by 6 h.a.l. Indeed, by this time a number of myelinated fibers have completely degenerated leaving only large vacuolated spaces in the nerve parenchyma. Swelling and vacuolization of the sheath are among the earliest signs of myelin degeneration.

The ependymoglial cell response to optic nerve lesion is manyfold and dramatic. By 6 h.a.l. there are signs of burgeoning ependymoglial processes which begin to resemble scar formation (gliosis) by 48 h.a.l. The morphological evidence is consistent with the concept of an important phagocytic role of ependymoglial cells during the early stages of optic nerve degeneration.
Localization of actin and myosin in the rat oocyte and follicular wall by immunofluorescence
Authors: Amsterdam Abraham , Lindner Hans R. , Gröschel‐Stewart Ute
Published: February 2005

The distribution of actin and myosin in the rat ovary at different stages of postnatal development was studied by examination of cryostat sections treated with antibodies to chicken smooth muscle (gizzard) myosin or to chicken (pectoral muscle) actin and subsequently with fluoresceinated goat anti‐rabbit γ‐globulins. Staining with either antiserum revealed several layers of intensely fluorescent elongated cells within the theca externa, forming a coherent band around the larger Graafian follicles. In smaller follicles, this band of fluorescent cells was incomplete, and ovaries of immature (6‐day‐old) rats were devoid of strongly fluorescent cells. Corpora lutea contained only scattered fluorescent cells at their circumference. Sections of mature ovaries incubated with antibodies raised against striated (pigeon pectoral) muscle myosin generated no significant fluorescence. Large oocytes stained with either anti‐actin or anti‐smooth muscle myosin showed a thin fluorescent band just beneath the zona pellucida, suggesting that actin and myosin are associated with the oolemma. The distribution of the two antigens in serial sections of follicles coincided, suggesting that the same cells contained both actin and myosin. It is suggested that follicular growth and maturation is attended by the development of a smooth muscle layer in the theca and that contraction of this layer in response to catecholamines and/or prostaglandins may play a role in the extrusion of the oocyte. The rǒle of contractile elements in the oocyte remains to be elucidated.
Preparation of biological tissues for electron microscopy by freeze‐drying
Authors: Coulter H. David , Terracio Louis
Published: February 2005

A dependable method for freeze‐drying tissues for electron microscopy has been developed. Thin slices of fresh tissue were frozen by bringing them into direct contact with a polished copper bar at liquid nitrogen temperature. The tissue was transferred to a copper specimen block equipped with a thermocouple and heating circuit for accurate control of the environmental temperature of the tissue, and evacuated in a glass freeze‐drier using clean high vacuum techniques for keeping the system free of hydrocarbons. The tissue was dried by increasing the temperature of the specimen block 10°C each hour while monitoring the rate of water removal from the tissue with a partial pressure analyzer. The dry tissue was fixed with OsO4 vapor, vacuum embedded in a low viscosity epoxy resin, sectioned, stained, and viewed with the electron microscope. Tissue processed in this manner exhibits excellent morphological preservation at both cellular and organellar levels without prefixation or the use of cryoprotective agents. The results of the experiments using the partial pressure analyzer indicate that small blocks of tissue can be dried in a short time at low temperature.
Epithelial influences on skeletogenesis in the mandible of the embryonic chick
Authors: Tyler Mary S. , Hall Brian K.
Published: February 2005

Intact mandibular processes and the enzymatically separated mesenchymal and epithelial components of the mandible from embryonic chicks of 2.5‐ to 5‐day incubation (Hamburger and Hamilton, '51: stages 16‐25) were grown individually, either in organ culture or as grafts to the chorioallantoic membranes of host embryos. The differentiation of cultured and grafted intact mandibular processes was histologically normal, but the time of histodifferentiation differed from that in vivo. The histodifferentiation of cultured and grafted mandibular mesenchyme grown isolated from its epithelium depended upon the age of the embryo from which the mesenchyme had been obtained. Intramembranous ossification producing membrane bones of the mandible occurred in mesenchyme isolated from 4.5‐ to 5‐day embryos (HH 24–25), but did not occur in mesenchyme isolated from younger embryos. Cartilage (Meckel's) and subperichondrial bone in the articular process of Meckel's cartilage differentiated in mesenchyme isolated from embryos of all age groups tested (HH 16–25). Mandibular mesenchyme, therefore, requires the presence of epithelium until 4.5 days of incubation if the membrane bones of the mandible are to differentiate; if epithelial influences are required for Meckel's cartilage and subperichondrial bone formation, they are not required beyond 2.5 days of incubation. Mandibular epithelium isolated from its mesenchyme became layers of squamous cells in culture; but when grafted onto the chorioallantoic membrane, the epithelium became underlain by host fibroblasts and differentiated into a stratified squamous epithelium. Mandibular epithelium, therefore, is capable of differentiation in the presence of foreign fibroblasts derived from the chorioallantoic membrane.
Enzymatic isolation of osteoblasts from fetal rat calvaria
Authors: Yagiela John A. , Woodbury Dixon M.
Published: February 2005

A microanatomical study of the immature rat calvarium was performed in order to develop a method for the isolation of osteoblasts by enzymatic means. Although generalized osteogenesis was evident in fetal rats, differential growth patterns were observed beginning at 19 days in utero. Considerable portions of the endocranial periosteal bone surface were lined by flattened, less active cells; discrete areas also contained multinucleated osteoclasts. Cell counts of whole calvaria revealed that one fifth of the total cell population were osteoblasts, most of which were located in the central portions of the frontal and parietal bones. Prior excision of these segments permitted the subsequent removal of virtually all periosteal tissues. Cleaned 19‐day fetal bones, incubated in crude collagenase for two hours, released about 40,000 cells/calvarium, consisting of 85‐90% osteoblasts and lesser amounts of connective tissue and bone marrow elements. Because of the relatively small sizes of most extraneous cells, purity on a cell volume basis was approximately 95%. It is predicted this preparation will be useful in the investigation of certain aspects of osteoblastic function.
Experimental cryptorchidism in adult male rats: Histological and hormonal sequelae
Authors: Jones Thomas M. , Anderson Winston , Fang Victor S. , Landau Richard L. , Rosenfield Robert L.
Published: February 2005

Mature male rats were rendered cryptorchid and followed for up to nine weeks during which serial blood specimens were obtained for multiple hormonal analyses; serial testicular samples were obtained as well. In contrast with control animals, cryptorchid rats showed transient rises in FSH which returned to normal at the end of the study; estrogen levels were high in the final weeks. Plasma testosterone levels were unchanged and LH levels changed little. Light and electron microscopic studies of testicular biopsy specimens showed prompt disruption of spermatogenesis which became more extensive with time. Sertoli cells underwent multiple changes including increased lipid storage and phagocytosis of spermatozoa. Comparisons are made between the sequence of hormonal changes and that of histological changes. In addition, questions are raised concerning the ways in which Sertoli cells are affected by experimental cryptorchidism.
Phagocytosis of spermatozoa by the rabbit vagina
Authors: Phillips David M. , Mahler Susan
Published: February 2005

Twenty‐four hours after mating in the rabbit, numerous spermatozoa are observed attached to the surface of the vaginal epithelium. Spermatozoa appear to be attached by their heads to microvilli of the simple columnar cells which compose the vaginal epithelium. Spermatozoa are taken up by the epithelial cells, and they are found within the cells in various stages of de generation up to seven days after mating. Epithelial cells frequently appear to be filled with numerous vacuoles containing sperm components in various stages of degeneration. It is suggested that some property of the surface of sperm heads may render them particularly susceptible to phagocytosis. Phagocytosis of spermatozoa may not have long‐term harmful effects for the epithelium since these epithelial cells presumably have a high rate of turnover.
Laparoscopic exposure and sequential observation of the ovary of the cycling bitch
Authors: Wildt David E. , Levinson Carl J. , Seager Stephen W. J.
Published: February 2005

A method was developed to alter surgically the bursa of the bitch to allow sequential observation of the ovary by means of laparoscopy. Adult anesthetized female dogs of three breeds underwent laparoscopic examinations in which each natural bursa slit was lengthened 1.0‐1.5 cm using laparoscopic hook scissors in conjunction with electrocautery. The ovary could be effectively and repeatedly exposed for laparoscopic viewing through the lengthened bursa slit. Neither Laparoscopic surgery nor frequent routine laparoscopic examinations of the reproductive organs had an effect on subsequent ovarian activity. All dogs subjected to the laparoscopic ovarian exposure technique exhibited estrus behavior, follicle development, ovulation and corpus luteum formation.

Preovulatory follicular development was detected as early as 11 days before ovulation with the most rapid follicular maturation occurring two to three days before ovulation. Follicular collapse and extensive hemorrhage at the rupture site during ovulation did not occur. Release of the cumulus mass from a vesicular follicle was observed in one bitch. The cumulative mass adhered to the follicular wall for an indefinite time following ovulation.

The structural size of the bitch corpus luteum was maximal four to eight days following ovulation. Corpora lutea remained visible on the ovarian surface for 16 weeks. No differences in cyclic ovarian morphology were observed among the three breeds of dogs studied.
The ultrastructure of follicle cells in fetal guinea‐pig ovaries
Authors: Jeppesen Th.
Published: February 2005

The development of the follicle cells in fetal guinea‐pig ovaries has been examined in the electron microscope.

The findings were as follows: at days 34 and 38 there were broad intercellular clefts within the germinal cords. However, a continuous layer of thin cytoplasmic processes from the follicle cells separated the germinal cords from the stromal compartment. The germinal cords were everywhere limited by a basal lamina. During all the period examined coated vesicles, possibly emptying their contents into the region of the basal lamina, were observed in the follicle cells.

At days 42, 46 and 50 the cellular membranes were closely apposed with an intercellular distance of about 200 A. Complexes of deeply interdigitating folds of the membranes of neighboring follicle cells were observed. The follicle cells forming part of the primordial follicles at days 54 and 58 were characterized by a disappearance of these folds and by the appearance of bundles of microfilaments in the cytoplasm. These were especially numerous at day 66.

At days 34 and 38 gap junctions were observed between the follicle cells, but not between the follicle cells and the germinal cells. During the entire period examined junctions resembling desmosomes without filaments were observed between the follicle cells as well as between the follicle cells and the germinal cells.

The ultrastructure of the follicle cells is considered in detail and the functional significance of the findings discussed.
Intrahepatic distribution of nerves in the rat
Authors: Reilly Frank D. , McCuskey Patricia A. , McCuskey Robert S.
Published: February 2005

The intrahepatic distribution of nerves in the rat was studied using neurohistochemical and electron microscopic methods. Innervation was restricted primarily to vessels in the portal space and hilus. Both adrenergic and cholinergic fibers were observed in the adventitia of hepatic arteries, and to a lesser extent adjacent to portal veins. Some of the cholinergic fibers, however, were not contiguous with the vasculature. Near the hilus many of these fibers were associated with ganglia while peripherally some coursed into the immediately adjacent parenchyma where end bulbs abutted on hepatocytes. Ultrastructurally, scattered small nerves, devoid of neurolemma, were found contiguous with the portal lamina of hepatocytes. Nerve fibers deeper within the lobule were not seen but numerous gap junctions were observed between contiguous hepatocytes. Central and sublobular hepatic veins lacked innervation but adrenergic nerves were demonstrated in the walls of larger hepatic veins. Innervation of the biliary system was sparse. While nerves were interposed between vessels and bile ducts, such nerves tended to be associated more closely with the vasculature.
Specialized cell types in the human fetal small intestine
Authors: Moxey Pamela Colony , Trier Jerry S.
Published: February 2005

In the present study we describe the time of appearance and morphological differentiation of specialized epithelial cells in human fetal small intestine (SB). Proximal and distal SB from 36 nonviable fetuses was studied by light and electron microscopy. During the 9‐ to 10‐week period, villi lined by simple columnar epithelium replaced the stratified epithelial lining which was two to six cell layers thick. During this transition, distinctive junctional complexes and a single secondary lumen were identified in the deeper layers of stratified epithelium, and there was evidence of cellular degeneration of some superficial cells. Oligomucous and mature goblet cells were present in both the stratified and simple columnar epithelium. Crypt formation began proximally at 10 to 11 weeks and, within a week, crypts lined by undifferentiated crypt cells (UCC) could also be identified in the distal SB. These cells resembled adult UCC's except for the presence of large aggregates of glycogen, and the absence of large adult‐type secretory granules (SG) until 16 weeks. At all ages SG's were smaller and less numerous than in adults. Paneth cells appeared with crypt development at 11 to 12 weeks. Unlike adult Paneth cells their SG's were structurally heterogeneous and frequently had cores with halos of differing density. Caveolated or tuft cells with dense bundles of microfila‐ments extending from microvilli into apical cytoplasm, apical granules, occasional caveolae, and a microvillus membrane denser than that of adjacent cells were identified by 16 weeks. Putative microfold (“M”) cells were seen in the distal SB of a 17‐week fetus. These cells had an unusual apical border with irregular projections, many small membrane bound vesicles in the cytoplasm, and were in direct contact with underlying lymphoid cells. The glandular cells of Brunner's glands at 14 to 15 weeks resembled those of normal adult.
PAS‐lead hematoxylin as a stain for small‐granule endocrine cell populations in the lungs, other pharyngeal derivatives and the gut
Authors: Sorokin Sergei P. , Hoyt Richard F.
Published: February 2005

Epithelial cells of the several subtypes that comprise the small‐granule cell population of the respiratory system are little studied, partly because adequate silver, monoamine fluorescence and other specific light microscopical preparations have been more difficult to obtain than in the gut and other organs possessing diffuse endocrine systems. Periodic acid‐Schiff (PAS) in combination with MacConaill‐Solcia's lead hematoxylin has in our hands proven dependable for routine staining of serial 2‐m̈m glycol methacrylate sections used in mapping the distributions of these cells along the airway. In lungs of mice, hamsters, kittens, and fetal rabbits, typical small‐granule cells stain weakly or not at all with lead hematoxylin alone, hence are easily overlooked. PAS adds to the cytoplasm a diffuse magenta coloration; and because it is diastase‐resistant, less brilliant than that of mucus but more so than bronchiolar cell secretions, and finer textured than lysosomal staining of other cells present, the effect is to highlight small‐granule cells whether solitary or in clusters. Additional PAS staining of basement membranes and lead hematoxylin staining of cilia enhance the combined stain's resolving power. In thyroid gland, parafollicular cells stand out boldly against follicular elements; in small intestine, hematoxylin‐positive endocrine cells are well differentiated from absorptive, mucous, and Paneth cells that surround them. Using a complementary monoamine fluorescence technique on plastic sections of lungs from control and 5‐hydroxytryptophan‐pretreated animals prior to staining, we can show that fluorescent epithelial cells are identical with those stained by PAS‐lead hema‐toxylin.
The surfactant system of human fetal lung organotypic cultures: Ultrastructural preservation by a lipid‐carbohydrate retention method
Authors: Stratton C. J. , Douglas W. J. H. , McAteer J. A.
Published: February 2005

Human fetal lung organotypic cultures consisted of epithelial elements (≃40‐100 m̈m in diameter) formed by the reaggregation of single cells from a monodisperse suspension of enzymatically dissociated fetal lung. These elements, termed alveolar‐like structures, were composed primarily of type II alveolar epithelial cells whose apical surfaces bordered the central lumen of the alveolar‐like structure. Pulmonary surfactant secreted by the type II cells was retained within the lumen and accumulated in close association with the epithelium. These characteristics made this culture system an advantageous model for the morphological study of human pulmonary surfactant in vitro. A lipid‐carbohydrate retention procedure which reduced the extraction of tissue components and thus provided improved preservation of multilamellar bodies and tubular myelin surfactant was used in an ultrastructural study of organotypically cultured surfactant. Human surfactant was observed for the first time with most of its structural components intact. In vitro human surfactant was found to be similar to in vivo rodent and non‐human primate surfactant, but with certain differences. Long surfactant tubules were not observed. There were more transformed multilamellar bodies present with more foci undergoing transformation. Each focus contained fewer layers of tubular myelin surfactant than occurs in rodent surfactant. No epiphase‐hypophase areas were observed, only tubular myelin surfactant. In addition, a previously unreported intrasurfactant matrix material was observed.
Ultrastructural features of the distended pulmonary arteries of the normal rat
Authors: Meyrick Barbara , Reid Lynne
Published: February 2005

Detailed study has been made of the structure of the normal pulmonary artery of rat by both light (1‐μ sections) and electron microscopy. After tying the pulmonary veins at the hilum, the lungs were fixed by simultaneous injection of glutaraldehyde into the pulmonary trunk and trachea. Study of distended arteries allows precise measurement and assessment of normal lung structure.

Four regions of the pulmonary artery can be identified by wall structure and are described here‐muscular, partially muscular, non‐muscular and the newly described thick‐walled oblique muscular. Electron microscopic examination has demonstrated in the non‐muscular regions of the partially muscular arteries, an “intermediate” cell and in the non‐muscular arteries, a pericyte. The intermediate cell lies internal to the single elastic lamina but external to the endothelial cell, is surrounded by its own basement membrane and contains filaments mainly along the adluminal region of the cell. The pericyte also lies internal to the single elastic lamina, is within the basement membrane of the adjacent endothelial cell and has previously been reported in the lung only in the walls of alveolar capillaries. The structure of the intermediate cell and its position suggest it is a transitional stage between the pericyte and smooth muscle cell.
Spermatid‐sertoli tubulobulbar complexes as devices for elimination of cytoplasm from the head region of late spermatids of the rat
Authors: Russell Lonnie D.
Published: February 2005

The traditional and generally accepted mode of elimination of excess spermatid cytoplasm, known to take place at the time of sperm release, occurs as a result of the disengagement of the residual cytoplasmic mass. The present study suggests that cytoplasm is also eliminated from the head region of the spermatid in the period prior to sperm release. Data presented herein indicates that the amount of cytoplasm eliminated in this manner is substantial since the volume of spermatid cytoplasm diminishes by about 70% in the period of formation and resorption of tubulobulbar complexes. Reports from this laboratory (Russell and Clermont, '76; Russell, '79) indicated that characteristic evaginations of spermatid cytoplasm, termed tubulobulbar complexes, are resorbed by Sertoli cells in the form of numerous small pockets of cytoplasm. These pockets of cytoplasm are organelle‐free and show a “watery” consistency. They are subsequently degraded by the Sertoli cell prior to sperm release.

During the period of turnover of tubulobular complexes the organelles of the cytoplasmic lobe, which at first are loosely organized, become clustered and tightly packed. As a consequence, the cytoplasmic lobe appears electron dense and is stained intensely with toluidine blue. This feature is interpreted, although not proven, to be the result of elimination of the watery component of the cytoplasm via resorption of tubulobulbar complexes by the Sertoli cell. During the period in which tubulobulbar complexes form, there is an open channel in which cytoplasm may flow from the flagellum to the head and out the head into tubulobulbar complexes.
The growth and development of the superior oblique muscle and trochlear nerve in juvenile and adult goldfish
Authors: Easter Stephen S.
Published: February 2005

Superior oblique muscle/trochlear nerve pairs from goldfish of various ages (1‐5 years) have been examined light and electron microscopically. The muscle grows by enlargement (longitudinally and transversely) of individual fibers, and by addition of new ones at the rate of about 250/year. The nerve grows by enlargement of fibers, but few and perhaps nonew axons are added. The somata enlarge, and the neuromuscular synapses become much more numerous. The ratio of muscle fibers to nerve fibers increases from about 5 in the young to about 16 in the old fish.
Neural crest and placodal contributions in the development of the glossopharyngeal‐vagal complex in the chick
Authors: Narayanan C. H. , Narayanan Y.
Published: February 2005

By using the method of quail‐to‐chick transplantation of neural crest in one series (VNG) and placodal ectoderm in a second series (VPG) we were able to determine the relative contribution of cranial neural crest and placodal ectoderm to the formation of the Glossopharyngeal‐vagal complex. In chimeric embryos, quail cells originating from cranial neural crest grafts of postotic levels end up in the root ganglia, while quail cells originating from placodal ectoderm of postotic levels end up in the trunk ganglia. The results clearly indicate that the caudal levels of the medulla and rostral cervical segments represent the site, and the neural crest the source, for the neurons of the root ganglia. The neurons form a homogenous population of the small‐cell type. This clearly rules out any contribution to the root ganglia from placodal ectoderm. On the basis of our experiments, it is also concluded that the neurons of the trunk ganglia are purely placodal in origin and are composed of a population of cells of the large‐cell type. Our experiments also provide convincing evidence for a neural crest origin for Schwann cell and ganglionic Satellite cells.
Morphological characteristics of cells with apical nuclei in the initial segment of the adult rat epididymis
Authors: Sun Eric L. , Flickinger Charles J.
Published: February 2005

The cytology of epithelial cells with apical nuclei in the initial segment of the rat epididymis was studied with the light and electron microscopes. Two types of cells were distinguished and were designated apical cells and narrow cells. The apical cells are more numerous than the narrow cells and closely resemble principal cells except for the location of the nucleus. They probably correspond to the apical cells of Reid and Cleland (′57) and may represent a variation of the principal cell. The narrow cells differ markedly from the apical cells in both light microscopic appearance and fine structure. Narrow cells stain intensely with toluidine blue and are characterized by a slender shape, many mitochondria with tubular cristae, and a large number of apical cup‐shaped cytoplasmic vesicles. The possible relationship of narrow cells to other cell types is discussed.
Differential effect of cytochalasin B on the aggregation of melanosomes in cultured mouse melanoma cells
Authors: Koyama Yoh‐Ichi , Takeuchi Takuji
Published: February 2005

Mouse B16 melanoma cells in culture were treated with 2 μg/ml cytochalasin B. Melanosomes, localized in dendrites as well as those in the peripheral cell body, formed aggregates which then showed centripetal migration. After 24 hr of treatment, melanosomes were found as large aggregates near the nucleus. However, cytochalasin B showed no effect on the distribution of mitochondria and endoplasmic reticulum. When cells were released from the 24 hr‐treatment with cytochalasin B, each melanosome began centrifugal migration. In this process, melanosomes were situated in the periphery, and were in close association with microtubules. Side arm‐like structures were observed between microtubules and melanosomes, or mitochondria. These results seem to indicate the presence of a mechanism(s) specific to melanosome migration, and possible participation of microtubules in this melanosome migration.
The use of potassium ferricyanide in neural fixation
Authors: Langford Lauren A. , Coggeshall Richard E.
Published: February 2005

The present study suggests a mixture of buffered osmic acid and 1.5% potassium ferricyanide as a post‐fixation to improve the fixation of neural tissue. This procedure results in an improved preservation of membranes as well as cytoplasm and cytoplasmic organelles. It is to be emphasized that the quality of the initial perfusion is the primary determinant of quality of the fixation, but the addition of 1.5% potassium ferricyanide to post‐fixation fluid makes good fixation better and allows data to be gathered from otherwise unusable material.