bluuebunny/crossref_metadata_2025 huggingface dataset:
Histochemistry of mucus in the skin of the frog, Rana pipiens
Authors: Dapson Richard W.
Published: February 2005

Histochemical characteristics of the integumentary mucous glands of the leopard frog (Rana pipiens) are described so that their role in water balance can be better understood. Mucus is acidic, due to its content of sulfate and carboxylic acids. The carbohydrate moiety contains periodate‐engendered groups which are not in close proximity to acid radicals. Protein was not demonstrated. Neuraminic acid is either absent or is not susceptible to neuraminidase digestion.
Development of peribiliary dense bodies in embryonic rat
Authors: Wood Richard L.
Published: February 2005

The formation of peribiliary dense bodies in developing rat liver was studied by electron microscopy. Dense bodies arise in close conjunction with an extensive Golgi apparatus which displays acid phosphatase, inosine diphosphatase and thiamine pyrophosphatase activity throughout development. The position of these enzymes within the Golgi apparatus appears somewhat variable. Dense bodies are present by the thirteenth day of development and gradually increase in number. They show acid phosphatase activity from their earliest appearance. These findings demonstrate that: (1) peribiliary dense bodies are lysosomal from their earliest appearance; (2) they apparently arise directly from a well‐developed Golgi apparatus; and (3) the Golgi apparatus contains several enzymes simultaneously, suggesting that it becomes multifunctional at an early stage of development.
X‐irradiation of pregnant mongolian gerbils
Authors: McGaughey R. W. , Chang M. C.
Published: February 2005

Female Mongolian gerbils were x‐irradiated at various doses from 200r to 1200r on day 2 (fertilized eggs at 2‐cell stage) or day 9 (embryos at the early primitive streak stage) after mating and examined on day 18. No significant differences in numbers of corpora lutea were observed between controls and females irradiated at 200–800r on day 2 or day 9, although irradiation at 1200r on day 2 caused regression of all corpora lutea. Preimplantation loss as determined by the proportion of eggs that failed to implant in the pregnant females, was significantly increased only in the females irradiated at 1200r on day 2 (100% loss) as compared with control animals. The mean numbers of fetuses were significantly reduced in the females irradiated on day 2 at 400r (3.00 ± .71) and at 800r (1.2 ± .37), or on day 9 at 400r (3.0 ± 1.14) or at 800r (0) as compared with controls (5.4 ± .51). The embryonic loss after but not before implantation was significantly increased in all irradiated animals except those irradiated at 200r on day 9. When mated females irradiated at 400r or 800r on day 2 were examined on day 12, 15 or 16 of pregnancy, the mean diameter of implantation sites was significantly smaller in the females irradiated at 800r on day 2 (5.4 ± 0.53 mm) than those in the control females (9.3 ± 0.17 mm). No gross abnormalities of fetuses were observed in the control animals, only two abnormal out of 21 fetuses were found in females irradiated on day 2, but various abnormalities, such as retarded development, cleft palate, spina bifida, acephaly or amorphous fetuses were observed in 20 out of 45 fetuses from females irradiated at 200–400r on day 9. Histological examination of ovaries revealed that all pregnant females had fully developed corpora lutea while the ovaries of females without implantation sites following irradiation contained regressing corpora lutea, and in some cases newly formed corpora lutea. The number and morphology of chromosomes of embryos from females irradiated at 400r or 800r were examined, but no differences were found as compared with embryos of control animals.

It appears that whereas x‐irradiation of the 2‐cell gerbil eggs increased the mortality of implanted embryos, irradiation of the early primitive streak stage caused embryonic death as well as developmental abnormalities. Chromosomal abnormalities of fetuses however were not observed.
The early development of the parotid gland around the facial nerve and its branches in man
Authors: Gasser Raymond F.
Published: February 2005

The manner in which the parotid gland forms around the related facial nerve branches was studied with the aid of reconstructions in 15 human embryos and fetuses 18 to 80 mm, crown‐rump length, 7+ to 13.5 weeks (w), menstrual age. Peripheral branches of the nerve terminate in the cervicomandibular region at 18 mm (7+w), when the unbranched parotid bud is farther rostral. By 22 mm (8w), a small nerve branch approaches the buccal region superficial to the bud that extends toward the preauricular region. At 26 mm (8.5w), several nerve branches course superficial to the parotid primordium which has first order ductules and is adjacent to the masseter muscle. Second order ductules form quickly (27 mm, 8.5w) as the primordium approaches the superficial aspect of the lower buccal, marginal mandibular and cervical nerve branches. The primordium enters the parotid space by 32 mm (9w) as third order ductules develop. At 37 mm (10w), it has fourth order ductules and the buccal nerve branches are superficial to the main duct. Nerve branches of the temporofacial ramus (temporal, zygomatic and upper buccal) occupy a superficial position in the primordium whereas branches of the cervicofacial ramus (lower buccal, marginal mandibular and cervical) are deeper. A similar arrangement is evident at 56–80 mm (11.5–13.5w) when the complex primordium has connections with its superficial and deep portions between many nerve branches.
The ultrastructure of the human circumvallate papilla. I. Cilia of the papillary crypt
Authors: Mattern Carl F. T. , Daniel Wendell A. , Henkin Robert I.
Published: February 2005

Cilia‐bearing cells have been observed near the bottom of the crypt of the human circumvallate papilla, between the lower taste buds and the duct of von Ebner's gland. It is likely that they serve one or more of the following functions: cleansing the papillary crypt, circulation of tastants, and bathing the pores of the taste bud in the various fluid secretions of the oral cavity.

The kinetosomes of these cells were observed to possess typical transitional fibers and rootlets with periodic structure. In addition, a single, lateral, satellite‐like projection from the midregion of the kinetosome was connected to microtubules which coursed deeply with the mitochondria‐rich cytoplasm as did fine fibrils and some rootlets.
The effect of aging on damage induced hair growth in C57BL/6J female mice
Authors: Argyris Thomas S.
Published: February 2005

Previously it has been shown that wounds made on the backs of female C57BL/6J mice result in the stimulation of growth of resting hair follicles surrounding the wound. Since aging is known to affect regenerative processes, the question arises if aging affects the stimulation of hair growth in wound healing.

Surgical wounds 5mm in length were made on the backs of female C57BL/6J mice between 367–544 days of age. Mice were examined daily for the stimulation of hair growth around the wound, as well as the amount of hair growth stimulation.

Damage results in the stimulation of growth of the resting hair follicles surrounding the wound. Hair growth stimulation is first grossly evident 20 days after wounding. This is not significantly different from the time hair growth stimulation appears in young female mice.

Aging results, however, in a significant decrease in the amount of hair growth stimulation surrounding the wounds in female mice.
Axon caliber related to neurofilaments and microtubules in sciatic nerve fibers of rats and mice
Authors: Friede Reinhard L. , Samorajski T.
Published: February 2005

The number of neurofilaments and microtubules present in nerve fibers was determined for sciatic nerves from adult mice and from rats of three different ages. More microtubules than neurofilaments were found in nonmyelinated fibers; the ratio of tubules/filaments was reversed in myelinated fibers and was found to change with axon caliber independent of the presence of a myelin sheath. A series of regression analyses indicated that axon caliber correlates best with the sum of the number of neurofilaments and microtubules per fiber. This correlation was only slightly better than that for neurofilaments alone. Axon caliber also correlated better with the filament‐tubular material than with the thickness of the myelin sheath. The results were similar for both rats and mice, and age differences were not apparent in the samples of nerves analyzed.
C cell follicles in the dog thyroid: Demonstration by in vivo perfusion
Authors: Teitelbaum Steven L. , Moore Kenneth E. , Shieber William
Published: February 2005

The histology and ultrastructure of the parafollicular cells of eight dog thyroids were studied by various methods of fixation. The best preservation resulted from in vivo perfusion with glutaraldehyde. When prepared in this manner clusters of C cells were seen to possess follicular and canalicular systems. Coated vesicles were noted at various luminal surfaces and at the basilar plasma membrane. The authors conclude that the maintenance of intracapillary pressure during fixation is essential for the demonstration of normal histological and ultrastructural anatomy of the thyroid.
Fine structure of the epithelial dental organ in the frog during early odontogenesis
Authors: Zaki A. E. , Yaeger James A. , Gillette Roy
Published: February 2005

A total of 227 tooth germs in different developmental stages were dissected from the maxillae of 58 leopard frogs (Rana pipiens). Five fixatives and three buffers were used and optimum preservation of the odontogenic epithelium was observed in specimens fixed in cold 4% glutaraldehyde at pH 7.3 for three hours followed by 1% osmium tetroxide for one hour. The inner dental epithelium showed mitotic figures limited to the initial stage of odontogenesis. The cells contained numerous free ribosomes, tonofilaments, few mitochondria and sporadic cisternae of endoplasmic reticulum. Their distal portions were drawn into processes studded with numerous hemidesmosomes. At a later stage of development yet prior to amelogenesis, these processes disappeared. The preameloblasts followed two pathways of histodifferentiation depending on their location. Ventrolabially the columnar cells exhibited progressive differentiation in contrast to the cuboidal cells on the ventrolingual surfaces of the cusps.

The external dental epithelial cells were flattened, closely packed and connected by numerous desmosomes. Their cytoplasm contained mainly mitochondria and tonofilaments, as well as few Golgi vesicles. With the beginning of amelogenesis large intercellular spaces and lysosomal‐like bodies were frequently observed and the Golgi complex is more prominent.

We concluded that at early odontogenesis the epithelio‐mesodermal interaction in the frog's dental organ is similar to that of mammalian species but the frog's internal epithelium shows a different pattern of histodifferentiation.
The prenatal development of the mouse eye
Authors: Pei Y. F. , Rhodin J. A. G.
Published: February 2005

The development of the eye has been studied in mouse embryos from the ninth day through the nineteenth day of gestation. The tissue was fixed in aldehydes, post‐osmicated and embedded in Epon. The entire eye was sectioned and studied under the light microscope. The development of the eye in the prenatal period is described as having seven stages. In the first stage, the close contact of the optic vesicle with the surface ectoderm is observed. The retinal disc and lens placode begins to form. The second stage shows the invagination of the optic vesicle and the contraction of the margin of the lens pit. In the third stage, the optic cup differentiates into an outer pigment epithelium and an inner retinal layer. The cells of the posterior lens wall start to elongate. During the fourth stage, the cavity of the lens vesicle is completely obliterated by primary lens fibers and the inner neuroblastic layer of the retina is formed with nerve fibers being traced from its cells to the optic stalk. The fifth stage is dominated by the appearance of lids, cornea and optic nerve, the formation of the anterior chamber and the consolidation of the intraocular portion of the embryonic vascular system. In the sixth stage, the eyelids fuse and the anterior margin of the optic cup begins to grow actively. In the last prenatal stage, the third neuron layer of the retina begins to differentiate. The iris and the folds of the ciliary body can be detected.
Structure and innervation of the ciliary processes of the albino rabbit eye
Authors: Pataky Paul E.
Published: February 2005

Various physiological and anatomical studies have suggested that the ciliary epithelium may be under the influence of adrenergic nerve fibers. This study was undertaken in an attempt to characterize the innervation of the ciliary epithelium. Both light and electron microscopy revealed that the ciliary epithelium is only sparsely innervated. In addition, the ciliary epithelium overlies a highly vascular stroma, and the distance between the large vascular channels and the ciliary epithelium is small. These features of the stroma indicate it is structurally suited for a transport function, a fact which supports earlier reports that the elaborate membrane infoldings of the ciliary epithelium are indicative of a transport function. The discrepancy between previous descriptions of the innervation of the ciliary epithelium, demonstrating complex subepithelial plexuses of adrenergic nerve fibers, and the results of the present study may be due to the fact that the fluorescence technique used in previous studies could have labelled some other tissue component in addition to adrenergic nerve fibers. Results with orcein and aldehyde fuchsin stains indicate that the disposition of elastic fibers in the ciliary processes is similar to previous descriptions of adrenergic nerve fibers as determined by fluorescent techniques.
The allantoic membrane of the rabbit: Evidence of a cholinergic electrical potential
Authors: Burt Alvin M. , Brzin Miro , Davies Jack
Published: February 2005

The electrical potential of the rabbit allantoic membrane is sensitive to acetylcholine, a sensitivity which can be altered or abolished by anticholinesterase compounds. Biochemical and histochemical studies indicates that acetylcholinesterase activity is present in the endodermal layer of the membrane. These findings suggest that the allantois may be a valuable model for investigations into the role of acetylcholinesterase in membrane excitability.
Radioautographic study of RNA synthesis in normal and actinomycin D treated rat embryos
Authors: Jordan Robert L. , Wilson James G.
Published: February 2005

Incorporation of tritiated uridine in embryonic and extraembryonic tissues of normal and actinomycin D treated rats was determined by radioautography on days 7 through 11 of gestation. Precursor incorporation was equated with RNA synthesis and correlated with developmental events and with previously determined teratogenic effects of actinomycin D.

Uptake of uridine increased progressively in untreated animals from days 7 through 10 in decidua, trophoblastic giant cells, and visceral and parietal yolk sac endoderm, and remained relatively high in all except visceral yolk endoderm which dropped sharply on day 11. Actinomycin D did not significantly alter uptake in decidua and parietal yolk sac endoderm but caused appreciable reduction of uptake in trophoblast and visceral yolk sac epithelium on days 9 and 10.

Uridine incorporation in embryonic ectoderm of untreated animals was relatively low but measurable at all times after day 7 and increased steadily through day 11. It was significantly depressed by actinomycin D on days 9 and 10. These observations correlated well with known developmental events and with teratogenic manifestations following actinomycin D treatment.

Tritiated actinomycin D was shown by radioautography to be present in the embryo on day 9, 10 and 11 of gestation, and was shown to be bound to DNA, by virtue of its disappearance after application of deoxyribonuclease. It was concluded that the teratogenic action of actinomycin D in rats is probably dependent on direct intraembryonic inhibition of RNA synthesis.
The occurrence and location of intrinsic cardiac ganglia and nerve plexuses in the human neonate
Authors: Smith R. B.
Published: February 2005

The principal intrinsic ganglion sites in the human infant's heart have been described. They are arranged in six main groups. While most ganglia are associated with the atria, ventricular neurons have also been identified and their significance regarding possible ventricular parasympathetic innervation is discussed. The ganglia vary considerably in size, with most of the larger ones lying on the superior aspect of the heart near the superior vena cava, the aorta and pulmonary artery. They all possess well‐defined capsules. Most of the contained neurons appear to be multipolar, but pseudounipolar and occasional bipolar forms have been detected. Two plexuses exist in the parietal pericardium. Large complicated nerve endings described by previous writers have not been identified, but free endings might exist. Networks in the subepicardium, subendocardium and associated with the coronary arteries have been demonstrated and their functional significance is discussed. Nerve endings, either simple or complicated, were not seen in relation to these plexuses in this investigation.
Morphologic studies of human subcutaneous adipose tissue in vitro
Authors: Smith Ulf
Published: February 2005

A simple method for in vitro studies of human subcutaneous adipose tissue is described. Explants of adipose tissue have been maintained in vitro for 30 weeks in Parker medium 199. The morphology of cultured explants compared well with that of freshly excised specimens. In the absence of serum there was no outgrowth of fibroblast‐like cells. When human serum was added to the medium at concentrations exceeding 5% there was a proliferation of fibroblast‐like cells. This cell proliferation could still be obtained when serum was added after two weeks of culture in a serum free medium. The adipose cells were isolated with collagenase and the cell size determined. Explants with an initial mean cell size larger than about 95 μ showed a significant decrease in cell size during the incubation. This could not be attributed to a traumatic effect. Metabolic differences between large and small adipose cells was suggested as a possible reason.
Glycogen content of rabbit tubular genitalia from mating through implantation
Authors: Gregoire A. T. , Hafs H. D.
Published: February 2005

Groups of five rabbits were killed at 0, 2, 4, 7, 10, 24, 48, 98, 168 and 240 hours after mating. The glycogen content of the lower half of the Fallopian tube was greater than in the upper half at each interval. Uterine and Fallopian tube levels of glycogen decreased during the interval from mating to ovulation. Both cervical and vaginal glycogen declined significantly within 24 hours after mating. Decidual uterine areas contained 1.5 and 5.0 times more glycogen on days 7 and 10, respectively, than interdecidual areas. Castrate rabbit Fallopian tube, uterus, cervix and vagina responded with glycogen synthesis to estradiol, but not to progesterone administration.
A light and electron microscopic study of the nearly mature enamel of rat incisors
Authors: Warshawsky H.
Published: February 2005

The structure of the organic matrix close to the mature enamel in 100 gm rat incisors was studied by light and electron microscopy using EDTA decalcified teeth.

Under the light microscope, in 0.5 μ Epon sections, the enamel layer of cross sectioned upper incisors was about 60 μ thick. The inner enamel was about 40 μ thick and consisted of an initial enamel layer (4 μ) adjacent to the dentin in which no rod profiles were seen, and an inner layer proper which contained six to eight rows of oval‐shaped rod profiles set in a homogeneous background. The profiles in any given row were inclined mesially or laterally and alternated in adjacent rows. The outer enamel was about 20 μ thick and consisted of an outer enamel proper and a 2–4 μ thick final enamel layer which smoothed out the enamel surface. The outer enamel proper contained smaller elliptical rod profiles in a more abundant background. These profiles were not arranged in rows and were oriented at right angles to the enamel surface. The final enamel layer contained no rod profiles and was lined on its outer surface by a PA‐Schiff positive layer resembling a basement membrane.

Under the electron microscope the matrix of rod profiles and interrod material could be distinguished. This consisted of aggregated tubular (and filamentous) subunits, 250 Å in diameter, with empty space between them. Within the rod profiles the subunits ran parallel to the rod's long axis, whereas in the interrod material the subunits were again parallel but but running at right angles to the subunits of the rods. In addition to forming the material between the rods, the interrod material also formed the initial and final enamel layers.
Morphology and microanatomy of the adrenal cortex of the coyote
Authors: Ogle Thomas F.
Published: February 2005

The left adrenal in adult coyotes (25) was heavier than the right (P < 0.005). Adrenal weights of pups (3 males and 3 females) were not different (P > 0.05). Absolute adrenal weight in adult females was greater than in adult males (P < 0.01). In the six pups which were under seven months old the adrenals of males were heavier than in females (P < 0.025).

Changes in the widths of adrenocortical zones were analyzed with regard to maturity. The width of the glomerular zone in immature coyotes was not different from mature animals. Immature males had a wider fasciculata than immature females (P < 0.01) and mature males (P < 0.01). The reticular zone exhibited the greatest relative growth with maturity in both sexes.

Zona glomerular cells were columnar epithelia with oval nuclei which contained one or two nucleoli. Fascicular cells were polyhedral shaped with central nuclei which contained as many as three nucleoli. The zona reticularis was characterized by anastomosing cords. Nuclei were highly variable in size. Nucleoli were often dispersed around the nuclear membrane. Lipids were stored as large irregularly‐shaped droplets in the fasciculata and as small, round droplets in the reticularis.

Cortical cells from coyotes of all ages showed the presence of histones; all zones reacted positively. Nucleoli and chromatin granules gave intense reactions, suggesting close association between histones and nuclear RNA and DNA.
The intermediate root of the trigeminal nerve in the dog (Canis familiaris)
Authors: Augustine James R. , Vidić Branislav , Young Paul A.
Published: February 2005

The intermediate root of the trigeminal nerve in the dog has been investigated both macroscopically and microscopically. Sixty‐two trigeminal complexes (trigeminal ganglion, trigeminal roots and the portion of the pons to which the roots were attached) in the dog were dissected out and removed. Each of the complexes was fixed in 10% formalin, dehydrated and embedded in paraffin. The paraffin blocks were cut serially at 10 μ. Every other slide was either stained with Luxol Fast Blue or impregnated with Bodian's silver method. In all cases, between the motor and sensory roots an intermediate root composed of one distinct rootlet was identified. Most frequently the intermediate root was attached to the pons from 0.5 to 3.0 mm lateral to the motor root and rostral to the sensory root from 0.5 to 2.0 mm. From its pontine attachment the intermediate root extended anteromedially for a distance of from 2.0 to 5.0 mm before it became incorporated in the lateral aspect of the free motor root. Closer to the trigeminal ganglion the motor root and the intermediate root fused with the expanding sensory root. The fibers in the intermediate root ranged from 1.5 to 7.5 μ in diameter with the majority of fibers (60 to 70%) having a diameter of from 4.0 to 6.0 μ. Approximately 10% of the fibers were unmyelinated. The total number of fibers in the intermediate root varied from 170 to 416 with an average of 266 fibers. The morphological data obtained in an experimental animal such as presented in this paper may provide a basis for future experimental work on the clarification of the functional role of the trigeminal intermediate root.
The cartilage endplates of the human vertebral column (some considerations of postnatal development)
Authors: Donisch E. W. , Trapp W.
Published: February 2005

The cartilage plates covering the lumbar vertebral bodies were examined macro‐ and microscopically in infants and children. Particular attention was given to the distribution of vascular canals within these plates. Some of the canals are responsible for the formation of spoke‐like ridges of cartilages. The latter develop as the vertebral body expands in height and girth. The canals show a characteristic distribution and end blindly in the neighborhood of the anulus fibrosus.

The cartilage plates are known to provide a growth zone for the center of the vertebrae. In addition, they appear to contribute also to the growing intervertebral disc. The present investigation suggests that an association exists between the blind endings of the vascular canals and the interstitial lamellar growth of the anulus fibrosus at the time of active, postnatal disc expansion.

Comparison of differences in shape of infantile lumbar vertebrae were made in various cases with a known history. These studies suggest that weight bearing and movement influence the development of a particular shape. It can be demonstrated that in the absence of normal stresses some lumbar vertebrae grow taller and have a decreased anterior‐posterior diameter.
Fine structural study on the origin and development of the sphincter pupillae muscle in the West Coast newt (Taricha torosa)
Authors: Tonosaki Akira , Kelly Douglas E.
Published: February 2005

The origin and development of the sphincter pupillae muscle was studied in Taricha torosa by electron microscopy. The larval optic cup with its inner and outer epithelial layers is completely enshrouded by a primary basal lamina. The epithelium can be divided into E and R regions, according to the types of distributed pigment granules, ellipsoidal (E) and round (R). The E region includes the outer layer except the pupillary zone; the R region the inner layer and pupillary zone. The boundary dividing these regions is distinct enough to be called the E‐R boundary. Clusters of fine filaments develop in the pigment‐containing R cells adjacent to the E‐R boundary during metamorphosis. Such R cells subsequently increase their population to form abundle swelling into the anterior ocular chamber. This bundle formation is accompanied by acquisition of a nerve supply from the iridial stroma, and the emergence of collagen fibers as well as secondary basal (or external) laminae surrounding each cell of the bundle. The adult muscle cells retain numerous round pigment granules, desmosomes, and intermediate junction.

These facts support the neuroectodermal origin of this sphincter pupillae muscle.
The uptake of tritiated thymidine by the dorsal epidermis of the fetal and newborn rat
Authors: Stern I. B. , Dayton L. , Duecy J.
Published: February 2005

The dorsal epidermis of fetal and newborn rats was examined to determine the difference in ability of the basal cells to bind tritiated thymidine during different stages of epidermal morphogenesis. Five rats were examined for each time period from the eleventh day of gestation to the fifth day after birth. The number of labeled cells in 5000 basal cells was counted and expressed as a percentage. The labeling index is ∼ 10% from the eleventh to the fifteenth fetal day. It increases to ∼ 30% by the eighteenth day, decreases to ∼ 10% from the twenty‐first day until the first postpartum day and drops to 5% or less from the second to fifth day. These changes in labeling index are accompanied by and apparently correlated with the normal differentiation of rat epidermis. The growth of the epidermis is continuous during the course of the study. Keratohyalin granules begin to form on the eighteenth day and by the twentieth day the first cornified cells appear. The s. corneum becomes progressively thicker each day thereafter. The s. Malpighii, on the other hand, decreases somewhat in thickness after birth. The labeling index curve represents a relationship between basal cell activity and control or influencing mechanisms inherent in the maturational system of skin. The increase and decrease are not related to growth alone, but appear to be related to differentiation.
The Function of the teres major muscle: An electromyographic study
Authors: Broome H. L. , Basmajian J. V.
Published: February 2005

Electromyographic activity of the teres major and latissimus dorsi muscles using indwelling bipolar fine‐wire electrodes was recorded during motion of the arm and shoulder without resistance, against resistance, and during static resisted activity. The teres major is active during static motion and during motion against resistance with medial rotation, adduction, and extension of the arm. It is not active during motion without resistance, although latissimus dorsi usually is.
Fine structure of the Leydig cell during postnatal differentiation of the mouse testis
Authors: Russo J.
Published: February 2005

It is possible to divide the ultrastructural events which take place in the mouse Leydig cell during postnatal differentiation into two periods. The first period includes the changes taking place during the first three weeks after birth, whereas the second period comprises the events occurring from the fourth week on. During the first period the cytoplasm contains a poorly developed smooth endoplasmic reticulum. After the tenth day a slight increase in the number of vesicles and tubules of the smooth endoplasmic reticulum is observed. Clusters of glycogen particles (beta type) and lipid droplets are very numerous in this period.

At the beginning of the second period the smooth endoplasmic reticulum hypertrophies considerably occupying a large area of the cytoplasm. This period is also characterized by the appearance of double‐walled tubules, of numerous interdigitations between neighboring Leydig cells and primary lysosomes in close relation to lipid droplets. A marked decrease in the number of glycogen particles and lipid droplets are also found. In the adult mouse (after day 50) numerous cisternae of the smooth endoplasmic reticulum are concentrically arranged (whorls).

The formation of new membranes in the Leydig cell undergoing differentiation and the control of such differentiation are discussed.
Intertubular circulation in the opisthonephric kidneys of adult and larval sea lamprey, Petromyzon marinus L.
Authors: Youson John H. , McMillan Donald B.
Published: February 2005

The opisthonephric kidneys of both larval and adult Petromyzon marinus lack a renal portal system. The tubules are supplied with arterial blood from the glomus through a system of efferent arterioles, capillaries, and sinusoids with the latter draining into the venous system. The adult kidney possesses a more complex and larger system of sinusoids than ammocoetes and these sinusoids reach the venous system through large subcapsular sinuses. Paralleling of tubules with sinusoids and arterioles in the ventral portion of the adult kidney resembles the association of the vasa recta with the tubules of the renal medulla in the mammalian kidney. This may suggest a mechanism important to tubular transport in adult lampreys. The intertubular tissue of ammocoetes is infiltrated with haemopoietic tissue while large numbers of phagocytes within the adult sinusoids may be involved in the destruction of blood cells.
Cell count correction factors for the quantitative histological analysis of the germinal epithelium of the ram
Authors: Lino Barry F.
Published: February 2005

The relationship between the Sertoli cell counts, some measurable parameters of the seminiferous tubules and the dimensions of the Sertoli cell nuclei were examined in both normal and degenerate testes. Highly significant differences were found between rams in the numbers and in the dimensions and volumes of the Sertoli cell nuclei and in the diameters of the seminiferous tubules. The Sertoli cell counts were corrected for the differences in nuclear volume by dividing the count by the calculated nuclear volume. The Sertoli cell counts were corrected for changes in the area of the seminiferous tubule wall by multiplying the count by the square of the tubule radius. Correction for either nuclear volume or tubule area alone increased the differences between the Sertoli cell counts, but a simultaneous correction for both factors equalized the counts so that there were no significant differences between rams in the number of Sertoli cells per tubule cross‐section. It was concluded that, in normal and degenerate ram testes, counts of the Sertoli cell nuclei in the seminiferous tubule cross‐sections, when corrected for differences in nuclear volume, would provide a valid basis for comparing volume‐corrected counts of spermatogenic cells in different animals and in different treatments.
Epithelial cell proliferation in the mouse vagina during the estrous cycle, pregnancy and lactation: A radioautographic study
Authors: Traurig Harold H.
Published: February 2005

A radioautographic study of epithelial cell proliferation in the vaginas of mice during the estrous cycle, pregnancy, lactation, and under certain experimental conditions is reported. Data were expressed as labeled cells per 1000 basal cells counted. The proportion of labeled cells that were basal or nonbasal was determined. The highest rates of proliferation were recorded during the estrous cycle, specifically during late diestrus, proestrus and early estrus. During pregnancy the rates of proliferation increased from metestrous levels beginning on day three and reaching a maximum on day 4 just before implantation, followed by a decrease on days 6 and 8. There was an increase on day 12 followed by a more marked increase on day 19, the last full day of pregnancy. On the first day post partum the rate of proliferation was very low. A small increase followed during early lactation.

Data on rates of vaginal epithelial proliferation were used to infer the estrogen secretion pattern during reproduction in the mouse. In addition it was concluded that progesterone augmented the proliferative response of the vaginal epithelium to estrogen, specifically promoting proliferation of nonbasal cells. Experiments using mated, castrated mice and estrogen or progesterone replacement confirmed these conclusions.

Data and conclusions are discussed relative to recently reported data on ovarian plasma estrogen and progesterone content in rats during reproduction.
The fine structure of a lateral recess of the subarachnoid space in the rat
Authors: Himango William A. , Low Frank N.
Published: February 2005

This study reports an electron microscopic investigation to the spinal meninges of the rat as they exist between the dorsal and ventral nerve roots in upper thoracic and cervical levels of the vertebral column. Between these roots, at a point where they penetrate the spinal dura, the leptomeninges are characterized by a histological pattern comparable to that elsewhere comprising the subarachnoid angle. However, this region is modified and possesses a number of heretofore unknown histological features. The most noteworthy is a lateral recess of the subarachnoid space.

The meninges located between the nerve roots do not form a definite lateral boundary for the subarachnoid space. Here the subarachnoid space opens into a lateral recess which extends peripherally between the dorsal and ventral nerve roots. Conspicuous amounts of cellular debris are collected within the lateral recess. Numerous free macrophages congregate here. The lateral recess may be a communicating pathway between the central and peripheral nervous systems by way of the endoneurium of the nerve trunk.
Weight standards for organs from early human fetuses
Authors: Tanimura T. , Nelson T. , Hollingsworth R. R. , Shepard T. H.
Published: February 2005

One hundred and thirty‐six unfixed fetuses below 500 gm of body weight were examined and the brain, liver, lung, kidney, heart, adrenal, thymus, spleen, and thyroid were weighed. The ratios of organ weight to body weight could be divided into four general patterns: (1) constant; liver, heart, brain, and thyroid (2) increasing; thymus, adrenal, and spleen (3) initially increasing and then reaching a plateau; kidney, and (4) increasing and then decreasing; lung. Graphs of the mean and 95% confidence levels along with the formulas used for derivation are given for each organ on the basis of body weight.
The isolated mucosa of turtle bladder
Authors: Lefevre M. E. , Gennaro J. F. , Brodsky W. A.
Published: February 2005

The mucosa of the turtle bladder was separated from underlying tissue by blunt dissection and its composition characterized. Although large amounts of non‐epithelial tissue were removed by the dissection, a considerable amount of connective tissue and a small amount of smooth muscle were always present in the isolated layer. The epithelial cells were described and anatomical features of significance in water and ion transport studies examined. The columnar epithelial cells of the mucosal layer were arranged in clusters bounded by crypts. The cells were larger near the bladder neck than in the distal regions of the bladder. Single smooth muscle cells were found immediately beneath the epithelial cell layer. Long intercellular channels separated the cells. Possible roles of these features in water and ion transport were discussed.
Cytological differentiation of the mesothelial cells of the yolk sac of the bat, Tadarida brasiliensis cynocephala
Authors: Stephens Robert J. , Cabral Linda J.
Published: February 2005

An ultrastructural analysis of the mesothelial cells of the yolk sac of the bat throughout gestation is presented. At first these cells are closely associated with the cytotrophoblast but become displaced by action of the allan‐tois and collapse of the yolk sac. The mesothelial cells are exposed to the exo‐coelom and develop cytological features characteristic of absorptive cells. Among these features are: (1) long microvilli extending from the apical and lateral plasma membranes and (2) absorptive canaliculi and tubules as well as absorptive vacuoles in the superficial cytoplasm. There is a paucity of mitochondria and rough endoplasmic reticulum throughout the existence of this cell type. After midgestation, granules containing numerous crystalloids appear in the cytoplasm of most of the cells. These are apparently the result of the absorption of protein‐aceous material from the exocoelom. The crystalloids disappear before birth, and the mesothelium becomes degenerative in appearance. This sequence of development of the cytological features suggests a dynamic role for the mesothelium throughout its existence that involves absorption and storage of proteinaceous material from the exocoelom for use by the embryo.
Ruthenium red and violet. II. Fine structural localization in animal tissues
Authors: Luft John H.
Published: February 2005

The inorganic dye, ruthenium red, stains extracellular materials in animal tissues which probably are acidic mucopolysaccharides. It complements other techniques, its advantages being fine grain, high resolution and good contrast. Localization is shown in mouse and rat muscle, heart, lung and intestine, frog cartilage and cells scraped from oral epithelium of human beings. Attention is paid to collagen bundles, the cell/collagen interface and particularly the myotendinal junction, cartilage matrix and agar gel, desmosomes, intestinal microvilli, erythrocytes and vascular endothelium, nerve fibers and the T‐system of striated muscle. Although ruthenium red generally is excluded by plasma membranes, it penetrates giving intracellular density, if the membrane is broken. Even when the cell membrane is intact, exceptions occur with selective staining of the T‐tubules or the sarcoplasmic sacs depending upon the state of contraction of the muscle cell, and with intracellular staining of certain nuclei and epithelial cells. Ruthenium red stains intracellular lipid droplets revealing lamellae, and stains myelin forms grown from crude egg lecithin but cannot penetrate deeply. It is localized in extracellular materials which have an important mechanical function. Its exclusion by cell membranes permits tracing tortuous cellular invaginations and those exceptions to its exclusion invite a comparison of the localization of the dye with the function of the cell.
Ultrastructural studies on elastic fibers using enzymatic digestion of thin sections
Authors: Daniel Bodley H. , Wood Richard L.
Published: February 2005

The enzymes elastase, chymotrypsin, pepsin, pronase, hyaluronidase, and collagenase were utilized on thin Epon sections to obtain further information on the nature of elastic fibers. Results showed that the central amorphous material was selectively removed by elastase and after hydrogen peroxide pretreatment it also was removed by chymotrypsin, pepsin and pronase. None of the enzymes removed the peripheral microfibrils, but pepsin did accentuate the density and periodic beading of these structures. The failure of proteases to remove the microfibrils under these conditions is discussed.
Temporary lobulation in cartilagenous models of long bones
Authors: Miller Marian L. , Basom Charles R. , McCuskey Robert S.
Published: February 2005

Vascular patterns and the vertical zones of maturing cartilage cells are arranged in geometric radiations. This lobular arrangement reflects a distribution of cells and matrix of differing maturity; those cells and matrix closest to the collagenous wall of the vascularized canal are maintained in an immature state longer than those located toward the periphery of the lobule. This configuration suggests a relationship between the oxygenation of cartilage, its maturity, and its ossification. Arteries in the cartilage canal frequently are destined to become the arteries located within themarrow cavity of mature bones.
The nature of endochondral ossification in the mandibular condyle of the mouse
Authors: Silbermann Michael , Frommer Jack
Published: February 2005

Through the application of histological and histochemical techniques, this study demonstrates that the ossification process of the mandibular condyle differs basically from that of other endochondral growth sites. In the epiphyseal plate of a typical long bone, the cartilage cells are known to undergo degenerative processes and death. In the mandibular condyle, however, the cartilage cells keep their vitality throughout the cartilage zones. In the lower border of the calcified cartilage, adjacent hypertrophic cartilage cells fuse after the dissolution of the intervening matrix to form multinuclear chondroclasts. These giant cells reveal marked positive reaction to mitochondrial and lysosomal enzymes. It is suggested that these enzymes are active in the resorption process of the calcified cartilage matrix, which is an integral phase of the ossification mechanism of the condylar growth center. It is believed that the mandibular condyle of the mouse demonstrates a specific type of endochondral ossification, in which the hypertrophic chondrocytes are not dying cells, but contribute actively to the process of bone formation.
Cartilage canals, their morphology and distribution
Authors: Wilsman Norman J. , Van Sickle David C.
Published: February 2005

The proximal humeral chondroepiphysis of newborn pups was shown to be well‐vascularized by a series of segmentally distributed cartilage canals which varied from short unbranched channels to channels which coursed half‐way across the epiphysis. Cartilage canals were observed to contain a muscular arteriole, venule, loose connective tissue and perivascular capillaries. The muscular arterioles originated from the dense perichondrial vascular network at regular intervals, coursed in the central portion of the cartilage canal, and terminated by dividing into a capillary glomerulus in the cartilaginous matrix.

These glomeruli were observed to assume a wide variety of sizes and shapes reflecting the metabolic needs of the areas they served. The capillaries of the glomerulus recombined into a single venule which rejoined the perichondrium via the same channel as the parent arteriole. The loose connective tissue surrounding these vessels was rich in fibroblasts and macrophages and was continuous with that of the perichondrium.

From the structural relationship of the cartilage canals and the articular surface, it was concluded that at birth the synovial fluid had little nutritional significance for the epiphysis, but with age the nutritional contribution from the synovial fluid became more important.

The particular arrangement of the venule and the perivascular capillaries allowed for metabolic exchange the entire length of the canal. Structures which appeared to be unmyelinated nerves and structures which contained a flocculent material and resembled lymphatics were seen in the connective tissue of the cartilage canals.
Hormonal regulation of the “fatted” phenomenon in squirrel monkeys
Authors: Nadler Ronald D. , Rosenblum Leonard A.
Published: February 2005

The hormonal basis of the ‘fatted’ phenomenon in squirrel monkeys was investigated by gonadectomy and androgen treatment of adult males and females. Significant correlations were found between testis weight and body weight and between testis weight and the sharp reductions in body weight that occurred following gonadectomy. of the males. Females lost little, if any weight, following gonadectomy. Androgen treatment of male castrates resulted in increased body size, weight and physical appearance, closely approximating the condition reported to occur in normal males during the mating season. Female castrates responded to androgen treatment with an analogous development of‘fattedness.’ The data suggest that the ‘fatted’ condition observed seasonally in the field is regulated by fluctuations in endogenous androgen levels of males and that females share that characteristic responsiveness to androgen.
Transmission of an ‘osteogenic message’ through intact bone after wounding
Authors: Melcher A. H. , Accursi G. E.
Published: February 2005

Wounds ˜ 1 mm wide were made in the middle third of the spine in both scapulae of 25 middle‐aged Wistar‐strain rats weighing ˜ 500 gm. Wounding of the body of the scapula was avoided. Some of the animals were injected with tetracycline, and sections from their scapulae were viewed in ultraviolet light. After one or more weeks of healing, bony callus was deposited on the dorsal surface of the blade of the scapulae in the vicinity of the wounds. Discrete deposits of bony callus were also deposited on the corresponding costal surface of the blade of the scapulae. These deposits, which were in no way connected with those on the dorsal surface, did not exhibit continuity with the wound in the spine. This observation has been interpreted as suggesting the passage of an ‘osteogenic message,’ whose nature can only be guessed, from the vicinity of the wound on the dorsal surface of the scapula to the corresponding costal surface. Lacunae of osteocytes in the scapulae, lying deep to periosteal and endosteal callus, fluoresced. This suggests that these osteocytes were activated by the trauma, and deposited mineral salts on the walls of their lacunae.