Ovoid Structure Research Articles

Cricoid Cartilage on Sonography in Pediatric Patients Mimics a Thyroid Mass

The purpose of this study was to describe the sonographic appearance of the uncalcified cricoid cartilage in pediatric patients and illustrate how this can be easily confused with a thyroid mass or residual thyroid tissue after thyroidectomy. We retrospectively reviewed the sonographic and computed tomographic examinations performed on 4 adolescent patients. Two patients had either thyroid cancer or thyroid nodules, and 2 healthy patients were reviewed to show normal anatomy. Results were compared with the clinical and surgical findings in each patient. Computed tomographic and sonographic examinations showed the normal anatomic relationships and imaging appearance of the cricoid cartilage. Findings from a follow-up sonographic examination on a patient with treated thyroid cancer were initially interpreted as residual thyroid tissue, but another examination revealed that this tissue was actually uncalcified cricoid cartilage. Another patient who had intraoperative sonography verified these findings. Uncalcified cricoid cartilage in a pediatric patient appears on sagittal sonography as a round or ovoid structure with variable echogenicity, located posteromedial to the thyroid gland. Awareness of this structure's sonographic appearance should prevent unnecessary biopsy or surgery.

Enterocutaneous fistula complicating a duodenal bezoar: an unusual presentation

View Large Image Figure ViewerDownload (PPT)View Large Image Figure ViewerDownload (PPT)View Large Image Figure ViewerDownload (PPT)View Large Image Figure ViewerDownload (PPT)A 76-year-old woman presented with dyspepsia, nausea, epigastric pain, and watery to purulent discharge from a small opening localized over an old hydatid cyst surgery scar at midline, about 5 cm above the umbilicus. CT of the abdomen revealed an open wound in the upper abdomen centrally (A, arrowhead), with an underlying large hypodense area extending to the gallbladder fossa and containing an irregular 2.5-cm calcification (A, arrow). A fistulogram outlined a large enterocutaneous fistula (B, arrowhead) communicating with the apex of a distended duodenal bulb that contained an irregular, large, filling defect (B, arrow). EGD showed a large, stony, hard bezoar occupying the duodenal bulb; the opening of the fistula was seen with minimal superficial ulceration (C and D). Exploratory laparotomy revealed perforation of the duodenum, which contained a large bezoar. Removal of the bezoar and primary closure of the duodenum then were performed. The bezoar consisted of a black-green, firm, ovoid structure that measured 4.5 × 3.5 × 1.5 cm and weighed 230 g (E). Two weeks after surgery, upper-GI series showed normal opacification of the GI tract, with complete closure of the previously described duodenocutaneous fistula. View Large Image Figure ViewerDownload (PPT)View Large Image Figure ViewerDownload (PPT)View Large Image Figure ViewerDownload (PPT)

Ileocecal valve: spectrum of normal findings at double-contrast barium enema examination.

To characterize the spectrum of normal findings of the ileocecal valve at double-contrast barium enema examination to allow differentiation between a normal valve and one infiltrated by tumor. A search of radiology and endoscopy files showed 106 patients who underwent double-contrast barium enema examination and colonoscopy. The radiographic images were reviewed by two authors to determine the morphology of the ileocecal valve and to evaluate whether it appeared normal or abnormal. The radiographic data were then correlated with endoscopic and pathologic findings. The ileocecal valve was visible in 91 (86%) of 106 patients. It was round or ovoid in 71 patients (78%) and triangular in 20 (22%). In the 88 patients with a normal valve at colonoscopy, mean valve height was 1.7 cm, and mean width was 2.8 cm. The valve was smooth in 75 patients (85%) and smoothly lobulated in 13 (15%). The lips of the valve were symmetric in 77 patients (88%) and asymmetric in 11 (12%). All 87 patients with a normal valve at double-contrast barium enema examination had a normal valve at colonoscopy, whereas the two patients with a valve suspicious for tumor at barium enema examination had neoplasms (one carcinoma and one villous adenoma) at colonoscopy. The ileocecal valve may show a spectrum of normal findings at double-contrast barium enema examination and may appear as a round, ovoid, or triangular structure with a maximal height of nearly 4 cm. The valve may be large, asymmetric, or smoothly lobulated, even in the absence of tumor.

Central olfactory structures in Pax-6 mutant mice.

During the development of the olfactory system, cells located in the olfactory placode/olfactory pit send their axons toward the rostral part of the telencephalic vesicles (TVs). Some of these enter the TV inducing the formation of the olfactory bulbs (OBs), whereas, mitral and tufted cell axons form the lateral olfactory tract (LOT). Our recent studies have shown that the beginning of the central olfactory projections is independent of the arrival of olfactory receptor neuron (ORN) axons to the TV. Here we have used the mouse carrying a mutation in the Pax-6 gene to study whether the nasal olfactory structures intervene in the formation of central olfactory structures. This mutant as well as lacking a nose and eyes, is reported to lack olfactory epithelium and OB. However, we have found an ovoid cellular structure localized in the rostral part of the brain, and some cells in this structure project axons toward the piriform cortex forming a presumptive LOT. We conclude that the referred structure is an OB, which fails to develop because the mutation in the Pax-6 gene affects the formation of nasal structures. As such, fibers of the ORNs are necessary for the protrusion and layered formation of the OB, but these inputs are not necessary for the establishment of the central olfactory projections.

Abdominal Cocoon: An Animal Model for a Complication of Peritoneal Dialysis

The purpose of this work was to develop an animal model of sclerosing encapsulating peritonitis, a complication of continuous ambulatory peritoneal dialysis in which the intestines are conglomerated into an ovoid cocoonlike structure. Toward this end, rats were injected with a chemical irritant (household bleach) intraperitoneally. One week later, before the resultant peritonitis could cause adhesions, 10 or 25 mL of fresh whole rat blood was injected into the peritoneal cavity. Two weeks later, the effect of the treatments was evaluated by macroscopic and microscopic study. The irritant caused a chemical peritonitis. The subsequently injected blood clotted on the surfaces of the inflamed intestines, and contraction of the clot (syneresis) was responsible for bringing the intestinal loops together. This conglomeration was made permanent by the fibrosis evoked by the chemical peritonitis. The end result was an ovoid encapsulated mass of intestines and other viscera. An animal model for an abdominal cocoon has been produced. It can be used for studies of the pathogenesis and prevention of this complication of peritoneal dialysis.

Relationship between the organization of the forepaw barrel subfield and the representation of the forepaw in layer IV of rat somatosensory cortex.

We studied the organization of the forepaw barrel subfield (FBS) in layer IV of adult rat somatosensory cortex using the mitochondrial marker cytochrome oxidase and related this organization to the representation of the forepaw. The FBS is an ovoid structure consisting of barrels and barrel-like structures, the most conspicuous of which form four centrally located medio lateral running bands. Each band contains three to four barrels. These centrally located bands are bordered along their entire lateral side by a nebulous zone of undifferentiated labeling. At the anterior border, two small barrels are located laterally and one or two larger barrels are located medially. Medial to the central zone are three well-defined barrels. The posterior border consists of a nebulous field of labeling and occasional barrel-like structures. The results from our electrophysiological recording and mapping revealed that the forepaw representation was topographically organized into a single map and that the forepaw map matches almost precisely with individual barrels and barrel-like structures in the FBS. Each of the four central bands is associated with the representation of a single glabrous digit. Digit two (D2) is represented anteriorly and followed posteriorly by D3 through D5. Within each digit band the digit is somatotopically organized, with the skin over the distal phalanx represented in the two lateral barrels and the middle and proximal phalanges represented in the medial barrel(s). The dorsal hairy digit skin and dorsal hand are represented in the lateral zone. D1 is represented by two small anteriorly located barrels. Medial to the representation of the glabrous digits is the representation of the palmar pads. The representation of these pads, in turn, lies between the representations of the thenar (located anteriorly) and hypothenar (located posteriorly) pads. Posterior to the hypothenar pad representation lie the representations of the wrist and forearm. While the present results support the conclusion that individual barrels are associated with discrete locations on the forepaw, examples were found where the recording site was not precisely located within the predicted barrel. Some of these errors may be accounted for by limitations in the mapping techniques; nevertheless, the FBS offers an excellent model system to study relationships between cortical structure and function.

Dorsal nucleus of the lateral lemniscus in the rat: Concentric organization and tonotopic projection to the inferior colliculus

A basic principle of organization in auditory centers is the topographic-tonotopic order. Whether this applies to the dorsal nucleus of the lateral lemniscus (DNLL), however, is still debated. To clarify this problem, we have utilized the neuroanatomical tracers horseradish peroxidase (HRP) and biotinylated dextran (BD) injected into different regions of the central nucleus of the inferior colliculus (CNIC) in the rat. After large injections of HRP that included most of the CNIC, retrogradely labelled neurons were found all across the ipsi- and contralateral DNLL, showing that all parts of this nucleus innervate the CNIC bilaterally. More neurons were seen consistently on the side contralateral to the injection site. Labelled fibers, however, were abundant ipsilaterally, but scarce in the contralateral DNLL. Single, small injections of HRP or BD into the CNIC resulted in labelling in restricted areas of the ipsi- and contralateral DNLL. In coronal sections, the neurons and fibers labelled in the ipsilateral DNLL formed a well-defined, ring-shaped structure made of dendrites and axons oriented parallel to each other, which we termed "annular band." The observation of serial sections revealed that the annular band seen in any individual section represents a slice through a more or less complete three-dimensional, hollow, ovoid structure oriented rostrocaudally. The position and diameter of the annular band changed as the injection site was shifted along the tonotopic axis of the CNIC. Single injections placed in the ventromedial, high-frequency region of the CNIC produced a large annular band along the periphery of the DNLL. After injections placed in progressively more dorsolateral, lower-frequency regions of the CNIC, the annular band became smaller in diameter and occupied a successively more central position in the DNLL. Double injections along the tonotopic axis of the CNIC resulted in two roughly concentric annular bands. The labelled neurons and fibers in the contralateral DNLL systematically occupied a position symmetric to the annular band seen ipsilaterally. These findings indicate that the rat DNLL is primarily composed of neurons with flattened dendritic arbors and flattened fields of terminal fibers. These two elements intermingle, forming concentric layers around the geometric center of the nucleus. The axons of neurons within corresponding layers on the two sides converge onto the CNIC of both sides in a strict topographic fashion: the peripheral layers project to the ventromedial, high-frequency region of the CNIC, and the central layers project to the dorsolateral, low-frequency region. These results suggest that the concentric arrangement of the DNLL is the substrate of its tonotopic organization.

Ultrastructure of the extraocular photoreceptor in the genitalia of a butterfly, Papilio xuthus

This paper describes the ultrastructure of a sensory neuron found in the extraocular photoreceptive site on the butterfly genitalia. Our previous studies have shown that there are two pairs of the photoreceptive sites in a butterfly (four per individual). Each photoreceptive site is recognizable by a transparent area in the pigmented cuticle of the genitalia. From the nerve that extends from the transparent cuticle to the last abdominal ganglion, a sustained train of single unit spikes can be recorded in response to a light flash. The single unit spikes disappear when the transparent cuticle is covered, thus indicating that a single photoreceptor exists close to it. Here, we examined complete serial semithin sections of plastic-embedded photoreceptive sites of both male and female, and observed an ovoid structure close to the transparent cuticle. The structure contained the cell body of a sensory neuron whose axon was in the nerve branch from which the photoresponse had been recorded. Further electron microscopy revealed that the cell body extended a few distal processes that protrude tubular membrane from the tip, forming a structure resembling the phaosome (from Greek; phaos = light, some = body) which was first described in the earthworm dermal photoreceptors. The sensory neuron was also found in a surgically isolated nerve-photoreceptor preparation that responded to the light. We therefore propose that the phaosome-containing sensory neuron is the butterfly genital photoreceptor.

Primary “Brown Pigment” Bile Duct Stones

Bile duct stones from 42 patients were morphologically and chemically analysed. The calculi from 27 patients had important primary bile duct stone (PBDS) features, consisting of a general ovoid shape and fragile structure, with alternating light and dark brown pigmented layers on cross-section. Chemically these stones contained low levels of cholesterol, with high levels of bilirubin and calcium. Subsequent infrared spectroscopy analysis showed that calcium bilirubinate and calcium palmitate were the only calcium salts present. Calcium palmitate was prominent in the light brown layers. A morphological and chemical comparison with gallbladder stones showed that bile duct “stasis stones” were similar in morphological and chemical composition to the brown pigment gallbladder calculi. However, they were distinct from most gallbladder stones, indicating that primary bile duct calculi have an aetiology that is different to 90% of gallbladder calculi. Primary bile duct calculi were observed to occur with or without the presence of a gallbladder, and more interestingly, in the bile duct of two patients with cholesterol gallbladder stones. Bile duct bile of patients with primary choledocholithiasis were always moderately to profusely infected and with abundant calcium bilirubinate precipitation. Moreover, this study has shown that PBDS chemical analyses profiles were consistent and correlated well with their defined morphology. Consequently, PBDS may be accurately identified at the time of operation by morphology. An important aetiological factor would appear to be infection, which would seem to promote bile duct bile stasis and eventual stone growth.

Structural model of porcine factor VIII and factor VIIIa molecules based on scanning transmission electron microscope (STEM) images and STEM mass analysis.

Porcine plasma factor VIII (fVIII) molecules are heterodimers composed of a 76,000-mol wt light chain (-A3-C1-C2) and a heavy chain ranging in molecular weight from 82,000 (A1-A2) to 166,000 (A1-A2-B). Proteolytic activation of fVIII by thrombin results in fVIIIa heterotrimers lacking B domains (A1, A2, A3-C1-C2). In this study, immunoaffinity purified fVIII was further fractionated by mono S or mono Q chromatography to prepare heterodimers containing a light chain and an A1-A2-B heavy chain (fVIII 166/76) or an A1-A2 heavy chain (fVIII 82/76). Mass analysis of scanning transmission electron microscopic (STEM) images of fVIII 166/76 indicated that heterodimers (mass 237 +/- 20 kD) had irregularly globular core structures 10-12 nm across, and frequently displayed a diffuse, occasionally globular to ovoid satellite structure extending 5-14 nm from the core, and attached to it by a thin stalk. Factor VIII 82/76 molecules (mass 176 +/- 20 kD) had the same core structures as fVIII 166/76 molecules, but lacked the satellite structure. These findings indicate that A1-A2 domains of heavy chains and the light chains of the fVIII procofactor molecule are closely associated and constitute the globular core structure, whereas the B domainal portion of heavy chains comprises the peripheral satellite appendage. Factor VIII core structures commonly displayed a finger-like projection near the origin of the B domainal stalk that was also a consistent feature of the free heavy chains (mass 128-162 kD) found in fVIII 166/76 preparations. Factor VIII light chain monomers (mass, 76 +/- 16 kD) were globular to c-shaped particles 6-8 nm across. These chains commonly possessed a v-shaped projection originating from its middle region, that could also be observed at the periphery of fVIII core molecules. Factor VIIIa preparations contained heterotrimers (mass 162 +/- 13 kD) that had the same dimensions as fVIII core structures, lacked the B domainal appendage, and sometimes possessed the same core features as fVIII molecules. Molecular species corresponding to heterodimers (mass, 128 +/- 13 kD) and unassociated subunit chains (40-100 kD) were also observed in fVIIIa preparations, suggesting that heterotrimers have an appreciable tendency to dissociate, a phenomenon that could explain the decay of fVIIIa activity after thrombin activation of fVIII.

The appearances on ultrasound of the female urethral sphincter.

A rounded or ovoid midline structure with mean measurements of 1.30 cm x 1.33 cm x 0.96 cm in longitudinal, transverse and antero-posterior dimensions was routinely imaged at the bladder base in 97 female patients on pelvic ultrasound examination. Its position and appearance are reminiscent of a smaller version of the male prostate, and it has been dubbed the "female pseudoprostate". It appears to correspond with the external rhabdo-sphincter of the bladder. Its rounded shape may be confusing but it should not be misread as pathological.

MR imaging of the carpal tunnel: normal anatomy and preliminary findings in the carpal tunnel syndrome.

MR imaging was performed through the carpal tunnel in 18 wrists of nine normal volunteers and compared with cryomicrotome sections from cadaver wrists. MR reliably imaged the flexor retinaculum and carpal bones and thus defined the borders of the carpal tunnel. In all cases the median nerve was seen as an ovoid structure of moderate signal intensity and was easily distinguished from the flexor tendons of the hands running in the carpal tunnel. The tendons were separated from each other by their tendon sheaths, and this allowed for identification of the various tendons. Anatomic variations encountered in the normal volunteers included anomalous positioning of the origin of the lumbrical muscles within the carpal tunnel in two, persistent median arteries in two, and interposition of the median nerve between the flexor pollicis longus and the superficial flexor tendon to the index finger in one. Preliminary observations in 10 wrists of patients with carpal tunnel syndrome include segmental and diffuse swelling of the median nerve in six, distortion of the nerve in one, and thickening of the tendon sheaths in one. We conclude that MR imaging accurately and reliably displays the normal anatomy of the carpal tunnel and can detect morphologic changes in patients with carpal tunnel syndrome.

Lepidotrachelophyllum fornicis, n. g., n. sp., a Ciliate with an External Layer of Organic Scales (Ciliophora, Litostomatea, Haptoria)1

Lepidotrachelophyllum fornicis n. g., n. sp. was discovered in White Lake, Ontario, Canada, under winter ice. The genus is Trachelophyllum-like, being highly flattened, elongate, and very extensible. The major feature that separates it from other genera in the family Trachelophyllidae is the presence of a dense layer of organic scales which covers the exterior of the cell and through which the cilia emerge. The scales are composed of filamentous material which is organized as an ovoid structure. The “rim” of the baseplate is formed of interwoven filaments. The baseplate is broken by circular or polygonal apertures. The same filaments form an arched superstructure broken by even larger, less regular apertures.

Anomalous systemic venous return: recognition by two-dimensional echocardiography.

The two-dimensional echocardiographic features of anomalies of systemic and coronary venous return are described as they were seen in 23 patients with this diagnosis proven at angiography. A left-sided superior vena cava draining to the right atrium via an enlarged coronary sinus was correctly identified in all 17 patients with this condition by observing a characteristically moving ovoid structure in the region of the posterior atrioventricular groove. This structure opacified before the right side of the heart following bolus injections of contrast material from a left arm vein. Injection from the right arm in 12 patients or femoral vein in four patients of this group produced contrast echoes within the right heart only. A left-sided superior vena cava draining directly to a left atrium in three patients, or left side of a common atrium in two patients with atrial situs inversus, was identified by the immediate opacification of the left-sided chamber following injection from the left arm. Two patients with hemiazygos inferior vena caval return to the left superior vena cava or left atrium were studied using injections of contrast from the femoral vein which successfully identified the venous abnormality. Two-dimensional echocardiography, when combined with peripheral venous injections of contrast will reliably demonstrate anomalies of systemic venous return, and thus provides important information before more invasive procedures.

746 A DE NOVO Y/A TRANSLOCATION WITH XO MOSAICISM IN A VIETNAMESE INFANT

A two-day old Vietnamese infant with ambiguous genitalia was referred to us for cytogenetic evaluation. He was the 2680 gram product of a full term pregnancy to a 20 year old mother. There was no family history of usage of drugs or birth control pills, or congenital anomalies. Physical findings were normal except that the genitourinary examination revealed a 3 cm long phallus with bifid scrotum, hypospadias, bilateral palpable gonads, normal kidneys, and midline ovoid structure consistent with an infantile uterus. There was no physical evidence of a vagina. Blood chromosome analysis by G-banding revealed two cell populations: 48 percent with 45,XO and 52 percent with 46,X,t(Y;Y) (p11;q12). The abnormal chromosome resembled a C-group chromosome in conventionally stained cells since the Y chromosome in Oriental populations normally has a large amount of heterochromatin. The heterochromatic segment involved in the translocation was confirmed by Q- and C-banding. The father's karyotype was normal, and the centromeric index of his Y chromosome was used to confirm our findings. The predominance of testicular tissue is due to the presence of complete euchromatic segments of the Y chromosome while the ambiguity of the genitalia may have resulted from the XO mosaicism.

Scarpa's ganglion in the rat and guinea pig.

This study describes the location of the cell-bodies of the primary afferent vestibular neurons (Scarpa's ganglion) in relation to the internal auditory meatus of the temporal bone in rats and guinea pigs. In these species the internal auditory meatus consists of three distinct opening or pores (foramina) into the temporal bone. The superior division of the vestibular nerve emerges from the dorsal-most foramen and the pars superior of Scarpa's ganglion is visible as a ridge or 'frill' which occupies the foramen. The inferior division of the vestibular nerve emerges from the cochlear foramen and the cell-bodies of the pars inferior of Scarpa's ganglion lie in the dorsal and rostral area of this foramen. A thin layer of cell-bodies, the isthmus ganglionaris, stretches across the bony transverse crest separating these two foramen. In the newborn rat Scarpa's ganglion is an ovoid structure lying within the cranial cavity.

Variation in the Susceptibility of African Acacia (Leguminosae) to Seed Beetle Attack

Summary. This paper is concerned with the apparent infestation anomalies which exist amongst various Acacia species, based on our present knowledge, and the need for further work to highlight the part played by beetles in the ecology of the various species. For those who have not seen either the adults or the damage caused by the larvae it may be useful to describe briefly the life-cycle. In most instances the female selects a ripening pod or, rarely, an already ripened one which has dehisced, and lays an egg, which (depending on the species concerned) is either a round or ovoid flattened structure closely adhering to the surface and held there by a secretion placed over it by the female. Alternatively the egg may be cylindrical and held to the pod by strands of ropelike secretion. The young larva on hatching bores through the pod wall and wanders around until it finds a suitable developing seed. It burrows into this ripening seed and hollows out a chamber, which it enlarges as it grows. When full- grown, it eats away the cotyledon and epidermal layer until a thin circular 'window' of very thin testa is left. The larva then pupates within its feeding chamber and the adult emerges by gnawing at the thin 'window' and pushing its way out. In a few species the full-grown larva leaves the seed and pod through a small circular hole, drops to the ground on a thread of silk and forms a pupal cocoon in the soil under the tree or shrub.

2. Ultrastructural Development of the Early Rat Otocyst

The ultrastructural development and differentiation of cells forming the rat otocyst were studied from the 9th to the 13th postcoital day (PCD). The earliest stage investigated was a simple ovoid structure with a connecting stalk to the surface ectoderm. A process of programmed cellular death involving surface ectoderm, connecting stalk, and lateral otocyst wall rapidly detached the otocyst. The cells forming the otocyst were roughly columnar, the organelles were polarized; mitochondria occurred in greatest number basally and in the supranuclear area; Golgi membranes when present were supranuclear. Luminal cells had many microvilli and cilia of various lengths were detected. The shorter, incompletely formed cilia terminated in small knob-like blebs. With each day the otocysts became more complicated and the endolymphatic duct made its appearance as an evagination of the otocyst. Many more cells were seen to have cilia in various stages of development, and by the 12th PCD possibly each cell of the main otocystic cavity had a kinocilium. Growth of the otocyst due to mitosis occurred to a great extent from a single ventromedial center. Cells in mitosis, although seen at other sites, were in greatest abundance in this area; cellular involution apparently was a related function. Together the process of over-production and programmed cellular involution of supranumerary cells not lost to other causes (e.g., environmental) may represent an evolutionary advantage.

The structure of human thyroglobulin

The structure of human thyroglobulin molecules was studied in the electron microscope using a negative staining technique. Molecules from normal, well-iodinated thyroid glands showed an ovoid structure similar to that described for bovine and rat thyroglobulin. Poorly iodinated thyroglobulin molecules were obtained from patients with nontoxic nodular goiter and carbimazol treated toxic diffuse goiters. In two cases more than 50% of the thyroglobulin molecules appeared as cylindrical structures, similar to those found in preparations of poorly iodinated rat thyroglobulin. However, in another two low-iodinated preparations almost all molecules appeared as ovoids with a shape similar to that of normal thyroglobulin. It is concluded that although the proportion of cylindrical molecules may increase in iodine deficiency, iodine is not an indispensable factor for the conversion of cylindrical molecules to ovoid molecules.

Three-dimensional structure of the osmium-impregnated Golgi apparatus as seen in the high voltage electron microscope.

AbstractOsmication in an unbuffered aqueous solution of osmium tetroxide allows the forming face of the Golgi apparatus to be labeled in many cell types. This property was utilized to study the spatial configuration of this organelle by examining stereopairs of the same field taken at 1,000 KV after tilting a thick (1 to 7 μUm) section of − 7° or + 7° from the original (0°) position. When examined in 1 μm thick sections at magnifications ranging from 13,000 to 18,000 times, the osmic acid‐impregnated element of the Golgi apparatus of ganglion nerve cells, Leydig cells or Sertoli cells takes the appearance of a single layered polygonal network of tubules. This network can only be seen at electron microscope magnifications and is referred to as the primary network or structure of the forming face of the Golgi apparatus. When 2 to 7 μm thick sections are examined under progressively lower magnifications, the details of the primary structure remain discernible but become less conspicuous. The osmiophilic portion of the Golgi apparatus now extends over large areas of the cytoplasm to form an extensive continuous structure. This structure which is in the range of visibility of the light microscope is referred to as the secondary network or structure of the forming face. In ganglion nerve cells, the secondary structure consists of a perinuclear network showing slender projections reaching the nucleus and wider expansions approaching the cell surface; in the Leydig cells it appears as an ovoid structure located at one pole of the nucleus whereas in Sertoli cells it forms a cylindrical structure located in the main shaft of the cytoplasm and extending from the nucleus towards the lumen of the seminiferous tubule. Thus the forming face of the Golgi apparatus displays a primary structure; the tubular roughly polygonal network, which is similar in the three cell types and a secondary structure which varies from cell to cell.