Thalamic projections of the superior colliculus in the rhesus monkey, Macaca mulatta. A light and electron microscopic study.

The projections of the superior colliculus to the thalamus have been studied in the monkey, Macaca mulatta, with anterograde degeneration techniques. The superior colliculus has been shown to project to the inferior nucleus of the pulvinar in a topographical manner with the lower visual field represented dorsomedially and the upper field ventrolaterally. The peripheral zone is located along the medial border and the fovea at the dorsolateral angle adjacent to the lateral geniculate nucleus. The superior colliculus also sends a dense projection to the ipsilateral intralaminar complex, i.e., to the parafascicular, central lateral and paracentral nuclei, and a lesser projection to the same contralateral nuclei. Degenerating tectal fibers were also found in the lateral geniculate nuclei. Four types of vesicle containing profiles were observed in the inferior pulvinar and paracentral nucleus. The large RL and small RS terminals contain round vesicles of uniform size and form asymmetric contacts mainly with large and small dendrites respectively. The F terminal contains a mixture of small round and flat vesicles. It forms symmetric contacts with dendrites and cell somata. The P profile is very pale and contains a relatively sparse population of vesicles showing a great variation in size. It forms symmetric contacts with medium to large dendrites. It is frequently found postsynaptic to the other types, especially the RL terminal, and is regularly seen as the intermediate element of serial and triadic synaptic arrangements. The experimental electron microscopic study has shown that many fibers from the superior colliculus terminate as RL profiles, undergoing direct dense degeneration, in both the inferior pulvinar and the paracentral nucleus. Others probably end as smaller RS terminals.

Bilateral thalamic glioma: review of eight cases with personality change and mental deterioration.

PURPOSE: To describe the clinical, radiographic, and neuropathologic features of bilateral thalamic glioma. METHODS: We searched our hospital records (1963 to present) to identify patients diagnosed as having the disease. RESULTS: Our search revealed eight patients, ranging in age from 8-63 years, with bithalamic tumor diagnosed by angiography, CT, and/or MR. All patients displayed personality changes and/or mental deterioration, including memory loss, inattention, confusion, hallucination, hyperphagia, or slow mentation. Unilateral motor weakness was also noted in six cases. The tumor always involved the medial aspect of the left and right thalami, but was often more extensive. The pathology was determined to be grades I-IV astrocytoma, confirmed by stereotactic biopsy or autopsy in six. Mild to moderate hydrocephaly occurred in some cases and was considered to be a contributing factor to mental deterioration. No correlation was found between age and type of tumor. CONCLUSIONS: Bilateral glioma of the dorsomedial and intralaminar nuclei of the thalamus can be a primary cause of dementia that has not been well-recognized in the past. CT and particularly MR should be considered for patients presenting with personality change or dementia, because of the possible presence of this unusual but devastating disease.

A reinvestigation of the spinovestibular projection in the cat using axonal transport techniques.

There are numerous discrepancies within the literature concerning the sources of spinovestibular fibers and their distribution in the vestibular complex. Sources of afferents from all spinal levels were sought using the retrograde transport of wheat germ agglutinin conjugated to horseradish peroxidase. Following injections of this tracer in all portions of the vestibular complex retrograde labelling was densest at upper cervical levels, especially within the contralateral central cervical nucleus. Labelling was also observed in laminae VI (ipsilaterally), IV, V, VII, and VIII (bilaterally). At progressively more caudal levels, numbers of labelled cells decreased but were similarly distributed in these laminae. The terminal distribution of spinal efferent fibers within the vestibular complex was revealed by injecting wheat germ agglutinin conjugated to horseradish peroxidase or tritiated amino acids into various levels of the spinal cord. These studies showed that all spinal levels project to the descending vestibular nucleus and group x. The f-tail of the descending vestibular complex receives projections from upper cervical and thoracic levels. Terminations within the medial vestibular nucleus arise from both upper cervical and lumbar levels. No conclusive evidence was found supporting the presence of substantial direct spinal projections to the lateral vestibular nucleus, superior vestibular nucleus, or group z. Possible functional roles for the spinovestibular projection in posture and gaze are discussed.

Ultrastructure of the ventral lateral geniculate nucleus (LGNv) receiving tectal afferents in the cat.

The ultrastructure of the ventral lateral geniculate nucleus (LGNv) associated with the superior colliculus was investigated. In addition to normal synaptic morphology tectal input was examined following unilateral ablation of the superior colliculus at survival times of 2 to 12 days. Eight cats were used (six experimental, two control). Examination of the ventromedial LGNv revealed a prevalence of Flat-Symmetric (FS) synapses (58.2 +/- 1.9%), relative to the usually more abundant, Round-Asymmetric (RA) contacts (41.8 +/- 1.8%). The functional morphology of terminating tectal fibres (although infrequent) was suggestive of the FS type. Since FS connections usually serve an inhibitory purpose, it is suggested that the tectal LGNv connection has a negative modulation function in the fixation and tracking process.

Comparison of androst-16-ene steroid levels determined by a colorimetric assay with boar taint estimated by a trained sensory panel.

A group of 17 intact male pigs and 3 gilts ranging in weight from 96 to 260 kg was selected for sensory evaluation of boar taint in loin chops. Samples were evaluated by 10 trained judges using a 10-cm graphic scale for rating off-aroma, off-flavor, pork flavor, softness, tenderness, juiciness, and residual tissue. In addition, a fry test for taint was conducted by four experienced testers on fat samples from all animals. Androst-16-ene steroid levels were measured in salivary gland and fat. Two versions of a colorimetric assay for the androst-16-ene steroids were used, a complete version, in which cholesterol was removed from the tissue extracts using a digitonin-Sepharose affinity column, and a simplified version, which does not include this step. The off-aroma and off-flavor sensory scores showed a good correlation with the androst-16-ene levels in fat and salivary glands and high correlations were obtained between the androst-16-ene steroid levels in fat and salivary glands. The levels of the androst-16-ene steroids in the salivary gland were highly correlated with the levels of estrogen in the blood and to a lesser extent with the levels of testosterone in the blood. Similar correlation coefficients were obtained between salivary gland androst-16-ene steroid levels measured using either the complete or simplified versions of the colorimetric assay and the off-aroma and off-flavor sensory scores. The results of the fry test were variable and no statistically significant correlations were obtained between the fry test results and the off-aroma and off-flavor sensory scores from the trained sensory panel.(ABSTRACT TRUNCATED AT 250 WORDS)

Attempts to restore abduction of the paralyzed equine arytenoid cartilage. I. Nerve-muscle pedicle transplants.

The purpose of this project was to adapt a surgical technique from humans and dogs to horses in which a portion of an accessory muscle of respiration and its nerve supply is transplanted to a denervated dorsal cricoarytenoid muscle. Anatomical dissections in seven horses revealed two possible donor nerve-pedicle grafts: the omohyoid and the sternothyrohyoid, both innervated by a branch of the first and second cervical nerves. Histochemical evaluations in two ponies of the dorsal cricoarytenoid, omohyoid and sternothyrohyoid muscles revealed similar proportions of fiber types 1 and 2 in all three muscles. Electromyographic studies in these two ponies revealed that the omohyoid and sternothyrohyoid muscles contract synchronously with respirations during forced inspiration under general anesthesia. Based on surgical ease of access, a 1 cm2 portion of the omohyoid muscle at the point of penetration of the second cervical nerve was used as a nerve-muscle pedicle graft in an attempt to reinnervate the left dorsal cricoarytenoid muscle in four ponies. These four ponies (as well as three others which served as controls) had previously undergone left recurrent laryngeal nerve transection. All seven ponies endoscopically showed signs of complete left laryngeal hemiplegia immediately postoperatively. Animals were monitored endoscopically for 30 weeks after surgery. The three control ponies showed no abduction of the arytenoid cartilage. In addition, in these three ponies, histological and histochemical expected changes of muscle fiber atrophy and fibrosis were present in the dorsal cricoarytenoid muscle.(ABSTRACT TRUNCATED AT 250 WORDS)

Attempts to restore abduction of the paralyzed equine arytenoid cartilage. II. Nerve implantation (pilot study).

The purpose of this project was to attempt restoration of abduction of a recently experimentally denervated left dorsal cricoarytenoid muscle by implanting a transected nerve-end into the paralyzed muscle. In six ponies the cut end of the second cervical nerve was implanted into a slit made in the left dorsal cricoarytenoid muscle. The nerve end was secured in place with one 5-0 polypropylene suture connecting the epineurium to the epimysium. The left recurrent laryngeal nerve was transected during this procedure. All six ponies showed signs of complete left laryngeal hemiplegia immediately after surgery. Postoperatively all ponies were evaluated qualitatively on a monthly basis by subjective examination for evidence of abduction of the arytenoid cartilages on endoscopy and quantitatively by measurement of the cross sectional area of the left and right half of the rima glottidis. Subjective endoscopic evidence of partial abduction was seen in four of the six ponies six months postoperatively. Measurement of the cross sectional area of the rima glottidis revealed a total loss of 38% of the area immediately postoperatively. There were no significant changes in cross sectional areas of the rima glottidis between the immediate postoperative evaluation to the six months postoperative evaluation. Gross postmortem examination revealed partial dorsal cricoarytenoid muscle atrophy as evidenced by a 24-55% decrease in muscle mass compared to the right dorsal cricoarytenoid muscle. Histopathological studies revealed regions with clusters of large muscle fibers.(ABSTRACT TRUNCATED AT 250 WORDS)

Attempts to restore abduction of the paralyzed equine arytenoid cartilage. III. Nerve anastomosis.

The purpose of this project was to attempt restoration of abduction of a recently denervated left dorsal cricoarytenoid muscle in the horse by anastomosing the first cervical nerve to the abductor branch of the left recurrent laryngeal nerve. Ten horses were used in the study. In six horses the left recurrent laryngeal nerve was transected and ligated while the ventral branch of the left first cervical nerve was anastomosed to the abductor branch of the left recurrent laryngeal nerve. The remaining four horses also had the left recurrent laryngeal nerve transected and ligated but had no nerve anastomosis performed. Each horse was evaluated preoperatively, and at one week, three and six months after surgery, by endoscopy and determination of upper airway resistance. The endoscopy was performed with the horses breathing room air and while breathing 10% carbon dioxide. All ten horses showed endoscopic signs of complete laryngeal hemiplegia immediately postoperatively. Starting at three months postoperatively clonic movements of the left arytenoid cartilage were observed in four of the six reinnervated horses but not in the sham operated horses. At the sixth postoperative month five reinnervated horses had clonic movements of the left arytenoid cartilage. The comparison of upper airway resistance measurements before surgery and at one week, three and six months after surgery showed no significant differences in either control or experimental horses. Following euthanasia at six months postoperatively, the left and right dorsal crioarytenoid muscles were compared for evidence of reinnervation. No significant difference in weight was noted in the reinnervated horses but the left dorsal cricoarytenoid muscle weighed less than the control horses.

Prevalence and types of birth defects in Ontario swine determined by mail survey.

Preweaning mortality in piglets constitutes a major loss to the swine industry. Congenital defects account for a small but significant proportion of these losses. To implement appropriate strategies to reduce such losses, it is necessary to identify the specific causes and their relative importance. Consequently, a mail survey of swine production in Ontario was carried out to determine the prevalence and types of birth defects. Statistical comparisons of the prevalence of overall defects were made between accurate and estimate records, breeds (cross vs. purebred), size of operation (number of sows) and geographic location. The mean litter size of 11 pigs born per sow was not significantly different for those with accurate versus estimate records, but the difference in the prevalence of defective pigs (live and dead) was significant (accurate 3.1% vs. estimate 4.1%). Splayleg (spraddleleg) was the most common defect. The next four defects for both groups were belly rupture, other rupture, ridglings and other, but not in the same ranking. Purebred and small farm operations (< 25 sows) had a significantly higher prevalence of birth defects for estimated data only. Geographic location had no effect. Further work is required to determine whether recording prevalence of birth defects in Ontario swine will provide a useful monitor of environmental stress. The study provides a baseline for the prevalence and type of defects in Ontario swine.

Schistosomus reflexus syndrome: a heritable defect in ruminants.

Schistosomus reflexus (SR) is a rare and fatal congenital disorder. Primarily observed in ruminants, its defining features include spinal inversion, exposure of the abdominal viscera because of a fissure of the ventral abdominal wall, limb ankylosis, positioning of the limbs adjacent to the skull and, lung and diaphragm hypoplasia. Variable components of SR include scoliosis, cleft sternum, exposure of thoracic viscera, and abnormalities of the digestive and urogenital systems. This report presents the findings from an anatomical analysis of a female Holstein SR calf with thoracoschisis, scoliosis and anomalies of the appendicular skeleton, cardiovascular, respiratory, digestive and urogenital systems. Many of these malformations have not been previously reported. The reproductive tract of this case is particularly unique, displaying Muellerian duct abnormalities. These abnormalities suggest SR occurs as early as the post-gastrulation embryo and involves the intermediate mesoderm. Preliminary analysis of associated cases suggests that SR has a genetic aetiology.

Two-headed, two-necked conjoined twin calf with partial duplication of thoracoabdominal structures: role of blastocyst hatching.

Gross anatomical analysis of a derodidymic monosomic stillborn male calf from an embryo transfer recipient was carried out. Two normal heads were present on two necks which were fused at the shoulders. Although the ribs were abnormal in shape and number, there was one trunk and four legs. The vertebrae were double and partially fused from the thoracic region to the sacrum, which was singular and normal. In the thoracic region there was a single vertebral canal that contained two incompletely fused spinal cords which shared common meninges. In the lumbar region there was a spina bifida. The medial neck musculature was variously fused. Two esophagi entered one enlarged rumen and the liver and gallbladder had extra lobes. Two sets of lungs occupied three pleural cavities and also part of the pericardial cavity. Two hearts were joined by a common cavernous venous sinous. The vasculature cranial to the heart reflected the doubling. The vasculature caudally was singular. The calf was uniscrotal and ipsilaterally cryptorchid. Our results are consistent with the hypothesis that atypical "hatching," that is, emergence of the blastocyst from the zona pellucida, may cause anomalous twinning.

Morphology of a two-headed piglet.

A live-born, one-day-old diprosopic piglet was presented to the Ontario Veterinary College. The piglet had a normal body with two heads, joined in the occipital region. There were two complete snouts, four eyes and three ears. The lower jaws were immobile because of overlapping mandibular rami. Although there was only one vertebral column, the bodies of the vertebrae, but not the neural arches, were doubled from the axis to T8. There was one thyroid gland and one larynx and hyoid apparatus. The two tongues were joined at their base just rostral to the single epiglottis. The palate was completely split in the right head but only partially split in the left. the cranial nerves were normal and doubled except for IX, X and XI. The brains were fused at the pon-medulla junction. An anomalous midline tag of neural tissue resembling remnants of the medical halves of two nervous systems extended form this point to the level of T8. Possible developmental mechanisms and rates of incidence are discussed.

Conjoined twin piglets with duplicated cranial and caudal axes.

BACKGROUND: Twins with doubling of the cranial and caudal poles, yet having a single thorax, are rare. METHODS: One set of diprosopus, dipygus porcine conjoined twins was studied. RESULTS: In addition to the conjoining anomaly, these twins also exhibited ambiguous internal reproductive features. The twins had two snouts, three eyes, a single thorax, and were duplicated from the umbilicus caudally. Radiography indicated a single vertebral column in the cervical region. The vertebral columns were separate caudally from this point. There was a total of six limbs--one pair of forelimbs and two pairs of hindlimbs. Many medial structures failed to develop in these twins. Medial cranial nerves V-XII were absent or displaced although apparently normal laterally. The medial palates were present but shortened, whereas the medial mandibular rami had folded back on themselves rostrally to form a midline mass between the two chins. Each twin had only one lateral kidney and one lateral testis. Medial scrotal sacs were present but devoid of a testis. There was a midline, "uterine"-like structure which crossed between the twins. However, histological analysis of this structure revealed it to be dysplastic testicular tissue. CONCLUSIONS: The relationship between the abnormal reproductive features in these twins and the conjoining is unclear. The anatomy of these twins, in addition to the literature reviewed, illustrates the internal anatomical heterogeneity of grossly similar conjoined twins. A review of the literature also suggests that conjoined twinning may be more common in swine than was previously suspected.

Clinical and anatomical observations of a two-headed lamb.

The clinical and anatomical features of a live-born diprosopic lamb are described. There are no complete anatomical analyses of two-faced lambs in the literature despite the frequency of conjoined twinning in sheep. The lamb had two heads fused in the occipital region. Each head had two eyes. The pinnae of the medial ears were fused. Caudal to the neck the lamb appeared grossly normal. The lamb was unable to raise its heads or stand. Both heads showed synchronous sucking motions and cranial reflexes were present. Nystagmus, strabismus, and limb incoordination were present. The respiratory and heart rates were elevated. There was a grade IV murmur over the left heart base and a palpable thrill on the left side. Each head possessed a normal nasopharynx, oropharynx, and tongue. There was a singular laryngopharnyx and esophagus although the hyoid apparatus was partially duplicated. The cranial and cervical musculature reflected the head duplications. The aortic trunk emerged from the right ventricle just to the right of the conus arteriosus. A ventricular septal defect, patent foramen ovale, and ductus arteriosus were present along with malformed atrioventricular valves. Brainstem fusion began at the cranial medulla oblongata between cranial nerves IX and XII. The cerebella were separate but small. The ventromedial structures from each medulla oblongata were compressed into an extraneous midline remnant of tissue which extended caudally to the level of T2. The clinical signs therefore reflected the anatomical anomalies. A possible etiology for this diprosopus might be the presence early in development of an excessively large block of chordamesoderm. This would allow for the formation of two head folds and hence two "heads."

Agonadal presumptive XX/XY leukochimeric pig.

BACKGROUND: XX/XY chimeric pigs are uncommon and their reproductive anatomy is variable and unpredictable. METHOD: A piglet was identified by its enlarged vulva as a possible intersex. Venous blood was collected at 1.5 and 9 months for karyotyping and determination of testosterone and estrone sulphate concentrations. At 1 year euthanasia was performed. The reproductive tract was carefully dissected and examined histologically. RESULTS: As the animal matured the vulva did not develop relative to the size of the animal. Lymphocyte cultures indicated a 70% XX/30% XY chimera. The reproductive tract consisted of a strand of tissue enveloped by fascia. Histological study revealed presumptive Wolffian derivatives, coiled bilateral ducts along the tract, and a Müllerian derivative, a medially located duct in the caudal third of the tract. No gonads were found. Plasma levels of estrone sulfate and testosterone were negligible. CONCLUSIONS: In utero exposure to exogenous androgens from a male co-twin or weak endogenous adrenal androgens may account for the enlarged vulva at birth and retention of the androgen dependent Wolffian duct primordia. An atesticular state is supported by retention of the Müllerian duct primordia and the negligible peripheral sex steroids.

Anatomical observations of holoprosencephaly in swine.

In a study of swine congenital anomalies, nine newborn piglets with varying degrees of optic hypotelorism including cyclopia were collected. Nasal and maxillary development were abnormal in all animals regardless of the degree of eye fusion. All animals except one had intact upper lips and hard palates that carried two or three small extopic teeth. The "snout" was only a medial wedge-shaped rudiment projecting from the upper lip. It was distally covered by a typical snout-like glabrous epithelium and carried small vibrissae. Six animals also had a tubular proboscis dorsal to the eye. The distal tip of the proboscis was covered by glabrous epithelium. External nares and nasal passageways, albeit blind-ended, were prominent in the proboscis. The nasofrontal bones projected into the base of the proboscis. Seven piglets were hairless except for fine vibrissae and some eyebrow hairs. All animals had some degree of ear abnormalities, e.g., malposition and absence of external auditory meatus. In all animals the brain was malformed. This abnormality varied from complete absence of the forebrain to an alobar structure with gyri. The remainder of the body of each animal was normal. Developmental anomalies of the nose and eye generally reflect malformations of the forebrain, although the etiology of these defects is unclear. The cyclopia associated with the medial proboscis suggests that both the telencephalon and diencephalon are dysplastic. The presence of glabrous epithelium in two regions on the face suggests that studies of the development of the midline face in the swine will help to elucidate the etiology of the holoprosencephalic series. In this way the pig may prove to be an excellent modeling system for human holoprosencephaly.

Rectal resection in the dog. A new surgical approach and the evaluation of its effect on fecal continence.

Thirteen healthy mixed breed dogs (6 female and 7 male) underwent rectal transection and resection of 0 to 6 cm using a dorsal approach. Rectoanal sphincter pressure studies were performed preoperatively and 6 weeks after surgery using a double balloon manometer device. Sphincter pressure profiles were altered in the 6 cm resection dogs. Clinical observations of defecation and degree of continence were made over a 10 week period postoperatively. The transection only and 4 cm resection dogs defecated normally. All dogs in the 6 cm resection group involving the peritoneal reflection were incontinent but retained some normal posturing behavior. Surgical complications included minor infection in two dogs, rectocutaneous fecal leakage in four dogs, breakdown of the anastomotic site in four dogs, and incontinence in all of the dogs that underwent 6 cm resections. Barium enemas were performed on the rectums postmortem to ascertain the degree of stricturing induced by the surgery. The index of stenosis measured did not correlate well with the extent of straining in each group. Histopathologic findings on dogs in the transection only and 4 cm resection groups without dehiscence showed mild granulomatous proctitis with normal myenteric plexi seen. Dogs suffering dehiscence had suppurative proctitis, necrosis, and obliteration of the myenteric plexi.