Fetal Cats Research Articles

Stereological study of cerebellar morphology in feline fetuses: Insights from the final gestational stage

This study aimed to conduct a morphoquantitative and stereological evaluation, analyzing the cerebellum of domestic cat fetuses in the latter third of the gestational period. Fetal samples were obtained from a neutering campaign conducted in the municipality of Guarulhos, São Paulo, Brazil. The procedures and protocols used in this work adhere to the guidelines established by the ethics committee of the School of Veterinary Medicine and Animal Science at the University of São Paulo (FMVZ/USP), under the number CEUA 1935251121. The five selected fetuses were fixed in 4 % formaldehyde, and their gestational age was determined by Crown Rump (CR) measurements, followed by an assessment of external characteristics. The cerebella were subjected to the evaluation of morphometric parameters and histological processing using stereology techniques. The obtained means for the cerebellar parameters were as follows: length: 1.0-centimeter, width: 0.54 centimeters, thickness: 0.44 centimeters, and weight: 0.84 g. Using stereology, the following parameters were determined: cerebellar volume, averaging 0.847 cm³; volume density of the cortex: 0.496 or 49 % (molecular layer), 0.0314 or 3.14 % (Purkinje cell layer), 0.232 or 23 % (granular layer), and 0.234 or 23 % (medullary white center). Consequently, the average total volume of the cerebellar cortex is 0.419 cm³ for the molecular layer, 0.026 cm³ for the Purkinje cell layer, 0.196 cm³ for the granular layer, and 0.196 cm³ for the medullary white center. The findings presented here have contributed to an in-depth discussion of the neuro-motor development and cerebellum of domestic cats.

Protease activated receptor 2 and matriptase expression in the joints of cats with and without osteoarthritis.

The aim of this study was to determine the presence of protease-activated receptor 2 (PAR2) and matriptase proteins and quantify PAR2 and matriptase mRNA expression in the articular cartilage and synovial membrane of cats with and without osteoarthritis (OA). A total of 28 articular cartilage samples from adult cats (14 OA and 14 normal), 10 synovial membranes from adult cats (five OA and five normal) and three cartilage samples from 9-week-old fetal cats were used. The presence of PAR2 and matriptase in the cartilage and synovial membrane of the adult samples was detected by immunohistochemical (IHC) staining, while real-time PCR was used for mRNA expression analyses in all samples. PAR2 was detected in all OA and normal articular cartilage and synovial membrane samples but confined to only a few superficial chondrocytes in the normal samples. Matriptase was only detected in OA articular cartilage and synovial membrane samples. PAR2 and matriptase mRNA expression were, however, detected in all cartilage and synovial membrane samples. PAR2 and matriptase mRNA expression levels in OA articular cartilage were five (P <0.001) and 3.3 (P <0.001) times higher than that of the healthy group, respectively. There was no significant difference (P = 0.05) in the OA synovial membrane PAR2 and matriptase mRNA expression compared with the normal samples. Detection of PAR2 and matriptase proteins and gene expression in feline articular tissues is a novel and important finding, and supports the hypothesis that serine proteases are involved in the pathogenesis of feline OA. The consistent presence of PAR2 and matriptase protein in the cytoplasm of OA chondrocytes suggests a possible involvement of proteases in cartilage degradation. Further investigations into the PAR2 and matriptase pathobiology could enhance our understanding of the proteolytic cascades in feline OA, which might lead to the development of novel therapeutic strategies.

Morphology and topography of internal reproductive organs in the female cat during prenatal and postnatal development: Scanning electron microscope and three-dimensional reconstruction study.

The study describes the morphology and topography of internal reproductive organs in the domestic cat from the early prenatal period to maturity, using macroscopic and scanning electron microscope (SEM) observations with three-dimensional (3D) reconstructions. Fifty-seven female cat fetuses aged between the 27th and 63rd day postconception (p.c.), two newborn cats, three juveniles (3-month-old) cats, and three mature (12-month-old) cats were used in the study. The age of fetuses was determined on the basis of the growth curve for the domestic cat. The rudiments of cat ovaries develop on the ventral surface of the mesonephroi and within 30 days p.c. move to the sides of the abdominal cavity, which is similar to the position of the ovaries in the adult cat. The mesonephroi regress at about the 50th day p.c., when the residual mesonephric ducts are still found in the lower part of the body of the uterus. The paramesonephric ducts develop on the lateral surface of the mesonephroi and by the 45th day p.c., differentiate into the uterine tubes and the uterus. The arrangement of the paramesonephric ducts in the abdominal cavity changes from the U- to the V-shaped system. The final topography of the uterine tubes is established between the 54th and 60th day p.c., as the uterine tubes become convoluted. Before the 54th day p.c., the uterine horns undergo rapid elongation and convolution, forming the W-shaped system. By the third month of postnatal life, the uterine horns become straight, as in the adult cat.

Schistosomus reflexus in a Dog and a Cat

Background: Schistosomus reflexus (SR) is a congenital anomaly, that the animal presents exposed abdominal and thoracic organs. The alterations includes limbs malformation, abnormal spinal column, liver and diaphragm hypoplasia, genitourinary and gastrointestinal changes, on this way, the fetus can not survive. The aim of this study was to report the first SR case in dog and cat in Brazil, and describe anatomical, pathological and radiographic changes.Case: The puppy had ventral midline defect in the abdominal and thoracic wall extending from the sternum to the pubis with viscera exposition, including the heart, lung, liver, stomach, intestine, spleen, kidneys, moreover right army was abnormal, however no spinal column was present. It was performed radiography to evaluate bone abnormalities, and was diagnosed agenesis of carpal, metacarpal and phalange bones. The kitten had ventral midline defect measuring 4 x 2 cm, in the abdominal wall and exposition of liver, stomach, intestine and spleen, as well as tibiotarsal joint arthrogryposis on both lags. It was performed fetus radiography and no spinal column change was diagnosed.Discussion: Schistosomus reflexus is a congenital abnormality common in ruminants. Although it was few reported in dogs and cats. The two cases in this study are the firsts reposts in Brazil in these especies. In our case, the dog had exposition of abdominal and thoracic organs and died one hour after born, similar to this, another author reported a case where the thoracic and abdominal evisceration and the puppy died ten minutes after born. However, in another case with abdominal evisceration only, the puppy survived for eight days. Probably it happened because respiratore function was not compromised. The kitten had abdominal opening only, in turn, other authors reported a case whose abdominal viscera exposition was by pelvic fissure, and another case, what presented thoracic and abdominal evisceration, like our dog case. Some authors affirm that this defect causes fetal dystocia on ruminants, because of the vertebral column abnormality, what promote passage difficult at born moment. On the other hand, dogs did not present these kind of changes and dystocia was not related to this pathology on cases in dogs and cats, however most of these authors performed cesarean because the female did not get normal born. As well as, on two cases in kitten were reported vertebral column abnormalities, what can be related to dystocia. Even no animal of our study present any vertebral column abnormality, other bone changes were found, like carpal, metacarpal and phalange agenesis on army of the dog and tibiotarsal joint arthrogryposis on both lags of the cat fetus. The others report in dogs did not found vertebral column or bone changes, but in cats it was observed vertebral column abnormalities and other changes, like arthrogryposis on four limbs, skull flattening, mandibular brachignathism, reduced ossification of the cranial vault bones, palatoschisis and unfused eyelids. SR etiology is not clearly known, it may be related with genetic, mechanic, endocrine, metabolic, nutrition and infectious factors. The moment of embryonic development, where these factors influence the changes is related with abnormality grade. Although, Chromosomic abnormalities, like chromatid and chromosome breaks, non-homologous pairing of chromosomes was shown. In this study the bitch did not present any metabolic, endocrine or nutritional change, on other hand the queen was submitted to exogenous hormonal treatment to avoid pregnancy, what may be related to SR development. SR is a rare abnormality in dog and cat, fetus radiographic, anatomical and pathological findings confirmed to being this congenital defect, and this are the first reports in Brazil in these species.

Вплив трансплантації культур клітин на перебіг експериментального цукрового діабету у тварин

As we know from the literature data, type 1 diabetes mellitus occurs due to the loss of β-cells of island of Langerhans, manufacturing insulin, by the organism, which causes its deficiency. The treatment of this type of diabetes, even at early stages, lies in the substitution therapy together with a careful control of blood glucose which may last for life. It is for this reason that the cellular technologies as an alternative method of treatment of this pathology are growing more and more relevant.Objective of the study: to study the impact of allogenic transplantation of the cultures of bone marrow, lipid tissue and pancreas cells on the course of experimentally generated diabetes mellitus in animals.Task: 1. To obtain the cultures of bone marrow, lipid tissue and pancreas cells in rats. 2. To compare the impact of allogenic transplantation of the cultures of bone marrow, lipid tissue and pancreas cells in the course of experimentally generated diabetes mellitus in rats. 3. To study the impact of pancreas cells culture on the course of experimental diabetes mellitus in cats.The studies were conducted using clinically healthy animals (30 males of white non-pedigree rats with body weight of 200–250 g, aged 4–5 months; 9 white non-pedigree junior rats aged 12 days; 4 mongrel cats aged 15–17 months) and missed fetuses of cats remained after obstetric aid.Alloxan diabetes was generated by means of single subcutaneous injection of alloxane monohydrate in the dose of 150 mg/kg in the form of 5% solution on citrate buffer (pH 4.5) after preliminary 24-hour absolute diet with free access to water.The cultures of bone marrow and pancreas cells were obtained from the bone marrow of tubular bones and pancreas of puppies aged 12 days correspondingly, lipid tissue – from rats aged 4–5 months. The culture of cats’ pancreas cells was obtained from the pancreas of cat fetuses. Cell culture process was carried out according the standard method in CO2- incubator. Glucose level in blood serum was determined by means of electrochemical analysis.The results of the study. The authors studied the impact of allogenic transplantation cells culture of bone marrow, lipid tissue and pancreas on the course of experimentally generated diabetes mellitus in rats. The study revealed the decrease of glucose level in the blood of the animals under investigation at cell material transplantation. The most efficient culture for experimental diabetes mellitus therapy is the culture of pancreas cells which has become the cause of its further study in cats.During allogenic transplantation cells culture of pancreas in cats the authors observed abrupt decrease of glucose level in the blood of the animals under investigation immediately after cell transplantation with the further approximation to the initial state.The experimental models presented the positive effect of cell culture transplantation providing the grounds for the further implementation of this diabetes mellitus therapy method in the clinical practice.

Efficient Transduction of Feline Neural Progenitor Cells for Delivery of Glial Cell Line-Derived Neurotrophic Factor Using a Feline Immunodeficiency Virus-Based Lentiviral Construct

Work has shown that stem cell transplantation can rescue or replace neurons in models of retinal degenerative disease. Neural progenitor cells (NPCs) modified to overexpress neurotrophic factors are one means of providing sustained delivery of therapeutic gene products in vivo. To develop a nonrodent animal model of this therapeutic strategy, we previously derived NPCs from the fetal cat brain (cNPCs). Here we use bicistronic feline lentiviral vectors to transduce cNPCs with glial cell-derived neurotrophic factor (GDNF) together with a GFP reporter gene. Transduction efficacy is assessed, together with transgene expression level and stability during induction of cellular differentiation, together with the influence of GDNF transduction on growth and gene expression profile. We show that GDNF overexpressing cNPCs expand in vitro, coexpress GFP, and secrete high levels of GDNF protein—before and after differentiation—all qualities advantageous for use as a cell-based approach in feline models of neural degenerative disease.

Disseminated Cutaneous Mast Cell Tumors with Epitheliotropism and Systemic Mastocytosis in a Domestic Cat

A 15-year-old female domestic, medium-haired cat presented to the referring veterinarian with a 2-month history of multiple, raised, disseminated, nodular skin lesions. A biopsy of 1 of the lesions was submitted to the Oklahoma Animal Disease Diagnostic Laboratory for evaluation. Histologically, there were multiple dermal nodules composed of sheets of neoplastic round cells. Multifocally, the neoplastic cells formed multiple small clusters of 3 to 5 cells within the epidermis. Distinct cytoplasmic granules were evident within the neoplastic cells with toluidine blue and Giemsa stains. The neoplastic cells were immunoreactive for c-KIT and lacked immunoreactivity for cluster of differentiation 3 with immunohistochemistry. Based on these findings, multiple epitheliotropic cutaneous mast cell tumors were diagnosed. The cat's health declined rapidly despite aggressive treatment, and the animal was humanely euthanatized. A complete necropsy revealed sheets of similar neoplastic mast cells within the spleen, liver, and individual cells scattered within the bone marrow. Exon 11 of the c-KIT messenger RNA from 1 of the cutaneous masses and the spleen was amplified with reverse transcription polymerase chain reaction, sequenced, and compared with the published c-KIT messenger RNA sequence from fetal cat tissues. The maximum identity was 100% for both tissue samples. To the authors' knowledge, the present report is the first to describe disseminated cutaneous mast cell tumors with epitheliotropism and systemic mastocytosis in a domestic cat.

Developmental Changes of Muellerian and Wolffian Ducts in Domestic Cat Fetuses

At 0.8 cm of crown-rump length (CRL) in sexually undifferentiated cat fetuses, the Wolffian duct is already observable on the ventro-lateral side of the mesonephros. At 1.2 cm CRL, the anlage of the Müllerian duct growing caudally in close parallel with the Wolffian duct was first observed. At 2.8 cm CRL in sexually differentiated fetuses, the Müllerian duct reached the urogenital sinus but remained indiscernible. Subsequently, at 3.2 cm CRL, regression of the upper part of the Müllerian duct was visible in males, while both ducts continued to grow in females. This suggests that the Müllerian inhibiting substance is produced before 3.2 cm CRL. At 7.0 cm CRL, male and female Wolffian ducts were reduced in diameter by about 50%, accompanied by involution of the mesonephros. Thereafter, the Wolffian duct was retained in the male; however, at 8.5 cm CRL in the female, the Wolffian duct was greatly reduced, by about 80% in diameter, then disappeared completely at 9.0 cm CRL.

Cellular localization of GDNF and its GFRalpha1/RET receptor complex in the developing pancreas of cat

Glial cell line-derived neurotrophic factor (GDNF) acts through RET receptor tyrosine kinase and its co-receptor GFRalpha1. In an effort to better understand the possible biological contribution of the GDNF and GFRalpha1/RET complex in pancreatic development, in this study we report the cellular localization of these proteins in the pancreas of domestic cat embryos and fetuses by immunocytochemical methods. In early embryos, GDNF, GFRalpha and RET immunoreactivity (IR) was localized in closely intermingled cells. GDNF and RET immunoreactive cells displayed chromogranin (an endocrine marker) and PGP 9.5 (a neuronal marker) IR, respectively. GFRalpha IR was present in both a few GDNF/chromogranin and RET/PGP 9.5 immunoreactive cells. In elderly fetuses, GDNF and GFRalpha IR were co-localized in glucagon cells and RET IR was detected in few neurons and never co-localized with GFRalpha or GDNF IR. In early embryos, the presence of GDNF IR in chromogranin immunoreactive cells and GFRalpha1/RET complex IR in PGP9.5 immunoreactive cells seems to suggest a paracrine action of GDNF contained in endocrine cell precursors on neuronal cell precursors expressing its receptor complex. The presence in different cell populations of RET and its co-receptor GFRalpha1 IR could be due to independent signaling of GRFalpha1. Thus, the co-presence of GDNF and GFRalpha1 in chromogranin and glucagon cells could lead to the hypothesis that GDNF can act in an autocrinal manner. In fetuses, RET IR was detected only in intrapancreatic ganglia. Because of the lack of GFRalpha1 IR in pancreatic innervation, RET receptor could be activated by other GFR alphas and ligands of GDNF family. In conclusion, these findings suggest that in differently aged embryos and fetuses the GDNF signal is differently mediated by RET and GFRalpha1.

Neural progenitor cell transplantation and imaging in a large animal model

To evaluate neural stem/progenitor cell (NPC) transplantation therapy in cat models of neurodegenerative diseases, we have isolated, expanded and characterized feline NPCs (fNPCs) from normal fetal cat brain. Feline NPCs responsive to both human epidermal growth factor (hEGF) and human fibroblast growth factor 2 (hFGF2) proliferated as neurospheres, which were able to differentiate to neurons and glial cells. The analysis of growth factors indicated that both hEGF and hFGF2 were required for proliferation of fNPCs. In contrast to the effect on human NPCs, human leukemia inhibitory factor (hLIF) enhanced differentiation of fNPCs. Expanded fNPCs were injected into the brains of normal adult cats. Immunohistochemical analysis showed that the majority of transplanted cells were located adjacent to the injection site and some fNPCs differentiated into neurons. The survival of transplanted fNPCs over time was monitored using non-invasive bioluminescent imaging technology. This study provided the first evidence of allotransplantation of fNPCs into feline CNS. Cats have heterogeneous genetic backgrounds and possess neurological diseases that closely resemble analogous human diseases. The characterization of fNPCs and exploration of non-invasive bioluminescent imaging to track transplanted cells in this study will allow evaluation of NPC transplantation therapy using feline models of human neurological diseases.

Morphological study of lingual papillae in the fetal cat at mid-gestation, as revealed by light and scanning electron microscopy.

Tongues were removed from five cat fetuses, after approximately 1 month of gestation, for examination by light and scanning electron microscopy. Rudiments of filiform papillae were visible over the entire dorsal surface of the tongue. The epithelium of the dorsal surface of the tongue was of the stratified cuboidal type. No evidence of keratinization was detected anywhere in the entire dorsal lingual epithelium. Rudiments of fungiform papillae were recognizable only at the lingual apex; none were recognizable on other parts of the dorsal surface of the tongue at this stage. By contrast, rudiments of circumvallate and foliate papillae were already distinguishable from the filiform papillae. Differences between these results and those obtained previously in rats and mice are discussed.

Binocular competition does not regulate retinogeniculate arbor size in fetal monkey

Binocular interactions play a prominent role in shaping the axonal arbors of geniculocortical fibers and the arbors of Y cells in the retinogeniculate pathway of the fetal cat. Fiber interactions between the two eyes have also been suggested to regulate the formation of retinal projections to the dorsal lateral geniculate nucleus (dlgn) of the fetal monkey, but whether this reflects structural refinements of retinal arbors has not been established. To address this issue, we quantified the morphologic properties of individual fibers in two macaque monkeys at embryonic day (E) 110 and E121 that had an eye removed at E69 and E61, respectively. Fibers were labeled by DiI crystals into the fixed optic tract and were visualized by confocal microscopy. Three measurements were made: the number of branch points within the axon terminal arbor, the total arborization length, and the incidence of axonal side branches on the preterminal axon within the confines of the geniculate. There were no significant differences with respect to these parameters between the prenatal enucleates and normal monkeys of comparable age. This was the case for retinal fibers innervating the magnocellular and the parvocellular segments of the dlgn. The arbors stemming from the remaining eye were widely distributed in the dlgn, with some terminating in territories normally innervated by the other (enucleated) eye. These results lend support to the hypothesis that the expanded projection from the remaining eye to the lateral geniculate nucleus of the prenatally enucleated monkey is due to the maintenance of a contingent of retinal fibers normally eliminated by ganglion cell death. J. Comp. Neurol. 427:362–369, 2000. © 2000 Wiley-Liss, Inc.

Binocular competition does not regulate retinogeniculate arbor size in fetal monkey

Binocular interactions play a prominent role in shaping the axonal arbors of geniculocortical fibers and the arbors of Y cells in the retinogeniculate pathway of the fetal cat. Fiber interactions between the two eyes have also been suggested to regulate the formation of retinal projections to the dorsal lateral geniculate nucleus (dlgn) of the fetal monkey, but whether this reflects structural refinements of retinal arbors has not been established. To address this issue, we quantified the morphologic properties of individual fibers in two macaque monkeys at embryonic day (E) 110 and E121 that had an eye removed at E69 and E61, respectively. Fibers were labeled by DiI crystals into the fixed optic tract and were visualized by confocal microscopy. Three measurements were made: the number of branch points within the axon terminal arbor, the total arborization length, and the incidence of axonal side branches on the preterminal axon within the confines of the geniculate. There were no significant differences with respect to these parameters between the prenatal enucleates and normal monkeys of comparable age. This was the case for retinal fibers innervating the magnocellular and the parvocellular segments of the dlgn. The arbors stemming from the remaining eye were widely distributed in the dlgn, with some terminating in territories normally innervated by the other (enucleated) eye. These results lend support to the hypothesis that the expanded projection from the remaining eye to the lateral geniculate nucleus of the prenatally enucleated monkey is due to the maintenance of a contingent of retinal fibers normally eliminated by ganglion cell death.

Histochemical demonstration of lipase activity in the gastric mucosa of the cat.

The aim of the present study was to determine, histochemically, the onset and location of production of preduodenal lipase in fetal, suckling, weaned and adult cats. Strong enzymatic activity was localized in the surface mucous cells of the gastric mucosa in animals at postpartal day 1 after ingestion of milk. Activity of gastric lipase persisted as long as animals were nursed. No gastric lipase could be demonstrated in weaned and adult cats. Lingual lipase was not found at any developmental stage examined. Thus, in the newborn cat, lipase of the gastric mucosa is responsible for milk fat lipolysis.

Dendritic development of retinal ganglion cells after prenatal intracranial infusion of tetrodotoxin.

The dendritic form of a cell may be established by many factors both intrinsic and environmental. Blockade of action potentials along the course of axons and in their postsynaptic targets dramatically alters the development of axonal morphology. The extent to which blockade of target cell activity retrogradely alters the dendritic morphology of the presynaptic cells is unknown. To determine whether the establishment of dendritic form by developing retinal ganglion cells depends on activity within their targets, the sodium channel blocker, tetrodotoxin (TTX), was administered via minipumps to the diencephalon of cat fetuses from embryonic day 43 (E43) to E57. At E57 retinae were removed and living retinal ganglion cells injected in vitro with Lucifer yellow to reveal their dendritic morphology. In the TTX-treated animals both alpha and beta types of retinal ganglion cells were present, as were putative gamma cells. Overall, the dendrites of retinal ganglion cells in TTX-treated animals appeared qualitatively and quantitatively similar to those of untreated animals. The only significant change in the TTX-treated cases was a small increase in the number of dendritic spines on the non-beta cells. These results indicate that the acquisition of basic dendritic form of developing ganglion cells is not influenced by the action potential activity within their targets, and that it is also independent of the terminal branching patterns of their axons.

Innervation of the caudate nucleus, thalamus and red nucleus by the remaining sensorimotor cortex in cats with fetal or neonatal unilateral frontal cortex removal

We studied the projections to the caudate nuclei, thalami and red nuclei from the remaining sensorimotor cortex in adult cats that had sustained a unilateral frontal cortex resection prenatally or neonatally. Four cats had the lesion at age E 50–55 and six animals sustained the ablation at age P 8–14 (seven cats were intact controls). All cats grew to young adulthood and then received injections of tritiated leucine-proline in the remaining sensorimotor cortex. Injection sites and axon terminal fields were reconstructed using autoradiography-processed tissue. In all cats the label filled a similar extent of the right pericruciate cortex. Terminal field densities in the subcortical nuclei were estimated using computer-based video software. Three medial-lateral sectors at five coronal levels were examined in the caudate nucleus. Three nuclear groups were analyzed in the thalamus (intralaminary, ventralis lateralis and ventrobasal complex). For the red nucleus, the four quadrants were examined at four coronal levels. The main goal of the study was to assess possible changes in the cortical innervation of the nuclei ipsilateral to the lesion. Therefore, the mean particle counts per nucleus (and per area or sector of nuclei) and per animal group were used to calculate percentage values for the decussated (crossed, or contralateral to the injection site) as a function of the non-decussated (uncrossed, or ipsilateral to the injection site) innervation. The percentage values for the crossed projections were: (a) for the entire caudate nucleus, 61.3% for the intact, 56.7% for the fetal-lesioned and 42.7% for the neonatal-lesioned cats, with no statistical differences between groups; (b) for the thalamus the proportion of crossed projections was minimal fluctuating between a low 0.06–0.16% for the nucleus ventralis lateralis and a high of 2.01–3.46% for the intralaminary nuclei, with the highest values belonging to the lesioned groups but with no significant differences between groups; (c) for the entire red nucleus, 1.98%, 12.74% ( P < 0.05) and 6.76% for the intact, fetal- and neonatal-lesioned cats respectively. In the lesioned cats, the topography of the distribution of the axon terminals was bilaterally the same as in the controls. In conclusion, only the red nucleus of the frontal-lesioned cats showed an increased crossed innervation from the remaining sensorimotor cortex but this was relatively weak and statistically significant only for the fetal-lesioned animals. These results as well as the literature suggest that: (a) the crossed corticorubral projections in fetal cats may represent true reinnervation (i.e., newly originated, no preexisting terminals); (b) the relative paucity of the crossed projections in the present cats as compared to the extensive reorganization of subcortical terminals seen after cerebral hemispherectomy (our original postnatal lesion model) may be due to the much smaller size of the present cortical lesion which presumably induced only a limited amount of subcortical nuclear deafferentation.

The Effect of Neocortical Lesions on the Number of Cells in Neonatal or Adult Feline Caudate Nucleus: Comparison to Fetal Lesions

After a unilateral resection of the frontal cortex in fetal cats the volume of the caudate nucleus increases while the packing density of neuronal and glial cells does not change. In the present report we address the questions of whether a similar lesion sustained neonatally or a more extensive neodecortication sustained neonatally or in adulthood may have the same unusual effect. Stereological methods were used to determine bilaterally the volume of the caudate nucleus as well as to estimate the total number and packing density of neurons and glial cells in the caudate nucleus ipsilateral to the lesion. Comparisons between each of three experimental groups and intact animals were made at a time when all animals were young adults. In cats with a unilateral frontal cortical lesion performed between postnatal days 8 and 14, none of the measured parameters changed significantly compared to intact controls. In cats with removal of the entire left neocortex in adulthood, the ipsilateral caudate nucleus volume decreased by 18.1% and by 21.5% relative to intact and to neonatal hemidecorticated cats respectively ( P<0.05), with no change in the contralateral caudate. In the ipsilateral caudate the total number of neurons decreased by 21.8% ( P<0.05) compared to controls while the number of glial cells did not change significantly. In the same caudate the packing density of neurons did not change significantly (except for a 17.1% decrease, P<0.05, relative to frontal-lesioned cats) while that of glial cells increased by 19.9% and by 24.7% compared to intact and neonatal neodecorticated cats respectively ( P<0.05). In adult cats in which a similar hemineodecortication was performed between postnatal days 8 and 13, the only significant changes were a 25.8% ( P<0.05) and a 30.6% ( P<0.05) decrease in neuron packing density compared to intact and frontal-lesioned cats, respectively. In summary, a restricted unilateral neocortical resection in neonatal cats did not induce any morphological changes in the caudate nucleus that we could detect with the methods employed. In contrast, an extensive neodecortication sustained in adulthood produced ipsilateral caudate shrinkage with substantial neuron loss and increase in packing density of glial cells, while a similar lesion but sustained neonatally only altered substantially the packing density of glial cells (decreased). Therefore, we concluded that (i) the caudate nucleus hypertrophy which we reported after a unilateral discrete cortical removal during the prenatal period is a unique phenomenon which is peculiar to the cat brain during the last third of gestation; (ii) the caudate nucleus changes seen in the cats with hemineodecortication in adulthood are degenerative in nature and closely resemble those which we reported for other subcortical nuclei following a similar lesion; and (iii) the animals with neonatal hemidecortication are relatively spared from these degenerative effects. Overall, these results indicate that, as for other structures, the morphological changes of the caudate nucleus following neocortical damage depend on the maturational state of the brain at the time of the injury and on the size of the lesion, and support the notion that the consequences of cerebral cortex lesions upon subcortical brain nuclei are of a different nature when sustained in prenatal as compared to postnatal cats.

Enhanced Excitotoxicity in Primary Feline Neural Cultures Exposed to Feline Immunodeficiency Virus (FIV).

The ability of feline immunodeficiency virus (FIV) to induce neurodegenerative changes in vitro similar to those due to HIV was examined as a potential model to examine the mechanisms underlying AIDS dementia. Primary cultures of feline neural tissue (neurons, astrocytes and microglia) were established from E40-E57 fetal cat cortex and challenged by inoculation with the NCSU1 strain of FIV. Proviral FIV was detected in the cultures and correlated with the presence of microglia. No direct toxicity of FIV was seen. Stimulation of FIV-inoculated cortical cultures with 20 uM glutamate resulted in a greatly enhanced acute swelling response in approximately 14-24% of the neurons and an increase in the number of dead cells after 24 h relative to control cultures. The enhanced responses were due to an increase in the sensitivity of the cells to glutamate and were dependent on the presence of a soluble factor in the medium. The similarity of the indirect excitoxic effects of FIV to current models of HIV-gp120 neurotoxicity and the versatility of the in vitro cultures, indicate that FIV should provide a valuable model for the investigation of the mechanisms of neurodegeneration in AIDS dementia.

Topographic organization in the retinocollicular pathway of the fetal cat demonstrated by retrograde labeling of ganglion cells

The topographic organization of the developing retinocollicular pathway was assessed by making focal deposits of a retrograde tracer (usually rhodamine latex beads) into the superficial layers of the superior colliculus of fetal cats at known gestational ages. Subsequently, the distributions of labeled cells in the contralateral and ipsilateral retinas were examined. At all stages of development, a high density of labeled cells was found in a delimited area (core region) of both retinas. The locations of the retinal regions containing the high density of labeled cells varied with the locus of the tracer deposit in the superior colliculus in a manner consistent with the topographic organization of the mature cat's retinocollicular pathway. Additionally, some labeled ganglion cells, considered to be ectopic, were found to be scattered throughout the contralateral and ipsilateral fetal retinas. Such ectopic cells were few in number throughout prenatal development. For every 100 cells projecting to the appropriate region of the colliculus, we estimate that less than one ganglion cell makes a gross projection error. The incidence of ectopic cells did not differ between the contralateral and ipsilateral retina, even though the overall density of crossed labeled cells was always greater than that of uncrossed labeled cells. In the youngest fetal animals, tracer deposits into the caudal portion of the superior colliculus resulted in a core region of labeled cells in the contralateral nasal retina as well as in the nasal ipsilateral retina. Such uncrossed nasal cells, not seen in more mature animals, appear to innervate the appropriate topographic location of the superior colliculus, but on the wrong side of the brain. Most likely, these uncrossed nasal ganglion cells contribute to the widespread distribution of the ipsilateral retinocollicular pathway observed in fetal cats after intraocular injections of anterograde tracers (Williams and Chalupa, 1982). Collectively, our findings demonstrate that the developing retinocollicular pathway of the fetal cat is characterized by a remarkable degree of topographic precision. © 1996 Wiley-Liss, Inc.

Topographic organization in the retinocollicular pathway of the fetal cat demonstrated by retrograde labeling of ganglion cells

The topographic organization of the developing retinocollicular pathway was assessed by making focal deposits of a retrograde tracer (usually rhodamine latex beads) into the superficial layers of the superior colliculus of fetal cats at known gestational ages. Subsequently, the distributions of labeled cells in the contralateral and ipsilateral retinas were examined. At all stages of development, a high density of labeled cells was found in a delimited area (core region) of both retinas. The locations of the retinal regions containing the high density of labeled cells varied with the locus of the tracer deposit in the superior colliculus in a manner consistent with the topographic organization of the mature cat's retinocollicular pathway. Additionally, some labeled ganglion cells, considered to be ectopic, were found to be scattered throughout the contralateral and ipsilateral fetal retinas. Such ectopic cells were few in number throughout prenatal development. For every 100 cells projecting to the appropriate region of the colliculus, we estimate that less than one ganglion cell makes a gross projection error. The incidence of ectopic cells did not differ between the contralateral and ipsilateral retina, even though the overall density of crossed labeled cells was always greater than that of uncrossed labeled cells. In the youngest fetal animals, tracer deposits into the caudal portion of the superior colliculus resulted in a core region of labeled cells in the contralateral nasal retina as well as in the nasal ipsilateral retina. Such uncrossed nasal cells, not seen in more mature animals, appear to innervate the appropriate topographic location of the superior colliculus, but on the wrong side of the brain. Most likely, these uncrossed nasal ganglion cells contribute to the widespread distribution of the ipsilateral retinocollicular pathway observed in fetal cats after intraocular injections of anterograde tracers (Williams and Chalupa, 1982). Collectively, our findings demonstrate that the developing retinocollicular pathway of the fetal cat is characterized by a remarkable degree of topographic precision.