Development of a comprehensive, sustained community mental health system in post-earthquake Haiti, 2010-2019.

Between 2010 and 2019 the international health care organization Partners In Health (PIH) and its sister organization Zanmi Lasante (ZL) mounted a long-term response to the 2010 Haiti earthquake, focused on mental health. Over that time, implementing a Theory of Change developed in 2012, the organization successfully developed a comprehensive, sustained community mental health system in Haiti's Central Plateau and Artibonite departments, directly serving a catchment area of 1.5 million people through multiple diagnosis-specific care pathways. The resulting ZL mental health system delivered 28 184 patient visits and served 6305 discrete patients at ZL facilities between January 2016 and September 2019. The experience of developing a system of mental health services in Haiti that currently provides ongoing care to thousands of people serves as a case study in major challenges involved in global mental health delivery. The essential components of the effort to develop and sustain this community mental health system are summarized.

Structure of rapidly frozen gap junctions.

The structure of gap junctions in the rabbit ciliary epithelium, corneal endothelium, and mouse stomach and liver was studied with the freeze-fracturing technique after rapid freezing to near 4 degrees K from the living state. In the ciliary epithelium, the connexons were randomly distributed, separated by smooth membrane matrix. In the corneal endothelium, both random and crystalline arrangements of the connexons were observed. In the stomach and liver, the connexons were packed but not crystalline. Experimental anoxia or lowered pH caused crystallization of the connexons within 20-30 min. In the ciliary epithelium, the effects of prolonged anoxia or low pH could not be reversed . In addition, invaginated or annular gap junctions increased in number, but their connexons were usually distributed at random. Rapid freezing thus demonstrates that gap junctions of different tissues are highly pleiomorphic in the living state, and this may explain their variations in structure after chemical fixation. The slow time-course and irreversibility of the morphological changes induced by prolonged anoxia or low pH suggest that connexon crystallization may be a long-term consequence rather than the morphological correlate of the switch to high resistance.

Preparing to launch the 'Thinking Healthy Programme' perinatal depression intervention in Urban Lima, Peru: experiences from the field.

BACKGROUND: An estimated 19-25% of perinatal women in low- and middle-income countries are affected by depression which, untreated, is associated with multiple health problems for mothers and children. Nonetheless, few perinatal women have access to depression care. The Thinking Healthy Programme (THP), promoted by the World Health Organization (WHO), is an evidence-based, non-specialist delivered depression intervention that addresses this care gap. However, the WHO THP manual explains intervention delivery but not the antecedents to implementation. Here, we describe a principled, planned approach leading to the implementation of THP in Lima, Peru by the non-profit organization Socios En Salud with community health workers (CHW) to inform its implementation in other settings. METHODS: The Replicating Effective Programs (REP) framework guided THP implementation, following four phases: (I) pre-conditions; (II) pre-implementation; (III) implementation; and (IV) maintenance and evolution. This paper centers on REP phases I and II, including (1) documented high perinatal depression rates in Peru; (2) designation of perinatal depression as a government priority; (3) THP Implementation Team orientation and training; (4) data collection plan development; (5) public health system coordination; (6) CHW selection and training; and (7) THP launch. RESULTS: Between December 2016 and March 2017, a THP training program was developed and seven CHW were trained to deliver the intervention to 10 perinatal women, the first of whom was enrolled on 17 April 2017. CONCLUSIONS: THP was rapidly implemented by a community-based organization with no prior experience in delivering non-specialist perinatal depression care. The steps followed may inform the implementation of THP in other settings.

Mental disorders and drug/alcohol use in patients commencing extensively drug-resistant tuberculosis treatment.

Mental disorders and alcohol/drug use worsen treatment outcomes for multidrug-resistant tuberculosis (TB), but data are lacking for extensively drug-resistant (XDR) TB. We investigated the association of baseline mental disorders and alcohol/drug use on XDR-TB treatment outcomes in a retrospective study of 53 XDR-TB Peruvian patients during 2010-2012. Logistic regression estimated the odds ratios for unfavourable XDR-TB treatment outcomes. Overall treatment success was 25%. Mental disorders and drug/alcohol use were found in respectively 22.4% and 20.4% of patients; neither were associated with unfavourable treatment outcomes. Future research should explore the relationship between mental health and drug/alcohol use in XDR-TB treatment outcomes.

Les troubles mentaux et la consommation d'alcool/de drogue entravent le résultat du traitement de la tuberculose multirésistante (TB-MDR), mais on manque de données pour la TB ultrarésistante (TB-XDR). Nous avons examiné l'association de troubles mentaux préexistants et de consommation d'alcool/de drogue sur le résultat du traitement de la TB-XDR dans une étude rétrospective de 53 patients péruviens atteints de TB-XDR en 2010­2012. Une régression logistique a estimé les odds ratios de résultat défavorable du traitement de la TB-XDR. Le taux d'ensemble de succès du traitement a été de 25%. Des troubles mentaux et une consommation d'alcool/de drogue ont été constatés chez respectivement 22,4% et 20,4% des patients ; aucun n'a été associé à un résultat défavorable du traitement. Des recherches ultérieures devraient explorer la relation entre santé mentale et consommation de drogue/alcool et leur impact sur le traitement de la TB-XDR.

Los trastornos mentales y el consumo de alcohol y de drogas agravan los desenlaces terapéuticos de la tuberculosis multidrogorresistente (TB-MDR), pero no existen datos en cuanto a la TB extremadamente resistente (TB-XDR). En un estudio retrospectivo en 53 pacientes peruianos que padecieron TB-XDR del 2010 al 2012, se investigó la asociación de la presencia inicial de trastornos mentales y consumo de alcohol o drogas con los desenlaces del tratamiento de la TB-XDR. Mediante un modelo de regresión logística se calcularon los cocientes de posibilidades de desenlaces terapéuticos desfavorables. La tasa global de éxito terapéutico fue de 25%. Se encontró que el 22,4% de los pacientes sufría trastornos mentales y el 20,4% consumía alcohol o drogas; ninguna de estas características se asoció con desenlaces desfavorables del tratamiento. Nuevas investigaciones tendrán que explorar la correlación que existe entre la salud mental y el consumo de alcohol o drogas y los desenlaces terapéuticos de la TB-XDR.

Closing the gap: decentralising mental health care to primary care centres in one rural district of Rwanda.

Setting: Programmes that integrate mental health care into primary care settings could reduce the global burden of mental disorders by increasing treatment availability in resource-limited settings, including Rwanda. Objective: We describe patient demographics, service use and retention of patients in care at health centres (HC) participating in an innovative primary care integration programme, compared to patients using existing district hospital-based specialised out-patient care. Design: This was a retrospective cohort study using routinely collected data from six health centres and one district hospital from October 2014 to March 2015. Results: Of 709 patients, 607 were cared for at HCs; HCs accounted for 88% of the total visits for mental disorders. Patients with psychosis used HC services more frequently, while patients with affective disorders were seen more frequently at the district hospital. Of the 68% of patients who returned to care within 90 days of their first visit, 76% had a third visit within a further 90 days. There were no significant differences in follow-up rates between clinical settings. Conclusion: This study suggests that a programme of mentorship for primary care nurses can facilitate the decentralisation of out-patient mental health care from specialised district hospital mental health services to HCs in rural Rwanda.

Contexte : Les programmes qui intègrent les soins de santé mentale dans les structures de soins de santé primaires pourraient réduire le fardeau mondial des troubles mentaux en augmentant la disponibilité du traitement dans des contextes de ressources limitées, notamment au Rwanda.Objectif : Nous décrivons les caractéristiques démographiques des patients, leur utilisation des services et la rétention des patients en traitement dans les centres de santé (HC) participant à un programme innovant d'intégration dans les soins de santé primaires, comparés aux patients recourant aux consultations spécialisées existantes, basées dans les hôpitaux de district.Schéma : Une étude rétrospective de cohorte basée sur des données recueillies en routine dans six centres de santé et dans un hôpital de district, entre octobre 2014 et mars 2015.Résultats : De 709 patients, 607 ont été soignés dans les HC et les HC ont totalisé 88% de l'ensemble des consultations pour troubles mentaux. Les patients atteints de psychose ont plus souvent utilisé les services des HC, tandis que les patients atteints de troubles affectifs ont été plus souvent vus à l'hôpital de district. De 68% des patients qui sont revenus dans les 90 jours suivant leur première consultation, 76% ont eu une troisième consultation au cours des 90 jours suivants. Il n'y a pas eu de différences significatives en termes de taux de suivi entre les deux contextes cliniques.Conclusion : Cette étude suggère qu'un programme de tutorat destiné aux infirmiers de soins de santé primaires peut faciliter la décentralisation de la prise en charge de la santé mentale en consultation externe des services de santé mentale des hôpitaux spécialisés de district vers les HC dans le Rwanda rural.

Marco de referencia: Los programas que integran la atención de la salud mental al entorno de la atención primaria podrían reducir la carga mundial de morbilidad por trastornos mentales, al aumentar la disponibilidad del tratamiento en los medios con escasos recursos, por ejemplo en Rwanda.Objetivo: Se describen las características demográficas, la utilización de los servicios y la retención en la atención, de los pacientes atendidos en los centros de salud que participan en un programa innovador de atención primaria y se comparan con los pacientes que acuden a la consulta ambulatoria especializada que se presta en un hospital distrital.Método: Fue este un estudio de cohortes retrospectivo a partir de los datos recogidos de manera sistemática en seis centros de salud y un hospital distrital, de octubre del 2014 a marzo del 2015.Resultados: De los 709 pacientes, se atendieron 607 en los centros de salud y estos centros realizaron el 88% del total de consultas por trastornos mentales. Los pacientes con trastornos psicóticos utilizaban con mayor frecuencia los servicios en los centros de salud, pero los pacientes con trastornos del afecto se atendían con mayor frecuencia en el hospital distrital. El 68% de los pacientes regresaron al servicio de atención en los 90 días que siguieron a su primera consulta y el 76% de ellos acudió a una tercera consulta en los siguientes 90 días. No se observaron diferencias significativas en las tasas de seguimiento en los diferentes entornos clínicos.Conclusión: Los resultados del presente estudio ponen de manifiesto que un programa tutorial dirigido al personal de enfermería de los centros de atención primaria puede facilitar la descentralización de la atención ambulatoria de los pacientes con trastornos de salud mental, desde el hospital distrital con servicios especializados hacia los centros de salud en zonas rurales de Rwanda.

Mental health training for secondary school teachers in Haiti: a mixed methods, prospective, formative research study of feasibility, acceptability, and effectiveness in knowledge acquisition.

BACKGROUND: Engagement and training of educators in student mental health holds promise for promoting access to care as a task sharing strategy but has not been well-studied in low-income regions. METHODS: We used a prospective and convergent mixed methods design to evaluate a customized school mental health 2½ day training for teachers in rural Haiti (n = 22) as the initial component of formative research developing a school-based intervention to promote student mental health. Training prepared teachers to respond to student mental health needs by providing psychoeducational and practical support to facilitate access to care. We examined level of participation and evaluated feasibility, acceptability, and perceived effectiveness by calculating mean scores on self-report Likert-style items eliciting participant experience. We examined effectiveness of the training on improving mental health knowledge and attitudes by comparing mean scores on an assessment administered pre- and post-training. Finally, we examined self-report written open-ended responses and focus group discussion (FGD) interview data bearing on perceived feasibility, acceptability, and effectiveness to contextualize participant ratings of training and to identify recommendations for enhancing the utility of mental health training locally for educators. RESULTS: Mean scores of knowledge and attitudes significantly improved between the pre-test and post-tests; e.g., knowledge improved from 58% correct at baseline to 68% correct on the second post-test (p = 0.039). Mean ratings of the training were favorable across all categories and FGD data demonstrated widespread participant endorsement of training acceptability and effectiveness; participants recommended extending the duration and number of training sessions. CONCLUSIONS: Findings support feasibility, acceptability, and a limited scope of effectiveness of brief mental health training for secondary school teachers in Haiti. Further development of approaches to engage teachers in promoting school mental health through training is warranted.

Structure of the synaptic membranes in the inner plexiform layer of the retina: a freeze-fracture study in monkeys and rabbits.

The internal structure of the synaptic membranes in the inner plexiform layer (IPL) of the retina of monkeys and rabbits was studied with the freeze-fracturing technique. In ribbon synapses, the presynaptic active zone is characterized by an aggregate of P-face particles, images of synaptic vesicle exocytosis, and forming coated vesicles which occupy distinct, contiguous membrane domains from apex to base of the synaptic ridge. The postsynaptic membrane contains a prominent aggregate of homogeneous particles which remain associated with the E-face. In the presynaptic membrane of conventional synapses, images of synaptic vesicle exocytosis are intermingled with large P-face particles, whereas forming coated vesicles surround the active zone. Three types of internal organization characterize the postsynaptic membrane of conventional synapses. Usually, the postsynaptic membrane exhibits the same internal structure as the surrounding nonjunctional plasmalemma. A second, less common type of conventional synapse contains a loose aggregate of heterogeneous particles which remain associated with the P-face. Finally, synapses were exceptionally found which are macular in shape and contain an aggregate of E-free particles within the postsynaptic membrane. The freeze-fracture evidence suggests that the axonal endings of bipolar cells--or at least some of them--make excitatory synapses, whereas the vast majority of amacrine cell dendrites make inhibitory synapses. Additional specializations of the cell surface in the IPL include gap junctions, puncta adhaerentia, subsurface cisterns, and cell corner aggregates.

Conjunctival and episcleral blood vessels are permeable to blood-borne horseradish peroxidase.

The vessels of the conjunctival and episcleral plexuses of Macaca mulatta eye are of the continuous type. Most of the vessels in the conjunctival plexus have the diameter of capillaries, while the vast majority of the vessels in the episcleral plexus are venules. Both types of vessels have a simple wall, which consists of an endothelium and a discontinuous layer of pericytes. The aim of this study was to establish their permeability properties to blood-borne horseradish peroxidase (HRP). After intravenous injection of HRP, in 200 microns chopper sections of the anterior segment of the eye examined with the light microscope, the subconjunctival and episcleral tissues appear intensely and diffusely stained by the reaction product. The electron microscope shows that HRP escapes from the vessels lumen by crossing the interendothelial clefts and, in addition, a great number of pinocytotic vesicles loaded with HRP are present on the luminal, tissue front and in the cytoplasm of the endothelial cells. HRP, which rapidly penetrates the loose connective tissue of the region, reaches the spaces between the cells of the conjunctival epithelium where it is finally blocked by the zonulae occludentes that connect the most superficial epithelial cells. A slow diffusion into the compact tissue of the cornea and of the sclera was also observed. Thus, under normal conditions, blood-borne macromolecules can freely diffuse into the subconjunctival and episcleral loose connective tissues. On the other hand, one can equally expect that the aqueous humor that reaches the episcleral and conjunctival blood plexuses through the canal of Schlemm and collector channels can freely diffuse into the subconjunctival spaces across the walls of these permeable vessels.

Schwalbe line's cells: a new cell type in the trabecular meshwork of Macaca mulatta.

In the eye of Macaca mulatta, at the anterior end of the trabecular meshwork, just beneath the ridge known as Schwalbe line in gonioscopy, cells are present that contain secretory inclusions. These cells have been termed Schwalbe line's cells. They form a discontinuous cord, oriented circumferentially at the corneal periphery, deep to the endothelial lining of the anterior chamber. They are characterized by a prominent Golgi apparatus and by two types of secretory granules: round bodies, up to 0.6 micron in diameter and containing moderately dense material, and larger inclusions, up to 1 micron in diameter and consisting of stacks of osmiophilic lamellae. Membrane whorls and fragments are also commonly found in the spaces between the cells and possibly arise from exocytosis of the lamellar bodies. Schwalbe line's cells have been observed in young as well as in old animals. They are joined to one another by gap junctions and puncta adhaerentia. Because their cytoplasmic inclusions bear a striking morphological resemblance to the multilamellar bodies or cytosomes of the type II alveolar epithelial cells of the lung, the hypothesis is advanced that Schwalbe line's cells produce a phospholipid material that is released in the aqueous humor and thus facilitates its movement through the tissues of the sclerocorneal angle.

Intercellular junctions in the ciliary epithelium.

The fine structure of the intercellular junctions in the ciliary epithelium of rhesus monkeys and rabbits was studied with conventional electron microscopy of thin-sectioned specimens and the freeze-fracturing technique. In the rhesus monkey, a zonula occludens, zonula adhaerens, gap junctions, and desmosomes interconnect the nonpigmented cells, whereas gap junctions, puncta adhaerentia, and desmosomes connect pigmented to nonpigmented cells, and pigmented cells to one another. In the rabbit, desmosomes are absent between nonpigmented cells, and substituted for by puncta adhaerentia. The zonula occludens between nonpigmented cells greatly varies in its complexity in different regions of the cell perimeter, and in places, it may consist of very few intramembrane strands; this suggests that the ciliary epithelium is relatively leaky to ions and small molecules. Gap junctions are ubiquitous in the ciliary epithelium and particularly numerous at the interface between pigmented and nonpigmented layers; this finding indicates that the cells of the ciliary epithelium are joined in a metabolic syncytium. All gap junctions are characterized by the crystalline configuration which is typical of the uncoupled state; furthermore, in specimens fixed by immersion, they may be caused by uncoupling and take place in the time interval elapsing between interruption of the blood supply and arrival of the fixative fluid. Puncta adhaerentia resemble zonulae adhaerentes in their structural details but are macular in shape instead of encompassing the cell perimeter in a beltlike fashion. In contrast with desmosomes, the intercellular cleft of puncta adhaerentia has an irregular width and contains opaque material, but this never gives rise to the central band typical of desmosomes. On the inner aspect of the junctional membranes, there is a layer of fluffy material but no plaque of insertion for a bundle of tonofilaments. Finally, puncta adhaerentia have no representation in the interior of the plasmalemma and are intimately associated with cytoplasmic microfilaments. They probably anchor to the plasmalemma the contractile apparatus of the ciliary epithelial cells.

Paracellular route of aqueous outflow in the trabecular meshwork and canal of Schlemm. A freeze-fracture study of the endothelial junctions in the sclerocorneal angel of the macaque monkey eye.

The intercellular junctions of the endothelial cells of the trabecular meshwork and canal of Schlemm were examined with the electron microscope in the macaque monkey eye by both thin-sectioned specimens and the freeze-fracturing technique. The endothelial cells that line the beams of the meshwork are joined by gap junctions and short, isolated strands of tight junction; zonulae occludentes are absent. Thus aqueous humor can freely traverse the patent endothelial clefts of the trabecular meshwork. The endothelial cells of the canal of Schlemm are joined by zonulae occludentes and a small number of minute gap junctions. In 57% of their length, the tight junctions consist of one or two strands; the strands are rarely more than four. They remain preferentially associated with the E-face of the membrane, run parallel to one another, and only exceptionally branch or anastomose. Thus they are provided with free endings and do not form a bidimensional network. As a result of this organization, the zonula occludens is traversed by meandering channels of extracellular space or split pores, which connect the open endothelial clefts on the luminal and tissue fronts of the junction. The frequency of slit pores is 0.134 per micrometer of zonula occludens. They occupy 0.87% of the intercellular boundary and 0.0015% of the area of the endothelium. Estimates of the fluid conductance of the zonulae occludentes indicate that the intercellular clefts of the endothelium of Schlemm's canal filter but a small fraction of the amount of aqueous humor that leaves the anterior chamber through the conventional route.

A simple staining method for blood vessels in flat preparations of ocular tissues.

We describe a technique for light microscopic visualization of the vasculature of the retina, choroid, ciliary body, and iris in flat preparations. The technique is based on the intravenous injection of horseradish peroxidase, the histochemical demonstration of this enzyme's activity, and the bleaching of the melanin that hinders the visualization of the injected vessels. This technique is reproducible and much simpler than other available methods in which dyes suspended in different media are injected directly into the ocular vessels.

Unidirectional vesicular transport mechanism in retinal vessels.

When horseradish peroxidase (HRP) is introduced into the bloodstream, it is retained in the lumen of the retinal vessels (blood-retina barrier). In this paper, we report that when the same tracer is injected into the vitreous body, it penetrates the lumen of retinal vessels by transcellular vesicular transport. This unidirectional movement of macromolecules out of the eye is not inhibited by ouabain, fluoroacetate, or low temperatures.

Asymmetric distribution of charged domains on the two fronts of the endothelium of iris blood vessels.

The authors have studied the distribution of anionic and cationic sites on both luminal and abluminal endothelial aspects of iridial vessels in Macaca mulatta and Macaca fascicularis. With the animals in general anesthesia, anionic ferritin (AF) and cationic ferritin (CF) were either injected intravenam or perfused at known intraocular pressure (15-20 mmHg) through the anterior chamber. AF introduced intravenam was retained in the vessels' lumen. The tight junctions between the endothelial cells were impermeable and the plasmalemmal vesicles did not transport tracer to the iridial stroma. In contrast, when perfused through the anterior chamber, AF was present in the vessels' lumen. Here again the tight junctions between the endothelial cells were impermeable, but AF was contained within a great number of plasmalemmal vesicles. Iridial vessels were impermeable to CF perfused into the lumen, but a continuous layer of CF particles was found to adhere to the luminal plasma membrane. When perfused through the anterior chamber, CF was bound to the proteoglycans associated with collagen fibrils of the iridial stroma and basal laminae of stromal, pericytic, and endothelial cells but was never found in the vessels' lumen. These results indicate that different electrical charges are associated with the plasmalemmal vesicles on the luminal and abluminal fronts of iridial vessels. The authors suggest that in these vessels a unidirectional vesicular transport is responsible for the selective movement of anionic organic substances from the tissues of the eye to the bloodstream.

The homogeneous structure of blood vessels in the vascular tree of Macaca mulatta iris.

This study reports the results of a systematic analysis of the iris vasculature in Macaca mulatta. Through the application of a variety of morphologic procedures it has been demonstrated that in rhesus monkeys, all iridial vessels, regardless of their diameter, have a similar structure. Their walls consist of (1) endothelial cells in a continuous layer resting on a basal lamina, which are provided with a small number of blunt luminal protrusions and slender basal lamellae; (2) pericytes sandwiched between two layers of the basal lamina, which are characterized by a smooth basal surface and adluminal processes that interdigitate with the basal leaflets of the endothelial cells; and (3) an adventitia of fibroblasts, melanocytes, and occasional macrophages arranged in one or more layers. Typical smooth muscle cells are not found in any vessels of M. mulatta iris. Thus the vessels of the rhesus monkey iris have a remarkably homogeneous morphologic appearance and cannot be classified according to the traditional criteria for arterioles, capillaries, and venules.

Freeze-fracture analysis of the interendothelial junctions in the blood vessels of the iris in Macaca mulatta.

The interendothelial cell junctions in the blood vessels of the rhesus monkey iris were examined by both conventional electron microscopy and the freeze-fracturing technique. Endothelial cells of iris blood vessels were joined by two types of intercellular junctions: zonular tight junctions and gap junctions. The zonulae occludentes were represented by a complex network of branching and anastomosing strands that remained preferentially associated with the E fracture face. They varied in complexity from a single strand to eight or more but usually consisted of from two to four strands. Small gap junctions were inserted within the tight junctional network. Junctions similar to those typical of muscular and visceral venules were absent. Thus the intercellular clefts of all iris vessels are closed by zonulae occludentes that exhibit a degree of complexity intermediate between the endothelial junctions of the cerebral cortex and those of striated muscles and viscera. This finding strongly suggests that the blood vessels of the iris participate only minimally in aqueous humor dynamics.

Unidirectional transport mechanism of horseradish peroxidase in the vessels of the iris.

When horseradish peroxidase (HRP) is introduced into the blood stream it is retained in the lumen of the iridial vessels. In this paper, we report that when the same tracer is perfused into the anterior chamber of macaque monkeys, it permeates the stroma of the iris and penetrates the lumen of iridial vessels by transcellular vesicular transport. This unidirectional movement of HRP out of the eye is not inhibited by ouabain or fluoroacetate.

The structural basis of the blood-aqueous barrier in the chicken eye.

In order to identify the structural basis of the blood aqueous barrier in the chicken eye, the morphology of the blood vessels and epithelium of the ciliary body were examined with light microscopy, conventional electron microscopy, and the freeze-fracturing technique; the permeability properties of the vessels and epithelium were tested with intravascular injection of horseradish peroxidase (HRP). The ciliary body and iris of the adult chicken are supplied principally by a single temporal long posterior ciliary artery that, by dividing into two branches, gives rise to the great circle of the iris. From this circle multiple branches reach the iris, while a few run posteriorly to the ciliary body stroma. Most of the blood supply to the ciliary body stroma is derived from vessels that return from the iris, run in the valleys between ciliary processes, and are continuous, at the ora serrata, with the veins of the vortex system. Electron microscopy shows that the vessels of the ciliary body stroma differ from their counterpart in mammals in two respects: (1) the endothelial cells are joined by simple but continuous zonulae occludentes; (2) the openings in the endothelial lining (plasmalemmal vesicles, fenestrae, and transendothelial channels) are less numerous. The walls of these vessels retard, but do not prevent the diffusion of intravenously injected HRP into the surrounding connective tissue spaces. From the ciliary body stroma, HRP diffuses into the intercellular clefts of the ciliary epithelium, but its progression toward the posterior chamber is blocked by very complex zonulae occludentes between the nonpigmented cells. Thus, in chickens as in mammals tight junctions between the nonpigmented cells of the ciliary epithelium represent the structural equivalent of the blood-aqueous barrier.

Intercellular junctions between fibroblasts in connective tissues of the eye of macaque monkeys. A thin section and freeze fracture analysis.

Thin-section electron microscopy and freeze fracture were used in the analysis of the intercellular junctions between fibroblasts in connective tissues of the eye of Macaca mulatta, M. fascicularis, and M. arctoides. Fibroblasts located in the subconjunctival loose connective tissue, anterior sclera, scleral spur, iris stroma, ciliary body stroma, and posterior choroid were jointed by three kinds of junctions. Gap junctions were of different sizes and frequently composed of a small number of connexons organized in polygonal aggregates or linear arrays. Tight junctions were represented by isolated strands and never composed a continuous belt around the cells. Intermediate junctions were seen in thin sections but did not have any representation in the interior of the plasma membrane. It remains to be established whether, as is the case in other tissues, pathologic conditions of the eye are accompanied by some changes in the morphology and distribution of intercellular junctions between fibroblasts.

The structural basis of the inner blood-retina barrier in the eye of Macaca mulatta.

This is a morphological analysis of the inner blood-retina barrier in various segments of the retinal vasculature in the eye of Macaque monkeys. The primary aims of this study are to identify the components of the walls of the arteries, central capillaries, peripheral capillaries and veins of the retina using light and electron microscopy, and to compare and contrast junctional morphology as revealed by thin section electron microscopy and freeze-fracture. The walls of these vascular segments are composed of continuous endothelium, muscle cells or pericytes, and connective tissue. Endothelial cells are joined by tight and gap junctions. In freeze-fracture replicas, tight junctions consist of a continuous, complex network of branching and anastomosing strands which do not possess free endings. The intramembrane strands of tight junction remain preferentially associated with the outer membrane leaflet or E-face of the endothelial plasma membrane and sit at the bottom of linear strands or grooves. However, particles and fragments of the intramembrane strands may be avulsed from the E-face during the fracture process and are associated with ridges on the inner membrane leaflet or P-face. The total number of plasmalemmal vesicles per unit area of endothelial cell for each vascular segment in thin sections is less than non-barrier endothelium, but greater than barrier endothelium. The paucity of plasmalemmal vesicles and the complexity of the tight junctional network contribute to the barrier function of the retinal vascular endothelium.