Biomedical subjects

T van Veen

Publications and source records attributed to T van Veen.

At least 37 records · Page 2Linked to original sources

PubMed1994

Myofibrillar Ca2+ sensitization predominantly enhances function and mechanical efficiency of stunned myocardium.

BACKGROUND: Myocardial stunning is characterized not only by a decreased regional postischemic function but also by a relatively high oxygen consumption (ie, decreased mechanical efficiency). Several lines of evidence suggest that the underlying mechanism may involve a decreased sensitivity of the myofibrils to calcium, but in vivo evidence is lacking. We therefore evaluated this hypothesis in vivo using EMD 60263, a calcium-sensitizing agent, which is devoid of any phosphodiesterase-inhibiting properties. METHODS AND RESULTS: We first established the effect of two consecutive doses of EMD 60263 (0.75 and 1.5 mg/kg i.v., n = 7), administered at 15-minute intervals, on segment length shortening (SLS), external work index (EW; the area inside the left ventricular pressure-segment length loop), myocardial oxygen consumption (MVO2), and mechanical efficiency (EW/MVO2) in anesthetized pigs with normal myocardium. After the highest dose of EMD 60263, SLS in the distribution area of the left anterior descending coronary artery (LADCA) increased from 13 +/- 1% at baseline to 17 +/- 1% (P < .05). However, EW, MVO2, and EW/MVO2 were not significantly affected (123 +/- 10%, 98 +/- 9%, and 85 +/- 13% of baseline, respectively). In 14 other anesthetized pigs, myocardial stunning was induced by two sequences of 10 minutes of LADCA occlusion and 30 minutes of myocardial reperfusion. After induction of stunning, the two doses of EMD 60263 (n = 7) or saline (3 and 6 mL, n = 7) were infused. In the distribution area of the LADCA, the stunning protocol caused decreases in SLS from 16 +/- 1% to 8 +/- 1% (P < .05) and in EW to 49 +/- 5% of baseline (P < .05), whereas MVO2 was only minimally affected (P > .05). Consequently, mechanical efficiency decreased to 59 +/- 8% of baseline (P < .05). Saline infusion did not affect any of these regional myocardial variables, but after administration of EMD 60263 SLS recovered dose-dependently to 15 +/- 2% after the highest dose of the drug. EW and mechanical efficiency also recovered dose-dependently to 89 +/- 4% (P < .05 versus stunning) and to 88 +/- 7% (NS versus baseline) of baseline, respectively. In the not-stunned segment, SLS increased from 15 +/- 2% (at baseline) to 18 +/- 2% (after the highest dose), and EW per beat was not changed significantly. An adrenergic mode of action of EMD 60263 was excluded by blocking the alpha- and beta-adrenergic receptors with phentolamine and propranolol, respectively, 15 minutes before administration of EMD 60263 (ie, 15 minutes into the second reperfusion period) in five additional experiments. In these experiments the EMD 60263-induced increases in SLS and EW were not attenuated. Because EMD 60263 decreased heart rate from 106 +/- 4 to 76 +/- 3 beats per minute (P < .05) in the animals with stunned myocardium, we performed five experiments with the specific negative chronotropic compound zatebradine (UL-FS 49, 0.1 to 0.5 mg/kg) to rule out bradycardia as a factor contributing to the effects of EMD 60263. These zatebradine doses lowered heart rate from 116 +/- 5 to 55 +/- 1 beats per minute (P < .05) but had no effect on SLS of stunned and not-stunned myocardium. CONCLUSIONS: Calcium sensitization affects function and mechanical efficiency of stunned myocardium more profoundly than of not-stunned myocardium, lending support to the hypothesis that Ca2+ desensitization of the myofibrils is involved in myocardial stunning.

Animals↗

PubMed1994

Expression of phototransduction cascade genes in the ground squirrel retina.

PURPOSE: This study describes the expression and distribution of phototransduction cascade gene products in the cone-dominant retina of the ground squirrel Spermophilus tridecemlineatus. METHODS: Messenger RNA expression was studied by blot hybridization, and the distribution of the gene products was investigated by immunocytochemistry. RESULTS: RNA blot hybridization showed messages for the alpha 2, beta 1, and beta 3 subunits of transducin but was negative for rhodopsin, alpha 1-transducin, and the alpha, beta, and gamma subunits of cyclic guanosine monophosphate (cGMP) phosphodiesterase. Immunocytochemical labeling indicated that the approximate ratio of the photoreceptor types in ground squirrel retina is 90.6% for green cones, 6.3% for rod-like cells, and 3.1% for blue cones. Rod-like cells were immunopositive for rhodopsin and blue opsin. All photoreceptor elements were labeled by antibodies against alpha 1-transducin (which recognizes both the alpha 1 and alpha 2 isoforms), beta 3-transducin, and the rod gamma subunit of phosphodiesterase, whereas no cells were labeled by antibodies against the rod alpha and beta subunits of phosphodiesterase or against the rod cGMP-gated cation channel. Rod-like cells and blue cones were stained by antibodies against beta 1-transducin. CONCLUSIONS: The authors demonstrate new cone-like traits in the biochemical make-up of rod-like cells, and a distribution of the transducin beta subunit in the ground squirrel is different from that found in other mammals.

Animals↗

PubMed1994

Selective development of one cone photoreceptor type in retinal organ culture.

PURPOSE: The authors have established an organ culture method in which the the postnatal development and the structural integrity of the mouse retina can be maintained for at least 6 weeks. Additionally, they have examined the emergence and in vitro morphogenesis of the photoreceptors and the development of insoluble components of the interphotoreceptor matrix. METHODS: Neural retinas and retinal pigment epithelia from 48-hour-old C3H ++/++ mice were cultured. At various ages, the tissues were fixed and cryosectioned or wholemounted. Photoreceptor development was studied by immunocytochemistry with visual pigment antibodies and by lectin cytochemistry. The ultrastructure of the photoreceptors was studied by electron microscopy. RESULTS: Immunopositive rods and short-wave sensitive cones were detectable as early as 3 days after explantation. From this time on, matrix domains around cones were also identifiable and labelled with peanut agglutinin lectin. However, the antibody specific to the middle-wave sensitive cone pigment failed to recognize any cones throughout the 6-week culture period. CONCLUSIONS: Both basic photoreceptor types appeared and developed in this organ culture system according to a timetable comparable to normal in vivo development. Surprisingly, under these circumstances, one of the two cone pigments was not expressed by any photoreceptors.

Animals↗

PubMed1994

Expression of soluble phototransduction-associated proteins in ground squirrel retina.

PURPOSE: This study describes the expression and distribution of arrestin, phosducin, and recoverin in the cone-dominant retina of the ground squirrel Spermophilus tridecemlineatus. METHODS: mRNA expression was studied by blot hybridization of ground squirrel retinal RNA, with human and murine RNA as controls. The distribution of the gene products in the ground squirrel retina was investigated by immunocytochemistry using radial and consecutive tangential sections. RESULTS: Northern blot hybridization showed messages for arrestin (1.9 kb), phosducin (1.4 kb), and recoverin (1.2 kb) in ground squirrel retinal RNA. Both controls showed transcripts of the same or similar sizes. Rod-like cells and blue cones were stained by antibodies against arrestin and phosducin. The arrestin antiserum stained the whole cell bodies, most intensely in the myoid region, whereas phosducin immunoreactivity was confined to the outer and inner segments, which were stained with approximately equal intensity. The strongest immunoreaction was found in the photoreceptor plasma membrane. Recoverin antibodies recognized the entire soma of all photoreceptor cells. The myoid region and the synaptic pedicles were most heavily stained. No light-dependent migration was observed with either antiserum in any photoreceptor type. CONCLUSION: The presence of arrestin immunoreactivity in rod-like cells and blue cones is consistent with previous reports on other mammals. However, it has not been reported previously that phosducin immunoreactivity is distributed in the same way. The colocalization of arrestin and phosducin in rod-like cells and blue cones is yet another trait distinguishing blue cones from red and green cones.

Animals↗

PubMed1994

Complementary cone fields of the rabbit retina.

PURPOSE: Complementary cone fields have been considered a unique feature of the mouse retina. In an attempt to map the arrangement of the color-specific cones in other mammals, the authors investigated the rabbit, a commonly used experimental animal for vision research. METHODS: For the identification of the different cone types immunocytochemistry was used with two monoclonal antibodies, each specific to the middle- to long-wave (red-green) and short-wave (blue) sensitive visual pigments, respectively. RESULTS: The major part of the retinal surface, including the visual streak, exhibited a dominance of M (middle-wave sensitive) cones (6 to 13,000/mm2) versus S (short-wave sensitive) cones (1 to 2,500/mm2). In contrast, the lower 5% to 6% of the total retinal area showed a complete lack of green cones and a high density of blue cones (11,000/mm2). The authors designate this crescent-like area the blue streak of the rabbit retina. CONCLUSION: In addition to the visual streak primarily abundant in green cones, there is a specialized area of the rabbit retina that is densely and exclusively populated with blue cones. Although the relative extension of this peculiar cone field is considerably smaller than the S-field of the mouse retina, its position is similar in that it occupies the lowermost part of the retina. The functional implication of this area is unknown.

Animals↗

PubMed1993

Spatial and temporal differences between the expression of short- and middle-wave sensitive cone pigments in the mouse retina: a developmental study.

In an earlier study we found a topographic separation of middlewave-sensitive (M) and shortwave-sensitive (S) cones in the adult mouse retina. In the present study we investigated the development of the two colour-specific cone types to see whether there is also a temporal difference between the expression of the specific cone visual pigments. Using two anti-cone visual pigment antibodies, COS-1 and OS-2, we compared the densities of immunopositive cone outer segments on retinal whole mounts derived from mice of various ages. The first detectable cone outer segments were the S-cones which appeared in the inferior half of the retina on postnatal day 4. At this stage, the density of the S-cones was very low (30-40 cones/retina) but increased steadily on the following days to reach a value comparable to that of adults by P30 (18,000/mm2). This cone type always remained much more abundant in the lower part of the retina throughout the whole retinal development. In the superior half of the retina, a few S-cones appeared from postnatal day 7; however, their number always remained about one order of magnitude lower than in the inferior part. In contrast, M-cone outer segments were not identifiable earlier than postnatal day 11 and were confined exclusively to the superior part of the retina during the whole developmental process. On postnatal day 12, their density was 1,900/mm2 and increased to a value of 11,000/mm2 by postnatal day 30, which represented the adult stage. As shown by comparison of isodensity lines derived from immunocytochemical reactions of whole mount retinas, the two cone types occupied complementary halves of the mouse retina with maximum density centres located in opposite retinal quadrants. We conclude that 1) in contrast to the primate retina, mouse S-cones precede the M-cones in their development, and 2) the spatial arrangements of the two cone types is maintained throughout the whole differentiation process.

Animals↗

PubMed1993

Hyperplastic neuroretinopathy and disorder of pigment epithelial cells precede accelerated retinal degeneration in the SJL/N mouse.

We have found a complex eye disease in the SJL/N mouse. This animal is closely related to the SJL/J mouse, which is homozygous for retinal degeneration (rd) and which also suffers from extraocular reticulum cell sarcomas at around 200 days of age. In the SJL/N animal, a high incidence of subretinal tumor is present at 9 days after birth. Furthermore, we have observed an extensive neuroretinal hyperplasia, a phenomenon that is termed "hyperplastic neuroretinopathy", and that is probably the consequence of elevated levels of cytokines in the animals. In addition to these anomalies, the SJL/N mouse shows progressive dystrophy of the retinal pigment epithelium (RPE) from day 4 onwards, and accelerated photoreceptor cell degeneration is completed by day 16. The early RPE dystrophy appears to be a secondary autoimmune disease, since cells in this structure and in the choroid develop MHC class II antigens, whereas we suspect that the accelerated photoreceptor cell loss is induced by a soluble toxic agent. The F1 progeny derived from cross-breeding the SJL/N and Balb/c +/+ strains also shows a high incidence of subretinal tumor and hyperplastic neuroretinopathy, but neither the RPE dystrophy nor retinal degeneration.

Age Factors↗

PubMed1993

Diethylene glycol distearate (DGD): a versatile embedding medium for retinal cytochemistry.

Embedment in diethylene glycol distearate (DGD) was shown to be highly desirable and versatile for retinal cytochemical studies, including in situ hybridization, immuno- and lectin cytochemistry. This method allows for preservation of fine tissue detail as well as good reaction sensitivity. It appears to be more suitable than most other methods currently used for light microscopic retinal cytochemistry.

Animals↗

PubMed1993

Photoreceptor-specific protein expression of mouse retina in organ culture and retardation of rd degeneration in vitro by a combination of basic fibroblast and nerve growth factors.

Previously we have presented the morphological features of a neonatal mouse retinal explant kept in culture for 3 to 4 weeks. To further evaluate the organotypic parameters of the tissue we have examined the presence of opsin, S-antigen, and interphotoreceptor retinoid-binding protein (IRBP) in the same experimental paradigm, using light microscopic immunocytochemistry. In vitro, opsin and S-antigen staining is found in photoreceptor somata from genetically normal explants and those derived from mice with the rd or the rds mutation. When present, inner and outer segments label more intensely. No IRBP staining has been found in cell bodies of any genotype. However, some labeling is found in the plexiform layers and in the inner segments. The results indicate that photoreceptor proteins are continuously produced in vitro. This further establishes the organotypic nature of the retinal explant in culture. The administration of growth factors to these explants has been investigated. Neither basic fibroblast growth factor nor nerve growth factor alone has affected the explants phenotype. However, the combination of these proteins has significantly retarded rd cell loss in vitro.

Animals↗

PubMed1993

Difference in PNA label intensity between short- and middle-wavelength sensitive cones in the ground squirrel retina.

PURPOSE: Peanut agglutinin lectin (PNA) is known for its selective binding to cone cells and to the cone domains of the interphotoreceptor matrix. In the current study, the authors investigated whether there is any difference in PNA binding between color-specific cones of the cone-dominant ground squirrel. METHODS: Consecutive serial sections of the retina of Spermophilus tridecemlineatus were reacted alternately with PNA and antivisual pigment antibodies. The PNA labels associated with short- and middle-wavelength-sensitive cones (S-cones and M-cones, respectively) were compared with fluorescent lectin cytochemistry. RESULTS: Although all rod-like cells were left unstained, the cones exhibited a specific lectin label. There was, however, a significant difference between the two cone types; the intensity of the ring-like PNA label in the matrix sheath around S-cones significantly exceeded that of the M-cones. CONCLUSIONS: The difference in PNA label intensity indicates a difference in the composition of the matrix sheaths surrounding the two respective cone types. To the authors' knowledge, this is the first report on lectin-cytochemical discrimination of cone matrix sheaths and the first lectin study in the ground squirrel retina leading to the observation that PNA can distinguish the three characteristic photoreceptor types in this animal. In this respect, the rod-like cells of the ground squirrel retina were shown to be no different from rod cells of other species.

Animals↗

PubMed1993

Structural changes of the interphotoreceptor matrix in an inherited retinal degeneration: a lectin cytochemical study of progressive rod-cone degeneration.

PURPOSE: In the retinal disorder progressive rod-cone degeneration (prcd) in miniature poodle dogs, the photoreceptor layer degenerates slowly in the course of 5 to 7 years. Components of the interphotoreceptor matrix form a continuous extracellular lattice around photoreceptors. The purpose was to study the photoreceptor cell-matrix interactions during the disease and degeneration phases. Because degeneration rate was slower in cones, the authors also wanted to investigate whether there was a link between the degeneration and the photoreceptor-specific interphotoreceptor matrix domains. METHODS: Rod- and cone-specific interphotoreceptor matrix domains were examined during two periods: before morphological signs of disease had appeared and during the degenerative stages. Two lectin probes were used; wheat germ agglutinin and peanut agglutinin. By their affinity for terminal carbohydrates, the lectins visually separated the two photoreceptor-specific domains and allowed follow-up of the fate of the rod and cone matrices separately. RESULTS: Before and during the course of disease, the lectin distribution in rod and cone domains remained normal, however, in the degenerative phase of the disease, there were structural changes in the matrix domains. The matrix connections between the individual domains was disrupted and single domains were formed. Cone domains and, to a lesser degree rod domains, were thickened around the inner and outer segments. CONCLUSIONS: The changes occurring in the photoreceptor-specific domains were indicative of structural adaptation to cell death and to degenerative conditions. There was no evidence of an active involvement of the interphotoreceptor matrix components studied in the disease process.

Animals↗

PubMed1991

Rod and cone specific domains in the interphotoreceptor matrix.

The insoluble matrix domain of the interphotoreceptor matrix (IPM) from normal dog, cat, and mouse retinae were characterized using lectin cytochemistry. The lectins WGA (wheat germ agglutinin) and PNA (peanut agglutinin) were used to label interphotoreceptor matrix microdomains in cryosections of retinal tissue and in extracted insoluble matrix. Retinal cryosections and extracted matrix were examined by epifluorescence microscopy and scanning confocal laser microscopy, the latter allowed for the removal of all background fluorescence and gave increased resolution. The insoluble matrix was extracted as a continuous sheet that was comprised of two photoreceptor-specific matrix domains distinguished both by the size of the domains, and by differential binding of WGA and PNA lectins. Each domain encloses a photoreceptor inner and outer segment. Individual rod-associated domains were connected into a hexagonal lattice and this pattern was regularly interrupted by the larger cone-associated domains which have 8-10 surrounding rod domains. The PNA lectin primarily labeled the cone-associated matrix with faint binding to the rod matrix; the WGA lectin labeled both the rod- and cone-associated matrix.

Animals↗

PubMed1991

Photoreceptor degeneration and loss of immunoreactive GABA in the Abyssinian cat retina.

GABA (gamma-amino butyric acid) and its synthesizing enzyme, GAD (glutamate decarboxylase; EC 4.1.1.15) were localized in the retina of Abyssinian cats homozygous for a recessively inherited retinal degenerative disorder which in several respects is similar to the human disease, retinitis pigmentosa. Clinically normal mongrel cats and heterozygous Abyssinian cats were studied for comparison. The GABA and GAD immunoreactive neurons of the heterozygous or young homozygous (clinically unaffected animals) had the same distribution and morphology as normal mongrel European type cats. The neuronal GABA immunoreactivity in both the inner and outer parts of the retina gradually disappeared in the course of the disease, with little or no loss of GAD immunoreactive neurons. Early in the disease, the changes were most severe in patches in the mid periphery of the eye and then spread both centrally and peripherally. Loss of photoreceptors was a prerequisite for the loss of GABA immunoreactivity. The observations show that retinal changes are not limited to the photoreceptors. The GABA loss is not likely to be due to a loss of neurons, because of the persistence of GAD immunoreactive neurons.

Animal Husbandry↗

PubMed1990

Development and degeneration of retina in rds mutant mice: ultraimmunohistochemical localization of S-antigen.

In the developing photoreceptor cells of the homozygous rds mutant mice S-antigen is localized over the ciliary protrusion as in the control mice, and to a lesser extent over the inner segments, perikaryal cytoplasma and the cell terminals. As the outer segments develop in the normal retina, the discs become increasingly immunoreactive. In the rds/rds retina the outer segments fail to develop but small membrane bound vesicles, immunoreactive for S-antigen are extruded and phagocytized by the retinal pigment epithelium. In the retina of older mutant mice, as the photoreceptor cells degenerate slowly, the surviving cells continue to show persistent immunoreactivity for S-antigen in the different regions of the photoreceptor cells. In the heterozygotes the outer segments are reduced and appear abnormal, but the localization of S-antigen is similar to normal. In the receptor region of the normal retina and in the deviant membranous structures in the mutant retina the localization of S-antigen is similar to that of opsin. However, some differences in the subcellular localization of these two photoreceptor specific proteins have been observed. It is concluded that the rds gene acts subsequent to the synthesis of these proteins and possibly at the site of disc assembly.

Animals↗

PubMed1990

Postnatal development of photoreceptor-specific proteins in mice with hereditary retinal degeneration. An immunocytochemical study.

The postnatal development of immunoreactivity for photoreceptor-specific markers was studied in mice carrying the genes rd (retinal degeneration) and rds (retinal degeneration slow) in different combinations. Antibodies raised against three specific photoreceptor proteins (opsin, alpha-transducin and S-antigen) were applied on retinae from mice with the following allelic combinations at the rd and rds loci: +/+, +/+ (control); rd/rd, +/+; rds/rds, +/+; rds/+, +/+; and rd/rd, rds/rds. Immunoreactivity for each antibody appeared simultaneously in normal and mutants. Thereafter, the immunoreactivity patterns in the mutants diverged from the normal phenotype. Except for a dramatic loss of photoreceptor cells in the mutants, the main divergence from the normal development consisted of a progressive loss of the intracellular immunoreactivity compartmentalization for each protein. As degeneration progressed, the remaining photoreceptors became homogeneously labelled; one this labelling pattern was acquired, it was maintained during subsequent stages of development. It is proposed that this pattern, common for all phenotypes studied, may be due to the loss of structural and biochemical polarity of the photoreceptor cells undergoing degeneration, and that this may be an important primary or secondary aspect of the disease process.

Animals↗

PubMed1989

Reduced level of interphotoreceptor retinoid-binding protein (IRBP), a possible cause for retinal degeneration in the Abyssinian cat.

Retinae of Abyssinian cats homozygous for a retinal degeneration gene, and normal controls, have been investigated using antibodies directed against opsin, transducin alpha (TD-alpha), S-antigen (48K protein), interphotoreceptor retinoid-binding protein (IRBP), and cone outer segments. IRBP-immunoreactivity (IR) is much reduced at stage 2 of the disease in affected retinae; later massive photoreceptor cell death occurs. In cats, at a late stage of the disease, the retina exhibits few S-antigen-IR cells in the peripheral part of the retina whereas, in the central part, some patches of cells exhibiting opsin-IR, TD-alpha-IR, and S-antigen-IR are present in remnants of the outer nuclear layer (ONL). No IRBP-IR is detectable at this stage. The form and size of the majority of these remaining cells, however, does not resemble that of normal photoreceptors. No, or only rudimentary, inner and outer segments are present; long bifurcating basal protrusions often occur. These cells, which could be remains of cone elements, are S-antigen immunoreactive. Double labelling for different retina-specific proteins reveals a co-localization of opsin, TD-alpha and S-antigen in some, but not all, remaining photoreceptor elements. Cells exhibiting opsin-IR also show TD-alpha-IR and S-antigen-IR located within the entire cell and its protrusions. In control retinae and retinae at early stages of the disease, immunoreactions are comparable with all antibodies used. However, TD-alpha-IR is less intensive in the photoreceptor terminals. S-antigen-IR cones are most frequently present in the peripheral retina. Reduction of IRBP at an early stage of the disease could be one of the factors leading to photoreceptor cell death at later stages.

Animals↗

PubMed1989

Postnatal development of photoreceptor proteins in mutant mice and Abyssinian cats with retinal degeneration.

Using immunocytochemical techniques, development of opsin, transducin alpha and S-antigen in photoreceptor cells of the mice homozygous or heterozygous for the rd or rds genes has been found to be similar to that of control animals during the first postnatal week. Even though the absolute amounts of these proteins are low (eg. opsin in the rds retina) or decrease in the postnatal period (as in the rd retina), we can demonstrate their persistence during the entire degeneration process. In fact, the content of the proteins in the photoreceptor perikarya actually appear to be higher after postnatal day 11 in all mutants studied. Thus, one of the major manifestations of the mutant retinae is a loss of polarity of the photoreceptor cells at the time of ROS degeneration without a loss in the ability to synthesize these important proteins of the visual cycle. This correlates well with the apparent defect in IRBP secretion and its intracellular accumulation in mutant photoreceptor cells as previously observed (van Veen et al. 1986). In the Abyssinian cat model for progressive retinal atrophy, the development an cellular distribution of all the proteins studied are similar in affected and control retinae until the beginning of stage 2 of the disease. At this time, outer segments begin to degenerate and immunoreactivity increases in the photoreceptor perikarya. The IRBP content of the retina declines markedly at stage 2, preceding extensive loss of photoreceptors.

Aging↗

PubMed1988

Temporal disparity in pineal and retinal ontogeny.

The development of photoreceptors and two putative neurotransmitter systems in the pineal organ and retina was studied during embryogenesis in the three-spined stickleback Gasterosteus aculeatus L. The investigation was performed by aid of immunocytochemistry using well characterized antisera to the retinal proteins alpha-transducin (TD alpha) and S-antigen (SA) (photoreceptor-markers), antisera against L-glutamic acid decarboxylase (GAD), gamma-aminobutyric acid (GABA), choline-O-acetyltransferase (ChAT) and with acetylcholinesterase (AChE) histochemistry (neurotransmitter-markers). It was possible to set up the following developmental time-table concerning the first appearance of positive immuno- and enzyme-reactive cells in the pineal organ and retina: I AChE-activity and TD alpha- and SA-immunoreactive cells in the pineal organ; II GAD- and GABA-immunoreactive cells in the pineal organ and retina; ChAT immunoreactivity and AChE activity in the retina; III hatching; IV SA-immunoreactive cells in the retina. The obtained results provide good evidence that while photoreceptor cells develop much earlier in the pineal organ than in the retina, neurons develop simultaneously in the pineal organ and retina.

Acetylcholinesterase↗