Asunto(s)
Hemoglobinas/química , Secuencia de Aminoácidos , Animales , Electroforesis , Peces , Globinas/química , Globinas/genética , Globinas/aislamiento & purificación , Guanosina Trifosfato/metabolismo , Hemoglobinas/metabolismo , Concentración de Iones de Hidrógeno , Modelos Moleculares , Datos de Secuencia Molecular , Oxihemoglobinas/química , Oxihemoglobinas/metabolismo , Relación Estructura-ActividadAsunto(s)
Agregación Celular , Diferenciación Celular , Animales , Células Cultivadas , Embrión de PolloRESUMEN
Studies were performed on spherules of approximately 100-300 micrometer in diameter obtained from in vitro cultures of reaggregates of embryonic fragments of cerebellum from 10-12 day-incubated chick embryos, dissociated with trypsin and cultivated in a rotating shaker for a maximum of 21 days. The differentiated neurons within these spherules included a few Purkinje cells, many granule cells and type II Golgi cells, as well as many glial cells. Zones rich in synaptic knobs and other simple synaptic structures as well as complex synaptic systems with numerous active points of contact, were visible in various parts of the spherule. Typical "glomeruli" consisting of a varicosity of "rosette" joined to the dendritic claws of the granule cells, and "en marron" systems with perikarya of type II Golgi cells were easily recognised. The complete absence of extracerebellar afferents confirms that both the granule and Golgi cells are capable of making synaptic connections with afferents different from those normally formed by extracerebellar mossy or climbing fibres. The experimental findings confirm that the recipient neurons determine the specific synaptic pattern regardless of the nature of the afferents, and furthermore demonstrate that the clinging activity of the recipient neuron determines the synaptogenic behaviour of nervous pathways.
Asunto(s)
Cerebelo/citología , Sinapsis , Animales , Diferenciación Celular , Cerebelo/embriología , Embrión de Pollo , Técnicas de Cultivo , Neuroglía , Células de Purkinje , Factores de TiempoRESUMEN
Optic vesicles from embryos of Rana esculenta at a stage corresponding to stage 19 in the development of Rana pipiens were cultured for 15 days. The eyes which differentiated in vitro were much smaller than controls of the same age, due partly to the absence of the vitreous body. In many specimens a well-stratified retina surrounded by a layer of pigmented cells was found. The features of all the components of the retinal layers are described. The complete differentiation of photoreceptors, including their outer segments, is the most interesting result obtained in these organ cultures, and is in contrast with the observations previously reported for retinal tissue cultures. The authors suggest that the source of the material (amphibia instead of birds or mammals) is the main reason for this discrepancy. Frog embryo cells are practically self-sufficient since they are endowed with nutritional substances, amongst which Vit. A and antioxidative agents (Vit. E and ascorbic acid) have been indicated as the most important factors for the structural organization and integrity of the outer segments. The role played by the pigment epithelium is also discussed.