TY - JOUR
T1 - Ontogenetic development of the pineal organ, parapineal organ, and retina of the three-spined stickleback, Gasterosteus aculeatus L. (Teleostei) - Development of photoreceptors
AU - Ekström, P.
AU - Borg, B.
AU - van Veen, Theo
PY - 1983/9/1
Y1 - 1983/9/1
N2 - The ontogenetic developments of the pineal organ, parapineal organ, and retina were studied by the use of light and electron microscopy in embryos and fry of the teleost, Gasterosteus aculeatus, from 60 to 168 h after fertilization. Sixty to 66 h after fertilization, the primordium of the pineal complex is discernible in the diencephalic roofplate; the parapineal anlage is located rostral to the pineal anlage. Photoreceptor cells endowed with outer segments are present in the embryonic pineal organ already after 72 h, whereas outer segments of retinal photoreceptors could not be demonstrated before 144 h (hatching occurs between 120-144 h). Furthermore, neuropil formations with synaptic specializations are present in the rostral part of the pineal organ 108 h after fertilization. At 72 h, the embryonic parapineal parenchyma is already differentiated into parapinealocytes, which give rise to the parapineal tract, and glia-resembling elements. Although parapinealocytes carry cilia (9 × 2 + 0), only a single outer segment of the photoreceptor type could be demonstrated in the parapineal organ of one adult stickleback. Photoreceptors present in the pineal organ of unhatched embryos are hardly involved in visual functions, but may already at this early developmental stage serve as photoneuroendocrine transducers.
AB - The ontogenetic developments of the pineal organ, parapineal organ, and retina were studied by the use of light and electron microscopy in embryos and fry of the teleost, Gasterosteus aculeatus, from 60 to 168 h after fertilization. Sixty to 66 h after fertilization, the primordium of the pineal complex is discernible in the diencephalic roofplate; the parapineal anlage is located rostral to the pineal anlage. Photoreceptor cells endowed with outer segments are present in the embryonic pineal organ already after 72 h, whereas outer segments of retinal photoreceptors could not be demonstrated before 144 h (hatching occurs between 120-144 h). Furthermore, neuropil formations with synaptic specializations are present in the rostral part of the pineal organ 108 h after fertilization. At 72 h, the embryonic parapineal parenchyma is already differentiated into parapinealocytes, which give rise to the parapineal tract, and glia-resembling elements. Although parapinealocytes carry cilia (9 × 2 + 0), only a single outer segment of the photoreceptor type could be demonstrated in the parapineal organ of one adult stickleback. Photoreceptors present in the pineal organ of unhatched embryos are hardly involved in visual functions, but may already at this early developmental stage serve as photoneuroendocrine transducers.
KW - Development
KW - Gasterosteus aculeatus L. (Teleostei)
KW - Parapineal organ
KW - Photoreceptors
KW - Pineal organ
KW - Retina
UR - http://www.scopus.com/inward/record.url?scp=0021035917&partnerID=8YFLogxK
U2 - 10.1007/BF00212227
DO - 10.1007/BF00212227
M3 - Article
C2 - 6684991
AN - SCOPUS:0021035917
SN - 0302-766X
VL - 233
SP - 593
EP - 609
JO - Cell and Tissue Research
JF - Cell and Tissue Research
IS - 3
ER -