[A preliminary study on development of human visual system in fetus by DiI-tracing].
OBJECTIVE
To reveal the morphological features and dynamic processes of the development of inter-connections in the retina, lateral geniculate nucleus (LGN), superior colliculus (SC) and visual cortex (VC) in human fetal life by using a fluorescent tracer, 1, 1'-dioctadecyl-3, 3, 3', 3'-tetramethylin-docarbocyanine perchlorate (DiI).


METHODS
DiI was embedded into the optic tract, brachium of superior colliculus and subplate of visual cortex in fixed postmortem human tissues of 7 fetuses. The tissue was incubated at 37 degrees C for 4 to 10 weeks (ws). After DiI had satisfactorily diffused via axons of the visual system, the tissue was sectioned, mounted and observed under a confocal laser scanning microscope.


RESULTS
In 12 week-fetus, retinogeniculate axon has already reached LGN, but there was no cellular lamination. After embedment, axons from retina arrived at SC, and the fibers were distributed along the dorsal part of the SC. At 12 and 22 ws, there were subplates under visual cortex.


CONCLUSIONS
The retinogeniculate axon reaches LGN before 12 ws and forms cellular lamination after 12 ws. The axon from retina reaches SC before 12 ws. The subplate under visual cortex forms before 12 ws and disappears after 22 ws. DiI can be easily and effectively used to label the axon of visual system of human fetus to study the prenatal development of human visual pathway.
Qu
Jia
J
School of Ophthalmology & Optometry, Wenzhou Medical College, Wenzhou 325003, China.
Zhou
Xiangtian
X
Zhang
Luanling
L
Ni
Hailong
H
Ashwell
Ken
K
Lu
Fan
F
D001369:Axons / Q000502:physiology; D002232:Carbocyanines; D005333:Fetus; D005456:Fluorescent Dyes; D005829:Geniculate Bodies / Q000196:embryology; D006801:Humans; D018613:Microscopy, Confocal; D009900:Optic Nerve / Q000196:embryology / Q000502:physiology; D012160:Retina / Q000196:embryology; D014793:Visual Cortex / Q000196:embryology; D014795:Visual Pathways / Q000196:embryology*
D002232:Carbocyanines; D005456:Fluorescent Dyes; C024286:3,3'-dioctadecylindocarbocyanine