T. L. Hickey

Tritiated thymidine experiments in the cat: a description of techniques and experiments to define the time-course of radioactive thymidine availability

Tritiated thymidine [(3H]thymidine) autoradiographic techniques have been used to define birthdates for cells in a variety of animals. In an effort to include [3H]thymidine experiments in our ongoing studies of visual system development, we have used an intrauterine injection procedure that affords [3H]thymidine labeling of dividing nerve cells in the cat. This report contains a detailed description of the injection procedures used, as well as the results of experiments undertaken to define the period of time during which the exogenous [3H]thymidine introduced by such injections remains available for uptake.

Abnormal laminar patterns in the lateral geniculate nucleus of an albino monkey

Albino animals have abnormal retinogeniculate pathways characterized by reduced ipsilateral retinal projections 2,8,s-12,14,15,1s-22. The lateral geniculate nucleus in many albino animals exhibits large, abnormally fused cellular regions that receive contralateral retinal input and smaller, somewhat segregated, islands of cells innervated by the ipsilateral eye. In normally pigmented humans and other old world primates the lateral geniculate nucleus is made up of well-defined laminae, with cells receiving input from opposite eyes being separated by relatively cell-free interlaminar zones16,17. The principles that seem to govern the formation of these laminae have been described previously 17. In the albino human, however, the pattern of lamination in the lateral geniculate nucleus is quite different from that seen in a normally pigmented individual, including many abnormal fusions between adjacent parvocellular laminae and, in some parts of the nucleus, a reduction in the number of magnocellular layers 13. Although the abnormal retinogeniculate pathway has been described in a variety of albino animals besides humans, it has not to date been described in an albino subhuman primate. Since the albino condition in man is usually associated with several visual system anomalies including strabismus, nystagmus and amblyopia ~,4-7 it is important to find an appropriate experimental animal in which the condition can be studied using experimental techniques not applicable to humans. In this brief report we will describe an abnormally laminated lateral geniculate nucleus in an albino subhuman primate, the African green monkey. Although we were unable to carry out any experimental procedures prior to the death of this animal, our analysis of the laminar pattern in the lateral geniculate nucleus suggests that albino animals of this species may serve as excellent experimental models for the human albino condition. Two male African green monkeys (Cercopithecus aethiops) were used in the present experiment. One monkey was normally pigmented and was obtained as an adult. The second monkey had no pigmentation of the skin or hair and exhibited a noticeable

A method for combining Golgi impregnation procedures and light microscopic autoradiography

The following is a description of a technique for directly combining Golgi impregnation of neurons with light microscopic autoradiography. Golgi impregnation procedures have been combined with [3H]thymidine labeling of dividing neurons. This method is useful to investigations that could combine Golgi impregnation of neurons with any permanent radioactive marker.