The development of the habernular nuclei in SPF - cats: a light microscopic and morphometric study

The ontogenesis of the habenular nuclei in SPF-cats is described with respect to cytodynamic processes and the development of differentiations in the epithalamic ventricular wall. The volume was measured in 61 male SPF-cats aged 39 to 584 ontogenetic days. On the 156th ontogenetic day both sides of the nucleus medialis habenulae attain a mean fresh volume of 3.2 mm3 with a growth factor of 2.4 and a half value time of 70 ontogenetic days. Both sides of the nucleus lateralis habenulae reach a mean fresh volume of 4.9 mm3 on the 168th ontogenetic day with a growth factor of 2.8 and a half volume time of 74 ontogenetic days. Both habenular nuclei show early volumetric development in the CNS, whereby the medial nucleus develops before the lateral one. Nerve cell counts are reported for the right nucleus medialis and lateralis habenulae in 29 male SPF-cats aged from 39 to 584 ontogenetic days. During this period, the number of neurons in the right medial habenular nucleus decreases by about 48% and attains a final value of 148,000 neurons on the 83rd ontogenic day. The number of neurons in the right nucleus lateralis habenulae decreases by about 38% and attains its final value of 61,000 neurons on the 72nd ontogenetic day. Since the experimental animals were maintained in a specific pathogen free environment, exogenous pathological influences can be excluded as the cause for this reduction in cell number.