A Golgi and electron microscope study of the ventral septum in the reptile, Podarcis hispánica.

The ventral septum of the reptile Podarcis hispánica has been studied using cytoarchitectonical and Golgi methods as well as electron microscopy techniques. The ventral septum is located in the medial wall of the telencephalon, just ventral to the dorsal septum. 2 different cell masses or nuclei can be easily appreciated in this structure: the Ventro-lateral Nucleus, located close to the ventricle, and the Ventro-medial Nucleus, located close to the medial hemispheric wall. Using Golgi methods, 3 classes of neurons have been distinguished: Big Polymorphic (BP) neurons, Small Polymorphic (SP) neurons and Horizontal (H) neurons. BP neurons are located within Ventro-medial Nucleus and they are characterized by a large dendritic 3 with numerous dendritic spines (50 spines per 100 microns). SP neurons are located within Ventro-lateral Nucleus and they are characterized by a small dendritic tree which is covered by numerous dendritic spines (48 spines per 100 microns). H neurons are located around both nuclei and they are characterized by a linear dendritic tree and a low number of dendritic spines. Using E.M. techniques 3 classes of neuronal cell bodies can be distinguished: big neuronal somata, small neuronal somata and spindle-like neuronal somata Big somata are located within Ventro-medial Nucleus. Small somata are located within Ventro-lateral Nucleus. Spindle-like somata are located either close to the lateral ventricle or close to the medial hemispheric wall. We have identified 4 different types of synaptic endings in the neuropil, depending on the vesicle morphology: A) endings with slightly pleomorphic vesicles; B) endings with big round vesicles; C) endings with dense core vesicles and D) endings with small round vesicles.