Lab 1

Question 1

What are functional paths? What are 4 different types? How many neurons are in a functional path?

Answer 1

Circuits of at least 2 neurons.

Motor, sensory, visceral, association

It varies depending on the path, but lots and lots

Question 2

In the PNS, what is a group of neuronal cell bodies called? A group of axons? In the CNS, what are they called?

Answer 2

Ganglion; Nerve

Nucleus; Tract

Question 3

What are the nuclei of motor neurons like?

Answer 3

spherical, Large, centrally located.

Question 4

Where are protoplasmic astrocytes located? What do their processes look like? Where are fibrous astrocytes located? What do their processes look like?

Answer 4

gray matter

short, thin, heavily branching (mossy)

White matter

Longer, thicker, less branching (spider)

Question 5

What are oligo nuclei like in an H & E stain? What about astrocytes?

Answer 5

nucleus is small, spherical, and stains darkly due to its dense chromatin.

nucleus is larger, oval or elongated, and stains lightly.

Question 6

What are astrocytes and oligodendrocytes like under an EM?

Answer 6

This micrograph is from the neuropil of the cat thalamus and shows a protoplasmic astrocyte lying next to an oligodendrocyte. The main ultrastructural features of an astrocyte are its watery or translucent cytoplasm and its irregular shape. The astrocyte nucleus (1) is irregular or elongated and the nuclear envelope is indented. The chromatin is distributed relatively evenly throughout the nucleus although some clumping does occur, especially beneath the nuclear envelope. The cytoplasm (2) is very lucent and it is confined to a narrow rim surrounding the nucleus. It contains mitochondria (3) and scanty amounts of rough endoplasmic reticulum and other organelles. Numerous processes (4) emanate from the cell body and ramify as thin sheets (5) among the axons and dendrites in the neuropil.

The main ultrastructural features of the oligodendrocyte are its dark appearance, small size, and round shape. The oligodendrocyte nucleus (6) usually lies in an eccentric position, is round or oval, and contains dense clumps of chromatin. The cytoplasm (7) appears very dark and contains abundant amounts of rough endoplasmic reticulum, numerous free ribosomes, and Golgi apparatuses. Mitochondria are also numerous but they are inconspicuous because of the density of the cytoplasm. The remainder of the neuropil contains unmyelinated and myelinated axons, dendrites, boutons, and synaptic junctions