Cytological § tructure, Hypothalamic Nuclei, Functional Connections 75 
pattern is quite uniform. The chromidia are finely granular and. 
In most of these neurons, form a very compact perinuclear ring. 
They rarely have a peripheral distribution. 
HyporHaramic NUCLEI MADE UP CHIEFLY OF PERIPHERAL 
VISCERAL EFFERENT NEURONS 
Nucleus Supraopticus: This nucleus is located ventrolaterally 
in the rostral Portion of the hypothalamus (Fig. 3 A), just dorsal 
to the fibers of the optic tract. Is is divided, throughout most 
of its extent, into a lateral, large-celled portion, and a medial, 
medium-sized and small-celled portion. The lateral division in- 
cludes the greater part of the nucleus and contains the peripheral 
visceral efferent neurons. The larger neurons of the medial 
division are central visceral efferent; the smaller ones are asso- 
Ciational. The neurons of the large, lateral divisions are regard- 
ed as those whose axons form the supraoptico-hypophyseal ace 
Nucleus Filiformis Principalis: |The main body of this 
nucleus lies in the medial portion of the tuber cinereum a short 
distance lateral to the third ventricle (Fig. 3B). The neurons 
are not compactly aggregated, particularly in the anterior pert of 
the nucleus where most of them are in other respects identical 
to those of the lateral portion of the nucleus supraopticus, but 
slightly smaller central visceral efferent and associational neurons 
occur among those of the peripheral visceral efferent type. 
Nucleus Filiformis Lateralis: This nucleus lies lateral to 
the dorsal tip of the nucleus filiformis principalis and is sepa- 
Fated from the latter by undifferentiated periventricular gray 
matter. The presence of peripheral visceral efferent —— 
Suggests functional connections similar to those of the — 
Portion of the nucleus supraopticus. These neurons are ue 
What smaller than the peripheral visceral efferent neurons in a 
supraoptic nucleus and the chromidial dust in them is less marked. 
Central visceral efferent and associational neurons also are present. 
