Abstract
The so-called "nuclei magnocellularis hypothalami ", i. e. the supraoptic and paraventricular nuclei, in the fowls are the most prominent nuclei in the hypothalamus.
These nuclei are the ones which have been shown to be nuclei of origin of hypothalmo-hypophysial fibers.
In the fowls, the cell groups are as follows :
Nucleus magnocellularis praeopticus et supraopticus
pars ventrocaudalis (figs. 2, 3, 7(1)(2)(3), 8)
pars medialis(figs. 2, 3, 4, 5, 7 (4) (5), 9, 11)
pars lateralis(figs, 2, 3, 10) Nucleus magnacellularis paraventricularis
pars principalis(figs. 4, 5, 6, 7 (6) (7), 12)
pars accessorius (figs. 5, 6, 7, (8) (9)) 10) (11), 13)
Cell counts were made on every 5th section for the supraoptic and paraventricular nucleus. Table 1 gives the cell population and number in these nuclei.
The praeoptico-hypophyseal tract and the supraoptico-hypophyseal tract arise from the praeoptic nucleus and supraoptic nucleus respectively. These tracts, perhaps together with a few fibers of the uncleus magnocellularis paraventricularis pars principalis, form a distinct tract which can be followed to the neurohypophysis. This tract is therefore called tractus praeoptico-supraoptico-hypophyseus.
