The existence of the pituitary body has been known
since very early times. The Greeks, believed that the
waste products of a certain chemical reaction in the
brain flowed down the funnel-shaped infundibulum to the
pituitary gland. From the gland, ducts were supposed to
pass these waste products into the nasal cavity to form
the " pituita" or nasal mucus.
The fact that the pituitary body consists of two
anatomical divisions, the anterior and posterior lobes,
as well as the fact that its embryological origin is from
two divergent primitive tissues, was disregarded in all
pathological, physiological, and clinical work, until
almost the close of the last century.
Notwithstanding the numerous studies to which the
pituitary has been subjected since the beginning of this
century, many problems remain unsolved. It has claimed
the attention of anatomists, histologists, embryologists,
and physiologists because it is, as has been stated by
Sir Walter Brown (1870 -1946), the "leader of the
endocrine orchestra ".
The morphology of the P ituitary gland has been fully
established for relatively few mammals, and for even
fewer birds and reptiles, but nevertheless, recent
studies (see below) of the hypophysial anatomy in several
mammals have revealed marked variations in its
morphology.
Studies relating to the development of the pituitary
body have been numerous, although in many of them the
consideration of the hypophysis has been only incidental
to the other interests of the observer, and no single
investigator has given a complete account of the
morphogenesis of the gland throughout the whole of its
development.
Consequently, this study was undertaken in an
attempt to trace the complete development of the pituitary
body in a single mammal, namely the albino rat.
The albino rat (Mus norvegicus) was chosen because:
1) the animal can breed well in confined quarters,
2) it has a short gestation period (21 days),
3) it has large litters,
4) the pituitary of the adult animal has been
subjected to extensive cytological and experimental
work, and
5) so far as it has been recorded, no investigation;
except Schwind (1928), has attempted to describe
the development of the pituitary in the rat.
In particular, this present study is concerned
with the morphogenesis of the pituitary body from the
time of its first appearance during the embryonic life,
until the age of sexual maturity of the animal. Special
attention has been paid to the origin, topography, and
cytology, as well as the qualitative and quantitative
growth of its various lobes. The study also deals with
some related problems such as the development of the
cephalic end of the notochord in relation to the
developing gland, and the development of the surrounding
membranes, the nervous and blood supply, and the
functional activity of the pituitary as shown by
histological differentiation.
