Paper - The development of the adrenal gland in man: Difference between revisions

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=The Development Of The Adrenal Gland In Man, With Special Reference To Origin And Ultimate Location Of Cell Types And Evidence In Favor Of The “Cell Migration” Theory=
 
==Introduction==
 
A voluminous literature has accumulated on the development of the adrenal gland. In 1902, Iosef \Viesel
apologized for adding one more article. Others, including the present author, have not been so restrained.
 
In a study of the sources of certain of the adrenal
hormones, a review of the literature on the embryology
and histology of the gland was undertaken. In spite
of the number of articles published on the subject, including extensive reviews (Parkes, I945; Lanman, 1953),
there was no consecutive life history of the source and
ultimate distribution of the various cell types found in
the gland. and, therefore, it was not possible to associate
the synthesis of the adrenal hormones with specific cell
types.
 
The wealth of closely seriated, well preserved, and adequately stained material available in the Carnegie Embryological Collection, in Baltimore, Maryland, made a complete histologic and embryologic study possible.’
 
The study was begun with the idea of determining the
types of cells in the adrenal cortex. It was soon found
that, to do this adequately, the whole embryologic history
must be reviewed. The results of this undertaking are
set forth herein. It is hoped not only that they will assist
in an understanding of the sequence of events in the
histogenesis of the adrenal cortex and clarify a few of
the points of controversy, but also that the descriptions
of cell types in the cortex may be of value in determining
the oligoplasia or hypcrplasia of certain of these cell types
in relation to many clinical entities.
 
==Definitions==
 
The following terms are defined to clarify the presentation:
 
Fetal cortex: The fetal adrenal cortex is composed of
the same cell types as the adrenal cortex of the adult
human, but the proportions and arrangements differ.
 
Medullary cells: The cells of neural origin which take
up a location in the central portion of the gland during
development. The process of localization begins in the
embryonic period and continues until childhood.
 
Cell types: Cell types in the cortex are differentiated
by the structure of their nuclei; they are numbered according to the order of their appearance in the primordium, as C-I (fig. 38, pl. 8), C-II (fig. 39, pl. 8), and
C-III (fig. 40, pl. 8). As will be made clear, three distinct
cell types may be recognized in the development of the
medulla; these cells, designated M-I, M-II, and M-III, are
described beginning on page 202.
 
Celomic epithelial cells: The cells of the adrenal cortex
which have their origin in the celomic epithelium. They
are of two types: Type C-I (fig. 38, pl. 8), the first cells
to enter the primordium, are large polyhedral cells, each
of which contains a large round nucleus with little
chromatin, a large round nucleolus, and a spherical, refractile inclusion. In a later stage, type C-III cells (Hg. 40,
pl. 8) begin to emerge from the celomic epithelium,
together with type C-I. Type C-III cells are smaller than
type C-1, and each contains a smaller round nucleus
which stains more deeply with hematoxylin. In the
nucleus. there is a large amount of chromatin, which
 
‘The ideas herein expressed are those of the author and do
not reflect those of the United States Navy.
 
195
 
tends to aggregate into four to five major clumps and
one or two globules or vacuoles.
 
Cells of mesonephric origin: These cells arise from
Bowman's capsule of the mesoncphros. They are designated as type C-II cells (fig. 39, pl. 8), and are first seen
streaming from the glomerular capsule across the ventral
portion of the early primordium (figs. 14, 15, pl. 2). The
type C-II cells and their successors form most of the
adrenal capsule, and, during horizon xxiii, are diverted
inward by the arteriolar capillaries. Thereafter, they are
found in the cords of cells within the cortex. Their
nucleus is round, and stains a little more deeply than
does that of type C-I. The chromatin is distributed in
fine strands in a spider-like manner just beneath the
nuclear membranes, the nucleolus corresponding to the
body of the spider. The center of the nucleus is occupied
by one or more large globules or vacuoles.
 
Immigration and migration: The passage of cells from
one region to another; the addition of cells by movement
from an adjacent region. Ameboid movement is not
implied.
 
Invasion: The entrance of cells after destruction or disruption of pre-existing tissue, and the assumption of position without rcference to former relations.
 
Staging of embryos: The dating of the embryos follows the horizons described and graphed by Streeter
(1951). This method of seriation affords a much better
concept of the progress of development than does measurement of the length. Frequently, the organogenesis
of the adrenal gland was found to be in a much further
advanced stage in an embryo with a shorter crown-rump
length than in a longer one, particularly in the earlier
 
 
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Latest revision as of 11:19, 26 July 2020