On the origin and prenatal development of the bovine adrenal gland

Abstract

Decisive steps of bovine prenatal adrenal development were investigated in 46 embryos and fetuses using histological, electron microscopical, immuno-, enzyme and lectin histochemical methods. About day 30, the intermediate mesoderm between the cranial mesonephros and coelomic cavity is segmentally organized. It consists of proliferating tissue complexes that are connected to the coelomic cavity by vestigial nephrostomial tubules. This segmental organization soon disappears, however, due to longitudinal fusion of the tissue complexes into a continuous joined blastema. This blastema of intermediate mesodermal (nephric) origin becomes positive for alkaline phosphatase at about 30 days, and slightly later also for acetylcholinesterase. The most cranial portions of this common blastema represent the adrenocortical anlage, the following portions the gonadal rete blastema. A reevaluation of the comparative anatomical record revealed that a nephric origin of adrenocortical or interrenal cells is a general feature of all vertebrates and that the erroneous assumption of the lateral plate-derived coelothelium as precursor of the adrenocortical (interrenal) blastema should be definitively abandoned. The first adrenomedullary precursor cells become visible in the bovine adrenal primordium at day 35. At 50 days, both components (medullary and cortical precursors) are present as interpenetrating plates and strands between large sinusoid vessels and exhibit a strong MIB-1 activity, indicative of a high proliferation rate. About day 60 the cellular proliferation slows down in some of the adrenocortical precursor cells, and the separation into a visible cortex and medulla is initiated. From about day 80 on, the medullary tissue coalesces into a large, continuous area in the interior of the gland, surrounded by a narrow cortical glomerulo-fasciculata that becomes positive for 3beta-hydroxysteroid dehydrogenase at about day 90. Autonomous nerves penetrate the blastemal region as early as day 31. When the separation into cortex and medulla starts, the nerves are more concentrated in the latter. From 130 days on, nerve fascicles reach the interior of the organ not only from its medial side, but also from the capsule surrounding the gland. The penetrating bundles traverse the zona glomerulo-fasciculata without ramification and split off at the border to the medulla. Here, in the outer zone of the medulla, they constitute a particularly dense plexus, whereas in the central medulla a less dense innervation is observed. Up until 90 days, cells with the characteristic features of primordial germ cells are present within the confines of the adrenal gland.

Differentiation of chromaffin cells in the developing adrenal gland of Testudo hermanni

“…The origin of adrenocortical tissue from mesoderm has been investigated mostly in mammals, where its association with gonads and kidney was described (Wrobel and Suss 1999), together with the increasing connection with chromaffin cells during development, in a structural and functional linkage. In mammals glucocorticoids regulate catecholamine synthesis by acting on the PNMT enzyme and also seem to be implicated in chromaffin cell differentiation (Hodel 2001).…”

The genus Acipenser as a model for vertebrate urogenital development: the müllerian duct

“…the gonadal rete blastema. This contact is particularly well conserved in marsupials (Buchanan and Fraser 1919;Burns 1941;Krause 1998), but is also clearly visible in the 35-day-old bovine embryo (Wrobel 2001;Wrobel and Süß 1999;, where the four joined primordia of nephrostomial tubular origin (müllerian infundibulum, adrenocortical blastema, rete blastema and the blastema of the gonad proper) are all characterized by a strong alkaline phosphatase reaction. During further development, the müllerian infundibular area and gonadal rete region generally remain in contact.…”

Morphogenesis of the bovine rete testis: the intratesticular rete and its connection to the seminiferous tubules

“…The rete and gonadal blastema on one side and the adrenocortical blastema on the other side are separated from each other between days 45 and 50 p. c. by the ascending metanephros. The rete blastema remains in contact with the regressing mesonephros, and the adrenal anlage accompanies the ascending definitive kidney (Wrobel and Süß 1999). Testicular differentiation begins in the bovine embryo at 39-40 days p. c. The first visible indication of this process is the appearance of a strong and specific histochemical acetylcholinesterase (AChE) reaction within the pre-Sertoli cells.…”