Development of the adrenal cortex in the fetal foal: an ultrastructural study.
Abstract: The adrenal cortex from twelve fetal foals (gestational ages from 61 to 300 days) was examined by light and electron microscopy. Adrenal glands from three newborn foals were also examined by light microscopy. Between 61 and 100 days of gestation the adrenal cortex became organised into two distinct regions, the zona glomerulosa and zona fasciculata, which grew steadily in thickness until the 300th day. Between 300 days and birth there was a dramatic increase in the width of the zona fasciculata. From 200 days a narrow band of compact cells marked the cortico-medullary border. Though these cells were ultrastructurally indistinguishable from those of the overlying zona fasciculata it seems possible that they may later give rise to the zona reticularis of the adult gland. The cells of the zona glomerulosa were columnar in shape and were tightly packed together into cell clusters. They contained smooth and rough endoplasmic reticulum and mitochondria with lamellar cristae. The ultrastructural characteristics of the cells of the zona glomerulosa changed little throughout the course of gestation. In the zona fasciculata the predominant cell type was angular in profile, and its cytoplasm contained smooth and rough endoplasmic reticulum and mitochondria with lamellar cristae. The second and larger cell type was situated nearer the cortico-medullary border. It contained an abundance of smooth endoplasmic reticulum, mitochondria with lamellar and/or vesicular cristae, and large perinuclear Golgi complexes. These cells, which appeared to be derived from the smaller more angular cells of the zona fasciculata, showed signs of a high level of metabolic and synthetic activity. As gestation progressed the number of functionally differentiated cells increased slowly in a radial direction towards the zona glomerulosa. Indirect evidence from two newborn foals suggests a rapid increase in the functional differentiation of zona fasciculata cells between 300 days and birth.
Publication Date: 1981-02-01 PubMed ID: 7264264
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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This study focuses on the development process of the adrenal cortex in fetal foals, from gestation to birth. Detailed light and electron microscopic examinations were performed on 12 fetuses at varying gestational ages and three newborn foals, revealing changes and growth in specific regions of the adrenal cortex, specifically the zona glomerulosa and zona fasciculata.
Development of Adrenal Cortex regions
- Organisation into two regions, the zona glomerulosa and zona fasciculata, was observed to happen between 61 and 100 days of fetal development. These regions continued to thicken until around the 300th day of gestation.
- Between the 300th day and birth, the width of the zona fasciculata increased drastically.
- Beginning at the 200th day, a clear band of cells became visible at the border of the cortex and medulla. There’s a possibility these cells may eventually develop into the zona reticularis in adult horses.
Cellular Characterisation
- The zona glomerulosa cells, closely packed in clusters, were observed to be columnar in shape with endoplasmic reticulum and mitochondria.
- The cellular structure of the zona glomerulosa appeared consistent throughout gestation.
- Within the zona fasciculata, two distinct cell types were observed. The first type was angular in profile, containing both smooth and rough endoplasmic reticulum and mitochondria.
- The second type of cell, located closer to the cortex-medulla border, displayed higher levels of metabolic activity, with an abundance of endoplasmic reticulum, mitochondria, and large perinuclear Golgi complexes.
- As gestation advanced, the proportion of differentiated cells grew in a radial direction towards the zona glomerulosa
Inferences from Newborn Foals
- From observations in two newborn foals, the researchers inferred a rapid increase in the functional differentiation of zona fasciculata cells between the 300th day and birth.
In summary, the study offers rich detail on the development of the adrenal cortex in foals, from gestation through to birth, outlining the growth and differentiation of key regions and cellular typologies. The findings could prove essential for understanding adrenal gland development and function in horses.
Cite This Article
APA
Webb PD, Steven DH.
(1981).
Development of the adrenal cortex in the fetal foal: an ultrastructural study.
J Dev Physiol, 3(1), 59-73.
Publication
Researcher Affiliations
MeSH Terms
- Adrenal Cortex / anatomy & histology
- Adrenal Cortex / growth & development
- Adrenal Cortex / ultrastructure
- Adrenal Glands / ultrastructure
- Animals
- Blood Vessels / ultrastructure
- Endoplasmic Reticulum / ultrastructure
- Fetus / physiology
- Gestational Age
- Golgi Apparatus / physiology
- Horses / embryology
- Lipids / physiology
- Mitochondria / ultrastructure
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