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Light and electron microscopic observation on the appearance of immunoreactive LHRH in perinatal rat hypothalamus
Insights
Researchers identified Luteinizing Hormone-Releasing Hormone (LHRH) in developing rat brains, revealing its presence in the hypothalamus during fetal development. This study tracks LHRH appearance and fiber growth, suggesting its role in the early hypothalamo-hypophysial system.
Area of Science:
- Neuroscience
- Developmental Biology
- Endocrinology
Background:
- Luteinizing Hormone-Releasing Hormone (LHRH) plays a crucial role in reproductive functions.
- Understanding the early development of LHRH in the hypothalamus is essential for comprehending the onset of the hypothalamo-hypophysial system.
Purpose of the Study:
- To investigate the appearance and localization of LHRH in the developing hypothalamus of perinatal rats.
- To characterize the morphological changes of LHRH-containing nerve fibers during fetal development.
Main Methods:
- Utilized the unlabelled antibody method for light microscopy.
- Employed pre-embedding immunohistochemistry for electron microscopy examination of the median eminence.
- Studied perinatal rat hypothalamus at specific gestational ages.
Main Results:
- Immunoreactive LHRH was first detected on day 18.5 of gestation in the OVLT and day 19.5 in the median eminence.
- LHRH-containing nerve fibers were observed in the median eminence by day 18.5, initially thin and sparse.
- A progressive increase in the number and size of these fibers, along with secretory granules, was noted with development.
Conclusions:
- LHRH is present in the hypothalamus during late fetal development in rats.
- The observed development of LHRH fibers suggests a role in the establishment of the hypothalamo-hypophysial system.
- Further research is warranted to elucidate the precise physiological significance of LHRH during fetal life.
Abstract:
The appearance and localization of LHRH were studied in the developing hypothalamus of perinatal rats using the unlabelled antibody method. By light microscopy, immunoreactive LHRH was first detected as brown dots on day 18.5 of gestation in the OVLT and on day 19.5 in the median eminence, respectively. When the median eminence was examined by the preembedding immunohistochemistry technique for electron microscopy, the occurrence of immunoreactive LHRH fibers could be demonstrated on day 18.5. These fibers were thin and very occasionally encountered near the surface of the lateral regions of the median eminence. The axoplasm contained a few immunopositive secretory granules and also extragranular immunoreactive products. With development, a gradual increase was noted both in number and size of nerve fibers with a concomitant accumulation of secretory granules within the axoplasm. A possible physiological significance of LHRH is discussed in relation to the onset of hypothalamo-hypophysial system in fetal life.