The neurosecretory substance in the hypothalamic-hypophysial system of the horse.

This research investigates the production of antidiuretic and oxytocic hormones in the horse, arguing that they originate not from the posterior lobe of the hypophysis (pituitary gland), but from a neurosecretory process in specific cells of the hypothalamus. The study also discusses ways to histologically identify these products.

Hormone Production in the Hypothalamus

• This research builds on the hypothesis that the antidiuretic and oxytocic hormones in horses are produced not in the posterior lobe of the hypophysis (or pituitary gland), but due to a neurosecretory process in the hypothalamus. This is contrary to traditional belief.
• These hormones are believed to be produced in the nerve cells of the supraoptic and paraventricular nuclei (parts of the hypothalamus), and are then transported along the nerve fibers of the supraoptico-hypophysial tract into the neurohypophysis (part of the pituitary gland). From here, they are stored and released when necessary.

Neurosecretory Neurons

• The study provides information about neurosecretory neurons, which have been described in many animal species, from invertebrates to humans. These are specialized nerve cells that also function like endocrine cells, releasing hormones directly into the bloodstream.
• The product of the neurosecretory cells is made up of a substance that carries a stainable component, in addition to hormones. This staining process is a way to visually identify these substances under a microscope.

Histological Demonstration of Neurosecretory Cells

• The products of the hypothalamic neurosecretory cells can be demonstrated histologically through certain methods. Histology is the study of the microscopic anatomy of cells and tissues, which involves staining these to identify their structure and components.
• The research mentions the chrome-alum-hematoxylin-phloxin-method (Gomori, 1941) as one technique used for the staining process, implying that this procedure was utilized in their study to verify the presence and nature of the neurosecretory cells.