What Is the Bulbourethral Gland?

The human pineal gland is a gray-red oval body with a length of (5-8) mm and a width of (3-5) mm. It weighs (120-200) mg, and its development reaches its peak at the age of 7-8 years. The pineal gland is located at the top of the interbrain, between the zygomatic and posterior commissures. The depression above the quadriplex is located at the top of the third ventricle, so it is also called the adrenal gland. Connected, the third ventricle protrudes into the stalk to form a pineal crypt. The surface of the pineal gland is covered with connective tissue membranes extending from the pia mater. The membranes extend into the parenchyma with the blood vessels and divide the parenchyma into many irregular leaflets. The leaflets are mainly composed of pineal cells, glial cells and nerve fibers composition.

The human pineal gland is a gray-red oval body with a length of (5-8) mm and a width of (3-5) mm. It weighs (120-200) mg, and its development reaches its peak at the age of 7-8 years. The pineal gland is located at the top of the interbrain, between the zygomatic and posterior commissures. The depression above the quadriplex is located at the top of the third ventricle, so it is also called the adrenal gland. Connected, the third ventricle protrudes into the stalk to form a pineal crypt. The surface of the pineal gland is covered with connective tissue membranes that extend from the pia mater. The capsules extend into the parenchyma with the blood vessels and divide the parenchyma into many irregular leaflets. The leaflets are mainly composed of pineal cells, glial cells, and nerve fibers. composition.

Chinese name

Pineal gland

Foreign name

pineal body

Shape

Reddish brown bean bodies

long

5 8mm

First, blood vessels and nerves:

The pineal gland is rich in blood vessels, and its blood flow is second only to that of the kidney. The arteries branching from the left and right choroidal arteries penetrate the pineal gland, travel between connective tissues, and then form a capillary network, which is gathered by the veins. Through the capsule to form the pineal glandular vein, and finally injected into the large vein of the brain.

The nerves of the pineal gland come from peripheral nerve fibers, including sympathetic nerves, parasympathetic nerves, connective nerves, and peptide nerves.

Second, the generation mechanism:

The pineal gland is derived from the neuroectoderm and is located at the top of the third ventricle. At 33 to 36 days of human embryos, the epithelium thickens here, which is the pineal primordium. Sometimes a small process can occur in front of it, called the para-pineal gland, which mostly disappears in the later stage of the embryo, but it can also remain as an adult cyst. At 2 months, the thickened pineal gland bulges outward, forming a small sac first, and later the cells proliferate to form a parenchymal organ, leaving only a small cavity at its base, which is the crypt. The pineal gland is formed at the junction of the pineal gland and the mesencephalon. At 5 months of the embryo, the cells differentiate into pineal cells and glial cells, and the cells gradually form clusters and cords. At 6 months, the pineal gland cells were clearly differentiated, and by the 8th month, the pineal gland was approximately adult. After birth, the pineal gland cells stopped proliferating, but the cells continued to grow, and the glial cells and interstitial cells increased. In later embryos and early juveniles, pineal somatic cells are composed of large, weakly pheochromophores and small (mature) cells with strong pheochromophores. When the cells mature, the nucleus appears sunken or lobulated, with nucleoli, and cytoplasm has fine particles of chromaffin. Electron microscopy showed that the pineal gland cells in the late embryo had secretory function. Generally speaking, human pineal gland cells have no light-sensing function, and several types of transition from light-sensing cells to endocrine cells cannot occur. For example, ciliated primary secretory thin-type light-sensing cells, intermediate light-sensing-endocrine cells, Completely endocrine cells.

Fourth, physiological functions:

1. Secret melatonin, inhibit the secretion of pituitary follicle stimulating hormone and luteinizing hormone, and secrete a variety of peptide hormones with strong anti-gonadotropin effect, thereby effectively inhibiting the activity of the gonads and the appearance of amphoteric sex . If the pineal gland is damaged, precocity and overdevelopment of the reproductive organs occur.

2. Secretion of hypoglycemic factor, its action time is longer than insulin, up to 24 hours.

3. The activities of pineal gland show obvious periodicity. The amount of melatonin secretion decreases with light and increases with darkness during the day and night. According to research, this may affect sleep and wakefulness. In addition, the pineal gland's activity also shows a cycle of months, seasons, and years. Scientists believe that the pineal gland may send a "time signal" to the central nervous system in this way, thereby affecting the body's "biological clock."