What is the answer to the smallest organ in the human body?

What is the smallest organ in the human body? The answer is as follows:

Parathyroid body

Parathyroid gland: small, round or oval, located near the thyroid gland. Domestic animals generally have two pairs of parathyroid glands. Parathyroid gland, one of endocrine glands, is an oblate ovoid body, about 3-8 mm long, 2-5 mm wide and 0.5-2 mm thick. It is located behind the lateral lobe of the thyroid gland and sometimes hidden in the thyroid parenchyma.

Generally divided into two pairs, each pair weighs about 35-50 mg. The surface of parathyroid gland is covered with a thin connective tissue capsule. The connective tissue of the capsule carries blood vessels, lymphatic vessels and nerves into the gland and becomes trabecula, which divides the gland into incomplete lobules. The parenchymal cells of the glands in the lobules are arranged in the form of cords or spheres, with a small amount of connective tissue and abundant capillaries.

Parathyroid gland is one of endocrine glands in human body. There are two pairs of parathyroid glands in the human body, which are brown and shaped like soybeans, and are located in the middle and lower parts of the back (or buried part) of the left and right thyroid.

There are generally two pairs of parathyroid glands, but there are often accessory glands. They are brownish yellow, oval and attached to the back of the thyroid gland. Each gland is 3 to 8 mm long, 2 to 5 mm wide and 0.5 to 2 mm thick. Several glands weigh 0.05 to 0.3g in total.

The upper pair of glands is located at the posterior part of the lateral thyroid lobe 1/3; The lower pair is mostly at the lower end of the back of the side blade. The parathyroid gland originates from the endoderm of pharyngeal pouch. The upper pair of glands originated from the fourth pharyngeal pouch. The lower pair of glands comes from the third pharyngeal pouch, which is very close to the position where the thymus appears. In the process of occurrence, it descends with the thymus, generally only to the lower end of the thyroid gland, and some can reach the vicinity of the thymus.

Extended data

Structure of parathyroid gland:

They have a thin layer of connective tissue wrapped by a membrane, and the membrane extends from the membrane to the parenchyma, and blood vessels, lymphatic vessels and nerves enter the parenchyma through the membrane. The parenchyma is composed of main cells and eosinophils, and the cells are arranged in a rope shape or a ball shape, and there are abundant capillaries between the cells.

1. Primary cells: Most cells are polygonal, with a diameter of about 7-65438 00μ m. The nucleus is round, the chromatin is sparse, and the staining is shallow, which is located in the center of the cell. Cytoplasmic staining is shallow and weakly eosinophilic.

2. Eosinophils: These cells are larger than the main cells, with fewer numbers, and often located between the main cells alone or in groups. The cells are polygonal or irregular, with small nuclei, deep staining and strong eosinophilic cytoplasm.