1. Observe the location and morphology of the thyroid, parathyroid, adrenal, pituitary and pineal glands.
2. Observe the microstructure of the thyroid, adrenal and pituitary glands.
Operation method
Endocrine system observation experiment
Materials and Instruments
Neck Anatomical Specimen Abdominal Anatomical Specimen Human Brain Anatomical Specimen and Model Thyroid Sections Adrenal Sections Pituitary Sections Thyroid Follicles Electron Microscope Pictures Move I. Location and morphology of endocrine glands For more product details, please visit Aladdin Scientific website.
Dissecting Plate Dissecting Forceps Dissecting Knife Microscope
1. The thyroid gland is located in the anterior part of the neck, brownish-red, "H", divided into left and right lobes, which are connected by the thyroid isthmus. The left and right lobes are attached to the outer side of the larynx and the upper part of the trachea, the upper end reaches the middle of the thyroid cartilage, and the lower part reaches the sixth tracheal cartilage. In some cases a tiny cone-shaped lobe extends upward from the isthmus. The thyroid gland is covered with a connective tissue peritoneum.
2. The parathyroid glands are two pairs of flat oval bodies, brownish-yellow in color, which are attached to the back of the left and right lobes of the thyroid gland. Sometimes they are buried in the thyroid tissue and are not easy to find.
3. Adrenal glands Adrenal glands, one on the left and one on the right, are located in the upper and inner sides of the two kidneys and are golden yellow in color. The left side is semilunar, the right side is triangular, and the surface is covered with connective tissue peritoneum. In the dissected adrenal specimen, the naked eye can distinguish the cortex and medulla.
The pituitary gland is located in the pituitary fossa above the pterygoid body and is transversely oval, connected to the hypothalamus by the pituitary stalk.
5. Pineal body is located in the shallow concavity between the two superior colliculi in the upper posterior part of the dorsal thalamus, resembling a pinecone, grayish-red in color.
Microstructure of endocrine glands
(I) Thyroid gland (H-E staining)
1. Low-magnification observation: There are many round or ovoid follicles in the glandular parenchyma, and the follicles are filled with colloid which is stained red by eosin. The gelatinous material is easily contracted to form many small round vacuoles.
2. High magnification observation: The follicle wall is surrounded by a single layer of cuboidal epithelium, the nucleus is rounded and the cell boundary is clear. However, it should be noted that the morphology of the follicular epithelial cells can be changed due to different functional states, so sometimes the section is not necessarily cubic, but flat or columnar. Some cell clusters with the same structure and staining as the follicular epithelial cells can be seen in the connective tissue between the follicles. This is due to the fact that the section only cuts into the follicular wall but not the follicular lumen. Parafollicular cells are ovoid, larger than follicular epithelial cells, and lighter in H-E stained sections. The parafollicular cells were often embedded in the follicular wall singly or in groups of three or five in the interfollicular connective tissue.
(II) Thyroid gland (silver staining)
Parafollicular cells are easily recognized in this section. The brownish parafollicular cells are first found with low magnification, and then with high magnification, the cells are seen to contain brownish silver-loving granules.
(C) Adrenal gland (H I E) staining.
1. Naked eye observation The outer deep purplish-red part is the cortex, which accounts for most of the entire gland. The middle part which is void and light blue is the medulla.
2. Low-power microscopic observation: the outer part is covered with connective tissue, and the substance of the gland is divided into cortex and medulla, which are clearly demarcated.
(1) Cortex According to the arrangement of glandular cells, it is divided into three layers from the peritoneum inward, i.e., globular band, fascicular band and reticular band. The globular band is located under the peritoneum, this band is narrower, the cells are arranged into globular clusters, the cell volume is smaller, the nucleus is darker. There were capillaries and a small amount of connective tissue between the spherical cell clusters. The fascicular zone was the thickest, accounting for most of the cortex, and consisted of polygonal cells arranged in single or double rows of cords. The light coloration of the fasciculus is due to the large number of lipid-like droplets contained in the cytoplasm, which are dissolved during the preparation process and become vacuolated. Between the cords are capillaries and a small amount of connective tissue. The reticular band is connected with the medulla, the cells are arranged into cords, the cords cross and anastomose to form a network, and the inter-network is capillaries and a small amount of connective tissue. The cytoplasm stains redder.
(2) medulla can be seen in many polygonal cells, arranged in cords or clusters, the cytoplasm stained light blue-purple, if the specimen is fixed with chromium salt-containing fixative, the cytoplasm shows brown chromophilic particles, and thus called this cell chromophilic cells. There are abundant blood sinuses in the connective tissue between the cells, and the central vein and its branches can also be seen with a large lumen and thin wall.
(D) Pituitary gland (H-E staining)
1. Naked eye observation, the organization is more compact and darker staining for the distal part, lighter staining for the neural part, the part between the two parts for the middle part.
2. Under low magnification, distinguish the following structures:
(1) Distal part: the cells are dense, arranged in clusters or cords, with abundant blood sinuses and a small amount of connective tissue.
(2) Intermediate section The intermediate section is narrow and located between the distal section and the nerve section. Cells are arranged in cords, and follicles of varying sizes surrounded by a single layer of epithelium can also be seen.
(3) Nervous part Lightly stained, with many nuclei, blood sinusoids and fibrous structures. Blue-purple clusters of varying sizes, i.e. Herring bodies, can also be seen.
(V) Pituitary gland (Heidenhain I Azan stain)
Observe the distal part of the pituitary gland under high magnification microscope, and distinguish three kinds of glandular cells according to the number, size and cytoplasmic coloring: eosinophilic cells with larger cytosol, more in number, cytoplasmic staining of red; basophilic cells with large cytosol, fewer in number, cytoplasmic staining of blue; smoky cells with smaller cytosol, more in number, cell boundaries are not clear, and the staining is light.
Demonstrate the electron microscopic structure of thyroid follicles.
Observe with a scanning electron microscope picture of a thyroid follicle. Disconnected thyroid follicles can be seen, in which the gelatinous material has been removed, and the follicular epithelial cells are dome-shaped protruding into the follicular lumen and covered with microvilli. Parafollicular cells are attached to the follicular wall or located between the follicles.