Immersion specimens have various applications in teaching:1、 Visual display of biological morphology and structurePlant teaching: In botany teaching, soaking specimens can effectively showcase the organs of plants. For example, when displaying immersed specimens of flowers, students can clearly see the number, shape, and color of petals, as well as the structure of stamens (including stamens and pistils). Soak specimens like lilies allow students to observe that they have 6 petals, 6 stamens, and 1 pistil, and can be stored for a long time, making it convenient for students to observe at any time without being limited by the flowering period. For the fruits and seeds of plants, soaking specimens can also display their external morphology and internal structure. For example, by soaking pea pod specimens, students can see the arrangement of pea seeds in the pods.Animal teaching: In animal science teaching, specimen immersion allows students to intuitively understand the appearance of animals. Taking fish as an example, immersion specimens can display the fish's body size, types of fins (dorsal fin, pectoral fin, pelvic fin, anal fin, and caudal fin), and their positions. Students can observe the morphological differences of fins in different fish species, such as the elongated dorsal fin of crucian carp and the wider dorsal fin of fighting fish. For some small invertebrates, such as earthworm specimens, their link structures can be clearly presented, helping students understand the characteristics of link animals.2、 Assist in explaining knowledge of biological classificationClassification display: Immersion specimens can serve as physical display materials for biological classification. For example, when explaining the classification of vertebrates, display immersion specimens from different classes (such as fish, amphibians, reptiles, birds, and mammals). By comparing the immersion specimens of fish (with gill respiration and fins) and amphibians (with gill respiration for juveniles, lung respiration and skin assisted respiration for adults, and limbs), students can more intuitively understand the main differences between different classes and master the basic knowledge of biological classification.Species diversity presentation: Teachers can use immersion specimens to display species diversity within a specific group. For example, when explaining the insect class, display immersion specimens of various insects such as locusts, butterflies, bees, etc. Students can observe differences in wing morphology (locusts have leathery forewings and membranous hindwings, butterflies have colorful and membranous wings) and mouthparts types (locusts have chewing mouthparts, butterflies have siphon mouthparts), and appreciate the richness and diversity of insect species.3、Help understand the ecological relationships of organismsFood chain display: A simple food chain model can be constructed for teaching through a series of immersion specimens. For example, by displaying immersion specimens of plankton, small fish, and large fish, teachers can explain the relationship between plankton as primary producers being preyed upon by small fish and small fish being preyed upon by large fish, allowing students to better understand the energy flow in the food chain and ecosystem.Biological habitat environment correlation: Immersion specimens can also be combined with an introduction to the biological habitat environment. For example, when displaying immersion specimens related to mangrove ecosystems, immersion specimens such as mangrove plants (such as okra), fiddler crabs, and mudskippers living in mangroves are also displayed, accompanied by pictures or videos of the muddy intertidal environment of mangroves, allowing students to understand the interrelationships between these organisms and their environment.

Tissue microtome is a kind of equipment for pathological section analysis of human tissues, animal and plant tissues. Tissue microtome are generally divided into rotary microtome and frozen microtome. Rotary microtome: It is used to slice by rotating the hand wheel. The wax block table is embedded in the metal clamp seat that can move up and down in the groove, and cuts the flat slice by pushing forward with the micro screw. Some rotary microtome are equipped with three knobs and a fastening knob on the head, which can deflect and tighten it in all directions, so as to adjust the section of the wax block. The cutting angle of the slicer can be adjusted. Because this microtome uses a heavy and large slicer knife, it generally does not vibrate when cutting hard tissue. The slice thickness can be adjusted from 1-30 microns to any thickness by the knob, and each gradient is 1 or 2 microns. The advantage of the rotary microtome is that the body is heavy, so it is more stable than the rocking microtome. It is very suitable for cutting paraffin sections. It can be ideal for cutting continuous sections and also for cutting large tissue blocks. 

In the process of making biological sections, in order to avoid tissue autolysis or damage by bacteria, and preserve its physical structure, once the tissue block is taken out of the living body, it should be immediately and properly disposed of. The treatment is fixation, usually by soaking the tissue in chemicals to preserve its morphology and chemical characteristics as much as possible.  The chemicals used to immobilize tissues are called fixatives. So how are they classified?  According to the composition of the fixing solution, it can be divided into single fixation, double fixation and multiple fixation. First, single fixation is only fixed with glutaraldehyde or starvation tetroxide, generally used for single-cell samples or permeable samples. Second, double fixation refers to the first use of glutaraldehyde or paraformaldehyde for pre-fixation, and then use osmium tetroxide for post-fixation, this method has good effect and is widely used. Third, multiple fixation refers to the combined use of three kinds of fixatives to achieve the purpose of complementing each other. The main purpose of this process is to truly preserve every detail of the ultrastructure of the cell at the molecular level, so that the slice structure is clearer and the morphology is more complete.