Skynet developed the technology to grow living tissue (or Cyborg tissue) over the endoskeleton of Terminator as Living tissue Infiltration outer sheath to make it the Infiltrator, allowing the machine to infiltrate the Resistance, as well as generate the bio-electric field necessary to send Terminator units back in time.
In the original timeline, the T-800 Terminator is the first truly successful Infiltrator unit, consisting of living tissue over a metal endoskeleton. In The New John Connor Chronicles timeline, it is T-799 as the first Terminator with living tissue, while in Terminator Salvation timeline, it is T-H Hybrid Human as the first Terminator Series featuring living tissue.
Since living tissue is the same as the real one on humans, it is able to bleed, sweat, breathe,  regenerate and age, making an Infiltrator gain the advantage to blend in human society. In addition, it was remarked that Infiltrators even had halitosis just like humans who failed to take care of their teeth. When the T-800 was having bullets removed from his back, it explained that the wounds would heal over time. The Guardian's outer sheath of its right arm was destroyed by acid, but the tissue was fully regrown after years as was the damage to the living tissue on his face. The same Terminator's living tissue also visibly aged from 1973 to 1984, something Kyle Reese commented on, stating that he'd never seen a Terminator look so old. After regrowing between 1984 and 2017, the Guardian's living tissue had aged further so he had a more elderly appearance, including white hair.
However, in original timeline, early version of living tissue can necrotize if damaged as after being shot multiple times during the shootout in the police precinct, the original T-800's skin had a noticeably pale color and flies were sitting on its face. At this point, the janitor of the building, which the T-800 was using as a safehouse, commented on the smell of decay coming from T-800's room: "Hey, buddy, got a dead cat in there, or what?" Hence, the early version of living tissue apparently may "die" or at least undergo extensive necrosis.
The sheaths used on the T-888 Infiltrators appear to be noticeably superior to previous models, as there are many instances where the flesh has repaired extensive damage within a few hours, leaving only scars that would disappear not too long after that. T-888 Infiltrator units are also capable of lasting extended periods. In addition, one unit had bricked itself inside a wall for over 40 years while its skin was still "alive" and "young". These machines also seem to nourish their organic components through consumption of certain foods, including mostly carbohydrates.
In Terminator Salvation timeline, a more advanced living tissue is developed and utilized within a T-H Hybrid Human as it is capable of regenerating an organ which has been previously removed over time even the subject when off-line as long as the brain. Living tissue of T-H will not age nor decay during hibernation. 
- See also: Infiltrator
Originally, Terminators were purely robotic and were not covered with living tissue. Starting with the T-600 Terminator, Skynet tried to cover the endoskeleton with rubber skin, which looked fake and was easy to be spotted. Skynet discovered a method that allowed them to grow living tissue over the endoskeleton, making the new Terminators almost impossible to spot.
Process of living tissue growth
Synthetic blood plasma culture tank
The process of growing living tissue on Terminators is made by surrounding the endoskeleton with a special liquid of synthetic blood plasma, which is done in industrial facilities of Skynet. Dudley, formerly an ER trauma surgeon and combat medic in the Resistance, was made into a mobile field unit for the maintenance of Skynet's newly perfected T-800 Infiltrator. In their initial fielding, it still took over a year to cultivate a viable human tissue sheath for the infiltration units, and Skynet needed something small and familiar with human tissue, able to maintain the perishable and hard to replace tissue sheaths. Tissue repair (again) became his primary function.The human-based cyborg
The Terminator endoskeletons are placed inside a mold, which are presumably filled with a liquid possible similar to the one mentioned above, but directly controlled in order to produce finished and natural infiltration sheaths.
Serena Burn's method
A more refined process was utilized by the I-950 Infiltrator in the creation of fully formed T-800 Terminators in the present utilizing a combination of contemporary materials and chemical extracts of her own enhanced blood. Fully formed infiltration sheaths with the Model 101 template were part of the two-month long crafting process in the Secret Terminator Lab. After adding tissue accellerants and remembering to alter key factors in the tissue matrix, a wider variety of appearances was available in a shorter time.
Synthetic blood plasma bath
In some cases, Terminators can grow living tissue by lowering themselves into a synthetic blood plasma bath. This field-expedient method of damaged tissue replacement requires the coercion and compliance of contemporary humans (theoretical hematologists, plastic surgeons), both to produce the synthetic bath, and to shape and refine the finished flesh product, as it is initially quite gruesome. The raw flesh generation and the corrective surgical procedures combined take several days to complete.
Terminator Salvation timeline
Known Terminator Series with living tissues
- Hybrid Human
- Series 8xx
- T-900 (Rise of the Machines)
- Main article: Model
The model of a Terminator, such as the Cyberdyne Systems Model 101, refers to the template of the living tissue sheath which surrounds the endoskeleton.
In order for this time travel to occur, the subject must be a living organism (or must be surrounded by living tissue) in order to generate the bioelectric field needed for the Time Displacement Equipment to operate.
The T-1000 Terminator is wrapped in a cocoon made of living tissue for time travel, while it is unknown if a T-X Terminatrix travels with the same method via Time Displacement Equipment or not.
- ↑ Terminator 2: Judgment Day teaser trailer
- ↑ The Terminator Collectible Card Game
- ↑ 3.0 3.1 The Terminator
- ↑ 4.0 4.1 Terminator 2: Judgment Day
- ↑ 5.0 5.1 5.2 Terminator Genisys
- ↑ James Cameron talks about his involvement with Terminator: Genisys
- ↑ "Self Made Man"
- ↑ Terminator Salvation: The Final Battle issue 07
- ↑ Terminators decanted from an accelerated matrix chamber have a full array of head, facial and body hair, and the physical appearance of a weather-beaten mid-to-late 30 year-olds.
- ↑ Terminator Salvation: The Final Battle
- ↑ Terminator Salvation
- ↑ Text commentary from Terminator 2: Judgment Day DVD Extreme Edition
- ↑ Terminator 2: Judgment Day novelization
| Infiltration Outer Sheath|