Sympathetic cholinergic transmission is seen in –
**Core Concept**
Sympathetic cholinergic transmission refers to the release of **acetylcholine** as a neurotransmitter from sympathetic nerves. This is an exception to the general rule that sympathetic nerves are adrenergic, releasing **norepinephrine**.
**Why the Correct Answer is Right**
The correct answer involves understanding that sympathetic cholinergic transmission occurs in specific instances, such as the innervation of **sweat glands**. Here, the sympathetic nervous system uses **acetylcholine** as the neurotransmitter, which then acts on **muscarinic receptors**.
**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because it does not specifically relate to the unique instance of sympathetic cholinergic transmission.
**Option B:** Incorrect as it is not the primary example of sympathetic cholinergic transmission.
**Option C:** Incorrect because, although it involves the sympathetic nervous system, it is not the correct context for cholinergic transmission.
**Clinical Pearl / High-Yield Fact**
A key point to remember is that sympathetic cholinergic fibers are involved in the regulation of **sweating**, highlighting the diversity of neurotransmitter use in the autonomic nervous system.
**Correct Answer:** D. Sweat glands.