Tonsils consist of:

Correct Answer: D

Rationale: The correct answer is D because tonsils are composed of lymphatic connective tissue with epithelially lined crypts. Tonsils play a crucial role in the immune system, containing lymphocytes to help fight infections. The other choices are incorrect. A, ordinary connective tissue with vascular sinusoids, does not accurately describe tonsils. B, adipose tissue, is not the main component of tonsils. C, serous glandular tissue, is not the primary constituent of tonsils. Hence, choice D is the correct answer based on the specific structure and function of tonsils.

Correct Answer: A

Rationale: Rationale: A: Taenia coli are discrete bands of longitudinal muscle along the large intestine, aiding in the formation of haustra. This is correct as they are unique anatomical structures. B: Crypts or mucosal glands are not Taenia coli. C: Submucosal glands are not Taenia coli. D: Compact regions of lymphoid tissue are not Taenia coli. In summary, the correct answer is A because Taenia coli specifically refer to longitudinal muscle bands in the large intestine, distinguishing them from the other structures mentioned in the choices.

Correct Answer: D

Rationale: The correct answer is D: anal canal. The anal canal is not characterized by simple columnar epithelium on the mucosal surface. Instead, it is lined by stratified squamous epithelium, which is more suited to withstand the mechanical stress associated with the passage of feces. The stomach (A), small intestine (B), and appendix (C) all have simple columnar epithelium to facilitate absorption and secretion. Therefore, the anal canal is the only region among the choices that does not have simple columnar epithelium, making it the correct answer.

Correct Answer: B

Rationale: The stomach has thick mucosa with diverse glandular cells (parietal, chief, etc.).

Correct Answer: D

Rationale: All listed features distinguish the pancreas (endocrine islets, centroacinar cells) from the parotid (adipocytes).