Final answer:
The spread of pathology from the external genitalia primarily involves the inguinal lymph nodes, which are palpable in the groin area. In the case of the ovaries, the para-aortic lymph nodes are the primary group, which typically are not palpable. Conditions like lymphogranuloma venereum cause lymph node swelling, illustrating the role of lymph nodes in urogenital infections.
Step-by-step explanation:
The lymphatic system plays a significant role in the spread of pathology from the external genitalia and gonads. The major lymph node groups involved in the drainage from the external genitalia include the inguinal lymph nodes, which are the first group palpable in this pathway. These nodes are found in the groin area and can swell in response to infections or malignancies.
For the gonads, specifically the ovaries, lymphatic drainage follows a different pathway. The primary lymph node groups include the para-aortic lymph nodes located in the abdomen, adjacent to the aorta, which are generally not palpable. From there, the lymph may also drain to the pelvic and inguinal lymph nodes, especially in cases of pathology with more extensive spread.
Conditions such as lymphogranuloma venereum, caused by certain serotypes of C. trachomatis, can specifically affect the lymphatic system and result in swollen lymph nodes, or buboes. This condition highlights the involvement of lymph nodes in urogenital infections.