Which of the choices below is NOT a glomerular filtration rate control method?

A. the clitoris: Both the penis and the clitoris originate from the same embryonic structure, the genital tubercle. They contain similar erectile tissues and sensory nerve endings, making them developmentally equivalent. This homology is a fundamental concept in the study of reproductive organ differentiation during embryogenesis.

B. the vagina: The vagina is the female copulatory organ and birth canal, which developmentally corresponds more closely to the male prostatic utricle. While it interacts with the penis during intercourse, it does not share the same embryonic precursor as the phallus. Its structural role and origin are distinct.

C. the cervix: The cervix is the inferior portion of the uterus that projects into the vaginal canal. It serves as a gateway for sperm and a protective barrier during pregnancy. It has no structural or developmental homology with the external genitalia of the male reproductive system.

D. the appendix: The vermiform appendix is a vestigial lymphoid organ attached to the cecum of the large intestine. It belongs to the digestive and immune systems rather than the reproductive system. There is no biological or embryonic relationship between the appendix and the male penis.

E. the urethra: While both males and females possess a urethra, it is a shared urinary structure rather than a homologous reproductive organ. In males, the urethra is much longer and carries semen, but the organ as a whole does not serve as a developmental counterpart to the penis.

A. hormones: Most small hormones, particularly steroid and peptide hormones not bound to large carrier proteins, are small enough to pass through the filtration membrane. They are often found in the initial filtrate in the capsular space. Their presence does not distinguish filtrate from plasma significantly.

B. plasma protein: The basement membrane and filtration slits are negatively charged and sized to repel large proteins like albumin. Consequently, the filtrate is essentially protein-free under normal conditions. The absence of these macromolecules is the primary chemical difference between plasma and glomerular filtrate.

C. glucose: Glucose is a small, uncharged molecule that moves freely across the filtration membrane into the capsular space. The concentration of glucose in the initial filtrate is identical to its concentration in the plasma. It is later reabsorbed entirely by the proximal convoluted tubules.

D. electrolytes: Ions such as sodium, potassium, and chloride are small enough to pass through the fenestrated capillaries and filtration slits without restriction. The electrolyte composition of the glomerular filtrate initially mirrors that of the blood plasma. Their balance is adjusted later during tubular processing.