The corpus spongiosum secretes a thick, clear, alkaline mucus just prior to ejaculation. fills with blood during arousal and causes an erection. nourishes and transports the mature sperm. aids in the production of sperm and hormones.

fills with blood during arousal and causes an erection.

Explanation:

The corpus spongiosum is a mass of tissue present in the under part of the penis (male sexual structure) that is actively responsible for erection of the penis. The corpus spongiosum, in conjunction with the corpus carvernosa works to maintain erection of the penis in males.

During sexual arousal, the corpus spongiosum, which surrounds the urethra (passage for urine and semen) helps keep the urethra open for semen to be released while the carvernosa becomes filled with blood. This constant flow of blood into the carvernosa makes the penis enlarge and assume an erect position.

c. genetic engineering

explanation:

during the process of dna replication, brdu can replace thymidine and incorporate into the newly synthesized dna, cell proliferation thus can be reflected in the extent of brdu incorporation.