What chemical secreted by the testes causes a developing organism to become a male?

Which type of neuron is the most numerous in the human nervous system?

a. Motor neurons b. Interneurons c. Sensory neurons d. Dendritic neurons

Which testing procedure uses high-frequency sound waves and is used as an adjunct to other procedures, such as amniocentesis?

a) Sonogram b) Sonoembryology c) Ultrasound sonography d) Embryoscopy