Final answer:
The SRY gene on the Y chromosome is critical for male sexual differentiation in embryos, as it starts the development of testes and male characteristics. Absence or mutations in this gene can lead to conditions where male traits do not develop despite having an XY genotype.
Step-by-step explanation:
The gene that plays an important role in sexual differentiation and development in male embryos is the SRY gene. This gene is located on the Y chromosome and is responsible for initiating a cascade of genetic events that leads to the development of male sex characteristics. Specifically, the SRY gene produces a protein that acts as a transcription factor, which in turn activates other genes that promote the development of testes from undifferentiated gonadal tissue. These testes then secrete hormones, such as testosterone, that are essential for the development of male reproductive organs. Without the presence of the SRY gene, the default development path for the embryo is female.
It is worth noting that a deletion or mutation in the SRY gene can lead to conditions like Swyer syndrome, where the individual has an XY genotype but does not develop male characteristics due to the lack of functional SRY protein. This gene, therefore, is crucial for male sex determination and any alteration to its function can have significant impacts on sexual development.